Isolation and identification of bioactive compounds responsible for the anti-bacterial efficacy of Lotus corniculatus var. S o Gabriel

Lotus corniculatus (Fabaceae) is considered a forage plant utilized as food for ruminants in the south of Brazil. This herb is also actually used to treat intestinal infection in these animals. In our experiments, we evaluated the anti-bacterial activity of crude extract from L. corniculatus var. Sγo Gabriel were assayed against Gram-positive and Gram-negative bacterium. The crude extracted did not show any anti-bacterial activity, but the hexane fraction did on Bacillus cereus (MIC=100 μg/mL) and on Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Acinetobacter calcoaceticus, and Providencia alcalifaciens (MIC=600, 800 or 1000 μg/mL). The Ethyl acetate fraction (AcOEt) also showed important anti-bacterial activity on Bacillus cereus, E. faecalis, and Acinetobacter calcoaceticus (MIC=800 μg/mL). The oleanolic acid isolated from hexane fraction showed the same effect on Staphylococcus aureus methycillin-resistant (MIC=100 μg/mL), L. monocytogenes (MIC=25 μg/mL), and Bacillus cereus (MIC=25 μg/mL). Further, Kaempferitrin isolated from ethyl acetate fraction has also shown anti-bacterial activity on Shighella flexinerii (MIC=100 μg/mL), Salmonella typhimurium (MIC=100 μg/mL), A. calcoaceticus (MIC=100 μg/mL), E. faecalis (MIC=3.9 μg/mL), and Bacillus cereus (MIC=8.5 μg/mL). This study suggests that L. corniculatus var. Sγo Gabriel have potential pharmacological property for a new anti-bacterial drug development.