A new flavan-3-ol and the anti-inflammatory effect of flavonoids from the fruit peels of Wisteria floribunda.

A new flavan-3-ol, (+)-afzelechin 5-O-β-d-glucopyranoside (2), together with 13 known flavonoids (1, 3-14), was isolated from the fruit peels of Wisteria floribunda. Their structures were assigned by detailed interpretation of NMR, MS, and CD spectroscopic data, as well as by comparing with published reports. The in vitro anti-inflammatory activity of the isolated compounds (1-14) was examined. Among them, compounds 3, 6, and 9 produced highest inhibitory effects on tumor necrosis factor alpha (TNF-α)-induced nuclear factor kappa-B activation in HepG2 cells with IC(50) values of 14.1, 16.5, and 11.9 μM, respectively. With the exception of compound 6, the compounds significantly inhibited the accumulation of pro-inflammatory inducible nitric oxide synthase and cyclooxygenase-2 proteins in TNF-α-stimulated HepG2 cells at a concentration as low as 0.1 μM.