Isolation of Novel Phenolic Compounds with Multidrug Resistance (MDR) Reversal Properties from Onychium japonicum

We isolated seven novel compounds, namely, 3′,4′,6‐trihydroxy‐2,4‐dimethoxy‐3‐(3″,4″‐dihydroxybenzyl)chalcone ( 1 ), 3′,6‐dihydroxy‐2,4,4′‐trimethoxy‐3‐(3″,4″‐dihydroxybenzyl)chalcone ( 2 ), α , β ‐dihydro‐3′,6‐dihydroxy‐2,4,6′‐trimethoxy‐3‐(3″,4″‐dihydroxybenzyl)chalcone ( 3 ), 3′,4,4′‐trihydroxy‐2,6‐dimethoxychalcone ( 4 ), 4′,5,7‐trihydroxy‐6‐(3″,4″‐dihydroxybenzyl)flavone ( 5 ), 3‐(3′,4′‐dihydroxybenzyl)‐6,7‐dihydroxycoumarin ( 6 ), 3‐(3′,4′‐dihydroxyphenyl)‐3,4‐dihydroisocoumarin ( 7 ), as well as a known compound, 3′,4′,7‐trihydroxy‐5‐methoxyflavanone ( 8 ) from the whole grass of Onychium japonicum , and elucidated their structures by spectroscopic methods. Compounds 1 – 3 exhibited significant multidrug resistance (MDR) reversal effects on MCF‐7/ADR and Bel‐7402/5‐Fu cell lines.