Chemotypic Variation of Nigerian Cannabis sativa Across Five Geopolitical Zones
Cannabis sativa L. remains Nigeria’s most widely cultivated and consumed illicit drug, yet its chemical characterization has remained largely unexplored due to legislative restrictions. This study presents the first comprehensive pharmacognostic and chemotypic evaluation of C. sativa samples collected from five geopolitical zones of Nigeria through the National Drug Law Enforcement Agency (NDLEA). Samples from Kaduna (North West; farm-cultivated and trafficker-confiscated), Adamawa (North East), Edo (South South), Enugu (South East), and Ondo (South West) were subjected to comparative pharmacognostic analysis including macroscopic/microscopic evaluation, physicochemical standardization, phytochemical screening, and cannabinoid profiling using Thin Layer Chromatography (TLC), High Performance Liquid Chromatography (HPLC), and Gas Chromatography-Mass Spectrometry (GC-MS).
Results revealed significant chemotypic variation among regions while maintaining core pharmacognostic identity. Quantitative microscopy parameters remained within acceptable ranges (stomata index 16.98-18.09%; palisade ratio 6.15-7.1) with no statistically significant regional differentiation. However, physicochemical constants showed marked variation, with the Edo sample exhibiting consistently elevated values distinguishing it from others. Phytochemical screening demonstrated uniform presence of carbohydrates, cardiac glycosides, and phenols across all samples, while flavonoids, tannins, and anthraquinones showed variable distribution. Saponins were uniformly absent.
Cannabinoid profiling revealed the most striking chemotypic diversity. HPLC quantification using cannabidiol (CBD) reference standard showed CBD concentrations ranging from 17.41 mg/g (Ondo) to 30.54 mg/g (Edo). GC-MS confirmed the presence of Δ⁹-tetrahydrocannabinol (THC) in samples from multiple regions, with the Ondo sample exhibiting the most diverse profile containing CBD, cannabichromene (CBC), THC, and cannabinol (CBN). The trafficker-confiscated sample from Kaduna showed close phytochemical and chromatographic similarity to the Ondo sample, suggesting potential southern origin of cannabis trafficked to northern Nigeria.
This study establishes baseline pharmacognostic data for Nigerian C. sativa and demonstrates that regional chemotypic variation can be exploited for forensic source attribution. The findings have significant implications for law enforcement, medicinal cannabis development, and evidence-based policy formulation in Nigeria’s evolving drug control landscape.
Keywords: Cannabis sativa, chemotype, pharmacognosy, Nigeria, cannabinoids, geographic variation, forensic science
