Cholinesterase inhibitory constituents from Onosma hispida

Hispidone, a new flavanone, has been isolated from Onosma hispida and assigned the structure (2S)-5,2'-di-hydroxy-7,4',5'-trimethoxyflavanone (1) by spectroscopic methods. In addition, (2S)-5,2'-dihydroxy-7,5'-dimethoxyflavanone (2), benzoic acid (3), and 4-hydroxy benzoic acid (4) are also reported for the first time from this species.