Antibacterial constituents from the roots of Erythrina herbacea against methicillin-resistant Staphylococcus aureus.

Two new compounds, erybacin A (1) and erybacin B (2), together with 10 known compounds (3- 12), were isolated from the roots of Erythrina herbacea. Their structures were established on the basis of spectroscopic analyses. Erybacin A is a rare, naturally occurring 1-hydroxy-1,3-diphenylpropan-2-one derivative. The isolated compounds were evaluated for their antibacterial activity against 13 strains of methicillin-resistant Staphylococcus aureus (MRSA). The new compound 2 showed a potent bactericidal activity against MRSA.