Antimicrobial activity of the methanolic leaf extract of Prosopis laevigata.

The appearance of antimicrobial-resistant pathogens has highlighted the need to search for new compounds that can effectively combat infectious diseases. A potential source of these compounds are the secondary metabolites of species that have been reported as effective traditional treatments of such diseases. Prosopis laevigata is a medicinal plant, and its chemical constituents have shown potential antimicrobial activity. In this study, the antimicrobial activities of the methanolic extract of the leaves of Prosopis laevigata against different bacterial and fungal strains of medical and agronomic interest were investigated in vitro. In addition, the chemical composition of this extract was investigated by HPLC-DAD, GC‒MS, and HPLC‒MS. The methanolic leaf extract contained 67 mg of GAE/g of total phenols (6.7%), 2.6 mg of QE/g of flavonoids (0.26%), and 11.87 mg of AE/g of total alkaloids (1.18%). Phenolic acids and catechol were the compounds identified by HPLC-DAD. The methanolic extract had strong antimicrobial activity, especially against Staphylococcus aureus (MIC = 0.62 mg/mL), Escherichia coli (MIC = 0.62 mg/mL), Candida tropicalis (MIC = 0.08 mg/mL) and Fusarium moniliforme (MIC = 4.62 mg/mL). These results suggest that the extract of P. laevigata leaves could be a source of antimicrobial molecules. However, it is necessary to delve into its chemical composition.