Metabolomics-Guided Identification of Bioactive Compounds in Rauwolfia vomitoria from Multiple Nigerian Phytogeographical Zones

Rauwolfia vomitoria is a pharmacognostically significant plant distributed across the rainforest and forest-savannah transition zones of Nigeria, used traditionally for hypertension, psychosis, and fever. Reserpine, its principal alkaloid and antihypertensive compound, was historically among the first plant-derived cardiovascular drugs. Despite this significance, metabolomic characterisation of Nigerian Rauwolfia vomitoria populations across diverse phytogeographical zones is unavailable. This study applies untargeted metabolomics to comprehensively characterise and compare the metabolite profiles of Rauwolfia vomitoria root bark collected from Edo (South South), Ondo (South West), and Enugu (South East) States. Root bark methanol extracts were analysed by UHPLC-QTOF-MS/MS, and data were processed using MZmine 3 and GNPS molecular networking. Multivariate statistical analysis (PCA, OPLS-DA) identified discriminating metabolites across phytogeographical populations. A total of 127 putative metabolites were detected, including 18 indole alkaloids, 22 phenolic acids, and 14 terpenoids. Reserpine, ajmaline, serpentine, and yohimbine were quantified in all populations; significant quantitative inter-population differences were observed in reserpine and ajmaline content. The Edo State population showed the highest total alkaloid content. Molecular networking revealed two previously unreported alkaloid features in the Ondo population. This metabolomics framework advances chemotaxonomic understanding of Nigerian Rauwolfia vomitoria and provides standardisation guidance for medicinal product sourcing. Keywords: Rauwolfia vomitoria, metabolomics, UHPLC-QTOF-MS, alkaloids, chemotaxonomy