Monoamine oxidase inhibitory constituents from the fruits of Cudrania tricuspidata

Abstract

A methylene chloride soluble fraction of the fruits of Cudrania tricuspidata significantly inhibited the mouse brain monoamine oxidase (MAO). Three known prenylated isoflavones were isolated and identified by activity-guided fractionation. Gancaonin A (1), 4′-O- methylalpinumisoflavone (2), and alpinumisoflavone (3) inhibited MAO activity in a concentration-dependent manner with IC50 values of 19.4, 23.9, and 25.8 μM, respectively. of these, gancaonin A (1) showed a selective and potent inhibitory effect against MAO-B (IC50 0.8 μM) than MAO-A (IC50 >800 μM). The kinetic analysis using Lineweaver-Burk plots indicated that gancaonin A (1) competitively inhibited MAO-B.