PHYTOCHEMICAL AND ANTIBACTERIAL ACTIVITY OF ANOGEISSUS LEIOCARPUS EXTRACTS AGAINST SALMONELLA ENTERICA AND VIBRIO CHOLERAE ISOLATED FROM DIARRHOEIC STOOL OF PATIENTS ATTENDING GENERAL HOSPITAL, MINNA, NIGER STATE

This study evaluated the phytochemical constituents and antibacterial activity of Anogeissus leiocarpus leaf and stem-bark extracts. Plant materials were collected, air-dried, pulverized, and extracted with methanol, distilled water, and n-hexane using cold maceration and their phytochemical composition determined. Antibacterial activity against Salmonella enterica serovars Typhimurium and Heidelberg, and Vibrio cholerae was assessed by agar well diffusion, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for active extracts. Phytochemical screening revealed the presence of phenols, flavonoids, tannins, alkaloids, phlobatannins, steroids, and terpenoids. The aqueous and methanol leaf extracts exhibited the significant inhibition against Salmonella enterica serovars Typhimurium (24.00 mm and 23.00 mm) and Heidelberg (25.00 mm and 24.00 mm) at 40 mg/mL. Vibrio cholerae was less susceptible, with maximum inhibition zones of 8.00 mm (aqueous extract) and 5.00 mm (methanol extract). Stem bark extracts were generally inactive, except the n-hexane extract, which produced zones of 23.00 mm against (S. Typhimurium) and 30.00 mm (S. Heidelberg) at 40 mg/mL. Fractionation yielded three fractions (FA1–FA3). At 20 mg/mL, FA1 was most effective against S. Heidelberg (17.00 mm), while FA2 was more active against S. Typhimurium (14.00 mm). FA3 showed weak inhibition, limited to V. cholerae (5.00 mm). The MIC values further showed FA2’s potency (5.0 mg/mL for S. Typhimurium), while FA1 and FA2 inhibited S. Heidelberg and V. cholerae at 10.0 mg/mL. The MBC of FA1 and FA2 ranged between 10.0-20.0 mg/mL, whereas FA3 showed activity only against V. cholerae (MBC 5.0 mg/mL). These results validate the traditional use of A. leiocarpus as a source of bioactive compounds and a plant-based therapeutic agent against Gram-negative enteric pathogens.