Phenolic compounds and antioxidant activities of Rumex hastatus D. Don. leaves

Abstract

In this study different solvent fractions (n-hexane, ethyl acetate, chloroform, butanol and aqueous) of the methanol extract of Rumex hastatus(RH) leaves were evaluated for antioxidant activities. The ethyl acetate fraction possessed high amount of total polyphenolics (106.3±3.93 mg GAE/g extract) while butanolic fraction was found with high flavonoid contents (59.8±1.94 mg RTE/g extract) as compared to other solvent fractions. Butanol fraction exhibited most promising DPPH (EC50 140±0.99 μg/ml), iron chelation (EC50 70±2.1 μg/ml) and for phosphomolybdate (EC50 31±1.25 μg/ml) scavenging activity. However, ethyl acetate fraction exhibited the highest scavenging potential for super oxide radicals (EC50 40±0.78 μg/ml), ABTS radicals (EC50 70±2.46 μg/ml), hydroxyl radicals (EC50 9±0.56 μg/ml) and inhibition of β-carotene linoleic acid peroxidation (EC50 54±5.67 μg/ml). Chloroform fraction showed the most potent antioxidant activities in scavenging of hydrogen peroxide (EC50 48±4.89 μg/ml). The high correlation coefficient was found between EC50 values of DPPH, superoxides, hydroxyl, hydrogen peroxide and ABTS radicals with total polyphenolic and flavonoids. HPLC studies of ethyl acetate fraction indicated the presence of luteolin (24.67±2.90 mg/g extract), kaempherol (17.03±1.67 mg/g extract), luteolin-7-O-glucoside (14.73±2.17 mg/g extract) and rutin (8.24±1.43 mg/g extract). Therefore, our study substantiated that RH leaves can be used as a good source of potential antioxidant or functional food material due to the presence of sufficient amount of phenolics such as luteolin and kaempherol. Key words: Rumex hastatus, antioxidant activity, flavonoids, phenolics, 2,2-diphenyl-1-picrylhydrazyl.