Hydroxyl radical-scavenging effects of spices and scavengers from brown mustard (Brassica nigra)

The effects of methanol extracts of 51 spices on . OH scavenging were studied in detail, 2-Deoxyribose oxidation and sodium benzoic acid hydroxylation methods were used for detecting the scavenging activity of . OH. Mustard varieties, thyme, oregano, clove, and allspice all exhibited strong . OH-scavenging activity, In particular, 3 varieties of mustard had above 90% . OH-scavenging activity with a 1 mu g/ml concentration of their extracts. The . OH scavenger of Brassica nigra (brown mustard) was isolated and purified by XAD-2 column chromatography and preparative HPLC, and was identified as a 3,5-dimethoxy-4-hydroxycinnamic acid methyl ester by MS, H-1-NMR, and C-13-NMR. The 3,5-dimethoxy-4-hydroxycinnamic acid methyl ester was prepared by methylating of sinapic acid with diazomethane.