Phytochemical Composition and Antimicrobial Activity of Combined Stem, Leaf and Root Extracts of Anogeissus leiocarpus Against Selected Pathogenic Microorganisms

Antimicrobial resistance limits the efficacy of conventional antibiotics, prompting interest in medicinal plants as potential sources of antimicrobial agents. This study evaluated the phytochemical composition and antimicrobial activity of combined stem bark, leaf, and root extracts of Anogeissus leiocarpus collected from Girei Local Government Area, Adamawa State, Nigeria. The combined plant material was extracted separately with ethanol and distilled water using cold maceration. The resulting ethanolic (EECPP) and aqueous (AECPP) extracts underwent qualitative and quantitative phytochemical screening. Antimicrobial activity was assessed against Staphylococcus aureus, Salmonella typhi, Candida albicans, and Aspergillus niger using agar well diffusion and minimum inhibitory concentration (MIC) determination. Alkaloids, flavonoids, phenolics, tannins, saponins, phytosteroids, and anthraquinones were detected in both extracts, whereas glycosides, coumarins, and triterpenoids were not detected. AECPP contained higher concentrations of flavonoids (4.53 mg/g) and tannins (0.381 mg/g), while EECPP contained higher concentrations of alkaloids (39.88 mg/g) and total phenolics (0.98 mg/g). Saponin and steroid levels were similar between extracts. Across all four microorganisms, EECPP consistently produced larger inhibition zones and lower MICs than AECPP. The largest inhibition zone was observed against C. albicans at an extract concentration of 400 mg/mL (26.77 mm); this organism also exhibited the lowest MIC (3.125 mg/mL). These findings indicate that ethanol was more effective than water in extracting antimicrobial constituents from the combined plant parts. The results provide preliminary experimental support for the traditional use of A. leiocarpus against infectious diseases and highlight its potential as a source of plant-derived antimicrobial agents.