Seasonal GC-MS Profiling and in silico Screening of Vernonia amygdalina Metabolites against Angiotensin-Converting Enzyme and Arginase

Abstract

Hypertension remains a major global health burden, and plant-derived products continue to be investigated as sources of bioactive compounds. Vernonia amygdalina Delile has documented experimental cardiovascular and angiotensin-converting enzyme (ACE)-related activity, but the extent to which its chemical profile varies across seasonal collection periods is incompletely characterised. This exploratory study compared season-associated GC-MS profiles of V. amygdalina leaves and prioritised selected metabolites by physicochemical/ADMET prediction and molecular docking against an ACE structural homologue and human arginase 1. Leaves were collected from ten randomly selected V. amygdalina trees on one farm in Ogbomoso, southwestern Nigeria, (8.133º North, 4.267º East) during pre-wet (March-May), wet (June-August), dry (September-November), and harmattan (December-February) periods of the year 2024. Methanolic extracts were analysed by GC-MS and library-matched peaks were treated as putative annotations. Sixty-seven compounds were carried forward to physicochemical and ADMET screening using ADMETLab 2.0, and selected compounds were docked with AutoDock Vina. PDB 2X8Z (Drosophila melanogaster AnCE) and PDB 6V7C (human arginase 1) were used as the structural targets. Seasonal comparisons were descriptive due to the unavailability of replicate-level inferential testing. The presented GC-MS tables contain 30 pre-wet, 22 wet, 18 dry, and 31 harmattan peak entries, with benzoic acid methyl ester and eugenol being the only two compounds detected in the four seasons. Among the prioritised plant metabolites shown for ACE docking, chondrillasterol had the most negative reported score (-8.5 kcal/mol), while captopril, a reference antihypertensive drug included in the screening, scored -5.5 kcal/mol. For arginase, cyclopentadecanone, 2-hydroxy- had the most negative displayed plant-metabolite score (-6.2 kcal/mol) surpassing the two reference antihypertensive drugs; indapamide and captopril screened along with the ligands. The data indicate season-associated differences in the putatively annotated chemical profile of V. amygdalina and identify compounds for subsequent experimental testing. Meanwhile, the docking values are computational rankings rather than evidence of biochemical inhibition, and the findings does not correspond to clinical antihypertensive efficacy. Confirmation requires orthogonal analytical identification and target-appropriate biochemical research.