Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xv, 122 leaves / Several herbs are well known for their nutritional applications. The reported study tested some herbs for their efficacy as antioxidants. The herbs and combinations thereof were analyzed for antioxidant activity using two comparative methods: the beta-carotene bleaching method and through measurement by the Rancimat apparatus. The efficacy of the antioxidants was also tested in a cosmetic base cream. The concentration of the natural antioxidant vitamins, such as vitamin C, vitamin E and beta-carotene was determined by analytical methods. The methods used for analysis provided adequate results for interpretation. All herbs exhibited antioxidant activity, at comparable levels. The two methods used for analysis showed variable results, as previous researchers have shown. In terms of antioxidant potency, the herbs were ranked as follows: fenugreek > coriander > oregano > sage (beta-carotene bleaching method), oregano > sage > coriander > fenugreek (Rancimat method). Oregano and sage were good synergists, when combinations of herbs were used. Fenugreek, unlike the other herbs under investigation, is a prooxidant when used at higher concentrations. A direct relationship was observed between the concentration of herbs and antioxidant potency for sage, oregano and coriander. Fenugreek which is prooxidant at higher concentrations, should be used as an antioxidant independently rather than a synergist. This was the most important finding in the reported study. Similar antioxidant activities of the herbs were observed in the base cosmetic formulation. The reported study has provided an adequate base for further quantitative research into the innovative topic of antioxidants.

Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xv, 122 leaves / Several herbs are well known for their nutritional applications. The reported study tested some herbs for their efficacy as antioxidants. The herbs and combinations thereof were analyzed for antioxidant activity using two comparative methods: the beta-carotene bleaching method and through measurement by the Rancimat apparatus. The efficacy of the antioxidants was also tested in a cosmetic base cream. The concentration of the natural antioxidant vitamins, such as vitamin C, vitamin E and beta-carotene was determined by analytical methods. The methods used for analysis provided adequate results for interpretation. All herbs exhibited antioxidant activity, at comparable levels. The two methods used for analysis showed variable results, as previous researchers have shown. In terms of antioxidant potency, the herbs were ranked as follows: fenugreek > coriander > oregano > sage (beta-carotene bleaching method), oregano > sage > coriander > fenugreek (Rancimat method). Oregano and sage were good synergists, when combinations of herbs were used. Fenugreek, unlike the other herbs under investigation, is a prooxidant when used at higher concentrations. A direct relationship was observed between the concentration of herbs and antioxidant potency for sage, oregano and coriander. Fenugreek which is prooxidant at higher concentrations, should be used as an antioxidant independently rather than a synergist. This was the most important finding in the reported study. Similar antioxidant activities of the herbs were observed in the base cosmetic formulation. The reported study has provided an adequate base for further quantitative research into the innovative topic of antioxidants.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xi, 114 leaves / Eighteen traditionally leafy vegetables consumed as food or medicinal compounds by a majority of people in the KwaZulu Natal province of South Africa were analysed for the presence of potentially harmful chemicals (antinutrients) and for their toxicity and mutagenicity. The purpose of the study was to determine whether leafy vegetables were safe for human consumption. Chemical analysis showed that none of the vegetables contained cyanogenic glycosides, however all the vegetables contained oxalic acid ranging from 24.1 mg/ml to 798.2 mg/ml with Solanum nigrum, Portulaca oleracea and Mormodica balsamina showing the highest concentrations. Most of the vegetables contained negligible amounts of phytic acid and saponins, except for Momordica balsamina (3.01 mg/ml and 1.83 mg/ml, respectively). Fourteen of the plants contained alkaloids with Portulaca oleracea having the highest content (1.53 g total alkaloids/5 g leaf material). Eight of the plants were found to inhibit trypsin activity. These chemical analyses were carried out in duplicate and the mean and standard deviation were used. The Ames test revealed that none of the leafy vegetables produced a mutagenic frequency above 1, except 10 000 µg/ml organic extract of Senna occidentalis (mutagenecity considered at mutagenic frequency above 2), thus none were considered mutagenic. All 18 organic extracts did not kill off more than 50% brine shrimp and were thus considered non-toxic. On the other hand the aqueous extracts of seven vegetables, namely, Physalis viscosa, Amaranthus dubius, Justicia flava, Bidens pilosa, Senna occidentalis, Chenopodium album and Ceratotheca triloba, killed more than 50% of the shrimp and are thus considered toxic above 100 µg/ml. The MTT assay carried out on the organic extracts indicated that 17 vegetables did not kill off more than 50% of HepG2 cells and were thus considered non-cytotoxic. The aqueous extracts of four vegetables, namely, Justicia flava, Asystasia gangetica, Momordica balsamin and Senna occidentalis, however killed more than 50% of the shrimp and were thus considered cytotoxic above 1 000 µg/ml. It may be concluded from the antinutrient analyses and the bioassays on the 18 vegetables that caution needs to be maintained with the consumption of certain leafy vegetables included in this study, especially Senna occidentalis.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xi, 114 leaves / Eighteen traditionally leafy vegetables consumed as food or medicinal compounds by a majority of people in the KwaZulu Natal province of South Africa were analysed for the presence of potentially harmful chemicals (antinutrients) and for their toxicity and mutagenicity. The purpose of the study was to determine whether leafy vegetables were safe for human consumption. Chemical analysis showed that none of the vegetables contained cyanogenic glycosides, however all the vegetables contained oxalic acid ranging from 24.1 mg/ml to 798.2 mg/ml with Solanum nigrum, Portulaca oleracea and Mormodica balsamina showing the highest concentrations. Most of the vegetables contained negligible amounts of phytic acid and saponins, except for Momordica balsamina (3.01 mg/ml and 1.83 mg/ml, respectively). Fourteen of the plants contained alkaloids with Portulaca oleracea having the highest content (1.53 g total alkaloids/5 g leaf material). Eight of the plants were found to inhibit trypsin activity. These chemical analyses were carried out in duplicate and the mean and standard deviation were used. The Ames test revealed that none of the leafy vegetables produced a mutagenic frequency above 1, except 10 000 µg/ml organic extract of Senna occidentalis (mutagenecity considered at mutagenic frequency above 2), thus none were considered mutagenic. All 18 organic extracts did not kill off more than 50% brine shrimp and were thus considered non-toxic. On the other hand the aqueous extracts of seven vegetables, namely, Physalis viscosa, Amaranthus dubius, Justicia flava, Bidens pilosa, Senna occidentalis, Chenopodium album and Ceratotheca triloba, killed more than 50% of the shrimp and are thus considered toxic above 100 µg/ml. The MTT assay carried out on the organic extracts indicated that 17 vegetables did not kill off more than 50% of HepG2 cells and were thus considered non-cytotoxic. The aqueous extracts of four vegetables, namely, Justicia flava, Asystasia gangetica, Momordica balsamin and Senna occidentalis, however killed more than 50% of the shrimp and were thus considered cytotoxic above 1 000 µg/ml. It may be concluded from the antinutrient analyses and the bioassays on the 18 vegetables that caution needs to be maintained with the consumption of certain leafy vegetables included in this study, especially Senna occidentalis.