Effect of hot water extracts from Tamogitake on the suppression of blood glucose elevation in non-insulin dependent diabetic mice

Abstract

The hot water extract fraction (W ; consisted of 80.3% of water) was prepared by concentration of the soup in which the fruiting bodies of Pleurotus cornucopiae (Tamogitake) dipped for 5 min. The W was incubated with β-1,3-glucanase and further treated with 3 volume of ethanol to obtain the ethanol soluble fraction (Et ; consisted of 34.1% of water). At 7 week of age, non-insulin dependent diabetic mice (KK-Ay) were fed either the control diet (C ; composed of 50% of water) or diet supplemented with 12.5% of W or with 3.1% of Et for 8 weeks. No deteriorative effect of the growth of mice was observed in group of W and Et. The plasma glucose level was significantly lower in group W than in group C in each week from 4th to 8th, and at each point of the glucose tolerance test, in that the mice were treated with 1 g/kg BW of glucose. The level of plasma insulin was also significantly lower in group W compared with group C. The levels of plasma glucose and insulin of group Et were between those of groups C and W, but not significantly different from values of group C. Normal C 57 BL/6 J mice were fed C or W from 7 week of age for 8 weeks. No significant difference was observed in plasma glucose in each week or at each point of the glucose tolerance test, and in the level of plasma insulin. Results indicate that consuming W improves the diabetic condition in diabetic mice and shows no effect on normal mice.