Browsing by Author "Mudyiwa, Misheck"

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Inhibitory effects of herbal medicines with claimed anticancer indications on cytochrome P450—An evaluation of drug-herb interactions risk
(Elsevier, 2023-08-03) Mudyiwa, Misheck; Sharma, Manju; Ray, Samarendra Kumar; Masimirembwa, Collen; Thelingwani, Roslyn Stella
Herbs have the potential to interact with conventional medicines or each other upon concurrent administration. This can be at the level of absorption, distribution, metabolism and excretion (ADME). With an estimation that 80% of the population in poor regions of the world utilise herbal medicines for primary healthcare, there is a likelihood that some people will take both herbal and conventional medicines. This could present a risk for herb-drug interactions (HDI) at the various levels of the ADME process. Most common HDI have been observed at metabolism level involving inhibition or induction of the major drug metabolising liver enzymes called cytochrome P450s. In this study, we investigated the inhibitory effects of Parinari curatellifolia (MC), Fluggea virosa (ST), Garcinia livingstonei (MT), Pterocarpus angolensis (M), Tapinanthus quequensis (MF) and Cussonia arborea (GM) on recombinant CYP1A2, CYP2D6, CYP2C9 and CYP2C19. Plate based fluorescent assays were used to follow enzyme activity. Inhibition was determined at 5 mg/ml and 100 mg/ ml of herbal extract, with IC50 determined for herbs that showed potent inhibition. A total of 10 out of 13 extracts showed significant inhibitory effects. Pterocarpus angolensis(bark), Fluggea virossa (leaf), Cussonia arborea(bark), Parinari curatellifollia (root) had very potent effects on CYP1A2 as indicated by an IC50 of <9.9 μg/ml. Based on the worst-case-scenario of complete absorption and exposure, these herbs are predicted to result in HDI if co-administered with medicines which depend on the affected CYPs for metabolism and elimination. Significance of the main findings: There is a potential threat of drug toxicities due to drug-herb interactions for patients undergoing chemotherapy or taking other medications where comorbidities exist during chemotherapy. Drugs that are substrates of CYP1A2 should be administered with caution for patients who are taking the herbs which have been studied in this research as risk for drug toxicities may be high. The findings act as a guide to medical doctors and patients in evaluating potential for herb-drug interactions during prescribing medications which are substrates for the studied CYPs.
An investigation on the causes of Escherichia coli and coliform contamination of cheddar cheese and how to reduce the problem
(International Journal of Nutrition and Food Sciences, 2014-09-20) Kwenda, Amanda; Nyahada, Moses; Musengi, Amos; Mudyiwa, Misheck; Muredzi, Perkins
The aim of this study was to investigate the causes of E. coli contamination of Cheddar cheese through the application of Hazard Analysis Critical Control Points (HACCP) principles. Cheese samples were analyzed for E. coli and coliforms after production, during the validation stage, as well as at the verification stage. Average E. coli and coliform counts were analyzed statistically using the t-test. Results showed that after the implementation of the corrective measures there was a decrease in E. coli and coliform counts at the 5% level of significance. Results presented in this study also show that manufacturing Cheddar cheese whole observing high standards of hygiene improves the reduces E. coli and coliform contamination of the product, even though the problem is not completely eliminated.
Isolation of citric acid producing Aspergillus niger strains
(LAP LAMBERT Academic Publishing, 2013-01-05) Muredzi, Perkins; Nyati, Hilda; Mudyiwa, Misheck
Proximate composition of pumpkin gourd (Cucurbita pepo) seeds from Zimbabwe ,
(International Journal of Nutrition and Food Sciences., 2014-06-30) Winini, Clive; Kwiri, Raphael; Musengi, Amos; Mudyiwa, Misheck; Nyambi, Clarice; Muredzi, Perkins; Malunga, Abigail
Curcubita pepo seeds have been widely consumed in Zimbabwe way back in the 1970s, but still locally, there is no data on the nutritional quality of Curcubita pepo seeds, hence the study attempted to avail this information. Curcubita pepo seeds from selected places in Zimbabwe were analysed. The proximate analysis including major nutrients and minerals were determined. The C. pepo seed had a moisture content of 5.662±0.016gkg-1. Significantly, Curcubita pepo had high amounts of crude oil and proteins as compared to other edible oil rich seeds. The crude oil content and protein were 43.460±0.098gkg-1 and 32.860±0.103gkg-1 respectively. Other components such as carbohydrates, crude fibre and energy were 12.160±0.142gkg-1, 2.578±0.007gkg-1 and 562.82±0.132gkg-1 correspondingly. Ash content was 3.324±0.010gkg-1 which was further analysed into various major minerals giving analysed means as Na (67.956±0.037gkg-1), Zn (1.244±0.010gkg-1), P (1040.8±0.663gkg-1), Fe (11.980±0.086gkg-1), Ca (141±0.316gkg-1) and Mg (344.6±0.245gkg-1). The findings indicated that C. pepo seeds are a good alternative source of highly nutritious food for instance proteins and lipids as well as minerals (Mg, Ca, Zn, P and Fe) that could greatly contribute to human nutritional requirements. However, it still remains important to further profile the quality of the lipids and proteins from C. pepo seed so as to verify their essentiality and availability to the human body as well as evaluating the presence of other bioactive and antinutritional factors that might be present in these seeds.