Antibacterial Activity of Ethanolic Extracts of Acacia nilotica var. adansonii (Pods and Bark) against Pathogenic Bacteria: A Promising Therapeutic Alternative in Chad

Abstract

Aims: Acacia nilotica var. adansonii is a medicinal plant widely used by Chadian populations to treat various ailments, including bacterial and fungal infections. Despite this widespread traditional use, few scientific studies have confirmed its antibacterial properties. The present study aimed to evaluate the antibacterial activity of ethanolic extracts from the pods and bark of this plant and to identify the secondary metabolites responsible for this activity. Methodology: Pods and bark of Acacia nilotica var. adansonii were collected in Abéché (Chad), dried, powdered, and extracted by ethanolic maceration. Antibacterial activity was assessed against five pathogenic strains (Escherichia coli, Staphylococcus aureus, Bacillus cereus, Shigella spp. and Salmonella enteritidis) using the agar diffusion method and broth microdilution to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). Results: Ethanolic extraction yielded 62.47% for the pods and 22.93% for the bark. Inhibition zone diameters ranged from 13.66 ± 0.57 to 15.00 ± 1.41 mm for the pods and from 12.00 ± 1.00 to 14.66 ± 2.56 mm for the bark. MIC values ranged from 0.39 to 1.56 mg/mL for the pods and from 0.19 to 1.56 mg/mL for the bark. MBC/MIC ratios revealed a bactericidal effect (MBC/MIC < 4) for most strains, with an MBC/MIC ratio of 1 for the bark against E. coli, Salmonella enteritidis, and Shigella spp. Phytochemical tests highlighted the combined presence of polyphenols, flavonoids, and gallic tannins in both extracts. Conclusion: These results scientifically confirm the traditional use of this plant and justify further investigations towards the development of phytomedicines.