Terminalia avicennioides root bark extract: A promising phytotherapeutic agent against methicillin-resistant Staphylococcus aureus hospital strains

Purpose: To investigate the antibacterial activity of a partially purified ethyl acetate fraction obtained from methanol extract of the root bark of Terminalia avicennioides (Family: Combretaceae) against a hospital strain of methicillinresistant Staphylococcus aureus (MRSA).Methods: Gas chromatography-mass spectrometry (GC-MS) was used to identify and characterize compounds in the bioactive fraction of T. avicennioides root bark, while Fourier Transform Infrared (FTIR) spectroscopy was used to elucidate the functional groups. The MRSA hospital strain was isolated from a clinical sample and the isolate biochemically characterized by colonial morphology, Gram staining, and strain reaction. Resistance to methicillin/oxacillin was confirmed by repeat susceptibility testing using oxacillin. The antibacterial efficacy of the fraction was compared with those of standard antibiotics including meropenem, amoxiclav, nitrofurantoin, ceftriaxone, nidof, and ciprofloxacin. Antimicrobial activity was evaluated using agar well diffusion method, while the minimuminhibitory concentration (MIC) was determined using a 10-fold serial broth dilution assay.Results: Mass spectrometry analysis revealed that the ethyl acetate fraction with anti-MRSA activity comprised a mixture of seven compounds in varying proportions, viz: n-hexadecanoic acid, 11-octadecenoic acid, oleic acid, octadecanoic acid, 3,11-tetradecadien-1-ol, 9-octadecenal, and (9Z)-9-tetradecenal. The FTIR spectra indicated the presence of alkyl halides. At 100 μg/mL, the ethyl acetate fraction exhibited a bacteriostatic effect, with a minimum bactericidal concentration (MBC) of 9.48 ± 0.90 μg/mL. Based on Kirby-Bauer standard, it demonstrated bactericidal activity (MBC) at 150 μg/mL, with mean inhibition zone diameter of 14 mm.Conclusion: The synergistic action of the seven identified compounds in the bioactive fraction may offer a promising foundation for developing novel drug candidates with potent bactericidal activity against hospital-acquired MRSA strains.