An investigation of antioxidant and antidiabetic effect of aqueous leaf extracts of mucuna pruriens

Abstract

Diabetes is currently a wide spread global disease. As a result of the side effects of the current therapies, herbal plants may present alternative source of drugs for management of the disease. Mucuna pruriens is a plant that is traditionally used for diabetes and anaemia. There are experimental reports of the hypoglycaemic effect of the alcoholic extracts but the anti-diabetic effects of the aqueous extract has not been investigated. Therefore, the aim of this project was to investigate the potential anti-diabetic mechanisms of the aqueous extract of Mucuna pruriens leaves. The leaf extract was prepared by decoction. The potential mechanisms of anti-diabetic effect of this extract was evaluated as follows: Antioxidant activity of the aqueous Mucuna pruriens leaf extract was investigated in reduced β-nicotinamide adenine dinucleotide (NADH)/phenazine methosulphate (PMS), and Xanthine /Xanthine oxidase superoxide generating systems. In addition, the effect of aqueous Mucuna pruriens leaf extract against oxidative stress was measured as cytoprotective effect of the extract against paraquat induced oxidant injury in NRK-52E renal cells. Cytoprotective effect was measured as cell viability and cell death using 3-(4,5-Dimethylthiazol-2-Yl)-2,5 Diphenyltetrazolium Bromide (MTT) and Lactose dehydrogenase (LDH) assays respectively. Finally the effect of aqueous Mucuna pruriens leaf extract on glucose uptake was evaluated in NRK-52E renal cells and 3T3-L1 adipocytes. The results revealed that aqueous Mucuna pruriens leaf extract had significant superoxide scavenging activity which increased from 21.35% to 99.8% in xanthine/xanthine oxidase and 36.15% to 62.4% in NADH/PMS superoxide generating systems at p<0.05. However, aqueous Mucuna pruriens leaf extract did not protect against paraquat induced oxidative stress. Data from glucose uptake experiments showed that 1mg/ml of aqueous Mucuna pruriens leaf extract inhibited glucose uptake in NRK-52E renal by 35.5% compared to control at p<0.05. This effect was comparable to 1mM Phloridzin (a non- selective inhibitor of sodium glucose transporters). Finally, 50 and 100μg/ml of both aqueous Mucuna pruriens leaf extract and its acid hydrolysed fractions prepared with liquid-liquid partitioning in diethyl ether, stimulated glucose uptake in 3T3-L1 adipocytes. Specifically, 50 and 100μg/ml aqueous Mucuna pruriens leaf extract stimulated glucose uptake be 57.06 and 86.24% respectively compared to negative control at p<0.05. Increase in glucose uptake was also observed in cells treated with diethyl ether acid hydrolysed fractions. Taken together, the results show that aqueous the Mucuna pruriens leaf extract used in this study may exert anti-diabetic effects via antioxidant and glucose uptake modulatory mechanisms.

Date of Award	Dec 2016
Original language	English
Awarding Institution	University of Brighton