Structure and absolute configuration of clerodane diterpene glycosides and a rearranged cadinane sesquiterpene glycoside from the stems of Tinospora sinensis

Three new clerodane diterpene glycosides, tinosposinensides A-C ( 1- 3), and a new rearranged cadinane sesquiterpene glycoside, tinosinenside ( 4), were isolated from the stems of Tinospora sinensis. The structure including the relative configuration was elucidated on the basis of spectroscopic analysis. The absolute configuration was determined by application of the modified Mosher's method and chemical transformation. The inhibitory activities of the isolated compounds against alpha-glucosidase are also described.