Study of the antimicrobial activities of <i>Solanum indicum</i> ssp. distichum (Schumach. and Thonning 1827) fruits (“gnangnan” berries) from a tropical humid zone (Côte d’Ivoire)

Abstract

The antibacterial activity of both aqueous and ethanolic extracts of Solanum indicum ssp. distichum (Schumach. and Thonning, 1872) fruits was investigated. These extracts were evaluated for antibacterial activity against two Gram positive (Listeria innocua LRGIA 01 and Staphylococcus aureus CNRZ3) and two Gram negative (Escherichia coli industrial strain and Pseudomonas aeruginosa ATCC 15742) strains. This evaluation was performed by following their growth by a spectrophotometric method in Brain Heart Infusion broth. L. innocua LRGIA01growth was completely inhibited by 0.04 g.mL-1 of aqueous extract of Solanum indicum berries, while a dose-dependent inhibition by 0.04 g.mL-1 and 0.1 g.mL-1 ethanolic extracts was observed. Conversely, the inhibitory activity of ethanolic extract on P. aeruginosa ATCC 15742 growth, was higher than that of aqueous extract. E. coli industrial strain and S. aureus CNRZ 3 growth were inhibited by 0.1 mg.mL-1 ethanolic extract but not by 0.04 mg.mL-1 ethanolic or aqueous extracts. These results suggest that different classes of compounds are likely responsible for the antibacterial activities. The high inhibitory activity of aqueous and ethanolic extracts on L. innocua LRGIA01 and P. aeruginosa ATCC 15742 strains, respectively calls for further studies to identify the antibacterial compounds present in Solanum indicum berries and their mechanisms of action.