Hypoglycemic activity of the antioxidant saponarin, characterized as a-glucosidase inhibitor present in tinospora cordifolia

Abstract

Tinospora cordifolia, used in anti-diabetic herbal drug preparations, was reported [12] to contain an a-glucosidase inhibitor, characterized as saponarin (apigenin-6-C-glucosyl-7-O-glucoside). The leaf extract had appreciable antioxidant and hydroxyl radical scavenging activities and contained the flavonoid in the range of 32.1 ^ 1.5–45.5 ^ 3.5 mg/g of dry solid. Saponarin showed mixed competitive inhibition on activities of a-glucosidase and sucrase of different origins. IC50, Ki and ki0 values determined were 48 mM, 8mM and 19.5mMrespectively for intestinal maltase and 35mM, 6 mM and 13 mM respectively for intestinal sucrase. When given orally to maltose-fed rat, saponarin showed hypoglycemic activity in the range of 20–80 mg/kg compared to 100–200 mg/kg for acarbose as reported [27].