Biotransformation products of phellopterin by rat liver microsomes and the inhibition on NO production in LPS-activated RAW264.7 cells

Four new coumarins (2′,3′-dihydroxyphellopterin, E-5-methoxytrichoclin acetate, Z-5-methoxytrichoclin acetate, and E-5-methoxytrichoclin) and three known coumarins (byakangelicol, byakangelicin, and Z-5-methoxytrichoclin) were produced by liver microsomes from rats pre-treated with sodium phenobarbital. The chemical structures were elucidated on the basis of their spectroscopic data. The inhibitory activities of nitric oxide (NO) production in lipopolysaccharide-activated macrophage-like cell line RAW264.7 were tested. The main biotransformation product, byakangelicin, showed inhibitory activities of NO production with the IC50 value of 217.83 μM, whereas the parent compound phellopterin showed cytotoxic effect on RAW264.7 cell at the concentration from 40 to 400 μM.