Polysaccharide from Gynura divaricata modulates the activities of intestinal disaccharidases in streptozotocin-induced diabetic rats.

During diabetes, structural and functional changes in the alimentary tract are known to take place resulting in an increased absorption of intestinal glucose and alterations in the activities of brush-border disaccharidases. To elucidate the effect of administrating polysaccharide from Gynura divaricata (PGD) on disaccharidase activities, the specific activities of intestinal disaccharidases, namely sucrase, maltase and lactase, were measured in streptozotocin-induced diabetic rats. Normal control and diabetic rats were treated by oral administration with PGD. Specific activities of intestinal disaccharidases were increased significantly during diabetes, and amelioration of the activities of sucrase and maltase during diabetes was clearly visible by the treatment with PGD. However, the increased activity of lactase during diabetes mellitus was remarkably alleviated by the administration of PGD only in the duodenum. Meanwhile, oral sucrose tolerance tests demonstrated that PGD alleviated the hyperglycaemia during diabetes mellitus, resulting from the amelioration in the activities of intestinal disaccharidases. The present investigation suggests that PGD exerted an anti-diabetic effect partly via inhibiting the increased intestinal disaccharidase activities of diabetic rats. This beneficial influence of administration of PGD on intestinal disaccharidases clearly indicates their helpful role in the management of diabetes.

Quality control of flavonoids in Ginkgo biloba leaves by high-performance liquid chromatography with diode array detection and on-line radical scavenging activity detection.

Flavonoids in plants used for the treatment of various cardiovascular, cancer diseases have been reported to possess potential protective effects against oxidative injury. Ginkgo biloba leaves, known for their antioxidant activity, were chosen for this study. In this paper, 12 flavonoids in G. biloba leaves were identified by HPLC-diode array detection (DAD)-electrospray ionization MS. HPLC-DAD coupled with chemiluminescence detection was used to determine free radical scavenging activity of flavonoids. It was found that the flavonol glycosides could markedly inhibit the luminescent signal, which indicated that they are mainly responsible for the antioxidant activities of G. biloba leaves. Total antioxidant activity of these flavonoids was used to evaluate the differences of G. biloba leaves collected in 13 habitats. The combination of chemical and activity analysis can provide a valid method to quantify the bioactive components in G. biloba leaves, and this may be a more rational approach to the quality assessment of G. biloba leaves.