Phytochemical analysis and antimicrobial activity of bitter leaf (Vernonia amygdalina) collected from Lapai, Niger State, Nigeria on some selected pathogenic microorganisms

Abstract

Vernonia amygdalina called ‘Shuwaka’ in Hausa is commonly used to treat stomach-ache and gastrointestinal troubles in Northern Nigeria ethno- medicine. This study was aimed to verify the claimed antimicrobial activity of V. amygdalina collected from Lapai, Niger State, Nigeria and analyse its phytochemicals. Phytochemical investigation and studies on antimicrobial activity of stem barks and roots extract of V. amygdalina were carried out on Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger using agar-well diffusion assay. Preliminary phytochemical screening revealed the presence of alkaloids, steroids, glycosides, flavonoids, tannins, saponins, phlobatannins, and phenolics in the stem bark and roots extract. The largest diameter of inhibition zone was observed on the acetone extract of stem bark against S. aureus (16 mm) and P. aeruginosa (16 mm). All the tested pathogens were resistant to the water extract of stem bark and root, except for S. aureus which showed inhibitory activity with 7 mm diameter of inhibition zone on stem bark extract. The outcomes of this work suggest the presence of pharmacologically active compounds in the extracts with antimicrobial activity against the pathogenic strains which justifies its ethno- medicinal use.

Keywords: Vernonia amygdalina, phytochemical, antimicrobial activity, pathogens