Todasinoid A, a New Eremophilane-type Sesquiterpene from the Plant Toddalia asiatica

A new sesquiterpene, named todasinoid A (1), together with eight known compounds (2-9) were isolated from the roots of Toddalia asiatica. The gross structure of todasinoid A were established by analyses of the NMR and HRESIMS data. A comparison of the experimental ECD spectrum of 1 with the calculated ECD spectra for a model compound (1a) resolved the absolute configuration of 1. The known compounds were identified to be bullatantriol (2), aculeatin (3), 6-(3-ethoxy-2-hydroxy-3-methylbutyl)-5,7-dimethoxy-2H-1-benzopyran-2-one (4), trans-N-p-coumaroyltyramine (5), feruloyltyramine (6), beta-sitosterol (7), sitosterol Dglucoside(8), 7 alpha-hydroxysitosterol (9) by comparing the NMR data and specific rotations with reported data in literature. Compound 1 is an eremophilane-type sesquiterpenoid containing a mercaptolactate side-chain that is rarely found in nature. Compounds 2, 5, and 9 were isolated from this plant for the first time. Bioassay study revealed that compound 5 exhibited inhibitory effects against.-glucosidase with an IC50 of 320 mu M, being more active than the positive control acarbose.