Seven isoprenylated flavonoids were isolated from Artocarpus styracifolius, including one new triisoprenylated flavone, styracifolin D (1), and six known ones, artocarpone B (2), kuwanon C (3), 6-C-prenyl luteolin (4), albanin A (5), 2,4,2′,4′-tetrahydroxy-3′-(3-methyl-2-butenyl)-chalcone (6), and 3′-[γ-hydroxymethyl-(E)-γ-methylallyl]-2,4,2′,4′-tetrahydroxychalcone 11′-O-coumarate (7). The structures of these compounds were determined by analysis of their spectroscopic and mass spectrometric data. Of them, 3 and 5 exhibited inhibitory effects on cathepsin K with IC50 values of 114.6 and 7.4 μM, respectively.
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