A New Diterpene: Abietane Glycoside from the Roots of Isodon rugosus Wall Ex Benth.

The methanolic extract of the roots of Isodon rugosus were subjected to chromatographic separation, yielded two diterpenes: a new compound named rugosodon 1 and a known compound oridonin 2. The new compound 1 was elucidated as 1-O-alpha-D-glucopyranosy1-7 alpha,13 beta-dihydroxyabieta-8(9)-en-11-one and the known compound 2 as 7 alpha,20-epoxy-1 alpha,6 beta,7,14-tetrahydroxy-kaur-16-en-15-one (oridonin), based on the chemical hydrolysis, physicochemical and spectroscopic data of IR, ESIMS, EIMS, 1D, and 2D NMR. The compounds 1-2 were subjected to bioassay studies of cytotoxicity and alpha-glucosidase inhibition potential. Rugosodon 1 showed significant potential of alpha-glucosidase inhibition with IC50 0.453 mg/mL, as compared to the standard acarbose (IC50 0.921 mg/mL). The compounds 1-2 failed to show any significant results for the cytotoxic screening against the three human cancer cell lines (NCI-H460, HeLa and MCF-7).