Antibacterial activity and acute toxicity effect of flavonoids extracted from Mentha longifolia.

Abstract

Abstract: The methanolic and ethanolic extracts of Mentha longifolia were tested for their antimicrobial activity against some clinical bacteria. Then, a phytochemical screening was realized for the ethanolic extract and the acute toxicity was measured for the identified flavonoids present in it. The results showed that the ethanolic extract was the most active against the tested bacteria. The phytochemical screening of this extract indicated that it contained mainly five flavonoids identified as luteolin-7-O-glycoside, luteolin-7,3’-O-diglycoside, apigenin, quercetin-3-O-glycoside and kaempferol-3-O-glycoside. Among these molecules, the quercetin-3-O-glucoside had the highest antibacterial activity, but the synergism between the apigenin, the quercetin-3-O-glycoside and the kaempferol-3-O-glycoside gave the best minimal inhibitory concentration for each tested species. The quercetin-3-O-glucoside had also the best acute toxicity effect on mice. The substitution type of flavonoids had and impact on the antibacterial activity but not on the acute toxicity effect.