The present work is designed to evaluate the antioxidant activities of hydroalcoholic extract (HAE) and its fractions (viz., hexane (HF), chloroform (CF), ethyl acetate (AF), n-butanol (BF) and water (WF)) obtained from aerial part of Rumex vesicarius L. by using different in vitro antioxidant assays. The content in pigments (carotenoids and chlorophylls), total phenolics, flavonoids and tannins were determined using spectrophotometric methods. Qualitative analyses of major phenolics by TLC analysis were also evaluated. Experimental results obtained show that R. vesicarius is a rich source of β-carotene (116.83 ± 1.60 μg/g DW), lycopene (156.40 ± 1.59 μg/g DW) and chlorophyll a (271.45 ± 3.46 μg/g DW). The greatest antioxidant activity was found in AF (IC50.DPPH = 0.07 ± 0.00 mg/ml) followed by BF and CF (0.15 ± 0.00 and 0.16 ± 0.00 mg/ml, respectively). These fractions were also better in their effect on reducing the oxidation of β-carotene. Reducing power of crude methanol extract/fractions increased with increasing concentration of the extract. The amount of total phenolics varied from 0.37 ± 0.01 to 43.28 ± 0.28 mg GAE/g of dry weight, HAE had the higher content (43.28 ± 0.28 mg GAE/g of DW). A negative correlation was found between phenolic compounds and the antioxidant efficiencies of the crude extract/fractions, suggesting that phenolic compounds are not the only contributors to the antioxidant activities of Rumex vesicarius. The present findings suggest that Rumex vesicarius L. can be used as natural antioxidant source to prevent damage associated with free radicals.
Keywords: Antioxidants; Phenolics; Pigments; Rumex vesicarius; TLC analysis.