Clerodane Diterpenoids with Anti-hyperglycemic Activity from Tinospora crispa.

Four new clerodane diterpenoids, tinosporols A-C (2-4) and tinosporoside A (5), together with six known analogues were isolated from the vines of Tinospora crispa. Their structures were established by extensive spectroscopic analysis. The relative configuration at C-12 in the known diterpenoid borapetoside E (1), the major component of the plant, was firstly established with the aid of molecular model. Compound 1 significantly reduced serum glucose levels at dose-dependent manners in alloxan-induced hyperglycemic mice and db/db type 2 diabetic mice.