Evaluation of the Antimicrobial Activity from Secondary Metabolites in Different Plant Families (Boraginaceae, Fabaceae, Lamiaceae, and Lauraceae)
For several decades, there has been an increased interest in the antimicrobial activities of different extracts obtained from traditional medicinal plants. There are more than 20,000 species of plants used in traditional medicines. Drugs can be derived from natural products, which are usually secondary metabolites and their derivatives. The increased prevalence of antibiotic-resistant bacteria emerging from the extensive use of antibiotics may render the current antimicrobial agents insufficient to control at least some bacterial infections. Therefore, the search for new antimicrobial agents is an important line of research. The objective of this study was to determine the antimicrobial activities of plant extracts from Sassafras albidum (Nutt.), Ehretia anacua (Terán & Berl.), Melissa officinalis (Linn.), Eysenhardtia texana (Scheele), and Melissa odorata. The ethanol and aqueous extracts were prepared for each of the five plant species and tested against Staphylococcus aureus, Pseudomonas aeruginosa, methicillin-resistant S. aureus, and vancomycin-resistant Enterococci faecium. The ethanol E. anacua extract was found to have a potential for anti-S. aureus activity. E. anacua was also subjected to soxhlet extractions with acetone, diethyl ether, and ethanol. These extracts were tested against S. aureus,
P. aeruginosa, Yersinia enterocolitica, Escherichia coli, Serratia marcescens, Candida albicans, Aspergillus niger, and Trichophyton mentagrophytes. The ethanol and diethyl E. anacua extracts were found to have anti-S. aureus activity. HPLC successfully isolated one major phytoconstitutent. Phytochemical analysis showed detectable presence of alkaloids and diterpenes in the ethanol and diethyl E. anacua extracts.