Antibacterial activity of lotus leaves (Nelumbo nucifera) against food-borne pathogens

Abstract

The antibacterial activity of different solvent extracts from lotus leaves against four food-borne bacteria (Escherichiacoli, Salmonellatyphimurium, Staphyloccocusaureus, Bacillussubtilis) was analyzed by agar diffusion method and the ethanol extract of the plant was found to have the highest antimicrobial activity with the diameter of inhibition zones ranging from 17.2 to 17.8 mm. Then the ethanol extract of lotus leaves were further separated by MCI-gel column and the antibacterial activity were investigated viamacrodilution broth method. Furthermore, preliminary phytochemical test were also carried out. Fraction 3 eluted from MCI-gel was found to have highest antibacterial activity with the minimum inhibitory concentration and minimum bactericide concentration values in the ranges of 0.0313~0.125 g mL-1 and 0.0626~0.25 g mL-1, respectively. Antifungal activity analysis showed that ethanol extract of lotus leaves had a low inhibitory activity against all fungi. The result of the phytochemical analysis of the extract showed the presence of phenolic compounds, flavones and alkaloids which may be responsible for its antibacterial activity. Furthermore, lotus leaves extract was observed to have a better antiseptic capacity than sodium benzoate in apple juice (preservative used in food). Therefore, lotus leaves may be used as a botanical natural food preservative against food-borne pathogens.