In vitro and in vivo antidiabetic effects of the ethanol extract from Lentinula edodes (Shiitake)

Abstract

We examined the expression patterns of glucose transporters (GLUTs) in Caco-2 human colon cancer cells that spontaneously or chemically differentiated into intestinal epithelial cells. RT-PCR analysis demonstrated that the expression of intestinal glucose transporters such as GLUT-1 and -2 was increased by both types of differentiation. We evaluated the inhibitory effects of extracts from Lentinula edodes on glucose transport in intestinal Caco-2 cells induced to differentiate by 5 mM sodium butyrate. The ethanol extract of L. edodes (LEE) at 0.1 mg/ml markedly inhibited glucose intake through the monolayer of differentiated Caco-2 cells; however, neither water nor the 50% (v/v) ethanol extract affected glucose transport through these cells at the same concentration. We also investigated the effects of LEE on plasma glucose levels in mice with hyperglycaemia induced by feeding with a high fat diet (HFD). The results obtained showed that LEE reduced plasma glucose levels by 64.0% in HFD-fed mice.