Phytochemical screening, Lc–Ms characterization and antimicrobial activity of Vernonia Kotschyana stem extract

Abstract

Medicinal plants remain important sources of structurally diverse natural products with potential pharmaceutical applications. This study investigated the phytochemical composition, LC–MS profile, and antimicrobial activity of the ethanolic stem extract of Vernonia kotschyana, a medicinal plant traditionally used in the management of inflammatory disorders, gastrointestinal disturbances, and infections. Fresh stems of V. kotschyana were collected, authenticated, shade-dried, pulverized, and extracted by maceration in ethanol. Preliminary phytochemical screening was carried out using standard qualitative procedures, while chemical profiling was performed by liquid chromatography–mass spectrometry (LC–MS). Antimicrobial activity was evaluated against selected clinical pathogens using standard microbiological assays. Phytochemical screening revealed the presence of tannins, flavonoids, saponins, phenols, terpenoids, and alkaloids in the ethanolic stem extract. LC–MS analysis demonstrated a chemically diverse metabolite profile comprising geranylhydroquinone, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-3,4-dihydro-2H-1-benzopyran-4-one, 5,7-dihydroxy-2-(4-hydroxyphenyl)-6,8-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one, reserpine, isoelaeocarpicine, 4-tert-butylcatechol, andrastin A, (−)-epicatechin, and nodakenin. These compounds belong to important phytochemical classes, including hydroquinones, flavanonols, flavanones, alkaloid-related compounds, catechol derivatives, meroterpenoids, flavanols, and coumarin glucosides, many of which are associated with antioxidant, anti-inflammatory, and antimicrobial activities. The extract exhibited inhibitory activity against the tested clinical pathogens, indicating the presence of bioactive constituents with antimicrobial potential. The observed antimicrobial effect may be attributed to the combined action of flavonoids, phenolic compounds, alkaloid-related metabolites, and other redox-active constituents identified in the extract. Overall, the findings provide chemical and biological support for the ethnomedicinal relevance of V. kotschyana stem and highlight its potential as a source of natural bioactive compounds for antimicrobial and medicinal chemistry applications.