In-vitro Antibacterial Activity of the 80% Methanolic Leaf Extract of Maytenus gracilipes (Welw. ex Oliv) Exell. (celastraciae) against Some Pathogenic Bacteria

Background: Challenges by drug-resistant bacteria have stimulated renewed interest in medicinal plants as a major source of new medicines. The leaf of Maytenus gracilipes has been used as ethnomedicine for the treatment of tonsillitis and ear infections in Ethiopia. However, its antimicrobial potential has not been evaluated. This study aimed to screen the antibacterial activities of M. gracilipes leaves. Methods: In this study, the antibacterial activities of crude methanolic leaf extract were tested against two Gram-positive and three Gram-negative bacteria using the agar well diffusion method at different concentrations (50 mg/ml, 100 mg/ml, and 200 mg/ml). Augmentin 0.3 mg/disc and Ciprofloxacin 0.05 mg/disc were used as a standard drug. The minimum inhibitory concentration of the crude extract was determined by the broth dilution method. A preliminary phytoconstituent analysis was also carried out. Results: The crude extract inhibited the growth of the tested bacteria in a concentration-dependent manner. Klebsiella pneumoniae and Escherichia coli were the most susceptible studied species. Promising antibacterial activities with the highest zone of inhibition (20 mm) were exhibited against K. pneumoniae at a concentration of 200 mg/ml. The highest dose of the extract was displayed zone of inhibitions against Staphylococcus aureus and K. pneumoniae without remarkable difference compared to the respective positive control. The MIC values of methanolic extract were ranged from 12.5 mg/ml to 25 mg/ml. The MBC values attained ranged from 25 mg/ml to 50 mg/ml. Conclusion: The extract showed a wide spectrum activity with better effect against Gram-negative bacteria. As such, the phytotherapeutic potential of this plant in treating bacterial infections should further be established through detailed in vitro and in vivo studies.