A New Flavonolignan from the Aerial Parts of Oryza sativa L. Inhibits Nitric oxide Production in RAW 264.7 Macrophage Cells

Fresh and chopped aerial parts of Oryza saliva were extracted in 80% aqueous mehthanol, and the concentrated extract was successively partitioned using n-hexane, ethyl acetate (EtOAc), n-butanol, and H2O. From the EtOAc fraction, a new flavonolignan (2) and a known flavonolignan, salcolin B (1), were isolated through repeated SiO2 and octadecyl silica gel column chromatography. Based on NMR, mass spectrometer, and IR spectroscopic data, the chemical structure of compound (2) was determined to be tricin-4'-O-[erythro-beta-guaiacyl-(7 ''-O-methyl)-glyceryl] ether, which has thus far never been reported and was named salcolin C (2). Salcolin B (1) and salcolin C (2) dose-dependently inhibited nitric oxide production in RAW 264.7 cells with IC50 values of 29.8 +/- 0.6 and 10.8 +/- 1.0 mu M, respectively, without visible toxic effect.