Phospholipase A2 Inhibitors from an Erythrina Species from Samoa

Three flavonoid phospholipase A 2 (PLA 2 ) inhibitors were isolated from a MeOH extract of the bark of the Samoan medicinal plant Erythrina variegata . Two of these compounds, 4‘-hydroxy-3‘,5‘-diprenylisoflavonone (abyssinone V) ( 1 ) and 3,9-dihydroxy-2,10-diprenylpterocarp-6a-ene (erycrystagallin) ( 3 ), have been previously reported as antimicrobial agents from plants belonging to other Erythrina species. The isoflavonone 4‘-hydroxy-6,3‘,5‘-triprenylisoflavonone ( 2 ) is a new compound, and its structure was determined by spectroscopic techniques. The IC 50 values for the PLA 2 enzyme were 6, 10, and 3 μM for 1 − 3, respectively.