The comparison of DPPH-scavenging capacity and anti-inflammatory effects of phenolic compounds isolated from the stems of Stewartia koreana Nakai.

The Stewartia koreana Nakai (SK) had been used in oriental traditional medicine as a remedy for acute gastroenteritis, liver diseases, quadriplegia and pain. The antioxidant activity guided isolation 80% methyl extract from stems of SK yielded eight phenolic compounds. We evaluated the anti-oxidative and anti-inflammatory effects of these compounds via assays of 1,1-diphenyl-2-picrylhydazyl (DPPH) radicals and inhibition of nitric oxide (NO) production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. The results demonstrated that syringaresinol (6) exhibited significant DPPH radical-scavenging activity and inhibitory effects on NO production compared with its positive controls, ascorbic acid and L-NMMA, respectively.