Investigation of antioxidant and antibacterial activities of Limnophila Aromatica (Ngò om) extract

Abstract

Limnophila aromatica has been locally used to treat fever and consumed as herb. It was known to contain large amount of phenolic compounds and flavonoids. In this work, the effects of solvent to water ratio and sample to solvent ratio on the extractability of total phenolics from Limnophila aromatica were tested. Chemical composition, the antioxidant scavenging and antibacterial activity of the extract was also investigated. The results show that the highest content of phenolic compounds was obtained when using an aqueous solution of 75% ethanol in water (v/v) and a ratio of sample to solvent of 1:100. The extract from Limnophila aromatica contained 10 major phenolic compounds which had high antioxidant capacity with %DPPH inhibition of 33.47% at concentration 156.25 µg/ml of phenolic extract, equivalent to capacity of 20 µg/ml ascorbic acid. The extract also had high inhibitory against two important pathogenic microorganisms, S. aureus and P. aeruginosa. As a result, L. aromatica can be considered as a natural source of phenolic compounds with good antibacterial and antioxidant capacity. Key words: Limnophila aromatica Phenolic compound Chemical composition Antioxidant activity Antibacterial activity