Antioxidant activity of some phenolic constituents from green pepper (Piper nigrum L.) and fresh nutmeg mace (Myristica fragrans)

Antioxidant potential of phenolic compounds from green pepper (Piper nigrum L.) and lignans from fresh mace (Myristica fragrans) were evaluated for their ability to scavenge 1,1′-diphenyl-2-picrylhydrazyl (DPPH) radical, inhibit lipid peroxidation and protect plasmid DNA damage upon exposure to gamma radiation. EC₅₀ values of the major phenolic compounds of green pepper namely, 3,4-dihydroxyphenyl ethanol glucoside, 3,4-dihydroxy-6-(N-ethylamino) benzamide and phenolic acid glycosides were found to be 0.076, 0.27 and 0.12 mg/ml, respectively, suggesting a high radical scavenging activity of these phenolics. These results were further confirmed with cyclic voltammetry. Acetone extract of nutmeg mace and its subsequent TLC isolated fractions constituted mainly of lignans as revealed by GC–MS analysis. The major compounds were tentatively identified from their mass spectral fragmentation pattern. DPPH radical scavenging capacity of the acetone extract as well as its fractions was comparatively lower than that of green pepper phenolics. In contrast, these fractions had a greater ability to inhibit lipid oxidation than phenolics from pepper as revealed by β-carotene–linoleic acid assay. A DNA protecting role of these compounds even at doses as high as 5 kGy further suggested the potential use of green pepper and fresh nutmeg mace and their extracts as a nutraceutical in preventing oxidative damage to cells.