HYPOGLYCEMIC ACTIVITY OF POLYSACCHARIDE FRACTION FROM RHIZOME OF REHMANNIA-GLUTINOSA LIBOSCH F-HUEICHINGENSIS HSIAO AND THE EFFECT ON CARBOHYDRATE-METABOLISM IN NORMAL MOUSE-LIVER

The ethanol precipitate fraction (RG-WP) obtained from the hot water extract from rhizome of Rehmannia glutinosa LIBOSCH. f. hueichingensis HSIAO is mainly composed of pectin-like polysaccharide, and exhibited hypoglycemic activity in normal and streptozotocin-induced mice by intraperitoneal adminstration of the fraction. The results obtained after chemical modification and proteinase treatments of RG-WP suggest that the activity exists in the polysaccharide moiety. Furthermore, the effect of RG-WP on the activities of enzymes responsible for the glucose metabolism in the liver of normal mouse was studied to elucidate the mechanism of the hypoglycemic activity. Administration of RG-WP to normal mice significantly increased the activities of hepatic glucokinase and glucose-6-phosphatase dehydrogenase, but decreased those of hepatic glucose-6-phosphatase and phosphofructokinase. RG-WP stimulated the secretion of insulin and reduced the glycogen content in the liver of normal mouse.