Medicinal foodstuffs. XXXIV.1) Structures of new prenylchalcones and prenylflavanones with TNF-αand aminopeptidase N inhibitory activities from Boesenbergia rotunda

Abstract

The methanolic extract from the rhizomes of Boesenbergia rotunda (Zingiberaceae) was found to show inhibitory effect on tumor necrosis factor-α(TNF-α)-induced cytotoxicity in L929 cells (IC 50=6.1 μg/ml). By bioassay-guided separation, four new prenylcalcones, (+)-krachaizin A (1a), (-)-krachaizin A (1b), (+)-krachaizin B (2a), and (-)-krachaizin B (2b), and four new prenylflavanones, rotundaflavones Ia (3a), Ib (3b), IIa (4a), and IIb (4b), were isolated together with 18 known constituents (5a-7b and 8-19). The structures of eight new compounds were elucidated on the basis of physicochemical evidence. Among them, (+)-krachaizin B (2a), (-)-krachaizin B (2b), (+)-4-hydroxypanduratin A (6a), (-)-4-hydroxypanduratin A (6b), (+)-isopanduratin A (7a), (-)-isopanduratin A (7b), alpinetin (10), cardamonin (14), and 2,6-dihydroxy-4- methoxydihydrochalcone (15) significantly inhibited TNF-α-induced cytotoxicity in L929 cells at 10 μm. In addition, 2a, 2b, (+)-panduratins A (5a), (-)-panduratin A (5b), 6a, 7b, and geranyl-2,4-dihydroxy-6-phenylbenzoate (17) were found to show strong inhibitory effects on aminopeptidase N activity. © 2008 Pharmaceutical Society of Japan.