Three New Constituents from the Roots of Erythrina variegata and Their Antibacterial Activity against Methicillin‐Resistant Staphylococcus aureus

Two new isoflavonoids, eryvarins V and W (1 and 2, resp.), and a new chromen-4-one derivative, eryvarin X (3), along with three known isoflavonoids, 4–6, were isolated from the roots of Erythrina variegata. Their structures were established by spectroscopic analyses. Compound 1 is a rare naturally occurring isoflavanone which possesses a OH group at C(3). Among the new compounds 1–3, 2 exhibited a potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains.