Extraction of diallyl sulfides and other similar compounds from tulbaghia violacea, a South African plant, for potential use as devulcanizing agents
- Authors: Sonti, Thembela Celia
- Date: 2018
- Subjects: Violaceae -- South Africa , Plant extracts Plant products Traditional medicine
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/23338 , vital:30533
- Description: Tulbaghia violacea is a plant that is commonly used for traditional medicine in the Eastern Cape and Kwa-Zulu Natal Provinces of South Africa for treatment of ailments, such as fever, colds, asthma, tuberculosis, stomach-ache and cancer of the oesophagus. This plant has been found to be rich in sulfur-containing compounds that may display good potential as devulcanizing agents. Commonly used chemical devulcanizing agents are disulfides, such as diphenyl disulfide. These have been found to be relatively expensive compared to other methods of devulcanization. This study aimed to show that the sulfur- containing compounds extracted from the readily available Tulbaghia violacea plant can be used as devulcanizing agents. The presence of sulfur-containing compounds in the plant was positively identified by qualitative phytochemical analysis. Extraction of sulfur-containing compounds from the bulk plant material was successfully performed using the Soxhlet extraction method with a 2% 2-propanol in n-hexane solvent mixture. There was a positive identification of sulfur compounds in the crude extracts of the bulbs, roots and leaves. Diallyl disulfides (DADS) extracted from the plant were successfully quantified using normal phase high-performance liquid chromatography (HPLC). The results showed that in a bulb crude extract of 9.89 mg/mL concentration, there was 7.74X10-2 mg/mL concentration of DADS. In the roots crude extract of 10.26 mg/mL concentration, there was 2.93X10-2 mg/mL concentration of DADS; and in leaves crude extract of 10.47 mg/mL concentration, there was 3.69X10-2 mg/mL concentration of DADS. The crude extracts were evaluated for their effectiveness as devulcanizing agents by reacting them with vulcanized 2,3-dimethyl-2-butene (TME), which was used as a model compound. A reverse phase HPLC method was used to identify crosslink species formed during vulcanization, and to monitor the broken crosslinks during devulcanization. It was observed that the di- and polysulfidic crosslinked vulcanized model compound species were not present in the devulcanized product. Furthermore monosulfidic crosslink species, a common end species of devulcanization, were observed to increase in concentration from the HPLC chromatograms. It was observed that the extracts from the bulbs and leaves of Tulbaghia violacea were more effective than the extract from the roots when applied to the vulcanized model compound. This study demonstrates that Tulbaghia violacea can be used as alternatives to petroleum-derived chemicals as devulcanizing agents.
- Full Text:
- Date Issued: 2018
- Authors: Sonti, Thembela Celia
- Date: 2018
- Subjects: Violaceae -- South Africa , Plant extracts Plant products Traditional medicine
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/23338 , vital:30533
- Description: Tulbaghia violacea is a plant that is commonly used for traditional medicine in the Eastern Cape and Kwa-Zulu Natal Provinces of South Africa for treatment of ailments, such as fever, colds, asthma, tuberculosis, stomach-ache and cancer of the oesophagus. This plant has been found to be rich in sulfur-containing compounds that may display good potential as devulcanizing agents. Commonly used chemical devulcanizing agents are disulfides, such as diphenyl disulfide. These have been found to be relatively expensive compared to other methods of devulcanization. This study aimed to show that the sulfur- containing compounds extracted from the readily available Tulbaghia violacea plant can be used as devulcanizing agents. The presence of sulfur-containing compounds in the plant was positively identified by qualitative phytochemical analysis. Extraction of sulfur-containing compounds from the bulk plant material was successfully performed using the Soxhlet extraction method with a 2% 2-propanol in n-hexane solvent mixture. There was a positive identification of sulfur compounds in the crude extracts of the bulbs, roots and leaves. Diallyl disulfides (DADS) extracted from the plant were successfully quantified using normal phase high-performance liquid chromatography (HPLC). The results showed that in a bulb crude extract of 9.89 mg/mL concentration, there was 7.74X10-2 mg/mL concentration of DADS. In the roots crude extract of 10.26 mg/mL concentration, there was 2.93X10-2 mg/mL concentration of DADS; and in leaves crude extract of 10.47 mg/mL concentration, there was 3.69X10-2 mg/mL concentration of DADS. The crude extracts were evaluated for their effectiveness as devulcanizing agents by reacting them with vulcanized 2,3-dimethyl-2-butene (TME), which was used as a model compound. A reverse phase HPLC method was used to identify crosslink species formed during vulcanization, and to monitor the broken crosslinks during devulcanization. It was observed that the di- and polysulfidic crosslinked vulcanized model compound species were not present in the devulcanized product. Furthermore monosulfidic crosslink species, a common end species of devulcanization, were observed to increase in concentration from the HPLC chromatograms. It was observed that the extracts from the bulbs and leaves of Tulbaghia violacea were more effective than the extract from the roots when applied to the vulcanized model compound. This study demonstrates that Tulbaghia violacea can be used as alternatives to petroleum-derived chemicals as devulcanizing agents.
- Full Text:
- Date Issued: 2018
Biological activities of selected South African medicinal plants traditionally used to treat urinary tract infections
- Mathobela, Kegomoditswe Prudence
- Authors: Mathobela, Kegomoditswe Prudence
- Date: 2016
- Subjects: Medicinal plants -- South Africa , Urinary tract infections -- Treatment , Anti-infective agents -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8059 , vital:24715
- Description: Plants have been an important part of medicine and since the existence of human beings; they have been used to cure a variety of ailments such as diarrhoea, wounds and sexually transmitted diseases. Far from being out-dated, the use of traditional medicinal plants plays a significant role in drug discovery and remains a source of medicine still used by many South Africans. Diseases of the urinary tract can be treated using traditional medicinal plants. Although most cases of urinary tract infections (UTIs) are acute and uncomplicated, a few cases do become chronic and complicated. Resistance of pathogens causing UTIs to antibiotics normally used for treatment is one of the reasons for infections developing into the chronic and complicated state. In this study, medicinal plants indigenous to South Africa and traditionally used to treat UTIs were investigated in vitro for antimicrobial activities against UTI-causing pathogens. The plants investigated were Bulbine latifolia, Eucomis autumnalis, Hypoxis hemerocallidea and Trichilia dregeana. American Type Culture Collection (ATCC) microbial strains together with clinical strains were tested against distilled water, methanol and acetone extracts of the plants. The microbial strains included Enterococcus faecalis, Staphylococcus saprophyticus, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. The agar well diffusion method was used to screen for antimicrobial activity; the microtiter dilution method to determine the minimum inhibitory concentration; and thin layer chromatography fingerprints to separate the mixtures of the extracts and determine the number of active compounds. The study also investigated the scientific rationale for the traditional use of plant combinations to treat diseases. Three plant combinations (1:1) were investigated for potential interactive properties, which were identified through the sum of the fractional inhibitory concentration index (ΣFIC) calculations. The plant combinations studied were Hypoxis hemerocallidea and Bulbine latifolia; Hypoxis hemerocallidea and Eucomis autumnalis; and Hypoxis hemerocallidea and Trichilia dregeana. In the study, more activity was observed in the microtiter dilution method as compared to the agar well diffusion method. This was true in both the studies of the plants independently and the combination studies. The independent plants displayed noteworthy MIC values (≤ 2 mg/ml) against E. coli, Kleb. pneumoniae, P. mirabilis, P. aeruginosa and C. albicans. The plant combinations studied did not show any synergistic interactions (ΣFIC ≤ 0.5). Only non-interactive (ΣFIC >1.0 - ≤4.0) and additive (ΣFIC >0.5-1.0) interactions were observed. The study contributes to the on-going investigation of antimicrobial activities of medicinal plants and highlights the need for further investigations on the synergistic interactions of the medicinal plants used in this study.
- Full Text:
- Date Issued: 2016
- Authors: Mathobela, Kegomoditswe Prudence
- Date: 2016
- Subjects: Medicinal plants -- South Africa , Urinary tract infections -- Treatment , Anti-infective agents -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8059 , vital:24715
- Description: Plants have been an important part of medicine and since the existence of human beings; they have been used to cure a variety of ailments such as diarrhoea, wounds and sexually transmitted diseases. Far from being out-dated, the use of traditional medicinal plants plays a significant role in drug discovery and remains a source of medicine still used by many South Africans. Diseases of the urinary tract can be treated using traditional medicinal plants. Although most cases of urinary tract infections (UTIs) are acute and uncomplicated, a few cases do become chronic and complicated. Resistance of pathogens causing UTIs to antibiotics normally used for treatment is one of the reasons for infections developing into the chronic and complicated state. In this study, medicinal plants indigenous to South Africa and traditionally used to treat UTIs were investigated in vitro for antimicrobial activities against UTI-causing pathogens. The plants investigated were Bulbine latifolia, Eucomis autumnalis, Hypoxis hemerocallidea and Trichilia dregeana. American Type Culture Collection (ATCC) microbial strains together with clinical strains were tested against distilled water, methanol and acetone extracts of the plants. The microbial strains included Enterococcus faecalis, Staphylococcus saprophyticus, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. The agar well diffusion method was used to screen for antimicrobial activity; the microtiter dilution method to determine the minimum inhibitory concentration; and thin layer chromatography fingerprints to separate the mixtures of the extracts and determine the number of active compounds. The study also investigated the scientific rationale for the traditional use of plant combinations to treat diseases. Three plant combinations (1:1) were investigated for potential interactive properties, which were identified through the sum of the fractional inhibitory concentration index (ΣFIC) calculations. The plant combinations studied were Hypoxis hemerocallidea and Bulbine latifolia; Hypoxis hemerocallidea and Eucomis autumnalis; and Hypoxis hemerocallidea and Trichilia dregeana. In the study, more activity was observed in the microtiter dilution method as compared to the agar well diffusion method. This was true in both the studies of the plants independently and the combination studies. The independent plants displayed noteworthy MIC values (≤ 2 mg/ml) against E. coli, Kleb. pneumoniae, P. mirabilis, P. aeruginosa and C. albicans. The plant combinations studied did not show any synergistic interactions (ΣFIC ≤ 0.5). Only non-interactive (ΣFIC >1.0 - ≤4.0) and additive (ΣFIC >0.5-1.0) interactions were observed. The study contributes to the on-going investigation of antimicrobial activities of medicinal plants and highlights the need for further investigations on the synergistic interactions of the medicinal plants used in this study.
- Full Text:
- Date Issued: 2016
Improving customer retention at a selected medical fund through internal service quality and customer relationship management
- Authors: Xaluva, Bongiwe Lumka
- Date: 2012
- Subjects: Customer relations -- Management , Customer services , Consumer satisfaction
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8638 , http://hdl.handle.net/10948/d1008118 , Customer relations -- Management , Customer services , Consumer satisfaction
- Description: In today’s competitive arena, organisations need strategically to shift their focus from primarily concentrating on new customer acquisitions and rather to realise the importance of improving customer defections, thus looking at strategically retaining the existing customer base. Customer retention to all intents and purposes reflects the core of any service offering organisation and drives the competitiveness and viability of the business. Customer retention is a concern for all sector organisations including the medical aid schemes industry. It has been proven that retaining customers is less costly than attracting new ones and through a satisfied customer a business can elevate its competitiveness in the market. The significance of the study hinges on the importance of each business having comprehensive knowledge of why customers remain loyal patrons or why they choose to defect. It is important to note that the financial resources and time the business expends on improving service to the customer become futile if not matched by the high performance of the internal business units’ strategies. Having an understanding of customer movement will assist the organisation in properly addressing such issues and employing strategic processes that will enable the business to improve its retention strategies and curb defections. The primary objective of the current study was to investigate the impact internal service quality and customer relationship management have on customer retention. The study employed the SERVQUAL model as a measuring tool in establishing the relationship. The study investigated how customer retention (the dependent variable) is influenced by the different elements of internal service quality, namely assurance, empathy, service reliability, responsiveness, tangibles and elationship management, which represented the independent variables. The sample comprised eighty-one (81) out of a possible 130 AA Medical Scheme participants through the organisation’s four national offices. The empirical results showed that of all the variables relationship management, responsiveness and the tangibles have a positive impact on customer retention in medical aid schemes.
- Full Text:
- Date Issued: 2012
- Authors: Xaluva, Bongiwe Lumka
- Date: 2012
- Subjects: Customer relations -- Management , Customer services , Consumer satisfaction
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8638 , http://hdl.handle.net/10948/d1008118 , Customer relations -- Management , Customer services , Consumer satisfaction
- Description: In today’s competitive arena, organisations need strategically to shift their focus from primarily concentrating on new customer acquisitions and rather to realise the importance of improving customer defections, thus looking at strategically retaining the existing customer base. Customer retention to all intents and purposes reflects the core of any service offering organisation and drives the competitiveness and viability of the business. Customer retention is a concern for all sector organisations including the medical aid schemes industry. It has been proven that retaining customers is less costly than attracting new ones and through a satisfied customer a business can elevate its competitiveness in the market. The significance of the study hinges on the importance of each business having comprehensive knowledge of why customers remain loyal patrons or why they choose to defect. It is important to note that the financial resources and time the business expends on improving service to the customer become futile if not matched by the high performance of the internal business units’ strategies. Having an understanding of customer movement will assist the organisation in properly addressing such issues and employing strategic processes that will enable the business to improve its retention strategies and curb defections. The primary objective of the current study was to investigate the impact internal service quality and customer relationship management have on customer retention. The study employed the SERVQUAL model as a measuring tool in establishing the relationship. The study investigated how customer retention (the dependent variable) is influenced by the different elements of internal service quality, namely assurance, empathy, service reliability, responsiveness, tangibles and elationship management, which represented the independent variables. The sample comprised eighty-one (81) out of a possible 130 AA Medical Scheme participants through the organisation’s four national offices. The empirical results showed that of all the variables relationship management, responsiveness and the tangibles have a positive impact on customer retention in medical aid schemes.
- Full Text:
- Date Issued: 2012
The perceptions of educators, in the Queenstown education district, of the labour dispute resolution system
- Authors: Rataza, Themba Theophilus
- Subjects: Labor disputes -- South Africa -- Queenstown , Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9434 , http://hdl.handle.net/10948/d1020542
- Description: The objective of this study is to conduct a survey concerning the perceptions of educators in the Queenstown education district of the labour dispute resolution system. The education department is one of the biggest departments in the Eastern Cape’s Provincial Administration system. The likelihood of disputes is high when there are many employees. The focus of the study therefore is on how educators perceive the role of the department in terms of ensuring that labour disputes with the department are resolved efficiently and speedily. The advent of a democratic dispensation resulted in the ushering in of progressive labour legislation such as Labour Relations Act 55 of 1995. The objective of this Act is to facilitate economic development, social justice, labour peace and democratization of the workplace. In other words this Act gave birth to the manner in which labour disputes should be resolved. The study was carried out not only to explore the perceptions of educators but also with a view to making recommendations on the findings in order to help contribute towards labour peace and productivity in the workplace. The attitudes of one hundred and forty-one educators were surveyed via questionnaires and six educators who have had labour disputes with the department were interviewed. The key findings of the study revealed that both the educators who were surveyed and those interviewed lack confidence in the effectiveness of the labour dispute procedures in the district; they perceive the system as being inaccessible to them; time taken to resolve disputes is too lengthy; the system lacks necessary independence from the department of education or government and the department is seen as not adhering to its own policies and legislation. Hence there are many disputes and there is a great need for more awareness and for improved training in handling labour dispute resolution systems for district officials and educators. The study recommends more awareness and training sessions for both district officials responsible for labour relations and educators at large. It also calls for an increasingly proactive role by teacher unions in partnership with the department of education to avoid labour disputes. Although the findings cannot be generalized toother districts of the province, they do however highlight critical areas in labour dispute resolution where attention can be paid and focus made in order to ensure labour peace in the workplace for improved productivity and effective teaching and learning.
- Full Text:
- Authors: Rataza, Themba Theophilus
- Subjects: Labor disputes -- South Africa -- Queenstown , Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9434 , http://hdl.handle.net/10948/d1020542
- Description: The objective of this study is to conduct a survey concerning the perceptions of educators in the Queenstown education district of the labour dispute resolution system. The education department is one of the biggest departments in the Eastern Cape’s Provincial Administration system. The likelihood of disputes is high when there are many employees. The focus of the study therefore is on how educators perceive the role of the department in terms of ensuring that labour disputes with the department are resolved efficiently and speedily. The advent of a democratic dispensation resulted in the ushering in of progressive labour legislation such as Labour Relations Act 55 of 1995. The objective of this Act is to facilitate economic development, social justice, labour peace and democratization of the workplace. In other words this Act gave birth to the manner in which labour disputes should be resolved. The study was carried out not only to explore the perceptions of educators but also with a view to making recommendations on the findings in order to help contribute towards labour peace and productivity in the workplace. The attitudes of one hundred and forty-one educators were surveyed via questionnaires and six educators who have had labour disputes with the department were interviewed. The key findings of the study revealed that both the educators who were surveyed and those interviewed lack confidence in the effectiveness of the labour dispute procedures in the district; they perceive the system as being inaccessible to them; time taken to resolve disputes is too lengthy; the system lacks necessary independence from the department of education or government and the department is seen as not adhering to its own policies and legislation. Hence there are many disputes and there is a great need for more awareness and for improved training in handling labour dispute resolution systems for district officials and educators. The study recommends more awareness and training sessions for both district officials responsible for labour relations and educators at large. It also calls for an increasingly proactive role by teacher unions in partnership with the department of education to avoid labour disputes. Although the findings cannot be generalized toother districts of the province, they do however highlight critical areas in labour dispute resolution where attention can be paid and focus made in order to ensure labour peace in the workplace for improved productivity and effective teaching and learning.
- Full Text:
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