Isolation and Lipoxygenase‐Inhibition Studies of Phenolic Constituents from Ehretia obtusifolia

The phenolic compounds methyl 2‐ O ‐feruloyl‐1a‐ O ‐vanillactate ( 1 ), caffeic anhydride ( 2 ), and trans 4‐hydroxycyclohexyl‐2‐ O‐p ‐coumaroyl β ‐ D ‐glucopyranoside ( 3 ) have been isolated from the AcOEt‐soluble fraction of Ehretia obtusifolia , along with methyl rosmarinate ( 4 ) and rosmarinic acid ( 5 ), which are reported for the first time from this species. Their structures were determined by means of 1D‐ and 2D‐NMR techniques. Compounds 1 – 5 inhibited lipoxygenase in a concentration‐dependent manner, with K i values ranging from 0.85–57.6 μ M . Compounds 1, 2, 4 , and 5 showed noncompetitive inhibition, whereas 3 was found to be an uncompetitive inhibitor of lipoxygenase.