Superoxide radical scavenging and antibacterial activities of different fractions of ethanol extract of Mentha spicata (L.)

Mentha spicata is a well-known spice that has a variety of biological properties and is abundantly available throughout the world. This study was designed to investigate the superoxide radical scavenging and antibacterial properties of different fractions (hexane, chloroform, ethyl acetate, and aqueous) of the ethanol extract of Mentha spicata. In addition, xanthine oxidase generated uric acid inhibition, reducing potential and iron chelating activity, also was investigated. Ethyl acetate fraction exhibited the highest (≤84%) superoxide radical scavenging and inhibition of uric acid formation at 40 μg/ml compared with the standard quercetin (≤81%) at 30 μg/ml. The highest reducing potential also is observed in ethyl acetate and aqueous fractions, which were comparable to the reducing potential of quercetin and ascorbic acid. Iron chelating activity of solvent fractions was found to be better than standard of EDTA (79% at 3 mg/ml). In addition, all fractions showed effective antibacterial activity against five human pathogenic bacteria among the ten samples used. However, aqueous fraction showed maximum growth inhibition zone (≤36 mm diameter at 6 μg/per disc) against Shigella boydii. Hence, we conclude that the ethyl acetate and aqueous fractions of ethanol extract of Mentha spicata exhibited higher superoxide radical scavenging and antibacterial activities.