Lipoxygenase inhibitory constituents from Periploca aphylla

Bisflavan-3-ols 1 and 2 and norterpenoid 3 have been isolated from the methanolic extract of the whole plant of Periploca aphylla. Their structures have been assigned on the basis of spectroscopic analysis including 1D and 2D NMR techniques. In addition, o-phthalic acid bis(2-ethylnonyl) ester (4), 1,3,6-trihydroxy-2,5-dimethoxyxanthone (5), and (+)-lyoniresinol (6) have been reported for the first time from this species. Compounds 1-3 displayed evident inhibitory potential against the enzyme lipoxygenase in a concentration-dependent fashion with IC50 values 19.7, 13.5, and 150.1 muM, respectively.