Antibacterial Effect of Gmelina Arborea Leaf Extracts on Pseudomonas Aeruginosa and Staphylococcus Aureus Clinical Isolates

Introduction: Pseudomonas aeruginosa and Staphylococcus aureus are bacterial species that have earned the reputation of “super bugs” due to their resistance to multiple classes of antimicrobial agents. The search for alternative therapies continues in the face of life-threatening infections caused by these organisms. Gmelina arborea, a deciduous tree native to the tropical regions of Asia, has been traditionally used in folk medicine for its potential therapeutic properties. Objectives: This study aimed to investigate the antibacterial activity of the ethanolic and aqueous extracts of Gmelina arborea leaves on P. aeruginosa and S. aureus isolates. The study also compared the antibacterial activity of the Gmelina arborea leaf extracts with those of commonly used antibiotics, which served as control. Methods: Clinical isolates were obtained from clinical samples. Fresh Gmelina arborea leaves were obtained and authenticated by a Botanist. Aqueous and ethanolic extracts were obtained using the Soxhlet extractor. Isolates were subjected to in vitro extract antibacterial testing in replicates using agar well diffusion method. One-way ANOVA was used to analyze for zones of inhibition. Results: Ethanolic leaf extract of Gmelina arborea at concentrations of 100mg/mL, 50mg/mL, 25mg/mL and 12.5mg/mL exhibited significant antibacterial activity with zone of inhibition diameters ranging from 30.2±0.2-17.1±0.14mm for P. aeruginosa and 28.5±0.15-16.0±0.17mm for S. aureus isolates. The MICs of ethanolic extracts varied between 3.125-6.25mg/mL and 6.25-12.5mg/mL while the MBCs were 6.25mg/mL and 12.5mg/mL for P. aeruginosa and S. aureus respectively. These results compared favourably with those of the standard antibiotic discs tested. In contrast, isolates were resistant to the aqueous extract. Conclusion: Ethanolic leaf extract of Gmelina arborea had antibacterial activity on P. aeruginosa and S. aureus. It could be a potential source of natural antimicrobial agents for the development of novel therapeutic strategies against P. aeruginosa and S. aureus infections.