Hydroxyl Radical-scavenging Effects of Spices and Scavengers from Brown Mustard (<i>Brassica nigra</i>)

TLDR

Methanol extracts of 51 spices were screened for hydroxyl‑radical scavenging using 2‑deoxyribose oxidation and sodium benzoate hydroxylation assays, and the active compound from brown mustard was isolated by XAD‑2 chromatography and preparative HPLC, identified by MS, ^1H‑NMR, and ^13C‑NMR, and synthesized by methylating sinapic acid with diazomethane. Several spices, notably three brown mustard varieties, exhibited strong hydroxyl‑radical scavenging, with the mustard extracts achieving over 90 % activity at 1 µg ml⁻¹, and the active agent was identified as 3,5‑dimethoxy‑4‑hydroxycinnamic acid methyl ester.

Abstract

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 μg/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-NMR, and 13C-NMR. The 3,5-dimethoxy-4-hydroxycinnamic acid methyl ester was prepared by methylating of sinapic acid with diazomethane.