Evaluating antidiabetic properties of selected African medicinal plants in a cell-based model
- Sirkhotte, Saeedah, Reddy, Shanika
- Authors: Sirkhotte, Saeedah , Reddy, Shanika
- Date: 2023-12
- Subjects: Medicinal plants -- South Africa , Insulin resistance , Gluconeogenesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62600 , vital:72827
- Description: The World Health Organisation lists diabetes as one of the major non-communicable diseases affecting the world, and its prevalence is expected to increase rapidly. Type II diabetes mellitus (T2DM) is characterised by insulin resistance and impaired blood glucose control. T2DM is of growing concern within South Africa, with 10.8% of the population currently diagnosed. The popularity, as well as availability, of traditional plant-based medicine in South Africa, might provide a solution. Antidiabetic potential is commonly tested by in vitro assays, however the methods to test this potential via gluconeogenesis are limited. This project aimed to optimise an in vitro hepatic gluconeogenesis model. In addition, this project aimed to determine the antidiabetic properties of Prunus africana, Hypoxis stellipilis, and Eriocephalus africanus by in vitro analysis. These properties were examined in human hepatoma cells (C3A cell line) and rat pancreatic cells (INS1 cell line) and methods included: cytotoxicity analysis, Amplex® red glucose oxidase assay, antibody staining, gene expression analysis by RT-qPCR, oxidative stress analysis, and calcium signaling for insulin release. Insulin resistance was successfully induced by exposing C3A hepatocarcinoma cells to a combination treatment of 50 μM dexamethasone, 1.25 mM fructose and 0.125 mM palmitic acid for a period of three days. Thereafter, gluconeogenesis was assessed using the Amplex® red glucose oxidase assay. The established model was effective in inducing insulin resistance and upregulating gluconeogenesis. Of the tested plant extracts, H. stellipilis showed the most potential as an antidiabetic treatment. It had low toxicity, significantly decreased hepatic glucose production and reduced the amount of phosphoenolpyruvate carboxykinase (PCK) and well as PCK gene expression, and reduced lipid content and reactive oxygen species (ROS) in the C3A cell line. H. stellipilis increased calcium signalling in INS1 rat insulinoma cells, however there was a decrease in expression of genes for insulin and glucose transporter 2 after 6 hr exposure. H. stellipilis appears be beneficial as an antidiabetic treatment. Although antidiabetic studies have been done on other Hypoxis species, this is the first study on the effects of H. stellipilis on gluconeogenesis and diabetes. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Sirkhotte, Saeedah , Reddy, Shanika
- Date: 2023-12
- Subjects: Medicinal plants -- South Africa , Insulin resistance , Gluconeogenesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62600 , vital:72827
- Description: The World Health Organisation lists diabetes as one of the major non-communicable diseases affecting the world, and its prevalence is expected to increase rapidly. Type II diabetes mellitus (T2DM) is characterised by insulin resistance and impaired blood glucose control. T2DM is of growing concern within South Africa, with 10.8% of the population currently diagnosed. The popularity, as well as availability, of traditional plant-based medicine in South Africa, might provide a solution. Antidiabetic potential is commonly tested by in vitro assays, however the methods to test this potential via gluconeogenesis are limited. This project aimed to optimise an in vitro hepatic gluconeogenesis model. In addition, this project aimed to determine the antidiabetic properties of Prunus africana, Hypoxis stellipilis, and Eriocephalus africanus by in vitro analysis. These properties were examined in human hepatoma cells (C3A cell line) and rat pancreatic cells (INS1 cell line) and methods included: cytotoxicity analysis, Amplex® red glucose oxidase assay, antibody staining, gene expression analysis by RT-qPCR, oxidative stress analysis, and calcium signaling for insulin release. Insulin resistance was successfully induced by exposing C3A hepatocarcinoma cells to a combination treatment of 50 μM dexamethasone, 1.25 mM fructose and 0.125 mM palmitic acid for a period of three days. Thereafter, gluconeogenesis was assessed using the Amplex® red glucose oxidase assay. The established model was effective in inducing insulin resistance and upregulating gluconeogenesis. Of the tested plant extracts, H. stellipilis showed the most potential as an antidiabetic treatment. It had low toxicity, significantly decreased hepatic glucose production and reduced the amount of phosphoenolpyruvate carboxykinase (PCK) and well as PCK gene expression, and reduced lipid content and reactive oxygen species (ROS) in the C3A cell line. H. stellipilis increased calcium signalling in INS1 rat insulinoma cells, however there was a decrease in expression of genes for insulin and glucose transporter 2 after 6 hr exposure. H. stellipilis appears be beneficial as an antidiabetic treatment. Although antidiabetic studies have been done on other Hypoxis species, this is the first study on the effects of H. stellipilis on gluconeogenesis and diabetes. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Antiproliferative activity of novel rhenium complexes and medicinal plant extracts
- Oosthuizen, Kenneth Thomas, Venables, Luanne
- Authors: Oosthuizen, Kenneth Thomas , Venables, Luanne
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Medicinal plants -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52028 , vital:43441
- Description: Cancer is a complex, multifactorial disease that affects millions of individuals every year. The adverse side effects and escalating costs of current therapies coupled with the increased incidence of resistance to these therapies make it imperative that we explore novel treatments for the disease. This study investigated two avenues for novel drug design namely, novel synthetic compounds and medicinal plant extracts. The benzimidazole ring system has shown potential as a scaffold for designing novel anticancer agents. Conjugation of the metal rhenium to novel variants of this ring system open up the possibility of designing novel drugs that serve both a diagnostic and a therapeutic function. This study investigated the in vitro anticancer potential of ten such complexes against selected breast and cervical cancer cell lines. The selectivity of the complexes for cancer cells over normal cells was also investigated while the mechanism of action of effective complexes was determined by exploring cell cycle arrest, biochemical markers of apoptosis and mitochondrial membrane disruption. All ten complexes were screened against MCF7 breast and HeLa cervical cancer cell lines with four showing antiproliferative activity against both cancer cell lines and one showing cell line specific toxicity against MCF7 breast cancer cells. When looking at the SAR of the compounds it was noted that activity was higher in compounds which contain two potentially bidentate benzothiazole ligands, while compounds with potentially tridentate ligands show good activity, but only if the benzothiazole moiety is not involved in coordination. The complexes showed greater antiproliferative activity against the MCF7 breast cancer cells with IC50 values ranging from 3.2 to 7.0 µM versus a range of 7.6 to 24.4 µM being obtained on the HeLa cervical cancer cells. Antiproliferative complexes were tested against confluent and log phase Vero cells at their respective IC50 values to determine their effect on “normal” cells. Confluent Vero cells showed less cell death than those in log phase indicating that the complexes show preference for proliferating cells. The mechanism of action of the complexes was studied on both cancer cell lines via cell cycle analysis and apoptosis assays investigating phosphatidylserine translocation, caspase -3 and -8 activation and mitochondrial membrane potential with most complexes inducing cell cycle arrest followed by cell death via both the extrinsic and intrinsic pathways of apoptosis. Since 1940, 49% of all the available anticancer drugs approved for cancer treatment were natural products or directly derived from natural products. Plants are an excellent source of secondary metabolites, many of which are unique chemical compounds that cannot be synthesized in a laboratory. Ethnobotanical surveys conducted in conjunction with Traditional Health Practitioners of the Mkuranga and Same districts in Tanzania identified 25 plants that are used for the treatment of cancer. Four of these plants (A. mossambicensis, C. adenocaule, C. pseudopulchelusis and R. natalensis) with ethnobotanically reported anticancer usage showed cytotoxic activity against brine shrimp and were selected for further in vitro anticancer studies. All four plants were found to have antiproliferative activity against HeLa cervical cancer cells with IC50 values ranging from 3.4 to 50.8 µg/mL. This study was also tasked with investigating the mechanism of action of C. pseudopulchelus on HeLa cervical cancer cells by exploring cell cycle arrest, biochemical markers of apoptosis and mitochondrial membrane x disruption. C. pseudopulchelus caused early M phase arrest followed by slippage and subsequent cell death via the extrinsic pathway of apoptosis. In conclusion, this study showed that both novel complexes as well as medicinal plant extracts represent an interesting avenue for the development of novel anticancer drugs that are cheaper and produce less side effects than current therapies. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Oosthuizen, Kenneth Thomas , Venables, Luanne
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Medicinal plants -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52028 , vital:43441
- Description: Cancer is a complex, multifactorial disease that affects millions of individuals every year. The adverse side effects and escalating costs of current therapies coupled with the increased incidence of resistance to these therapies make it imperative that we explore novel treatments for the disease. This study investigated two avenues for novel drug design namely, novel synthetic compounds and medicinal plant extracts. The benzimidazole ring system has shown potential as a scaffold for designing novel anticancer agents. Conjugation of the metal rhenium to novel variants of this ring system open up the possibility of designing novel drugs that serve both a diagnostic and a therapeutic function. This study investigated the in vitro anticancer potential of ten such complexes against selected breast and cervical cancer cell lines. The selectivity of the complexes for cancer cells over normal cells was also investigated while the mechanism of action of effective complexes was determined by exploring cell cycle arrest, biochemical markers of apoptosis and mitochondrial membrane disruption. All ten complexes were screened against MCF7 breast and HeLa cervical cancer cell lines with four showing antiproliferative activity against both cancer cell lines and one showing cell line specific toxicity against MCF7 breast cancer cells. When looking at the SAR of the compounds it was noted that activity was higher in compounds which contain two potentially bidentate benzothiazole ligands, while compounds with potentially tridentate ligands show good activity, but only if the benzothiazole moiety is not involved in coordination. The complexes showed greater antiproliferative activity against the MCF7 breast cancer cells with IC50 values ranging from 3.2 to 7.0 µM versus a range of 7.6 to 24.4 µM being obtained on the HeLa cervical cancer cells. Antiproliferative complexes were tested against confluent and log phase Vero cells at their respective IC50 values to determine their effect on “normal” cells. Confluent Vero cells showed less cell death than those in log phase indicating that the complexes show preference for proliferating cells. The mechanism of action of the complexes was studied on both cancer cell lines via cell cycle analysis and apoptosis assays investigating phosphatidylserine translocation, caspase -3 and -8 activation and mitochondrial membrane potential with most complexes inducing cell cycle arrest followed by cell death via both the extrinsic and intrinsic pathways of apoptosis. Since 1940, 49% of all the available anticancer drugs approved for cancer treatment were natural products or directly derived from natural products. Plants are an excellent source of secondary metabolites, many of which are unique chemical compounds that cannot be synthesized in a laboratory. Ethnobotanical surveys conducted in conjunction with Traditional Health Practitioners of the Mkuranga and Same districts in Tanzania identified 25 plants that are used for the treatment of cancer. Four of these plants (A. mossambicensis, C. adenocaule, C. pseudopulchelusis and R. natalensis) with ethnobotanically reported anticancer usage showed cytotoxic activity against brine shrimp and were selected for further in vitro anticancer studies. All four plants were found to have antiproliferative activity against HeLa cervical cancer cells with IC50 values ranging from 3.4 to 50.8 µg/mL. This study was also tasked with investigating the mechanism of action of C. pseudopulchelus on HeLa cervical cancer cells by exploring cell cycle arrest, biochemical markers of apoptosis and mitochondrial membrane x disruption. C. pseudopulchelus caused early M phase arrest followed by slippage and subsequent cell death via the extrinsic pathway of apoptosis. In conclusion, this study showed that both novel complexes as well as medicinal plant extracts represent an interesting avenue for the development of novel anticancer drugs that are cheaper and produce less side effects than current therapies. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
An assessment of the in vitro neuroprotective potential of selected Algerian and South African medicinal plant extracts
- Authors: Fewell, William
- Date: 2015
- Subjects: Medicinal plants -- South Africa , Nervous system -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/8608 , vital:26411
- Description: It is estimated by the World Health Organization (WHO) that by 2040 neurodegenerative disorders will collectively surpass cancer as the primary cause of death in industrialised countries (WHO,2006). Natural flora represents one of the most important therapeutic sources in modern drug discovery, however only a limited number of plant species have been screened for their neuroprotective value. The neuroprotective potential of eleven Algerian and two South African medicinal plant extracts were assessed in this study, aiming to identify promising candidates for future research. Neurodegenerative disorders such as Parkinson’s disease are characterised by distinct biochemical features, including protein misfolding/-aggregation, excessive oxidative stress and apoptotic cell death. As such, medicinal plant extracts were screened for biological properties directly relevant to neurodegeneration. The capacity to induce autophagy was also investigated as mounting evidence suggests that activation of this pathway may reduce abnormal protein aggregation and promote neuronal survival.
- Full Text: false
- Date Issued: 2015
- Authors: Fewell, William
- Date: 2015
- Subjects: Medicinal plants -- South Africa , Nervous system -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/8608 , vital:26411
- Description: It is estimated by the World Health Organization (WHO) that by 2040 neurodegenerative disorders will collectively surpass cancer as the primary cause of death in industrialised countries (WHO,2006). Natural flora represents one of the most important therapeutic sources in modern drug discovery, however only a limited number of plant species have been screened for their neuroprotective value. The neuroprotective potential of eleven Algerian and two South African medicinal plant extracts were assessed in this study, aiming to identify promising candidates for future research. Neurodegenerative disorders such as Parkinson’s disease are characterised by distinct biochemical features, including protein misfolding/-aggregation, excessive oxidative stress and apoptotic cell death. As such, medicinal plant extracts were screened for biological properties directly relevant to neurodegeneration. The capacity to induce autophagy was also investigated as mounting evidence suggests that activation of this pathway may reduce abnormal protein aggregation and promote neuronal survival.
- Full Text: false
- Date Issued: 2015
In vitro induction of cell death pathways by artemisia afra extract and isolation of an active compound, isoalantolactone
- Authors: Venables, Luanne
- Date: 2014
- Subjects: Medicinal plants -- South Africa , Cell death
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10363 , http://hdl.handle.net/10948/d1021087
- Description: Artemisia afra is one of the oldest, most well known and widely used traditional medicinal plants in South Africa. It is used to treat many different medical conditions, particularly respiratory and inflammatory ailments. There is no reported evidence of its use for the treatment of cancer but due to its reported cytotoxicity, an investigation of the mode of cell death induced by an ethanol A. afra extract using two cancer cell lines was done. IC50 values of 18.21 and 31.88 μg/mL of ethanol extracts were determined against U937 and HeLa cancer cells, respectively. An IC50 value of the aqueous extract was greater than 250 μg/mL. The ethanol extract was not cytotoxic against confluent control cell lines, Chang Liver and Vero cells. The effect of the cytotoxic ethanol A. afra extract on U937 and HeLa cells and their progression through the cell cycle, apoptosis and mitochondrial membrane potential was investigated. After 12 hours of treatment with A. afra a delay in G2/M phase of the cell cycle was evident. Apoptosis was confirmed using the TUNEL assay for DNA fragmentation, as well as fluorescent staining with annexin V-FITC. Apoptosis was evident with the positive control and A. afra treatment at 24 and 48 hours. JC-1 staining showed a decrease in mitochondrial membrane potential at 24 hours. It was deduced that A. afra ethanol extract induces caspase-dependent apoptosis in a mitochondrial dependent manner. Plants harbour many compounds that are not only useful to the plants but also to mankind. Many metabolites have been isolated from A. afra and their biological activity characterised. Due to observed apoptosis induction, isolation of cytotoxic compounds was done and a new sesquiterpene lactone from A. afra was isolated. Structural elucidation of the compound was done by IR, 1D and 2D NMR, CD and mass spectrometry and it was identified as isoalantolactone. HeLa cancer cells were treated with isoalantolactone and cytotoxicity was exhibited in a dose-dependent manner. A low IC50 value of 8.15 ± 1.16 μM was achieved. This study showed that isoalantolactone is partly responsible for the observed A. afra cytotoxicity. Due to the evidence of G2/M arrest, the anti-mitotic potential and the possible onset of mitotic catastrophe by A. afra and isoalantolactone was investigated. It was evident from various flow cytometric analysis of cyclin B1 and phospho-H3 and confocal microscopy that A. afra does possess anti-mitotic activity by causing hyperpolymerisation of tubulin and cells progress into the mitotic phase where M arrest is experienced. The anti-inflammatory activity of sesquiterpene lactones is well documented; however, the anti-inflammatory activity of A. afra is not. Here, it is reported that the production of NO and COX-2 protein levels in RAW 264.7 cells decrease in the presence of A. afra and isoalantolactone after stimulation with LPS. The activated NF-κB subunit, p65 was also investigated. The results suggest that A. afra and isoalantolactone inhibit p65 activation as a decrease in the activated subunit was evident. Thus, the results indicate that exposure to A. afra and isoalantolactone induces an anti-inflammatory response. In conclusion, this study shows, for the first time, the mechanism of induced apoptosis, the anti-mitotic and anti-inflammatory activity of A. afra and its isolated compound, isoalantolactone. It also proves that although extensive research may have been done on a particular plant, as with A. afra, more can be discovered leading to the identification of new compounds and integration of signalling pathways that can be exploited for the treatment of various diseases and ailments.
- Full Text:
- Date Issued: 2014
- Authors: Venables, Luanne
- Date: 2014
- Subjects: Medicinal plants -- South Africa , Cell death
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10363 , http://hdl.handle.net/10948/d1021087
- Description: Artemisia afra is one of the oldest, most well known and widely used traditional medicinal plants in South Africa. It is used to treat many different medical conditions, particularly respiratory and inflammatory ailments. There is no reported evidence of its use for the treatment of cancer but due to its reported cytotoxicity, an investigation of the mode of cell death induced by an ethanol A. afra extract using two cancer cell lines was done. IC50 values of 18.21 and 31.88 μg/mL of ethanol extracts were determined against U937 and HeLa cancer cells, respectively. An IC50 value of the aqueous extract was greater than 250 μg/mL. The ethanol extract was not cytotoxic against confluent control cell lines, Chang Liver and Vero cells. The effect of the cytotoxic ethanol A. afra extract on U937 and HeLa cells and their progression through the cell cycle, apoptosis and mitochondrial membrane potential was investigated. After 12 hours of treatment with A. afra a delay in G2/M phase of the cell cycle was evident. Apoptosis was confirmed using the TUNEL assay for DNA fragmentation, as well as fluorescent staining with annexin V-FITC. Apoptosis was evident with the positive control and A. afra treatment at 24 and 48 hours. JC-1 staining showed a decrease in mitochondrial membrane potential at 24 hours. It was deduced that A. afra ethanol extract induces caspase-dependent apoptosis in a mitochondrial dependent manner. Plants harbour many compounds that are not only useful to the plants but also to mankind. Many metabolites have been isolated from A. afra and their biological activity characterised. Due to observed apoptosis induction, isolation of cytotoxic compounds was done and a new sesquiterpene lactone from A. afra was isolated. Structural elucidation of the compound was done by IR, 1D and 2D NMR, CD and mass spectrometry and it was identified as isoalantolactone. HeLa cancer cells were treated with isoalantolactone and cytotoxicity was exhibited in a dose-dependent manner. A low IC50 value of 8.15 ± 1.16 μM was achieved. This study showed that isoalantolactone is partly responsible for the observed A. afra cytotoxicity. Due to the evidence of G2/M arrest, the anti-mitotic potential and the possible onset of mitotic catastrophe by A. afra and isoalantolactone was investigated. It was evident from various flow cytometric analysis of cyclin B1 and phospho-H3 and confocal microscopy that A. afra does possess anti-mitotic activity by causing hyperpolymerisation of tubulin and cells progress into the mitotic phase where M arrest is experienced. The anti-inflammatory activity of sesquiterpene lactones is well documented; however, the anti-inflammatory activity of A. afra is not. Here, it is reported that the production of NO and COX-2 protein levels in RAW 264.7 cells decrease in the presence of A. afra and isoalantolactone after stimulation with LPS. The activated NF-κB subunit, p65 was also investigated. The results suggest that A. afra and isoalantolactone inhibit p65 activation as a decrease in the activated subunit was evident. Thus, the results indicate that exposure to A. afra and isoalantolactone induces an anti-inflammatory response. In conclusion, this study shows, for the first time, the mechanism of induced apoptosis, the anti-mitotic and anti-inflammatory activity of A. afra and its isolated compound, isoalantolactone. It also proves that although extensive research may have been done on a particular plant, as with A. afra, more can be discovered leading to the identification of new compounds and integration of signalling pathways that can be exploited for the treatment of various diseases and ailments.
- Full Text:
- Date Issued: 2014
Evaluation of plant extracts : artemisia afra and annona muricata for inhibitory activities against mycobacterium tuberculosis and human immunodeficiency virus
- Authors: Pruissen, Megan Colleen
- Date: 2013
- Subjects: Plant extracts , Medicinal plants -- South Africa , Tuberculosis -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10341 , http://hdl.handle.net/10948/d1019845
- Description: Mycobacterium tuberculosis and Human Immuno-Deficiency Virus (HIV) have a high prevalence in South Africa. The development and spread of drug resistant tuberculosis is a serious problem which is exacerbated by tuberculosis (TB) co-infection in HIV patients. Traditional medicinal plants like Annona muricata and Artemisia afra are used for respiratory ailments and antiviral therapies respectively. The aim of this study was to evaluate Annona muricata (ethanolic extract) and Artemisia afra (ethanolic and aqueous extracts) for inhibitory activities against M. tuberculosis and HIV. In vitro bioassays for anti-TB activity included: microplate alamar blue assay (MABA), flow cytometry and ρ-iodonitrotetrazolium chloride assays while anti-HIV activity was determined using an HIV-1 reverse transcriptase colorimetric ELISA kit and an HIV-1 integrase colorimetric immunoassay. Cytotoxicity of plant extracts were assessed by the MTT assay on Chang Liver and HepG2 cells. Potential synergistic effects were determined using the basis of Combination Index. Potential interactions of plant extracts with drug metabolic pathways were evaluated with the Glutathione-S-Transferase assay kit as well as the CYP3A4 assay kit. A. muricata ethanolic extract exhibited anti-TB activity with MIC 125 μg/mL. MABA was shown to be the most sensitive and effective method for the detection of anti-TB activity. Artemisia afra aqueous extract showed HIV-1 reverse transcriptase inhibition exhibiting ˃85 percent inhibition at 1 mg/mL while the ethanolic extracts of A. afra and A. muricata showed inhibition of HIV-1 integrase activity at ˃86.8 percent and ˃88.54 percent respectively at concentrations >0.5 - 4 mg/mL. The aqueous extract of A. afra displayed inhibition of HIV-1 integrase ˃52.16 percent at 0.5 mg/mL increasing to 72.89 percent at 4 mg/ml of the extract. A. muricata was cytotoxic at an IC50 of 30 μg/mL and 77 μg/mL on Chang Liver and HepG2 cells respectively, whilst A. afra aqueous and ethanol extracts were not cytotoxic to both cell lines. The ethanolic extract of A. muricata showed both antagonistic and synergistic properties at various IC values, when used in conjunction with rifampicin. A. afra ethanolic extract interrupted GST activity while aqueous extracts of A. afra and A. muricata had a slight effect. All extracts interrupted CYP3A4 activity, however the ethanolic extracts of A. muricata and A. afra showed greater inhibition than the aqueous extract of A. afra. These extracts should be investigated further as they could be an important source of compounds for treatment of M. tuberculosis and HIV respectively.
- Full Text:
- Date Issued: 2013
- Authors: Pruissen, Megan Colleen
- Date: 2013
- Subjects: Plant extracts , Medicinal plants -- South Africa , Tuberculosis -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10341 , http://hdl.handle.net/10948/d1019845
- Description: Mycobacterium tuberculosis and Human Immuno-Deficiency Virus (HIV) have a high prevalence in South Africa. The development and spread of drug resistant tuberculosis is a serious problem which is exacerbated by tuberculosis (TB) co-infection in HIV patients. Traditional medicinal plants like Annona muricata and Artemisia afra are used for respiratory ailments and antiviral therapies respectively. The aim of this study was to evaluate Annona muricata (ethanolic extract) and Artemisia afra (ethanolic and aqueous extracts) for inhibitory activities against M. tuberculosis and HIV. In vitro bioassays for anti-TB activity included: microplate alamar blue assay (MABA), flow cytometry and ρ-iodonitrotetrazolium chloride assays while anti-HIV activity was determined using an HIV-1 reverse transcriptase colorimetric ELISA kit and an HIV-1 integrase colorimetric immunoassay. Cytotoxicity of plant extracts were assessed by the MTT assay on Chang Liver and HepG2 cells. Potential synergistic effects were determined using the basis of Combination Index. Potential interactions of plant extracts with drug metabolic pathways were evaluated with the Glutathione-S-Transferase assay kit as well as the CYP3A4 assay kit. A. muricata ethanolic extract exhibited anti-TB activity with MIC 125 μg/mL. MABA was shown to be the most sensitive and effective method for the detection of anti-TB activity. Artemisia afra aqueous extract showed HIV-1 reverse transcriptase inhibition exhibiting ˃85 percent inhibition at 1 mg/mL while the ethanolic extracts of A. afra and A. muricata showed inhibition of HIV-1 integrase activity at ˃86.8 percent and ˃88.54 percent respectively at concentrations >0.5 - 4 mg/mL. The aqueous extract of A. afra displayed inhibition of HIV-1 integrase ˃52.16 percent at 0.5 mg/mL increasing to 72.89 percent at 4 mg/ml of the extract. A. muricata was cytotoxic at an IC50 of 30 μg/mL and 77 μg/mL on Chang Liver and HepG2 cells respectively, whilst A. afra aqueous and ethanol extracts were not cytotoxic to both cell lines. The ethanolic extract of A. muricata showed both antagonistic and synergistic properties at various IC values, when used in conjunction with rifampicin. A. afra ethanolic extract interrupted GST activity while aqueous extracts of A. afra and A. muricata had a slight effect. All extracts interrupted CYP3A4 activity, however the ethanolic extracts of A. muricata and A. afra showed greater inhibition than the aqueous extract of A. afra. These extracts should be investigated further as they could be an important source of compounds for treatment of M. tuberculosis and HIV respectively.
- Full Text:
- Date Issued: 2013
A biochemical study of the antidiabetic and anticogulant effects of Tulbaghia Violacea
- Authors: Davison, Candice
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Diabetes -- Alternative treatment -- South Africa , Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Plants -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10311 , http://hdl.handle.net/10948/1523 , Medicinal plants -- South Africa , Diabetes -- Alternative treatment -- South Africa , Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Plants -- Analysis
- Description: Secondary metabolites derived from plants, especially those used by traditional healers, are at the forefront of new drug development in combating diseases such as cancer and diabetes. Garlic is employed in indigenous medicine all over the world for the treatment of a variety of diseases. Dietary garlic has been recognized for its beneficial health effects. In particular, garlic consumption has been correlated with (i) reduction of risk factors for cardiovascular diseases and cancer, (ii) stimulation of immune function, (iii) enhanced detoxification of foreign compounds, (iv) hepatoprotection, (v) antimicrobial effects, (vi) antioxidant effects, and most importantly (vii) its hypoglycemic and anticoagulant properties. Due to these beneficial properties, garlic and its closely related genera which includes Tulbaghia violacea, may be useful as coadjuvant therapy in the treatment of type 2 diabetes and some of its physiological complications. The aim of this study was to determine if T. violacea has antidiabetic and anticoagulant properties. This was performed in vitro using both aqueous and organic extracts of the roots, leaves and bulbs. An organic extract was able to improve glucose-stimulated insulin secretion (GSIS) in INS-1 pancreatic β-cells and glucose uptake in Chang liver cells. The BO extract had no effect on the glucose uptake in 3T3-L1 an adipose cell line and reduced glucose utilisation in C2C12, a skeletal muscle cell line. Some of the properties displayed by T. violacea in this study are consistent with those found in similar studies with garlic extracts. It was observed that the BO extract increased the membrane potential and Glut-2 expression in INS-1 cells cultured at hyperglycemic levels, however, at normoglycemic levels a reduction was observed. The oxygen consumption increased at both glycemic levels due to treatment with the BO extract. Platelets were exposed to the extracts to determine their effects upon platelet aggregation, adhesion and protein secretion. Since the BO extract displayed the highest potential at inhibiting platelet aggregation and adhesion. A rat model was used in ex vivo studies to determine if the extract exhibited the same effect in a physiological model. It was noted that the BO extract exhibited a higher degree of inhibition on platelet aggregation and adhesion than the positive control, aspirin. The BO extract reduced clotting times in the prothrombin time (PT) test, but prolonged the clotting time in the actived partial thromboplastin time (APTT) assay in the ex vivo model; however, it had no affect on these clotting assays in the in vitro model using human blood. The BO extract increased the D-dimer and Fibrinogen-C levels in the in vitro model, but had no effect on the D-dimer concentrations and lowered the Fibrinogen-C levels in the ex vivo model. The active compounds in the extract remain to be elucidated.
- Full Text:
- Date Issued: 2010
- Authors: Davison, Candice
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Diabetes -- Alternative treatment -- South Africa , Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Plants -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10311 , http://hdl.handle.net/10948/1523 , Medicinal plants -- South Africa , Diabetes -- Alternative treatment -- South Africa , Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Plants -- Analysis
- Description: Secondary metabolites derived from plants, especially those used by traditional healers, are at the forefront of new drug development in combating diseases such as cancer and diabetes. Garlic is employed in indigenous medicine all over the world for the treatment of a variety of diseases. Dietary garlic has been recognized for its beneficial health effects. In particular, garlic consumption has been correlated with (i) reduction of risk factors for cardiovascular diseases and cancer, (ii) stimulation of immune function, (iii) enhanced detoxification of foreign compounds, (iv) hepatoprotection, (v) antimicrobial effects, (vi) antioxidant effects, and most importantly (vii) its hypoglycemic and anticoagulant properties. Due to these beneficial properties, garlic and its closely related genera which includes Tulbaghia violacea, may be useful as coadjuvant therapy in the treatment of type 2 diabetes and some of its physiological complications. The aim of this study was to determine if T. violacea has antidiabetic and anticoagulant properties. This was performed in vitro using both aqueous and organic extracts of the roots, leaves and bulbs. An organic extract was able to improve glucose-stimulated insulin secretion (GSIS) in INS-1 pancreatic β-cells and glucose uptake in Chang liver cells. The BO extract had no effect on the glucose uptake in 3T3-L1 an adipose cell line and reduced glucose utilisation in C2C12, a skeletal muscle cell line. Some of the properties displayed by T. violacea in this study are consistent with those found in similar studies with garlic extracts. It was observed that the BO extract increased the membrane potential and Glut-2 expression in INS-1 cells cultured at hyperglycemic levels, however, at normoglycemic levels a reduction was observed. The oxygen consumption increased at both glycemic levels due to treatment with the BO extract. Platelets were exposed to the extracts to determine their effects upon platelet aggregation, adhesion and protein secretion. Since the BO extract displayed the highest potential at inhibiting platelet aggregation and adhesion. A rat model was used in ex vivo studies to determine if the extract exhibited the same effect in a physiological model. It was noted that the BO extract exhibited a higher degree of inhibition on platelet aggregation and adhesion than the positive control, aspirin. The BO extract reduced clotting times in the prothrombin time (PT) test, but prolonged the clotting time in the actived partial thromboplastin time (APTT) assay in the ex vivo model; however, it had no affect on these clotting assays in the in vitro model using human blood. The BO extract increased the D-dimer and Fibrinogen-C levels in the in vitro model, but had no effect on the D-dimer concentrations and lowered the Fibrinogen-C levels in the ex vivo model. The active compounds in the extract remain to be elucidated.
- Full Text:
- Date Issued: 2010
Implementation of novel flow cytometric methods to assess the in vitro antidiabetic mechanism of a Sutherlandia Frutescens extract
- Authors: Elliot, Gayle Pamela
- Date: 2010
- Subjects: Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10304 , http://hdl.handle.net/10948/1439 , Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Description: The ability of insulin to stimulate glucose uptake into muscle and adipose tissue is central to the maintenance of whole-body glucose homeostasis. Deregulation of insulin action manifests itself as insulin resistance, a key component of type 2 diabetes. Insulin resistance is also observed in HIV patients receiving protease inhibitors. An agent that can reversibly induce an insulin-resistant state would be a very useful tool in developing model systems that mimic the pathogenesis of type 2 diabetes. Insulin resistance can arise from defects in insulin signal transduction, changes in the expression of proteins or genes that are targets of insulin action, cross talk from other hormonal systems or metabolic abnormalities. Deterioration of the insulin-receptor-signalling pathway at different levels leading to decreased levels of signalling pathway intermediates and/or decreased activation through phosphorylation accounts for the evolution from an insulin-resistant state to type 2 diabetes. In addition, defects in GLUT4 glucose transporter translocation are observed, further fuelling impairments in skeletal muscle glucose uptake. Levels of insulin-induced GLUT4 translocation in the skeletal muscle of type 2 diabetic patients are typically reduced by 90%. Many cellular pathways & their intermediates are in some way or another linked to insulin signalling. This study focused on three of these namely the PI3-kinase/Akt pathway, the Mitogen Activated Protein Kinase (MAPK) cascade and the AMP Kinase pathway, with successful monitoring of the PI3-K pathway. Investigations involved observing and evaluating the effects of various compounds as well as an indigenous medicinal plant, Sutherlandia frutescens on the activities of key insulin signalling pathway intermediates within the three fore mentioned pathways including Akt, AMPK and MEK1/2 as well as membrane surface GLUT4 levels. Scientific research has in the past leant heavily on Western blotting as the method of choice for gaining vital information relating to signal transduction pathways, however for research into cellular mechanisms the negatives of this method outweigh the positives. The drawbacks include a need for large amount of cells, multiple washing steps which may be disadvantageous to any weak and transient interactions as well as lysing of cells which may interfere with the maintenance of the subcellular localisation of a specific signalling event. Based on these, the need for a better method in terms of speed & reliability to monitor phosphorylation states of signal transduction pathway intermediates & GLUT4 translocation was evident and was one VII of the main aims & successes of this study. The method created used the mouse muscle cell line C2C12 in conjunction with the quick, sensitive method of flow cytometry which allowed us to monitor these processes in these cells through immune-labelling. Adherent cell cultures such as the C2C12 cell line pose the problem of possible damage to plasma membrane receptors (including insulin receptors) during harvesting to obtain a cell suspension for flow cytometry. We however used C2C12 mouse myocytes to optimize a method yielding insulin responsive cells in suspension that were successfully used for flow cytometry after immunelabelling of insulin signalling intermediates. Insulin (0.1μM) significantly raised the levels of both P-Akt and GLUT4 above basal levels. This effect was shown to be dose dependent. At a concentration of 50μg/ml, Sutherlandia frutescens was able to act as an insulin-mimetic in terms of its ability to increase P-Akt levels, GLUT4 translocation and glucose utilisation in an acute manner. These increases could be reduced with the addition of wortmannin, a PI3-K inhibitor. Therefore, these results suggest the mechanism of the plant extract’s insulin-like activity may be in part due to the activation of the insulin signalling pathway leading to GLUT4 translocation, which involves the phosphorylation of insulin receptor- and subsequent PI3-K activity, leading to P-Akt activity. These results provide further evidence of this plant extract’s anti-diabetic potential. The effect of Sutherlandia frutescens on insulin secretion, calcium signalling and proliferation in INS-1 rat pancreatic cells was also investigated and it was found to increase the activities of all of these processes. However no change in the levels of GLUT2 glucose transporter was seen. Ritonavir is prescribed by the South African Department of Health in co-formulation with other protease inhibitors within its second regime in the treatment of HIV and AIDS. Using C2C12 cells, ritonavir decreased glucose uptake acutely and had no effect on GLUT4 translocation however surprisingly increased P-Akt levels. In conclusion, it was found that Sutherlandia frutescens has antidiabetic benefits, diverse in nature depending on tissue type as well as length of time administered. The establishment of novel flow cytometry techniques to assess antidiabetic properties using in vitro cell culture was achieved. These methods will be useful in the future for the assessment of insulin sensitivity and in the identification of novel compounds that stimulate the insulin signalling pathways.
- Full Text:
- Date Issued: 2010
- Authors: Elliot, Gayle Pamela
- Date: 2010
- Subjects: Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10304 , http://hdl.handle.net/10948/1439 , Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Description: The ability of insulin to stimulate glucose uptake into muscle and adipose tissue is central to the maintenance of whole-body glucose homeostasis. Deregulation of insulin action manifests itself as insulin resistance, a key component of type 2 diabetes. Insulin resistance is also observed in HIV patients receiving protease inhibitors. An agent that can reversibly induce an insulin-resistant state would be a very useful tool in developing model systems that mimic the pathogenesis of type 2 diabetes. Insulin resistance can arise from defects in insulin signal transduction, changes in the expression of proteins or genes that are targets of insulin action, cross talk from other hormonal systems or metabolic abnormalities. Deterioration of the insulin-receptor-signalling pathway at different levels leading to decreased levels of signalling pathway intermediates and/or decreased activation through phosphorylation accounts for the evolution from an insulin-resistant state to type 2 diabetes. In addition, defects in GLUT4 glucose transporter translocation are observed, further fuelling impairments in skeletal muscle glucose uptake. Levels of insulin-induced GLUT4 translocation in the skeletal muscle of type 2 diabetic patients are typically reduced by 90%. Many cellular pathways & their intermediates are in some way or another linked to insulin signalling. This study focused on three of these namely the PI3-kinase/Akt pathway, the Mitogen Activated Protein Kinase (MAPK) cascade and the AMP Kinase pathway, with successful monitoring of the PI3-K pathway. Investigations involved observing and evaluating the effects of various compounds as well as an indigenous medicinal plant, Sutherlandia frutescens on the activities of key insulin signalling pathway intermediates within the three fore mentioned pathways including Akt, AMPK and MEK1/2 as well as membrane surface GLUT4 levels. Scientific research has in the past leant heavily on Western blotting as the method of choice for gaining vital information relating to signal transduction pathways, however for research into cellular mechanisms the negatives of this method outweigh the positives. The drawbacks include a need for large amount of cells, multiple washing steps which may be disadvantageous to any weak and transient interactions as well as lysing of cells which may interfere with the maintenance of the subcellular localisation of a specific signalling event. Based on these, the need for a better method in terms of speed & reliability to monitor phosphorylation states of signal transduction pathway intermediates & GLUT4 translocation was evident and was one VII of the main aims & successes of this study. The method created used the mouse muscle cell line C2C12 in conjunction with the quick, sensitive method of flow cytometry which allowed us to monitor these processes in these cells through immune-labelling. Adherent cell cultures such as the C2C12 cell line pose the problem of possible damage to plasma membrane receptors (including insulin receptors) during harvesting to obtain a cell suspension for flow cytometry. We however used C2C12 mouse myocytes to optimize a method yielding insulin responsive cells in suspension that were successfully used for flow cytometry after immunelabelling of insulin signalling intermediates. Insulin (0.1μM) significantly raised the levels of both P-Akt and GLUT4 above basal levels. This effect was shown to be dose dependent. At a concentration of 50μg/ml, Sutherlandia frutescens was able to act as an insulin-mimetic in terms of its ability to increase P-Akt levels, GLUT4 translocation and glucose utilisation in an acute manner. These increases could be reduced with the addition of wortmannin, a PI3-K inhibitor. Therefore, these results suggest the mechanism of the plant extract’s insulin-like activity may be in part due to the activation of the insulin signalling pathway leading to GLUT4 translocation, which involves the phosphorylation of insulin receptor- and subsequent PI3-K activity, leading to P-Akt activity. These results provide further evidence of this plant extract’s anti-diabetic potential. The effect of Sutherlandia frutescens on insulin secretion, calcium signalling and proliferation in INS-1 rat pancreatic cells was also investigated and it was found to increase the activities of all of these processes. However no change in the levels of GLUT2 glucose transporter was seen. Ritonavir is prescribed by the South African Department of Health in co-formulation with other protease inhibitors within its second regime in the treatment of HIV and AIDS. Using C2C12 cells, ritonavir decreased glucose uptake acutely and had no effect on GLUT4 translocation however surprisingly increased P-Akt levels. In conclusion, it was found that Sutherlandia frutescens has antidiabetic benefits, diverse in nature depending on tissue type as well as length of time administered. The establishment of novel flow cytometry techniques to assess antidiabetic properties using in vitro cell culture was achieved. These methods will be useful in the future for the assessment of insulin sensitivity and in the identification of novel compounds that stimulate the insulin signalling pathways.
- Full Text:
- Date Issued: 2010
Leonotis leonurus: the anticoagulant and antidiabetic activity of Leonotis leonurus
- Authors: Mnonopi, Nandipha
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10323 , http://hdl.handle.net/10948/1194 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Description: Commercial marrubiin, aqueous and organic extracts of Leonotis leonurus were tested in vitro for their anticoagulant and antiplatelet activities. The aqueous extract inhibited platelet aggregation by 69.5 percent (100 μg/mL), while the organic extract (100 μg/mL) and marrubiin (5 μg/mL) showed 92.5 percent and 91.6 percent inhibition, respectively, by inhibiting the binding of fibrinogen to glycoprotein IIb/IIIa receptor in a concentration dependent manner. The extracts significantly prolonged activated partial thromboplastin time compared to untreated plasma controls. Fibrin and D-Dimer formation were drastically decreased. The extracts and marrubiin concentration-dependently inhibited calcium mobilization induced by collagen and thrombin. The formation of thromboxane A2 was also significantly reduced by both the extracts and marrubiin. Protein secretion and platelet adhesion were significantly reduced by both the extracts and marrubiin. The organic extract and marrubiin showed a more pronounced effect than the aqueous extracts in all the in vitro assays. The ex-vivo animal model confirmed the results obtained in vitro. Similar to the in vitro studies, activated partial thromboplastin time clotting time was prolonged by marrubiin and the number of aggregated platelets were significantly reduced relative to aspirin. The findings reflect that marrubiin largely contributes to the organic extract's anticoagulant and antiplatelet effect in vitro. INS-1 cells were cultured under normo- and hyperglycaemic conditions. Marrubiin and the two Leonotis leonurus extracts were screened for anti-diabetic activity in vitro. The stimulatory index of INS-1 cells cultured under hyperglycaemic conditions was significantly increased by 60 percent and 61 percent (p<0.01; n=5) in cells exposed to the organic extract (10 μg/mL) and marrubiin (500 ng/mL), respectively, relative to the normoglycaemic conditions. The gene expression of insulin was significantly increased by 76.5 and 71 percent, and of glucose transporter-2 by 93 and 92.5 percent for marrubiin and the organic extract, respectively, under the same conditions stipulated above (p<0.01; n=4). The extract and marrubiin similarly showed an increase in respiratory rate under hyperglycaemic conditions. Marrubiin increased insulin secretion, HDL-cholesterol, while it decreased total cholesterol, LDL-cholesterol and the atherogenic index in the in vivo rat model.
- Full Text:
- Date Issued: 2010
- Authors: Mnonopi, Nandipha
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10323 , http://hdl.handle.net/10948/1194 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Description: Commercial marrubiin, aqueous and organic extracts of Leonotis leonurus were tested in vitro for their anticoagulant and antiplatelet activities. The aqueous extract inhibited platelet aggregation by 69.5 percent (100 μg/mL), while the organic extract (100 μg/mL) and marrubiin (5 μg/mL) showed 92.5 percent and 91.6 percent inhibition, respectively, by inhibiting the binding of fibrinogen to glycoprotein IIb/IIIa receptor in a concentration dependent manner. The extracts significantly prolonged activated partial thromboplastin time compared to untreated plasma controls. Fibrin and D-Dimer formation were drastically decreased. The extracts and marrubiin concentration-dependently inhibited calcium mobilization induced by collagen and thrombin. The formation of thromboxane A2 was also significantly reduced by both the extracts and marrubiin. Protein secretion and platelet adhesion were significantly reduced by both the extracts and marrubiin. The organic extract and marrubiin showed a more pronounced effect than the aqueous extracts in all the in vitro assays. The ex-vivo animal model confirmed the results obtained in vitro. Similar to the in vitro studies, activated partial thromboplastin time clotting time was prolonged by marrubiin and the number of aggregated platelets were significantly reduced relative to aspirin. The findings reflect that marrubiin largely contributes to the organic extract's anticoagulant and antiplatelet effect in vitro. INS-1 cells were cultured under normo- and hyperglycaemic conditions. Marrubiin and the two Leonotis leonurus extracts were screened for anti-diabetic activity in vitro. The stimulatory index of INS-1 cells cultured under hyperglycaemic conditions was significantly increased by 60 percent and 61 percent (p<0.01; n=5) in cells exposed to the organic extract (10 μg/mL) and marrubiin (500 ng/mL), respectively, relative to the normoglycaemic conditions. The gene expression of insulin was significantly increased by 76.5 and 71 percent, and of glucose transporter-2 by 93 and 92.5 percent for marrubiin and the organic extract, respectively, under the same conditions stipulated above (p<0.01; n=4). The extract and marrubiin similarly showed an increase in respiratory rate under hyperglycaemic conditions. Marrubiin increased insulin secretion, HDL-cholesterol, while it decreased total cholesterol, LDL-cholesterol and the atherogenic index in the in vivo rat model.
- Full Text:
- Date Issued: 2010
Production of biologically active recombinant HIV-1 protease and intehrase for the purpose of screening medicianl plant extracts
- Authors: Bosch, Janine
- Date: 2009
- Subjects: Medicinal plants -- South Africa , HIV infections -- Alternative treatment -- South Africa , Materia medica, Vegetable -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10325 , http://hdl.handle.net/10948/1056 , Medicinal plants -- South Africa , HIV infections -- Alternative treatment -- South Africa , Materia medica, Vegetable -- South Africa
- Description: Human immunodeficiency virus (HIV) and its gradual weakening of the immune system is an ever growing threat. Acquired immune deficiency syndrome (AIDS), the final stage of HIV, renders a person vulnerable to various opportunistic infections, which in the end lead to death. Apart from intensive vaccine studies, treatment research mainly focuses on preventing the individual HIV enzymes (reverse transcriptase, integrase and protease) from performing their functions. Entry inhibitors, however, block viral entry into the cell, while antisense drugs lock onto the viral genome to keep it from functioning. In this study production of active recombinant HIV-1 protease and integrase was attempted for future drug screening programs. HIV-1 protease was cloned into a pET28b(+) vector and expressed in ROSETTA(DE3)pLysS cells. The protein was purified using a nickel-affinity column utilizing the hexa-histidine tag encoded by the vector. Gel filtration chromatography was attempted after refolding of the protease, but protease yield seemed to decrease with the additional purification step. Partially purified protease was characterized with kinetic studies. Kinetic parameters of HIV-1 protease were determined to be Km = 592 μM, Vmax = 0.59 μM/min and kcat = 31 s-1. HIV-1 integrase, which was cloned into a pET15b vector, was expressed in E. coli BL21(DE3) cells. The coding sequence had been mutated to introduce the amino acid substitutions F185K and C280S, increasing solubility of the protein. The first step in purification of this protein was nickel-affinity chromatography, after which cation exchange chromatography was attempted. HIV-1 integrase concentration was low throughout experiments and no clear elution from the cation exchange column could be observed. A non-radioactive enzyme linked HIV-1 integrase assay failed to detect integrase activity. Modifications to future studies of the integrase are suggested in the chapter involved.
- Full Text:
- Date Issued: 2009
- Authors: Bosch, Janine
- Date: 2009
- Subjects: Medicinal plants -- South Africa , HIV infections -- Alternative treatment -- South Africa , Materia medica, Vegetable -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10325 , http://hdl.handle.net/10948/1056 , Medicinal plants -- South Africa , HIV infections -- Alternative treatment -- South Africa , Materia medica, Vegetable -- South Africa
- Description: Human immunodeficiency virus (HIV) and its gradual weakening of the immune system is an ever growing threat. Acquired immune deficiency syndrome (AIDS), the final stage of HIV, renders a person vulnerable to various opportunistic infections, which in the end lead to death. Apart from intensive vaccine studies, treatment research mainly focuses on preventing the individual HIV enzymes (reverse transcriptase, integrase and protease) from performing their functions. Entry inhibitors, however, block viral entry into the cell, while antisense drugs lock onto the viral genome to keep it from functioning. In this study production of active recombinant HIV-1 protease and integrase was attempted for future drug screening programs. HIV-1 protease was cloned into a pET28b(+) vector and expressed in ROSETTA(DE3)pLysS cells. The protein was purified using a nickel-affinity column utilizing the hexa-histidine tag encoded by the vector. Gel filtration chromatography was attempted after refolding of the protease, but protease yield seemed to decrease with the additional purification step. Partially purified protease was characterized with kinetic studies. Kinetic parameters of HIV-1 protease were determined to be Km = 592 μM, Vmax = 0.59 μM/min and kcat = 31 s-1. HIV-1 integrase, which was cloned into a pET15b vector, was expressed in E. coli BL21(DE3) cells. The coding sequence had been mutated to introduce the amino acid substitutions F185K and C280S, increasing solubility of the protein. The first step in purification of this protein was nickel-affinity chromatography, after which cation exchange chromatography was attempted. HIV-1 integrase concentration was low throughout experiments and no clear elution from the cation exchange column could be observed. A non-radioactive enzyme linked HIV-1 integrase assay failed to detect integrase activity. Modifications to future studies of the integrase are suggested in the chapter involved.
- Full Text:
- Date Issued: 2009
In vitro testing to investigate the anticoagulant/antithrombotic and antidiabetic biological activity of Leonotis Leonurus
- Authors: Mnonopi, Nandipha Olivia
- Date: 2007
- Subjects: Leonotis leonurus -- Physiological aspects , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Plant bioactive compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10331 , http://hdl.handle.net/10948/693 , Leonotis leonurus -- Physiological aspects , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Plant bioactive compounds
- Description: The rising costs of prescription drugs in the maintenance of personal health and wellbeing have increased the interest in medicinal plants. The World Health Organization estimates that 65 percent-80 percent of the world’s population use traditional medicine as their primary form of health care. In this project the focus has been on the use of Leonotis leonurus extracts as a traditional medicine. The major chemical constituent of this plant is marrubiin, which is a diterpenoid labdane lactone formed from a precursor called premarrubiin. Aqueous and acetone extract (AL and OL extract, respectively) of this plant has been found to have an antithrombotic effect, with IC50 values of 3mg/ml and 6mg/ml, respectively. The extracts also have an effect on fibrinolysis, where the lysis time was decreased by more than 50 percent by the organic extract and standard marrubiin. In whole blood ADP-induced platelet aggregation, the organic extract inhibited aggregation by 68 percent at a final concentration of 138μg/ml (equivalent to 7.2μg/ml marrubiin). Marrubiin has also been screened for antithrombotic/anticoagulant activity; no antithrombotic activity has been observed but it increased the rate of fibrinolysis, by decreasing lysis time by 64 percent and also decreasing fibrin formation. From these findings it can be concluded that marrubiin has a fibrinolytic effect and antiplatelet aggregation effect. In the diabetic studies, in hyperglycemic condition, the OL (10μg/ml) extract and standard marrubiin significantly increased insulin secretion by 200 percent (2-fold) and 400 percent (4-fold), respectively, with respect to the control. The OL extract and standard marrubiin stimulated the release of insulin, the stimulatory index was significantly increased by 450 percent (4.5-fold) and 500 percent (5-fold), respectively, with respect to the control. In the apoptotic studies, in the normoglycemic and hyperglycemic conditions, the OL extract decreased the occurrence of apoptosis, in a dose-dependent manner, with the lower concentrations inducing apoptosis significantly higher than the relevant controls. Standard marrubiin did not have an effect on apoptosis in hyperglycemic condition, but it decreased the occurrence of apoptosis by 200 percent (2-fold) under normoglycemic conditions. The OL extract increased proliferation by 148 percent (1.48- fold) and 155 percent (1.55-fold) in normoglycemic and hyperglycemic conditions, respectively. The same effect was observed for standard marrubiin, where, proliferation was increased by 180 percent (1.8-fold) and 200 percent (2.0-fold) in normoglycemic and hyperglycemic conditions, respectively. RT-PCR displayed that standard marrubiin inhibited the expression of insulin by 50 percent under normoglycemic conditions.
- Full Text:
- Date Issued: 2007
- Authors: Mnonopi, Nandipha Olivia
- Date: 2007
- Subjects: Leonotis leonurus -- Physiological aspects , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Plant bioactive compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10331 , http://hdl.handle.net/10948/693 , Leonotis leonurus -- Physiological aspects , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Plant bioactive compounds
- Description: The rising costs of prescription drugs in the maintenance of personal health and wellbeing have increased the interest in medicinal plants. The World Health Organization estimates that 65 percent-80 percent of the world’s population use traditional medicine as their primary form of health care. In this project the focus has been on the use of Leonotis leonurus extracts as a traditional medicine. The major chemical constituent of this plant is marrubiin, which is a diterpenoid labdane lactone formed from a precursor called premarrubiin. Aqueous and acetone extract (AL and OL extract, respectively) of this plant has been found to have an antithrombotic effect, with IC50 values of 3mg/ml and 6mg/ml, respectively. The extracts also have an effect on fibrinolysis, where the lysis time was decreased by more than 50 percent by the organic extract and standard marrubiin. In whole blood ADP-induced platelet aggregation, the organic extract inhibited aggregation by 68 percent at a final concentration of 138μg/ml (equivalent to 7.2μg/ml marrubiin). Marrubiin has also been screened for antithrombotic/anticoagulant activity; no antithrombotic activity has been observed but it increased the rate of fibrinolysis, by decreasing lysis time by 64 percent and also decreasing fibrin formation. From these findings it can be concluded that marrubiin has a fibrinolytic effect and antiplatelet aggregation effect. In the diabetic studies, in hyperglycemic condition, the OL (10μg/ml) extract and standard marrubiin significantly increased insulin secretion by 200 percent (2-fold) and 400 percent (4-fold), respectively, with respect to the control. The OL extract and standard marrubiin stimulated the release of insulin, the stimulatory index was significantly increased by 450 percent (4.5-fold) and 500 percent (5-fold), respectively, with respect to the control. In the apoptotic studies, in the normoglycemic and hyperglycemic conditions, the OL extract decreased the occurrence of apoptosis, in a dose-dependent manner, with the lower concentrations inducing apoptosis significantly higher than the relevant controls. Standard marrubiin did not have an effect on apoptosis in hyperglycemic condition, but it decreased the occurrence of apoptosis by 200 percent (2-fold) under normoglycemic conditions. The OL extract increased proliferation by 148 percent (1.48- fold) and 155 percent (1.55-fold) in normoglycemic and hyperglycemic conditions, respectively. The same effect was observed for standard marrubiin, where, proliferation was increased by 180 percent (1.8-fold) and 200 percent (2.0-fold) in normoglycemic and hyperglycemic conditions, respectively. RT-PCR displayed that standard marrubiin inhibited the expression of insulin by 50 percent under normoglycemic conditions.
- Full Text:
- Date Issued: 2007
Metabolic effects brought about by tricyclic antidepressants and the contribution of a medicinal plant in alleviating high fat diet induced insulin resistance in male wistar rats
- Authors: Chadwick, Wayne
- Date: 2006
- Subjects: Rats -- Metabolism , Diabetes -- Research , Medicinal plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10329 , http://hdl.handle.net/10948/461 , Rats -- Metabolism , Diabetes -- Research , Medicinal plants -- South Africa
- Description: Type II diabetes is becoming a growing problem in developed countries worldwide. The median age for diagnosis was around sixty, but recent surveys have shown that the entire age distribution curve shifting left. The incidence of type II diabetes is thought to be parallel with the growing rate of obesity associated with an unhealthy western diet. Type II diabetes is an expensive disease to manage, it is for this reason that cheaper medication needs to be investigated in the form of traditional plants, such as Sutherlandia frutescens. Prescription medication, such as tricyclic antidepressants, may also increase body weight thereby playing a role in obesity. The cause of weight gain in such cases may go unrecognized or lead to cessation of the medication with or without the practitioner’s knowledge or approval. It is therefore necessary to investigate the causative agents responsible for the excessive weight gain. Drinking water containing extracts of S. frutescens or metformin was administered to two groups of eleven insulin resistant male Wistar rats. The insulin resistant control group received water without any medication. Rats were sacrificed after 8 weeks allowing for fasting blood glucose, insulin and tissue glycogen content determination. Glucose uptake was also determined using [3H] deoxyglucose. The effect of the medication and the diet on muscle post receptor insulin signaling proteins was determined through Western blots. Liver proteomics was also performed using 2-D electrophoresis. In a separate experiment 26 male Wistar rats were exposed to strepotozotocin toxin, 7 of these rats received intravenous insulin treatment, 7 rats received S. frutescens extract and 7 rats received a combination of both medications, the remaining 5 received no treatment and served as the control. Rats were sacrificed after 6 days allowing for fasting blood glucose, insulin and tissue glycogen content determination. Two groups of 14 male Wistar rats received amitriptyline or trimipramine (common tricyclic antidepressants) in their drinking water, the control group (30 rats) received water without any medication. The rats’ weight and food consumption was monitored throughout the trial and their oxygen consumption was also determined. Rats were sacrificed after 6 weeks or 14 weeks of medicinal compliance allowing for fasting blood glucose, insulin and tissue glycogen content determination. Glucose uptake was also determined using [3H] deoxyglucose. S. frutescens treatment normalized circulating serum insulin levels and significantly increased the rate of glucose clearance. Certain post receptor insulin signaling proteins were also significantly increased relative to the insulin resistant control group. 2-D electrophoresis identified the normalization of protein levels associated with the urea cycle. S. frutescens was also able to, independently; maintain normoglycaemic levels in the strepotozotocin treated group. The tricyclic antidepressants significantly increased blood glucose levels while significantly reducing tissue glycogen levels for both sacrifice periods. Serum insulin remained unchanged while a significant increase in insulin degradation and insulin degrading enzyme levels were found for both antidepressants. S. frutescens shows promise as a low cost antidiabetic medication for future use. Although the antidepressants did not promote weight gain, the increase in blood glucose levels may be cause for concern in patients with a pre-disposition toward developing diabetes.
- Full Text:
- Date Issued: 2006
- Authors: Chadwick, Wayne
- Date: 2006
- Subjects: Rats -- Metabolism , Diabetes -- Research , Medicinal plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10329 , http://hdl.handle.net/10948/461 , Rats -- Metabolism , Diabetes -- Research , Medicinal plants -- South Africa
- Description: Type II diabetes is becoming a growing problem in developed countries worldwide. The median age for diagnosis was around sixty, but recent surveys have shown that the entire age distribution curve shifting left. The incidence of type II diabetes is thought to be parallel with the growing rate of obesity associated with an unhealthy western diet. Type II diabetes is an expensive disease to manage, it is for this reason that cheaper medication needs to be investigated in the form of traditional plants, such as Sutherlandia frutescens. Prescription medication, such as tricyclic antidepressants, may also increase body weight thereby playing a role in obesity. The cause of weight gain in such cases may go unrecognized or lead to cessation of the medication with or without the practitioner’s knowledge or approval. It is therefore necessary to investigate the causative agents responsible for the excessive weight gain. Drinking water containing extracts of S. frutescens or metformin was administered to two groups of eleven insulin resistant male Wistar rats. The insulin resistant control group received water without any medication. Rats were sacrificed after 8 weeks allowing for fasting blood glucose, insulin and tissue glycogen content determination. Glucose uptake was also determined using [3H] deoxyglucose. The effect of the medication and the diet on muscle post receptor insulin signaling proteins was determined through Western blots. Liver proteomics was also performed using 2-D electrophoresis. In a separate experiment 26 male Wistar rats were exposed to strepotozotocin toxin, 7 of these rats received intravenous insulin treatment, 7 rats received S. frutescens extract and 7 rats received a combination of both medications, the remaining 5 received no treatment and served as the control. Rats were sacrificed after 6 days allowing for fasting blood glucose, insulin and tissue glycogen content determination. Two groups of 14 male Wistar rats received amitriptyline or trimipramine (common tricyclic antidepressants) in their drinking water, the control group (30 rats) received water without any medication. The rats’ weight and food consumption was monitored throughout the trial and their oxygen consumption was also determined. Rats were sacrificed after 6 weeks or 14 weeks of medicinal compliance allowing for fasting blood glucose, insulin and tissue glycogen content determination. Glucose uptake was also determined using [3H] deoxyglucose. S. frutescens treatment normalized circulating serum insulin levels and significantly increased the rate of glucose clearance. Certain post receptor insulin signaling proteins were also significantly increased relative to the insulin resistant control group. 2-D electrophoresis identified the normalization of protein levels associated with the urea cycle. S. frutescens was also able to, independently; maintain normoglycaemic levels in the strepotozotocin treated group. The tricyclic antidepressants significantly increased blood glucose levels while significantly reducing tissue glycogen levels for both sacrifice periods. Serum insulin remained unchanged while a significant increase in insulin degradation and insulin degrading enzyme levels were found for both antidepressants. S. frutescens shows promise as a low cost antidiabetic medication for future use. Although the antidepressants did not promote weight gain, the increase in blood glucose levels may be cause for concern in patients with a pre-disposition toward developing diabetes.
- Full Text:
- Date Issued: 2006
In vitro anti-HIV activities of Sutherlandia frutescens and Lobostemon trigonum extracts
- Authors: Harnett, Siobhán Margaret
- Date: 2004
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , HIV infections -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11072 , http://hdl.handle.net/10948/347 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , HIV infections -- Alternative treatment -- South Africa
- Description: Currently, the approved anti-HIV drugs on the market only target the three HIV enzymes: reverse transcriptase, protease and more recently, integrase. Due to the limited nature of the current therapy, it is possible that a multi-drug resistant virus can emerge. The main concerns in developing countries however, are the expense and availability of the drugs and because of this, it is essential to investigate all alternatives. Traditional medicine offers many advantages as compared to allopathic treatment in so far as being relatively cheaper, accessible and it is broadly accepted in the population groups of the developing countries. Little is known though, of the exact efficacy and toxicity of these remedies so it is vital that these possible leads be investigated thoroughly. For the purpose of this study, two plants, Sutherlandia frutescens and Lobostemon trigonum were studied to ascertain their potential anti-HIV activity. Sutherlandia has received international attention as a possible cheap herbal remedy to improve the health of AIDS sufferers. Anecdotal evidence from health workers claim that HIV- infected patients on Sutherlandia treatment have shown improved CD4 counts, decreased viral loads and a general improvement in well-being. Extracts were prepared from dried leaves and flowers in methanol, ethanol, acetone, methylene dichloride or distilled water. Sulphated polysaccharides have been described extensively in literature with regards to their anti-HIV activity, so as a form of dereplication; an ethanol precipitation was performed on the aqueous extracts to remove sulphated polysaccharides. A toxicity study was performed on all crude extracts using uninfected peripheral mononuclear blood cells (PBMCs) isolated from whole blood. To measure anti-HIV activity, HIV-infected PBMCs were cultured with each of the crude extracts and cell viability measured using the tetrazolium salt, XTT. HIV-infected CEM-NKR-CCR5 cells were also used and supernatant from the viral studies was tested for the HIV antigen p24. xii Results varied greatly between assays but with the inclusion of a point-scale system to evaluate the extracts it was clear that overall the organic extracts of the Sutherlandia flowers, especially the acetone extract (SFA), showed great anti-HIV potential. SFA in every case decreased p24 levels and in the toxicity study did not decrease cell proliferation. With the HIV-infected PBMCs SFA actually helped improve cell proliferation despite the infection. To determine the specific anti- HIV activity, all crude extracts were tested for inhibition of HIV-I reverse transcriptase, the glycohydrolase enzymes: a-glucosidase, ß-glucosidase, ßglucuronidase, HIV-I integrase and HIV-II protease. No significant inhibition was seen with these experiments except for the HIV-I RT assay. The aqueous extract of the Lobostemon leaves produced an inhibitor of HIV-RT with a very low IC50 value of 0.049mg/ml. Some inhibitory effect was lost with the removal of the sulphated polysaccharides and the addition of BSA to the assay, but still 64% inhibition of the HIVRT remained, which confirmed that the inhibitor could be something novel, and not of the polysaccharide or tannin compounds.
- Full Text:
- Date Issued: 2004
- Authors: Harnett, Siobhán Margaret
- Date: 2004
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , HIV infections -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11072 , http://hdl.handle.net/10948/347 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , HIV infections -- Alternative treatment -- South Africa
- Description: Currently, the approved anti-HIV drugs on the market only target the three HIV enzymes: reverse transcriptase, protease and more recently, integrase. Due to the limited nature of the current therapy, it is possible that a multi-drug resistant virus can emerge. The main concerns in developing countries however, are the expense and availability of the drugs and because of this, it is essential to investigate all alternatives. Traditional medicine offers many advantages as compared to allopathic treatment in so far as being relatively cheaper, accessible and it is broadly accepted in the population groups of the developing countries. Little is known though, of the exact efficacy and toxicity of these remedies so it is vital that these possible leads be investigated thoroughly. For the purpose of this study, two plants, Sutherlandia frutescens and Lobostemon trigonum were studied to ascertain their potential anti-HIV activity. Sutherlandia has received international attention as a possible cheap herbal remedy to improve the health of AIDS sufferers. Anecdotal evidence from health workers claim that HIV- infected patients on Sutherlandia treatment have shown improved CD4 counts, decreased viral loads and a general improvement in well-being. Extracts were prepared from dried leaves and flowers in methanol, ethanol, acetone, methylene dichloride or distilled water. Sulphated polysaccharides have been described extensively in literature with regards to their anti-HIV activity, so as a form of dereplication; an ethanol precipitation was performed on the aqueous extracts to remove sulphated polysaccharides. A toxicity study was performed on all crude extracts using uninfected peripheral mononuclear blood cells (PBMCs) isolated from whole blood. To measure anti-HIV activity, HIV-infected PBMCs were cultured with each of the crude extracts and cell viability measured using the tetrazolium salt, XTT. HIV-infected CEM-NKR-CCR5 cells were also used and supernatant from the viral studies was tested for the HIV antigen p24. xii Results varied greatly between assays but with the inclusion of a point-scale system to evaluate the extracts it was clear that overall the organic extracts of the Sutherlandia flowers, especially the acetone extract (SFA), showed great anti-HIV potential. SFA in every case decreased p24 levels and in the toxicity study did not decrease cell proliferation. With the HIV-infected PBMCs SFA actually helped improve cell proliferation despite the infection. To determine the specific anti- HIV activity, all crude extracts were tested for inhibition of HIV-I reverse transcriptase, the glycohydrolase enzymes: a-glucosidase, ß-glucosidase, ßglucuronidase, HIV-I integrase and HIV-II protease. No significant inhibition was seen with these experiments except for the HIV-I RT assay. The aqueous extract of the Lobostemon leaves produced an inhibitor of HIV-RT with a very low IC50 value of 0.049mg/ml. Some inhibitory effect was lost with the removal of the sulphated polysaccharides and the addition of BSA to the assay, but still 64% inhibition of the HIVRT remained, which confirmed that the inhibitor could be something novel, and not of the polysaccharide or tannin compounds.
- Full Text:
- Date Issued: 2004
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