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 ), − sitosterol ( 7 ), sitosterol D -glucoside( 8 ), 7 α -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 IC 50 of 320  M, being more active than the positive control acarbose.