Current and future biological control efforts against Solanum mauritianum (Solanaceae) in South Africa
- Venter, Nic, Cowie, Blair W, Olckers, Terence, Byrne, Marcus J
- Authors: Venter, Nic , Cowie, Blair W , Olckers, Terence , Byrne, Marcus J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414349 , vital:71138 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a14"
- Description: Solanum mauritianum Scop. (Solanaceae), colloquially referred to as bugweed in South Africa, remains a widespread invasive tree of global significance. Although biological control (biocontrol) efforts were undertaken from 1984 -2003 in South Africa, the programme eventually only released two agents, the sap-sucking lace bug Gargaphia decoris Drake (Hemiptera: Tingidae) and flowerbud-feeding weevil Anthonomus santacruzi Hustache (Coleoptera: Curculionidae). To date, these agents have been relatively ineffective in controlling S. mauritianum, largely due to low establishment success due to climatic incompatibility in relation to the widespread distribution of S. mauritianum. This has prompted the revival of S. mauritianum biocontrol research in 2018, with the programme focused largely on sourcing additional agents from climatically suitable regions in the plant’s native range in South America. Climate matching between cooler regions of South Africa and known S. mauritianum sites in South America identified Uruguay as a promising source of new agents. Field collections in Uruguay focused mainly on Anthonomus spp. but included stem-boring and shoot-galling weevils. Low incidence in the field and difficulties in culturing candidate species temporarily precluded research into stem-boring and shoot-galling candidates, but the rearing and assessment of the flowerbud-feeding weevil Anthonomus morticinus Clark (Coleoptera: Curculionidae) is ongoing. Host-specificity testing of A. morticinus has thus far confirmed a narrow host range, suggesting it has potential as a new agent.
- Full Text:
- Date Issued: 2021
- Authors: Venter, Nic , Cowie, Blair W , Olckers, Terence , Byrne, Marcus J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414349 , vital:71138 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a14"
- Description: Solanum mauritianum Scop. (Solanaceae), colloquially referred to as bugweed in South Africa, remains a widespread invasive tree of global significance. Although biological control (biocontrol) efforts were undertaken from 1984 -2003 in South Africa, the programme eventually only released two agents, the sap-sucking lace bug Gargaphia decoris Drake (Hemiptera: Tingidae) and flowerbud-feeding weevil Anthonomus santacruzi Hustache (Coleoptera: Curculionidae). To date, these agents have been relatively ineffective in controlling S. mauritianum, largely due to low establishment success due to climatic incompatibility in relation to the widespread distribution of S. mauritianum. This has prompted the revival of S. mauritianum biocontrol research in 2018, with the programme focused largely on sourcing additional agents from climatically suitable regions in the plant’s native range in South America. Climate matching between cooler regions of South Africa and known S. mauritianum sites in South America identified Uruguay as a promising source of new agents. Field collections in Uruguay focused mainly on Anthonomus spp. but included stem-boring and shoot-galling weevils. Low incidence in the field and difficulties in culturing candidate species temporarily precluded research into stem-boring and shoot-galling candidates, but the rearing and assessment of the flowerbud-feeding weevil Anthonomus morticinus Clark (Coleoptera: Curculionidae) is ongoing. Host-specificity testing of A. morticinus has thus far confirmed a narrow host range, suggesting it has potential as a new agent.
- Full Text:
- Date Issued: 2021
Photocatalytic and solar radiation harvesting potential of a free-base porphyrin-zinc (II) phthalocyanine heterodyad functionalized polystyrene polymer membrane for the degradation of 4-chlorophenol
- Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185772 , vital:44422 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113142"
- Description: In this work a novel porphyrin-phthalocyanine heterodyad (complex 4) was synthesized and embedded in polystyrene polymer membranes. The singlet oxygen generation of 4 improved in comparison to the parent porphyrin and phthalocyanine complexes giving singlet oxygen quantum yields of 0.67 and 0.51 (in dimethyl sulfoxide) where the porphyrin and phthalocyanine complementarily absorb respectively. Successful Buchwald-Hartwig coupling of complex 4 to amine functionalized polystyrene ((NH2)PS) gave a complex loading of 24.6 mg complex/g 4-PS. Embedding of 4-PS in polystyrene polymer membrane yielded the photoactive 4-memb which proved to be capable of degrading 4-chlorophenol at reaction rates of at least 1.12 × 10−7 molL-1 min-1 and half-life of 193 min in a pseudo first order reaction at an initial concentration of 3.10 × 10-5. Also, light harvesting experiments proved 4-memb to be active in the whole 300–700 nm wavelength range with the greatest activity being under white light.
- Full Text:
- Date Issued: 2021
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185772 , vital:44422 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113142"
- Description: In this work a novel porphyrin-phthalocyanine heterodyad (complex 4) was synthesized and embedded in polystyrene polymer membranes. The singlet oxygen generation of 4 improved in comparison to the parent porphyrin and phthalocyanine complexes giving singlet oxygen quantum yields of 0.67 and 0.51 (in dimethyl sulfoxide) where the porphyrin and phthalocyanine complementarily absorb respectively. Successful Buchwald-Hartwig coupling of complex 4 to amine functionalized polystyrene ((NH2)PS) gave a complex loading of 24.6 mg complex/g 4-PS. Embedding of 4-PS in polystyrene polymer membrane yielded the photoactive 4-memb which proved to be capable of degrading 4-chlorophenol at reaction rates of at least 1.12 × 10−7 molL-1 min-1 and half-life of 193 min in a pseudo first order reaction at an initial concentration of 3.10 × 10-5. Also, light harvesting experiments proved 4-memb to be active in the whole 300–700 nm wavelength range with the greatest activity being under white light.
- Full Text:
- Date Issued: 2021
SANCDB: an update on South African natural compounds and their readily available analogs
- Diallo, Bakary N, Glenister, Michael, Musyoka, Thommas M, Lobb, Kevin A, Taştan Bishop, Özlem
- Authors: Diallo, Bakary N , Glenister, Michael , Musyoka, Thommas M , Lobb, Kevin A , Taştan Bishop, Özlem
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451154 , vital:75023 , xlink:href="https://doi.org/10.1186/s13321-021-00514-2"
- Description: The dimeric dihydropyrimidine dehydrogenase (DPD), metalloenzyme, an adjunct anti-cancer drug target, contains highly specialized 4 × Fe2+4S2−4 clusters per chain. These clusters facilitate the catalysis of the rate-limiting step in the pyrimidine degradation pathway through a harmonized electron transfer cascade that triggers a redox catabolic reaction. In the process, the bulk of the administered 5-fluorouracil (5-FU) cancer drug is inactivated, while a small proportion is activated to nucleic acid antimetabolites. The occurrence of missense mutations in DPD protein within the general population, including those of African descent, has adverse toxicity effects due to altered 5-FU metabolism. Thus, deciphering mutation effects on protein structure and function is vital, especially for precision medicine purposes. We previously proposed combining molecular dynamics (MD) and dynamic residue network (DRN) analysis to decipher the molecular mechanisms of missense mutations in other proteins. However, the presence of Fe2+4S2−4 clusters in DPD poses a challenge for such in silico studies. The existing AMBER force field parameters cannot accurately describe the Fe2+ center coordination exhibited by this enzyme. Therefore, this study aimed to derive AMBER force field parameters for DPD enzyme Fe2+ centers, using the original Seminario method and the collation features Visual Force Field Derivation Toolkit as a supportive approach. All-atom MD simulations were performed to validate the results. Both approaches generated similar force field parameters, which accurately described the human DPD protein Fe2+4S2−4 cluster architecture. This information is crucial and opens new avenues for in silico cancer pharmacogenomics and drug discovery related research on 5-FU drug efficacy and toxicity issues.
- Full Text:
- Date Issued: 2021
- Authors: Diallo, Bakary N , Glenister, Michael , Musyoka, Thommas M , Lobb, Kevin A , Taştan Bishop, Özlem
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451154 , vital:75023 , xlink:href="https://doi.org/10.1186/s13321-021-00514-2"
- Description: The dimeric dihydropyrimidine dehydrogenase (DPD), metalloenzyme, an adjunct anti-cancer drug target, contains highly specialized 4 × Fe2+4S2−4 clusters per chain. These clusters facilitate the catalysis of the rate-limiting step in the pyrimidine degradation pathway through a harmonized electron transfer cascade that triggers a redox catabolic reaction. In the process, the bulk of the administered 5-fluorouracil (5-FU) cancer drug is inactivated, while a small proportion is activated to nucleic acid antimetabolites. The occurrence of missense mutations in DPD protein within the general population, including those of African descent, has adverse toxicity effects due to altered 5-FU metabolism. Thus, deciphering mutation effects on protein structure and function is vital, especially for precision medicine purposes. We previously proposed combining molecular dynamics (MD) and dynamic residue network (DRN) analysis to decipher the molecular mechanisms of missense mutations in other proteins. However, the presence of Fe2+4S2−4 clusters in DPD poses a challenge for such in silico studies. The existing AMBER force field parameters cannot accurately describe the Fe2+ center coordination exhibited by this enzyme. Therefore, this study aimed to derive AMBER force field parameters for DPD enzyme Fe2+ centers, using the original Seminario method and the collation features Visual Force Field Derivation Toolkit as a supportive approach. All-atom MD simulations were performed to validate the results. Both approaches generated similar force field parameters, which accurately described the human DPD protein Fe2+4S2−4 cluster architecture. This information is crucial and opens new avenues for in silico cancer pharmacogenomics and drug discovery related research on 5-FU drug efficacy and toxicity issues.
- Full Text:
- Date Issued: 2021
Synthesis of a near infrared-actuated phthalocyanine-lipid vesicle system for augmented photodynamic therapy
- Nwahara, Namdi, Managa, Muthumuni, Stoffels, Mihlali, Britton, Jonathan, Prinsloo, Earl, Nyokong, Tebello
- Authors: Nwahara, Namdi , Managa, Muthumuni , Stoffels, Mihlali , Britton, Jonathan , Prinsloo, Earl , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185395 , vital:44383 , xlink:href="https://doi.org/10.1016/j.synthmet.2021.116811"
- Description: The efficacy of photodynamic therapy (PDT) is often limited by the poor bio-distributive properties of conventional photosensitizers and the local hypoxic microenvironment that characterises most solid tumours. Herein, a novel in situ oxygenic lipid formulation for photodynamic therapy (PDT) is reported. Such a hybrid was synthesized by adsorbing bimetallic nanozyme, MnO2@PtNPs (NPs = nanoparticles) onto graphene quantum dots (GQDs) – zinc (II) phthalocyanine conjugates, followed by liposomal encapsulation, affording it enhanced water solubility. The MnO2@PtNPs, which are is shown to possess excellent catalase-like properties surpassing that of MnO2 or PtNPs alone, serves to catalyze H2O2 to O2, while the zinc (II) phthalocyanine (1) serves to transform the formed oxygen to generate cytotoxic singlet oxygen immediately. We show that by combining each function of the respective building blocks, the as-synthesized 1-GQDs-MnO2@PtNPs-liposomes not only maintains the properties of oxygen supplementation through H2O2 catalysis but also displays cooperative properties for enhanced singlet oxygen production. Consequently, a remarkably improved PDT efficacy was observed for 1-GQDs-MnO2@PtNPs-liposomes in both normoxia and hypoxia. These results demonstrate the potential applicability of such nanozyme constituted 1-GQDs-MnO2@PtNPs-liposomes for achieving tumour treatment in hypoxic conditions by PDT.
- Full Text:
- Date Issued: 2021
- Authors: Nwahara, Namdi , Managa, Muthumuni , Stoffels, Mihlali , Britton, Jonathan , Prinsloo, Earl , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185395 , vital:44383 , xlink:href="https://doi.org/10.1016/j.synthmet.2021.116811"
- Description: The efficacy of photodynamic therapy (PDT) is often limited by the poor bio-distributive properties of conventional photosensitizers and the local hypoxic microenvironment that characterises most solid tumours. Herein, a novel in situ oxygenic lipid formulation for photodynamic therapy (PDT) is reported. Such a hybrid was synthesized by adsorbing bimetallic nanozyme, MnO2@PtNPs (NPs = nanoparticles) onto graphene quantum dots (GQDs) – zinc (II) phthalocyanine conjugates, followed by liposomal encapsulation, affording it enhanced water solubility. The MnO2@PtNPs, which are is shown to possess excellent catalase-like properties surpassing that of MnO2 or PtNPs alone, serves to catalyze H2O2 to O2, while the zinc (II) phthalocyanine (1) serves to transform the formed oxygen to generate cytotoxic singlet oxygen immediately. We show that by combining each function of the respective building blocks, the as-synthesized 1-GQDs-MnO2@PtNPs-liposomes not only maintains the properties of oxygen supplementation through H2O2 catalysis but also displays cooperative properties for enhanced singlet oxygen production. Consequently, a remarkably improved PDT efficacy was observed for 1-GQDs-MnO2@PtNPs-liposomes in both normoxia and hypoxia. These results demonstrate the potential applicability of such nanozyme constituted 1-GQDs-MnO2@PtNPs-liposomes for achieving tumour treatment in hypoxic conditions by PDT.
- Full Text:
- Date Issued: 2021
The effects of the composition and structure of quantum dots combined with cobalt phthalocyanine and an aptamer on the electrochemical detection of prostate specific antigen
- Nxele, Siphesihle R, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185002 , vital:44315 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109407"
- Description: The ability to functionalize and modify graphene-based quantum dots has also allowed for the tuning of their activity in different applications. A comparative study is carried out in this work where a prostate specific aptamer (PSA) and cobalt phthalocyanine molecule are combined with graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (gCNQDs) in order to determine the effects of quantum dots type (and therefore composition) on the electrocatalytic ability of the sensor to detect the analyte of interest. For the detection of prostate-specific antigen, electrochemical impedance spectroscopy (EIS) is employed to determine detection limits as well as sensitivity and selectivity of the aptasensors. Results showed a good performance of all sensors fabricated with the NGQDs based aptasensor showing the best performance with a detection limit of 1.54 pM in EIS as well as negligible interference in mixed samples. This electrode was further verified in spiked human serum samples and good recovery and low detection limits were determined, putting this aptasensor in good stead as a reliable, efficient PSA aptasensor.
- Full Text:
- Date Issued: 2021
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185002 , vital:44315 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109407"
- Description: The ability to functionalize and modify graphene-based quantum dots has also allowed for the tuning of their activity in different applications. A comparative study is carried out in this work where a prostate specific aptamer (PSA) and cobalt phthalocyanine molecule are combined with graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (gCNQDs) in order to determine the effects of quantum dots type (and therefore composition) on the electrocatalytic ability of the sensor to detect the analyte of interest. For the detection of prostate-specific antigen, electrochemical impedance spectroscopy (EIS) is employed to determine detection limits as well as sensitivity and selectivity of the aptasensors. Results showed a good performance of all sensors fabricated with the NGQDs based aptasensor showing the best performance with a detection limit of 1.54 pM in EIS as well as negligible interference in mixed samples. This electrode was further verified in spiked human serum samples and good recovery and low detection limits were determined, putting this aptasensor in good stead as a reliable, efficient PSA aptasensor.
- Full Text:
- Date Issued: 2021
Ultrasound-Triggered Release of 5-Fluorouracil from Soy Lecithin Echogenic Liposomes
- Ezekiel, Charles I, Bapolisi, Alain M, Walker, Roderick B, Krause, Rui W M
- Authors: Ezekiel, Charles I , Bapolisi, Alain M , Walker, Roderick B , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183115 , vital:43913 , xlink:href="https://doi.org/10.3390/pharmaceutics13060821"
- Description: Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.
- Full Text:
- Date Issued: 2021
- Authors: Ezekiel, Charles I , Bapolisi, Alain M , Walker, Roderick B , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183115 , vital:43913 , xlink:href="https://doi.org/10.3390/pharmaceutics13060821"
- Description: Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.
- Full Text:
- Date Issued: 2021
Using Technology to Teach a New Generation
- Connan, James, Brown, Dane L, Watkins, Caroline
- Authors: Connan, James , Brown, Dane L , Watkins, Caroline
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465223 , vital:76584 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-030-92858-2_8"
- Description: Introductory programming courses attract students from diverse backgrounds in terms of ability, motivation and experience. This paper introduces two technological tools, Thonny and Runestone Academy, that can be used to enhance introductory courses. These tools enable instructors to track the progress of individual students. This allows for the early identification of students that are not keeping up with the course and allows for early intervention in such cases. Overall this leads to a better course with higher throughput and better student retention.
- Full Text:
- Date Issued: 2021
- Authors: Connan, James , Brown, Dane L , Watkins, Caroline
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465223 , vital:76584 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-030-92858-2_8"
- Description: Introductory programming courses attract students from diverse backgrounds in terms of ability, motivation and experience. This paper introduces two technological tools, Thonny and Runestone Academy, that can be used to enhance introductory courses. These tools enable instructors to track the progress of individual students. This allows for the early identification of students that are not keeping up with the course and allows for early intervention in such cases. Overall this leads to a better course with higher throughput and better student retention.
- Full Text:
- Date Issued: 2021
Battle of the large carnivores: spatial partitioning in a small, enclosed reserve?
- Comley, Jessica, Joubert, Christoffel J, Mgqatsa, Nokubonga, Parker, Daniel M
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462581 , vital:76316 , xlink:href="https://hdl.handle.net/10520/EJC-2037326828"
- Description: Interspecific competition among terrestrial carnivores can have widespread impacts on community structure and can ultimately determine which species are able to coexist. Within the carnivore guild, coexistence can be achieved through either spatial, temporal or dietary partitioning. The most effective method of avoiding competition may be spatial partitioning, as it removes the potential for negative interactions. The ways in which large carnivore species utilize and partition space in small, enclosed reserves in South Africa is currently poorly understood. This knowledge gap weakens our understanding of which mechanisms structure large carnivore communities in these systems. Thus, our aim was to use Global Positioning System (GPS) collars to investigate the spatial dynamics of large carnivores [four lions (Panthera leo), three leopards (Panthera pardus) and three spotted hyaenas (Crocuta crocuta)] on a small, enclosed reserve (Selati Game Reserve). Regarding home ranges, lions had considerable overlap among themselves (especially the females), leopards had minimal overlap, while spotted hyaenas had no home range overlap. Although we found no evidence for spatial partitioning amongst the collared large carnivores, differences in the habitat use patterns of the three large carnivore species is evident. The high prey abundance of Selati, carnivore predation strategies, behavioural adaptations and ecological separation could be facilitating the coexistence of lions, spotted hyaenas and leopards in Selati. We encourage future research to be aimed at investigating the interactions of multiple sympatric carnivores in an attempt to bridge the knowledge gap on which mechanisms structure carnivore communities.
- Full Text:
- Date Issued: 2020
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462581 , vital:76316 , xlink:href="https://hdl.handle.net/10520/EJC-2037326828"
- Description: Interspecific competition among terrestrial carnivores can have widespread impacts on community structure and can ultimately determine which species are able to coexist. Within the carnivore guild, coexistence can be achieved through either spatial, temporal or dietary partitioning. The most effective method of avoiding competition may be spatial partitioning, as it removes the potential for negative interactions. The ways in which large carnivore species utilize and partition space in small, enclosed reserves in South Africa is currently poorly understood. This knowledge gap weakens our understanding of which mechanisms structure large carnivore communities in these systems. Thus, our aim was to use Global Positioning System (GPS) collars to investigate the spatial dynamics of large carnivores [four lions (Panthera leo), three leopards (Panthera pardus) and three spotted hyaenas (Crocuta crocuta)] on a small, enclosed reserve (Selati Game Reserve). Regarding home ranges, lions had considerable overlap among themselves (especially the females), leopards had minimal overlap, while spotted hyaenas had no home range overlap. Although we found no evidence for spatial partitioning amongst the collared large carnivores, differences in the habitat use patterns of the three large carnivore species is evident. The high prey abundance of Selati, carnivore predation strategies, behavioural adaptations and ecological separation could be facilitating the coexistence of lions, spotted hyaenas and leopards in Selati. We encourage future research to be aimed at investigating the interactions of multiple sympatric carnivores in an attempt to bridge the knowledge gap on which mechanisms structure carnivore communities.
- Full Text:
- Date Issued: 2020
Chemical constituents, antioxidant and cytotoxicity properties of Leonotis leonurus used in the folklore management of neurological disorders in the Eastern Cape, South Africa
- Tonisi, Sipho, Okaiyeto, Kunle, Hoppe, Heinrich C, Mabinya, Leonard V, Nwodo, Uchechukwu U, Okoh, Anthony I
- Authors: Tonisi, Sipho , Okaiyeto, Kunle , Hoppe, Heinrich C , Mabinya, Leonard V , Nwodo, Uchechukwu U , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429384 , vital:72606 , xlink:href="https://doi.org/10.1007/s13205-020-2126-5"
- Description: In the present study, we evaluated the phytochemical compounds and antioxidant properties of chloroform, ethanol and acetone extracts for leaves and flowers of Leonutus leonurus (L. leonurus) alongside with their cytotoxic effects on human cervical carcinoma (HeLa) cell lines. The phytochemical compounds present in the leaves and flowers of L. leonurus included; phenolics, flavonoids and alkaloids. Their radicals scavenging effects against 2, 2-diphenyl-1-picrylhydrazyl [DPPH] 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) [ABTS·+], hydrogen peroxide, nitric oxide as well as metal chelating activities showed dose-dependent activities. Gas chromatography-mass spectrometry (GCMS) analyses revealed the presence of important bioactive compounds, which are associated with antioxidant; and the extracts exhibited toxicity effect against HeLa cells. The findings from this study divulge extracts of L. leonurus as prospective sources of antioxidant and anticancer agents; and hence, further study on their neuroprotective potentials becomes imperative.
- Full Text:
- Date Issued: 2020
- Authors: Tonisi, Sipho , Okaiyeto, Kunle , Hoppe, Heinrich C , Mabinya, Leonard V , Nwodo, Uchechukwu U , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429384 , vital:72606 , xlink:href="https://doi.org/10.1007/s13205-020-2126-5"
- Description: In the present study, we evaluated the phytochemical compounds and antioxidant properties of chloroform, ethanol and acetone extracts for leaves and flowers of Leonutus leonurus (L. leonurus) alongside with their cytotoxic effects on human cervical carcinoma (HeLa) cell lines. The phytochemical compounds present in the leaves and flowers of L. leonurus included; phenolics, flavonoids and alkaloids. Their radicals scavenging effects against 2, 2-diphenyl-1-picrylhydrazyl [DPPH] 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) [ABTS·+], hydrogen peroxide, nitric oxide as well as metal chelating activities showed dose-dependent activities. Gas chromatography-mass spectrometry (GCMS) analyses revealed the presence of important bioactive compounds, which are associated with antioxidant; and the extracts exhibited toxicity effect against HeLa cells. The findings from this study divulge extracts of L. leonurus as prospective sources of antioxidant and anticancer agents; and hence, further study on their neuroprotective potentials becomes imperative.
- Full Text:
- Date Issued: 2020
Enhanced Light-Driven Antimicrobial Activity of Cationic Poly (oxanorbornene) s by Phthalocyanine Incorporation into Polymer as Pendants
- Ahmetali, Erem, Sen, Pinar, Süer, N Ceren, Aksu, Burak, Nyokong, Tebello, Eren, Tarik, Sener, Kasim M
- Authors: Ahmetali, Erem , Sen, Pinar , Süer, N Ceren , Aksu, Burak , Nyokong, Tebello , Eren, Tarik , Sener, Kasim M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185976 , vital:44453 , xlink:href=" https://doi.org/10.1002/macp.202000386"
- Description: Amphiphilic poly(oxanorbornene)s are promising synthetic polymers that mimic the structural properties and antimicrobial functions of naturally occurring antimicrobial peptides. Here, poly(oxanorbornene)s bearing pendant zinc(II) phthalocyanine and triphenyl(ethyl) phosphonium functionalities are synthesized by ring-opening metathesis polymerization (ROMP). Fluorescence, singlet oxygen and triplet quantum yields of polymers are measured in dimethyl sulfoxide and aqueous medium. The singlet oxygen quantum yields of copolymers with the highest triphenyl and triethyl phosphonium content are found to be 0.29 and 0.41, respectively. Then, antimicrobial activities of polymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are investigated under both dark and light conditions. Synergistic effect of zinc(II) phthalocyanine and phosphonium-containing poly(oxanorbornene) is observed that the conjugate possessing the most triphenyl phosphonium side chains has the highest activity under light against both gram-positive and gram-negative bacterial strains after 80 min irradiation, reducing the survival of E. coli or S. aureus by 99.9999%. Hemolytic concentrations of the copolymers are found between 8 and 512 µg mL−1. Scanning electron microscopy (SEM) proves that the bacteria membrane deforms after contacting with the biocidal polymer.
- Full Text:
- Date Issued: 2020
- Authors: Ahmetali, Erem , Sen, Pinar , Süer, N Ceren , Aksu, Burak , Nyokong, Tebello , Eren, Tarik , Sener, Kasim M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185976 , vital:44453 , xlink:href=" https://doi.org/10.1002/macp.202000386"
- Description: Amphiphilic poly(oxanorbornene)s are promising synthetic polymers that mimic the structural properties and antimicrobial functions of naturally occurring antimicrobial peptides. Here, poly(oxanorbornene)s bearing pendant zinc(II) phthalocyanine and triphenyl(ethyl) phosphonium functionalities are synthesized by ring-opening metathesis polymerization (ROMP). Fluorescence, singlet oxygen and triplet quantum yields of polymers are measured in dimethyl sulfoxide and aqueous medium. The singlet oxygen quantum yields of copolymers with the highest triphenyl and triethyl phosphonium content are found to be 0.29 and 0.41, respectively. Then, antimicrobial activities of polymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are investigated under both dark and light conditions. Synergistic effect of zinc(II) phthalocyanine and phosphonium-containing poly(oxanorbornene) is observed that the conjugate possessing the most triphenyl phosphonium side chains has the highest activity under light against both gram-positive and gram-negative bacterial strains after 80 min irradiation, reducing the survival of E. coli or S. aureus by 99.9999%. Hemolytic concentrations of the copolymers are found between 8 and 512 µg mL−1. Scanning electron microscopy (SEM) proves that the bacteria membrane deforms after contacting with the biocidal polymer.
- Full Text:
- Date Issued: 2020
NIR Absorbing AzaBODIPY Dyes for pH Sensing
- Kubheka, Gugu, Mack, John, Nyokong, Tebello, Zhen, Shen
- Authors: Kubheka, Gugu , Mack, John , Nyokong, Tebello , Zhen, Shen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186668 , vital:44523 , xlink:href="https://doi.org/10.3390/molecules25163689"
- Description: Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes 2a and 2b were synthesized and characterized that differ depending on whether the dimethylaniline substituents are introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH2Cl2. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH2Cl2, and a fluorescence “turn-on” effect in the NIR region. The pH dependence studies reveal that the pKa values of the non-protonated 2a and 2b molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.
- Full Text:
- Date Issued: 2020
- Authors: Kubheka, Gugu , Mack, John , Nyokong, Tebello , Zhen, Shen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186668 , vital:44523 , xlink:href="https://doi.org/10.3390/molecules25163689"
- Description: Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes 2a and 2b were synthesized and characterized that differ depending on whether the dimethylaniline substituents are introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH2Cl2. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH2Cl2, and a fluorescence “turn-on” effect in the NIR region. The pH dependence studies reveal that the pKa values of the non-protonated 2a and 2b molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.
- Full Text:
- Date Issued: 2020
Resisting abortion stigma in situ: South African womxn's and healthcare providers' accounts of the pre-abortion counselling healthcare encounter
- Mavuso, Jabulile M-J J, Macleod, Catriona I
- Authors: Mavuso, Jabulile M-J J , Macleod, Catriona I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443749 , vital:74149 , xlink:href="https://doi.org/10.1080/13691058.2019.1674922"
- Description: Abortion providers and pregnant people who undergo abortion potentially face significant stigma. Researchers have started to explore how womxn respond to abortion stigma, usually focusing on individual strategies in managing or reducing stigma effects. Drawing on narrative data from research conducted on womxn’s and healthcare providers’ experiences of the pre-abortion healthcare encounter in the South African public health sector, we highlight how stigma may be resisted in social ways within this context. Everyday chatter and informal social support amongst womxn in the waiting room provided a counterpoint for health service providers’ ascription of shame to the womxn, and a sense of solidarity amongst the womxn. Health service providers narrated their decision to do abortion work through the socially affirming hero canonical narrative, and womxn described their counselling as helpful. These social and discursive practices resist the awfulisation of abortion and provide relief for the womxn and the healthcare providers in particular contexts.
- Full Text:
- Date Issued: 2020
- Authors: Mavuso, Jabulile M-J J , Macleod, Catriona I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443749 , vital:74149 , xlink:href="https://doi.org/10.1080/13691058.2019.1674922"
- Description: Abortion providers and pregnant people who undergo abortion potentially face significant stigma. Researchers have started to explore how womxn respond to abortion stigma, usually focusing on individual strategies in managing or reducing stigma effects. Drawing on narrative data from research conducted on womxn’s and healthcare providers’ experiences of the pre-abortion healthcare encounter in the South African public health sector, we highlight how stigma may be resisted in social ways within this context. Everyday chatter and informal social support amongst womxn in the waiting room provided a counterpoint for health service providers’ ascription of shame to the womxn, and a sense of solidarity amongst the womxn. Health service providers narrated their decision to do abortion work through the socially affirming hero canonical narrative, and womxn described their counselling as helpful. These social and discursive practices resist the awfulisation of abortion and provide relief for the womxn and the healthcare providers in particular contexts.
- Full Text:
- Date Issued: 2020
Synthesis and pharmacological evaluation of chlorin derivatives for photodynamic therapy of cholangiocarcinoma
- Gao, Ying-Hua, Li, Man-Yi, Saijad, Faiza, Wang, Jin-Hai, Meharban, Faiza, Gadoora, Malaz A, Yan, Yi-Jia, Nyokong, Tebello, Chen, Zhi-Long
- Authors: Gao, Ying-Hua , Li, Man-Yi , Saijad, Faiza , Wang, Jin-Hai , Meharban, Faiza , Gadoora, Malaz A , Yan, Yi-Jia , Nyokong, Tebello , Chen, Zhi-Long
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190873 , vital:45036 , xlink:href="https://doi.org/10.1016/j.ejmech.2020.112049"
- Description: Photodynamic therapy (PDT) has been developed as a promising therapeutic method in cancer treatment. The discovery of effective photosensitizer, which is the key factor of PDT, is highly desired. This paper reports the synthesis of novel chlorin derivatives, 5,10,15,20-tetraphenyl-[2:3]-[(methoxycarbonyl, carboxy)methano] chlorin I and 5,10,15,20-tetraphenyl-[2:3]- {[methoxycarbonyl, (2-hydroxyethyl)amide]methano}chlorin II. Their structures were characterized with UV–vis, 1HNMR, 13CNMR and HRMS spectroscopies. Photophysical and photochemical experiments results showed that compound I and II had an absorption maximum around 650 nm, with molar extinction coefficients of 1 × 104 M−1 cm−1. They had strong fluorescence emission in 650–660 nm upon excitation with 419–422 nm light. ESR showed that singlet oxygen was produced upon irradiation of compounds with 650 nm light in the presence of molecular oxygen. The photo-bleaching test indicated that the structure of compounds was stable. These new compounds exhibit excellent anti-tumor effects and lower toxicity compared to m-THPC in vitro and in vivo. Compound I and II had high tumor selectivity, which could induced tumor cells shrinkage and necrosis under 650 nm laser irradiation. Flow cytometry revealed that the compounds might mediate PDT effect at late apoptotic phase. These results make these compound I and II promising candidates for future study in photo-diagnosis and photodynamic therapy of cholangiocarcinoma.
- Full Text:
- Date Issued: 2020
- Authors: Gao, Ying-Hua , Li, Man-Yi , Saijad, Faiza , Wang, Jin-Hai , Meharban, Faiza , Gadoora, Malaz A , Yan, Yi-Jia , Nyokong, Tebello , Chen, Zhi-Long
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190873 , vital:45036 , xlink:href="https://doi.org/10.1016/j.ejmech.2020.112049"
- Description: Photodynamic therapy (PDT) has been developed as a promising therapeutic method in cancer treatment. The discovery of effective photosensitizer, which is the key factor of PDT, is highly desired. This paper reports the synthesis of novel chlorin derivatives, 5,10,15,20-tetraphenyl-[2:3]-[(methoxycarbonyl, carboxy)methano] chlorin I and 5,10,15,20-tetraphenyl-[2:3]- {[methoxycarbonyl, (2-hydroxyethyl)amide]methano}chlorin II. Their structures were characterized with UV–vis, 1HNMR, 13CNMR and HRMS spectroscopies. Photophysical and photochemical experiments results showed that compound I and II had an absorption maximum around 650 nm, with molar extinction coefficients of 1 × 104 M−1 cm−1. They had strong fluorescence emission in 650–660 nm upon excitation with 419–422 nm light. ESR showed that singlet oxygen was produced upon irradiation of compounds with 650 nm light in the presence of molecular oxygen. The photo-bleaching test indicated that the structure of compounds was stable. These new compounds exhibit excellent anti-tumor effects and lower toxicity compared to m-THPC in vitro and in vivo. Compound I and II had high tumor selectivity, which could induced tumor cells shrinkage and necrosis under 650 nm laser irradiation. Flow cytometry revealed that the compounds might mediate PDT effect at late apoptotic phase. These results make these compound I and II promising candidates for future study in photo-diagnosis and photodynamic therapy of cholangiocarcinoma.
- Full Text:
- Date Issued: 2020
The Rise of the Executive Dean and the Slide into Managerialism
- Authors: McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187139 , vital:44573 , xlink:href="http://dx.doi.org/10.17159/2221-4070/2020/v9i0a6"
- Description: Universities have long been characterised by hierarchical and paternalistic management structures and institutional cultures. Change is therefore to be welcomed but, in contexts where social change is urgently needed, it is possible to mistake a change in any direction as being worthwhile. Around the world, recent shifts in university leadership and management have been towards managerialist approaches that work against a shared responsibility for the academic project. Accusations of managerialism often refer to a general sense that institutions are becoming bureaucratic, or that it is the logic of the market that drives decision-making. But beyond vague complaints, these accusations fail to identify the exact processes whereby managerialism takes hold of the institution. This article hones in on one specific example of institutional change in order to argue that it is implicated in the move towards managerialism: most universities in South Africa have changed from having elected deans, selected by faculty, to executive deans, appointed by selection committee. Crudely distinguished, it can be said that elected deans represent the interests of their faculty up into various institutional structures whereas executive deans are tasked with implementing the decisions of top management down into faculty. This paper tracks the differences between the two forms of deanship through reflections on discussions about such a change at one South African institution, Rhodes University. It analyses the literature to argue that we do not have to choose between patriarchal management and compliance-based managerialism. Instead, we can choose shared responsibility for the academic project.
- Full Text:
- Date Issued: 2020
- Authors: McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187139 , vital:44573 , xlink:href="http://dx.doi.org/10.17159/2221-4070/2020/v9i0a6"
- Description: Universities have long been characterised by hierarchical and paternalistic management structures and institutional cultures. Change is therefore to be welcomed but, in contexts where social change is urgently needed, it is possible to mistake a change in any direction as being worthwhile. Around the world, recent shifts in university leadership and management have been towards managerialist approaches that work against a shared responsibility for the academic project. Accusations of managerialism often refer to a general sense that institutions are becoming bureaucratic, or that it is the logic of the market that drives decision-making. But beyond vague complaints, these accusations fail to identify the exact processes whereby managerialism takes hold of the institution. This article hones in on one specific example of institutional change in order to argue that it is implicated in the move towards managerialism: most universities in South Africa have changed from having elected deans, selected by faculty, to executive deans, appointed by selection committee. Crudely distinguished, it can be said that elected deans represent the interests of their faculty up into various institutional structures whereas executive deans are tasked with implementing the decisions of top management down into faculty. This paper tracks the differences between the two forms of deanship through reflections on discussions about such a change at one South African institution, Rhodes University. It analyses the literature to argue that we do not have to choose between patriarchal management and compliance-based managerialism. Instead, we can choose shared responsibility for the academic project.
- Full Text:
- Date Issued: 2020
A return to common-sense: why ecology needs transcendental realism
- Authors: Price, Leigh
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390324 , vital:68538 , xlink:href="https://doi.org/10.1080/14767430.2019.1580178"
- Description: Empirical realist ecologists, such as C. S. Holling, face significant methodological contradictions; for instance, they must cope with the problem that ecological models and theories of climate change, resilience and succession cannot make predictions in open systems. Generally, they respond to this problem by supplementing their empirical realism with transcendental idealism: they therefore say that their models are simply metaphorical or heuristic, that is, 'not true' in that they are not empirical. Thus, they explicitly deny an ontology for what their models are about. Nevertheless, in their practice, ecologists act as if their theories do have an ontology and thus tell us something truthful about the real world. This discrepancy leaves ecology vulnerable to unnecessary critique, such as that climate science is not real science. Transcendental realism offers a solution because it releases ecologists from the requirement to make predictions; but it does so without denying ontology. This provides several advantages to ecologists.
- Full Text:
- Date Issued: 2019
- Authors: Price, Leigh
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390324 , vital:68538 , xlink:href="https://doi.org/10.1080/14767430.2019.1580178"
- Description: Empirical realist ecologists, such as C. S. Holling, face significant methodological contradictions; for instance, they must cope with the problem that ecological models and theories of climate change, resilience and succession cannot make predictions in open systems. Generally, they respond to this problem by supplementing their empirical realism with transcendental idealism: they therefore say that their models are simply metaphorical or heuristic, that is, 'not true' in that they are not empirical. Thus, they explicitly deny an ontology for what their models are about. Nevertheless, in their practice, ecologists act as if their theories do have an ontology and thus tell us something truthful about the real world. This discrepancy leaves ecology vulnerable to unnecessary critique, such as that climate science is not real science. Transcendental realism offers a solution because it releases ecologists from the requirement to make predictions; but it does so without denying ontology. This provides several advantages to ecologists.
- Full Text:
- Date Issued: 2019
Cordidepsine is A Potential New Anti-HIV Depsidone from Cordia millenii
- Zeukang, Rostanie D, Siwe-Noundou, Xavier, Fotsing, Maurice T, Mbafor, Joseph T, Krause, Rui W M, Choudhary, Muhammad I, Atchade, Alex de Theodore
- Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
- Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
- Full Text:
- Date Issued: 2019
- Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
- Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
- Full Text:
- Date Issued: 2019
Deactivation of field cultivation in communal areas of South Africa: Patterns, drivers and socio-economic and ecological consequences
- Shackleton, Charlie M, Mograbi, Penelope, Drimie, Scott, Fay, Derick, Hebinck, Paul, Hoffman, Michael T, Maciejewski, Kristine, Twine, Wayne
- Authors: Shackleton, Charlie M , Mograbi, Penelope , Drimie, Scott , Fay, Derick , Hebinck, Paul , Hoffman, Michael T , Maciejewski, Kristine , Twine, Wayne
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398210 , vital:69384 , xlink:href="https://doi.org/10.1016/j.landusepol.2019.01.009"
- Description: Smallholder production is a significant contributor to rural livelihoods and rural economies in much of the developing world. Yet, there is evidence of increasing disengagement in some regions, including southern Africa. However, there has been little consideration of the rates and the livelihood, ecological and policy implications of such. In this paper we examine previous studies on rates of deactivation of crop fields by smallholders in the communal areas of South Africa, supported by repeat photo images and case study material. Together these various methods show that it is a widespread phenomenon occurring at variable rates. Over short periods deactivation of crop fields can be balanced through some reactivation or intensification of homegardens. But over longer periods there is a net decline in the area of fields cultivated in many areas, with corresponding increases in the area of fallow land which, through time, may undergo changes towards more natural vegetation. We review the drivers of this deactivation of field cropping, and then contemplate the possible socio-economic and ecological implications at local and national scales. We show that there are numerous and profound implications that require greater understanding and policy responses.
- Full Text:
- Date Issued: 2019
- Authors: Shackleton, Charlie M , Mograbi, Penelope , Drimie, Scott , Fay, Derick , Hebinck, Paul , Hoffman, Michael T , Maciejewski, Kristine , Twine, Wayne
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398210 , vital:69384 , xlink:href="https://doi.org/10.1016/j.landusepol.2019.01.009"
- Description: Smallholder production is a significant contributor to rural livelihoods and rural economies in much of the developing world. Yet, there is evidence of increasing disengagement in some regions, including southern Africa. However, there has been little consideration of the rates and the livelihood, ecological and policy implications of such. In this paper we examine previous studies on rates of deactivation of crop fields by smallholders in the communal areas of South Africa, supported by repeat photo images and case study material. Together these various methods show that it is a widespread phenomenon occurring at variable rates. Over short periods deactivation of crop fields can be balanced through some reactivation or intensification of homegardens. But over longer periods there is a net decline in the area of fields cultivated in many areas, with corresponding increases in the area of fallow land which, through time, may undergo changes towards more natural vegetation. We review the drivers of this deactivation of field cropping, and then contemplate the possible socio-economic and ecological implications at local and national scales. We show that there are numerous and profound implications that require greater understanding and policy responses.
- Full Text:
- Date Issued: 2019
Electrocatalytic Activity of Asymmetrical Cobalt Phthalocyanines in the Presence of N Doped Graphene Quantum Dots: The Push-pull Effects of Substituents
- Nkhahle, Reitumetse, Sekhosana, Kutloano E, Centane, Sixolile, Nyokong, Tebello
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
Fabrication of efficient nonlinear optical absorber using Zn phthalocyanine-semiconductor quantum dots conjugates
- Mgidlana, Sithi, Oluwole, David O, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
High throughput screening, docking, and molecular dynamics studies to identify potential inhibitors of human calcium/calmodulin-dependent protein kinase IV
- Beg, Anam, Khan, Faez I, Lobb, Kevin A, Islam, Asimul, Ahmad, Faizan, Hassan, M Imtaiyaz
- Authors: Beg, Anam , Khan, Faez I , Lobb, Kevin A , Islam, Asimul , Ahmad, Faizan , Hassan, M Imtaiyaz
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:74587 , xlink:href="https://doi.org/10.1080/07391102.2018.1479310"
- Description: Calcium/calmodulin-dependent protein kinase IV (CAMKIV) is associated with many diseases including cancer and neurodegenerative disorders and thus being considered as a potential drug target. Here, we have employed the knowledge of three-dimensional structure of CAMKIV to identify new inhibitors for possible therapeutic intervention. We have employed virtual high throughput screening of 12,500 natural compounds of Zinc database to screen the best possible inhibitors of CAMKIV. Subsequently, 40 compounds which showed significant docking scores (−11.6 to −10.0 kcal/mol) were selected and further filtered through Lipinski rule and drug likeness parameter to get best inhibitors of CAMKIV. Docking results are indicating that ligands are binding to the hydrophobic cavity of the kinase domain of CAMKIV and forming a significant number of non-covalent interactions. Four compounds, ZINC02098378, ZINC12866674, ZINC04293413, and ZINC13403020, showing excellent binding affinity and drug likeness were subjected to molecular dynamics simulation to evaluate their mechanism of interaction and stability of protein-ligand complex. Our observations clearly suggesting that these selected ligands may be further employed for therapeutic intervention to address CAMKIV associated diseases.
- Full Text:
- Date Issued: 2019
- Authors: Beg, Anam , Khan, Faez I , Lobb, Kevin A , Islam, Asimul , Ahmad, Faizan , Hassan, M Imtaiyaz
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:74587 , xlink:href="https://doi.org/10.1080/07391102.2018.1479310"
- Description: Calcium/calmodulin-dependent protein kinase IV (CAMKIV) is associated with many diseases including cancer and neurodegenerative disorders and thus being considered as a potential drug target. Here, we have employed the knowledge of three-dimensional structure of CAMKIV to identify new inhibitors for possible therapeutic intervention. We have employed virtual high throughput screening of 12,500 natural compounds of Zinc database to screen the best possible inhibitors of CAMKIV. Subsequently, 40 compounds which showed significant docking scores (−11.6 to −10.0 kcal/mol) were selected and further filtered through Lipinski rule and drug likeness parameter to get best inhibitors of CAMKIV. Docking results are indicating that ligands are binding to the hydrophobic cavity of the kinase domain of CAMKIV and forming a significant number of non-covalent interactions. Four compounds, ZINC02098378, ZINC12866674, ZINC04293413, and ZINC13403020, showing excellent binding affinity and drug likeness were subjected to molecular dynamics simulation to evaluate their mechanism of interaction and stability of protein-ligand complex. Our observations clearly suggesting that these selected ligands may be further employed for therapeutic intervention to address CAMKIV associated diseases.
- Full Text:
- Date Issued: 2019