Investigation of hypogycemic and hypolipidemic effects of an aqueous extract of <i>Llupinus albus</i> legume seed in Streptozotocin-induced type I diabetic rats

Abstract

Background: Lupinus albus (LA) seed is a legume food used traditionally for the treatment of diabetes. The aim of this study was to investigate the effects of an aqueous extract of LA on lipid and glucose levels in normal and STZ induced Type 1 diabetic rats. Methods: Aqueous extract of LA was prepared and used for animal treatments. Diabetes was induced by a single intraperitoneal injection of streptozotocin (60mg/kg body weight). Effects of LA on oral glucose tolerance in normal and diabetic rats were investigated by giving a single dose of distilled water (controls), 200 or 400mg/kg LA extract, metformin 300mg/kg or glibenclamide 500µg/kg after 12 hours of fasting (time 0 glucose). After 15 minutes, a glucose load (3g/kg) was given. Glucose levels were measured at 30, 60, and 120 minutes after glucose loading. To investigate long term effects, animals were given similar treatments daily for 4 weeks. At the end of the study, serum glucose, insulin, total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL-C), very low density lipoprotein (VLDL-C) and high density lipoprotein (HDL-C) cholesterol levels were measured or calculated. Results: LA demonstrated significant (P<0.001) hypoglycaemic effects in normal rats but not in diabetic rats after acute and long term treatment. Normal LA treated rats showed higher (P<0.001) insulin levels compared to normal controls but insulin remained very low in diabetic rats. Diabetic rats showed diabetes associated weight loss in both treated and untreated rats. However, LA was effective in reducing atherogenic lipid levels (TC, TG, LDL-C VLDLC; P<0.001) with no change (P>0.05) in HDL-C. Conclusion:We conclude that the use of Lupinus albus among various communities may not be effective in treating hyperglycaemia in type 1 diabetes but effective for treating diabetes induced dyslipidemia.Key words: glucose tolerance, lipids, Lupinus albus, streptozotocin, type 1 diabetes. IntroductionPlants have historically served as a source of food and drugs. The term "nutraceutical" was coined by Stephen De Feliceto blending the two plant functions (Scarafoni et al., 2007). Nutritionally, there is a worldwide shift towards using plant sources as protein in place of animal sources. This is deemed a healthier dietary choice towards the reduction of diet related diseases such as obesity, hypertension, cardiovascular disease and type II diabetes (Arnoldi and Greco, 2011). As such, storage proteins from legumes have been the choice substitute for animal proteins. Soya bean is the most used legume that also possesses cholesterol reducing effects (Anderson et al., 1995;Sirtori et al., 1998;Sirtori et al., 2007).Lately, there has been a growing interest in other legumes as protein sources for human nutrition. One such legume is white lupin, Lupinus albus. This is an annual plant belonging to the class Leguminosae. It is grown in the Middle East and Africa as a food legume. In South Africa it is mostly grown in the Western Cape for animal feed (Brand and Brandt, 2000). In addi...

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