The chemosystematics of the genus Zanthoxylum L. (Rutaceae) in Kenya

Abstract

Abstract Background and aim There is currently a significant taxonomic confusion in the genus Zanthoxylum which has a wide application in Kenyan herbal medicine. The significance of proper identification/classification of medicinal plants is key in connecting the ethnobotanical uses with the existing chemical and biological knowledge. This study aims at solving the challenges encountered in the classification of Zanthoxylum species in Kenya using metabolomics as a tool for chemosystematics. Methods Five Zanthoxylum species (Z. chalybeum, Z. gilletii, Z. holtzianum, Z. paracanthum and Z. usambarense) were analyzed using metabolomics approach where LC-MS analysis was used to establish the chemical profiles of each species. Hierarchical cluster analysis was used to show the relationship among the Zanthoxylum spp studied. Results Based on phytochemical production, the five Zanthoxylum species segregated into two clusters; cluster one composed of Z. gilletii Z. usambarense and Z. paracanthum while Z. chalybeum and Z. holtzianum constituted cluster two. The chemical markers (discriminants) were identified as; laudanine, kalambroside A, kalambroside B, gamma-sanshool, ochotensine, cis-N-methylcanadine, 18-hydroxylinoleic acid, dihydrochelerythrine, N-feruloylglycine, p-coumaric acid ethyl ester, dihydroberberine and one unknown compound. Conclusions Chemometric analysis of relatedness of Zanthoxylum group of plants conformed to the current classical taxonomy of Zanthoxylum species in Kenya.