Comparative Phytochemistry of Moringa oleifera Leaves from Three Agroecological Zones of Nigeria and Implications for Pharmaceutical Standardisation

Moringa oleifera is one of Nigeria's most nutritionally and pharmacologically significant plants, cultivated across diverse agroecological zones from the humid South to the Sahel belt of the North. Geographical variation in climate, soil composition, and agricultural practices may significantly influence the phytochemical composition of leaves from different regions. This comparative study characterised the phytochemical composition of M. oleifera leaves sourced from Kebbi State (Sudan Savanna zone), Nasarawa State (Guinea Savanna zone), and Imo State (Humid Rainforest zone). Standardised fresh leaf samples were collected from five farms in each zone, dried at 45 degrees Celsius, and powdered. Total phenolic content, total flavonoid content, and total glucosinolate content were quantified by validated spectrophotometric methods. Individual phenolic acids were profiled by RP-HPLC. Proximate composition and mineral content were also determined. Significant differences were found in total phenolic content across the three zones, with Guinea Savanna samples from Nasarawa showing the highest values at 68.4 mg GAE/g dry weight. Quercetin was the dominant flavonoid in all zones but was present at 1.9-fold higher concentration in Nasarawa samples compared to Imo State samples. Glucosinolate content was highest in Kebbi State samples. These findings confirm that Moringa leaf phytochemical composition is significantly influenced by agroecological origin, with important implications for standardisation protocols to be applied in pharmaceutical product development from Nigerian Moringa sources. Keywords: Moringa oleifera, phytochemistry, agroecological variation, standardisation, comparative analysis.