Comparative Study on the Antibacterial Activity of Selected Medicinal Plants against Escherichia coli and Staphylococcus aureus Clinical Strains

Abstract

Antibiotic resistance is one of the most significant challenges of the 21st century, leading to increased global healthcare expenditure due to the necessity for more complex and expensive treatments. In response, researchers are investigating target product profiles as alternative antimicrobial sources capable of combating this prevalent issue. Medicinal plants used in traditional practices have emerged as promising candidates for developing new drug leads effective against antibiotic resistant bacteria. This study aims to evaluate the in vitro antibacterial activity of selected medicinal plants against common human pathogenic bacteria; Escherichia coli (ATCC® 25922™) and Staphylococcus aureus (ATCC® 29213™). The plant materials examined included Abelmoschus moschatus (leaves and stems), Aporosa cardiosperma (Gaertn.) Merr. (leaves and stems), Celosia argentea (leaves and flowers) and Nauclea orientalis (leaves and roots). A sequential extraction procedure using industrial solvents, methanol, ethyl acetate, nd hexane, was performed, followed by qualitative phytochemical analysis to identify secondary metabolites present in the extracts. Antimicrobial susceptibility was assessed using the EUCAST disk diffusion assay. As the main findings of the research, the methanolic crude extracts of all plants exhibited inhibitory effects on the proliferation and growth of both test microorganisms. Among all plant extracts, 400 µg/mL concentrated crude methanolic extracts of Nauclea orientalis leaves exhibited the highest zone of inhibition against Gram-negative E. coli (12.67±0.58 mm) and Gram-positive S. aureus (10.00±2.65 mm). Preliminary phytochemical screening of plant extracts was conducted using standard qualitative methods; Hager's test, foam test, alkaline reagent test, and Ferric chloride test revealed the presence of alkaloids, saponins, flavonoids, phenols, and tannins, respectively. The antibacterial activity was observed in the plant extracts may be caused by the presence of these secondary metabolites. Hence, his study emphasizes the potential of the selected medicinal plants as sources of novel antibacterial agents that can be further improved and developed for pharmaceutical applications against antibiotic resistant bacteria.