Hypoglycaemic and antioxidant effects of the basidomycetes Lyophyllum connatum (Lyophyllaceae) and Tuber melanosporum (Tuberaceae) in mice

Abstract

The prevalence of Type 2 diabetes mellitus is on the rise and treatment failure is common. New agents that have superior profile in diabetic treatment are therefore needed. This present study investigates the aqueous and ethanolic extracts of the fruiting bodies of the basidiomycetes Lyophyllum connatum and Tuber melanosporum for antioxidant and hypoglycaemic activities. The effects of the extracts were tested in normoglycaemic and alloxan-induced hyperglycaemic mice intraperitoneally, at doses of 500, 1000 and 1500 mg/kg body weight. Blood glucose level was estimated with a hand held glucometer. The crude extracts were also assayed for DPPH scavenging property while phytochemical constituents of the extracts were determined using standard protocols. Results show that a significant time–dependent reduction in blood glucose concentration in normoglycaemic and hyperglycaemic mice, comparable to the reference drugs chlorpropamide. The aqueous extract of L. connatum induced a maximum fall of 33% in blood glucose concentration, greater than the 25% fall induced by the ethanolic extract at a dose of 1500 mg/kg. T. melanosporum lowered blood glucose level by up to 75%. Alkaloids, carbohydrates and flavonoids are the most abundant phytochemicals present in the extracts. The ethanolic extract of T. melanosporum showed the most potent DPPH radical scavenging activity with an IC₅₀ value of 251 μg/ml. The fruiting bodies of L. connatum and T. melanosporum have significant hypoglycaemic activity in mice but possess weak free radical scavenging activity which may be attributable to the presence of flavonoids.

Keywords: Lyophyllum connatum; Tuber melanosporum; Mushrooms; Diabetes mellitus; Hypoglycaemia