Phytochemical Composition and Antibacterial Activity of Cnidoscolus Aconitifolius (CHAYA) Leaf Methanolic Extract Against Selected Pathogenic Bacteria

Abstract

This study investigated the phytochemical composition and antibacterial activity of methanolic leaf extract of Cnidoscolus aconitifolius against selected pathogenic bacteria. Qualitative phytochemical screening was conducted to identify the major classes of secondary metabolites present in the extract. Antibacterial activity was evaluated against Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa and Klebsiella pneumoniae using the agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were also determined. The results revealed the presence of alkaloids, tannins, flavonoids, saponins and cardiac glycosides, while steroids and terpenoids were absent. The extract demonstrated concentration-dependent antibacterial activity, with K. pneumoniae showing the highest susceptibility, recording an inhibition zone of 29 mm at 200 mg/ml. E. coli, S. typhi and P. aeruginosa recorded maximum inhibition zones of 28, 24 and 20 mm, respectively. The MIC values were 50 mg/ml for K. pneumoniae, 100 mg/ml for E. coli and S. typhi, and 200 mg/ml for P. aeruginosa. The MBC/MIC ratios ranged from 1.0 to 2.0, indicating a bactericidal mode of action. Ciprofloxacin (10 µg) produced inhibition zones ranging from 28 to 34 mm against the test organisms. The findings demonstrate that methanolic leaf extract of C. aconitifolius possesses broad-spectrum bactericidal activity against Gram-negative pathogens. The observed activity may be associated with the presence of alkaloids, flavonoids, tannins and saponins. Further studies involving isolation and characterisation of the active compounds and toxicity evaluation are recommended to establish its potential for antibacterial applications.