Investigation of wild garlic plant extracts as potential devulcanizing agents
- Authors: Mpuputla, Mooketsi
- Date: 2020
- Subjects: Plant products , Plant extracts Traditional medicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49204 , vital:41610
- Description: Commercially available chemical compounds used as devulcanizing agents have been found to be relatively expensive, and harmful to human health. These include compounds such as diallyl disulfide (DADS) and diphenyl disulfide (DPDS). However, compounds like DADS and other sulfides are found in the readily available natural resource material, T. violacea, which is rich in sulfur-derived compounds that may exhibit potential use as devulcanizing agents. Hence, this study is aimed at examining the efficacy of the extracted sulfur compounds of T. violacea as potential devulcanizing agents. The sulfides of T. violacea were successfully extracted by means of sequential extraction using chloroform (CHCl3), ethyl acetate (EtOAc), and methanol (MeOH). Identification of present sulfides was done by phytochemical analysis, using the TLC method. The commercially available HPLC grade DADS reference standard was used to quantify the amount of DADS in each extract. Reversed-phase high-performance liquid chromatography (RP-HPLC) was used for quantification. The HPLC results showed that only the EtOAc and MeOH extracts contained DADS, while insignificant amount of DADS was seen in the CHCl3 extracts. The EtOAc roots, bulbs and leaf extracts (18.8 × 10-3, 8.84 × 10-3, 7.2 × 10-3 mg/mL) showed greater DADS concentration compared to the MeOH roots, bulbs and leaf extracts (5.3 × 10-3, 8.07 × 10-3, 1.9 × 10-3 mg/mL), respectively. RP-HPLC and Gel Permeation Chromatography (GPC) were the methods used to monitor and identify crosslink formation and devulcanizing. The vulcanization and devulcanization studies were carried out using the model compound, squalene. All extracts showed a decrease in the molecular weight distribution of the devulcanized products. The leaf extract, CHCl3 and EtOAc, showed the highest devulcanization efficacy overall, while the MeOH extracts showed least devulcanization efficacy as devulcanization agents. Thermal analysis studies were performed to investigate the interactions of the curatives used in the vulcanization system(s). Isothermal analysis of the vulcanization system was evident in a vulcanization reaction at an optimal time of 20 min, and at onset temperature of 177.6 oC. Upon devulcanization, DSC analysis gave evidence of the glass transition of squalene products. This indicates that no main-chain scission or backbone breakage occurred in reacting the vulcanized products with the devulcanizing agents.
- Full Text:
- Date Issued: 2020
- Authors: Mpuputla, Mooketsi
- Date: 2020
- Subjects: Plant products , Plant extracts Traditional medicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49204 , vital:41610
- Description: Commercially available chemical compounds used as devulcanizing agents have been found to be relatively expensive, and harmful to human health. These include compounds such as diallyl disulfide (DADS) and diphenyl disulfide (DPDS). However, compounds like DADS and other sulfides are found in the readily available natural resource material, T. violacea, which is rich in sulfur-derived compounds that may exhibit potential use as devulcanizing agents. Hence, this study is aimed at examining the efficacy of the extracted sulfur compounds of T. violacea as potential devulcanizing agents. The sulfides of T. violacea were successfully extracted by means of sequential extraction using chloroform (CHCl3), ethyl acetate (EtOAc), and methanol (MeOH). Identification of present sulfides was done by phytochemical analysis, using the TLC method. The commercially available HPLC grade DADS reference standard was used to quantify the amount of DADS in each extract. Reversed-phase high-performance liquid chromatography (RP-HPLC) was used for quantification. The HPLC results showed that only the EtOAc and MeOH extracts contained DADS, while insignificant amount of DADS was seen in the CHCl3 extracts. The EtOAc roots, bulbs and leaf extracts (18.8 × 10-3, 8.84 × 10-3, 7.2 × 10-3 mg/mL) showed greater DADS concentration compared to the MeOH roots, bulbs and leaf extracts (5.3 × 10-3, 8.07 × 10-3, 1.9 × 10-3 mg/mL), respectively. RP-HPLC and Gel Permeation Chromatography (GPC) were the methods used to monitor and identify crosslink formation and devulcanizing. The vulcanization and devulcanization studies were carried out using the model compound, squalene. All extracts showed a decrease in the molecular weight distribution of the devulcanized products. The leaf extract, CHCl3 and EtOAc, showed the highest devulcanization efficacy overall, while the MeOH extracts showed least devulcanization efficacy as devulcanization agents. Thermal analysis studies were performed to investigate the interactions of the curatives used in the vulcanization system(s). Isothermal analysis of the vulcanization system was evident in a vulcanization reaction at an optimal time of 20 min, and at onset temperature of 177.6 oC. Upon devulcanization, DSC analysis gave evidence of the glass transition of squalene products. This indicates that no main-chain scission or backbone breakage occurred in reacting the vulcanized products with the devulcanizing agents.
- Full Text:
- Date Issued: 2020
The effect of tulbaghia violacea plant extract on the growth of aspergillus species
- Authors: Belewa, Xoliswa Vuyokazi
- Date: 2009
- Subjects: Plant products , Plant extracts , Traditional medicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10315 , http://hdl.handle.net/10948/d1008186 , Plant products , Plant extracts , Traditional medicine
- Description: Traditional medicine has become an important part of healthcare worldwide. It is estimated that about 25 percent of prescribed medicines contain plant products or active compounds derived from plants. In South Africa, traditional medicine forms part of the culture and tradition of most communities. Garlic compounds have been shown to have a variety of antimicrobial properties. Amongst these are antifungal, antibacterial, antiviral and anti protozoal activities. Allicin and its breakdown products have been shown to be the main active compounds which possess these properties. Tulbaghia violacea has been used for the treatment of a variety of illnesses including asthma, fever, oesophageal cancer, constipation and hypertension. This study investigated the antifungal nature of T.violacea on the morphology, spore germination and lipid synthesis of Aspergillus flavus and Aspergillus parasiticus. The results of this study showed that the plant extract inhibited A. flavus growth at a minimal inhibitory concentration of 15mg/ml and was fungicidal at 20mg/ml and above. A. parasiticus was not inhibited at 25mg/ml indicating resistance to the inhibitory component of the plant extract. A measure of metabolic activity using the XTT assay showed reduced metabolic activity in the presence of increasing concentrations of the plant extract. Higher extract concentrations resulted in higher percentage inhibition of fungal growth for both fungal species with up to 98 percent inhibition being observed for the highest extract concentrations for both fungi. Germination was also delayed in the presence of 15mg/ml plant extract concentration by up to 60hr for A. flavus and 48hr for A. parasititcus. The TEM results showed increased thickening of the cell wall with higher extract concentrations. The thickening was greater for A. flavus than for A. parasiticus. Cell wall thickening may be the reason for the delay in germination in both species. Lipid production was reduced in the presence of plant extracts when compared to the control. The plant extracts inhibited triglyceride production at 15mg/ml for both A. flavus and A. parasiticus. The results therefore indicate that T. violacea extracts are antifungal and probably affect germination through interactions with the cell wall. It is possible that the extract affects lipid production in Aspergillus species.
- Full Text:
- Date Issued: 2009
- Authors: Belewa, Xoliswa Vuyokazi
- Date: 2009
- Subjects: Plant products , Plant extracts , Traditional medicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10315 , http://hdl.handle.net/10948/d1008186 , Plant products , Plant extracts , Traditional medicine
- Description: Traditional medicine has become an important part of healthcare worldwide. It is estimated that about 25 percent of prescribed medicines contain plant products or active compounds derived from plants. In South Africa, traditional medicine forms part of the culture and tradition of most communities. Garlic compounds have been shown to have a variety of antimicrobial properties. Amongst these are antifungal, antibacterial, antiviral and anti protozoal activities. Allicin and its breakdown products have been shown to be the main active compounds which possess these properties. Tulbaghia violacea has been used for the treatment of a variety of illnesses including asthma, fever, oesophageal cancer, constipation and hypertension. This study investigated the antifungal nature of T.violacea on the morphology, spore germination and lipid synthesis of Aspergillus flavus and Aspergillus parasiticus. The results of this study showed that the plant extract inhibited A. flavus growth at a minimal inhibitory concentration of 15mg/ml and was fungicidal at 20mg/ml and above. A. parasiticus was not inhibited at 25mg/ml indicating resistance to the inhibitory component of the plant extract. A measure of metabolic activity using the XTT assay showed reduced metabolic activity in the presence of increasing concentrations of the plant extract. Higher extract concentrations resulted in higher percentage inhibition of fungal growth for both fungal species with up to 98 percent inhibition being observed for the highest extract concentrations for both fungi. Germination was also delayed in the presence of 15mg/ml plant extract concentration by up to 60hr for A. flavus and 48hr for A. parasititcus. The TEM results showed increased thickening of the cell wall with higher extract concentrations. The thickening was greater for A. flavus than for A. parasiticus. Cell wall thickening may be the reason for the delay in germination in both species. Lipid production was reduced in the presence of plant extracts when compared to the control. The plant extracts inhibited triglyceride production at 15mg/ml for both A. flavus and A. parasiticus. The results therefore indicate that T. violacea extracts are antifungal and probably affect germination through interactions with the cell wall. It is possible that the extract affects lipid production in Aspergillus species.
- Full Text:
- Date Issued: 2009
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