Antimicrobial effect of the methanolic extract of the heartwood of Gliricidia sepium (jacq.) kunth ex Walp.

The demand for organic products is increasing due to their availability, fewer side effects, affordability, lower bacteria resistance, and high tolerance, making them preferable to synthetic drugs. Gliricidia sepium has been established to be one of the sources of herbal medicines in the primary health care sector, which is useful in various ways. This study examined the chemical constituents present in the crude heartwood extract of G. sepium using Fourier transfer infrared spectroscopy (FTIR), emphasizing its antibacterial activity. Methanolic extract of the heartwood of G. sepium was evaluated against two gram-negative bacteria strains ( Escherichia coli and Pseudomonas aeroginosa ) and two gram-positive bacteria strains (Staphyloccocus aureus and Bacillus sp) using the agar diffusion method. This method was used to measure the antibiotic resistance of the extract against bacteria growth. The standard antibiotics used as positive control include chloramphenicol and levofloxacin. The extract showed significant activity on all the tested bacteria, with it being highest against Pseudomonas aeruginosa (27-33mm) and Staphylococcus aureus (23-28mm). Although the methanolic heartwood extract activity on E. coli and Bacillus cereus was comparable with the standard antibiotics screened under similar conditions, E. coli was resistant to the two standard antibiotics with an inhibition zone lower than (10mm). In contrast, the heartwood extract had a higher effect than the standard antibiotics on Pseudomonas aeruginosa. In addition, the heartwood extracts of G. sepium possessed greater antibacterial activity over the standard antibiotics used. The results suggested that the extractive content in the heartwood of G. sepium is rich in valuable primary and secondary metabolites exhibiting antibacterial activities. Due to the emergence of antibiotic-resistant pathogens, plants are being looked upon as an excellent alternative to combat the spread of multi-drug-resistant microorganisms. Hence, G. sepium may be considered as one such alternative.