Saponins and Flavonoids from Ludwigia leptocarpa (Nutt) Hara (Onagraceae): Isolation, Characterization, Antibacterial and Antioxidant Activities
Florence Déclaire Mabou1 ,*, Jean-de-Dieu Tamokou2 , David Ngnokam1 , Dominique Harakat3 and Laurence VoutquenneNazabadioko4
Journal Title:Medical & Clinical Research
Diarrhea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. The most common microorganisms responsible for diarrhoeal diseases are Vibrio cholerae, Escherichia coli and Shigella spp. The present study aims to evaluate the antibacterial and antioxidant activities of extracts and compounds from Ludwigia leptocarpa, a plant traditionally used for its vermifugal, anti-dysenteric and antimicrobial properties. The MeOH extract was prepared by maceration from dried whole plant and successively extracted with ethyl acetate and n-butanol to obtain EtOAc and n-BuOH extracts respectively. The column chromatography of the EtOAc and n-BuOH extracts followed by purification of different fractions led to the isolation of six known compounds. Structures of isolated compounds were assigned on the basis of spectra analysis, and by comparison with those from the literature. The antioxidant activity was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. The antibacterial activity was assessed by performing minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) against the strains of Gram-positive bacterium, Staphylococcus aureus (a major cause of community and hospital-associated infection), and Gram-negative multi-drug resistant bacteria, Vibrio cholerae (causative agent of cholera) and Shigella flexneri (causative agent of shigellosis). All of the extracts showed different degrees of antioxidant and antibacterial activities. Compounds 2, 3 and 6 displayed the largest antibacterial and antioxidant properties which were in some cases equal or higher than those of reference drugs. The overall results of the present study shows that L. leptocarpa has potentials as a source of natural anti-diarrhoeal and anti-free radical products, given further investigations.