Systematic Phytochemical and Pharmacological Characterisation of the Genus Combretum in Nigeria: Building a National Chemotaxonomic Reference Database

The genus Combretum is one of the most pharmacognostically significant and medicinally utilised plant genera in Nigeria, with over 30 species distributed across the country's diverse phytogeographical zones from the Sahel savannah in the North to the rainforest belt in the South. Despite this significance, no systematic, multi-species chemotaxonomic characterisation and comparative pharmacological database exists for Nigerian Combretum populations. This research builds the first comprehensive national chemotaxonomic reference database for the Nigerian Combretum genus by integrating morphological taxonomy, molecular phylogenetics, untargeted metabolomics, and multi-endpoint pharmacological screening across 12 Combretum species collected from representative phytogeographical zones in all six geopolitical regions. Morphological vouchers were deposited in six regional herbaria. Species were authenticated by matK and rbcL DNA barcoding. Untargeted UHPLC-QTOF-MS/MS metabolomic profiling was performed on leaf and root bark extracts. Molecular networking via GNPS resolved 284 metabolite clusters, including ellagitannins, flavonoids, terpenoids, and unique sulphated flavone glycosides. Pharmacological screening encompassed antimicrobial, antiplasmodial, anti-inflammatory, and antioxidant activity panels across all 12 species extracts. Chemotaxonomic clustering showed strong species separation based on ellagitannin and terpenoid profiles. Combretum aculeatum from North East and Combretum glutinosum from North West demonstrated the most potent antimicrobial and antiplasmodial activity. A novel triterpenoid from Combretum zenkeri was isolated and characterised. The resulting Nigerian Combretum Chemotaxonomic Database is proposed as a freely accessible resource for future natural product and biodiversity research. Keywords: Combretum, chemotaxonomy, metabolomics, Nigeria, national database