Prenylated flavonoids of the leaves of Macaranga conifera with inhibitory activity against cyclooxygenase-2

Two prenylated flavonoid derivatives, 5-hydroxy-4-methoxy-2",2"-dimethylpyrano-(7,8:6",5")flavanone (1) and 5,4-dihydroxy[2"-(I-hydroxy-l-methylethyl)dihydrofurano]-(7,8:5",4")flavanone (2), were isolated from an ethyl acetate-soluble extract of the leaves of Macaranga conifera using an in vitro activity-guided fractionation procedure based on the inhibition of cyclooxygenase-2. Also obtained were eight known compounds, 5,7-dihydroxy-4'-methoxy-8-(3-methylbut-2-enyl)flavanone (3), lonchocarpol A (4), sophoraflavanone B (5), 5,7-dihydroxy-4'-methoxy-8-(2-hydroxy-3-methylbut-3-enyl)flavanone (6), tomentosanol D (7), lupinifolinol (8), isolicoflavonol (9), and 20-epibryonolic acid (10). The structures of compounds I and 2 were determined using spectroscopic methods. All isolates were tested for their inhibitory effects against both cyclooxygenases-1 and -2, and selected compounds were evaluated in a mouse mammary organ culture assay. (C) 2002 Elsevier Science Ltd. All rights reserved.