Three new isoflavanones from Erythrina costaricensis.

Three new isoflavanones, 5,7,3'-trihydroxy-4'-methoxy-6,5'-di(γ, γ-dimethylallyl)-isoflavanone (1), 5,3'-dihydroxy-4'-methoxy-5'-γ,γ-dimethylallyl-2'',2''-dimethylpyrano[5,6 : 6,7]isoflavanone (2) and 5,3'-dihydroxy-2'',2''-dimethylpyrano[5,6 : 6,7]-2''',2'''-dimethylpyrano[5,6 : 5,4]isoflavanone (3), along with two known isoflavonoids, cristacarpin and euchrenone b10, were isolated from the stems of Erythrina costaricensis. Their structures were established on the basis of spectroscopic evidence. Compound 3 is a rare isoflavanone possessing two 2,2-dimethylpyran moieties. Among the new isoflavanones, compound 1 showed potent antibacterial activity against methicillin-resistant Staphylococcus aureus. [ABSTRACT FROM AUTHOR]