Institutional Repository

Evaluation of traditional South African leafy plants for their safety in human consumption

DUT IR/Manakin Repository

Show simple item record

dc.contributor.author Mudzwiri, Mashudu
dc.date.accessioned 2008-07-16T12:45:46Z
dc.date.available 2008-07-16T12:45:46Z
dc.date.issued 2007
dc.identifier.other 308514
dc.identifier.uri http://hdl.handle.net/10321/304
dc.description Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xi, 114 leaves en_US
dc.description.abstract 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. en_US
dc.language.iso en en_US
dc.subject Plant products--Analysis en_US
dc.subject Plant biotechnology en_US
dc.subject Plants, Edible--South Africa--Analysis en_US
dc.subject Product safety en_US
dc.subject Plants, Edible--Biotechnology--South Africa en_US
dc.subject Medicinal plants--Biotechnology--South Africa en_US
dc.subject Food--Safety measures en_US
dc.subject Medicinal plants--Biotechnology--South Africa en_US
dc.subject Biotechnology--Dissertations, Academic en_US
dc.title Evaluation of traditional South African leafy plants for their safety in human consumption en_US
dc.type Thesis en_US


Files in this item

This item appears in the following Collection(s)

Show simple item record

Search DUT IR


Browse

My Account