Two new natural products from the fruits of Alpinia oxyphylla with inhibitory effects on nitric oxide production in lipopolysaccharide-activated RAW264.7 macrophage cells

Chemical investigation of the fruits of Alpinia oxyphylla led to an isolation of the two new natural products, 9-hydroxy epinootkatol (1) and (S)-2-pentanol-2-O-β-D-glucopyranoside (2), in addition to the nine known compounds, pinocembrin (3), tectochrysin (4), izalpinin (5), nookatone (6), yakuchinone A (7), protocatechuic acid (8), β-sitosterol (9), daucosterol (10) and β-sitosterol palmitate (11). Their structures were elucidated on the basis of physicochemical constants and NMR spectral data analysis. The effects of the isolated components on nitric oxide production in LPS-induced RAW 264.7 macrophages were examined. The two new natural compounds showed inhibitory activities with IC50 values of 21.8 and 32.8 μg/mL, respectively.