In-Vitro Antioxidant Activity and Acute Toxicity of the Alkaloidal Constituents of Zanthoxylum zanthoxyloides Leaves

Abstract

The roles of plant-derived products in the management of diseases and their safety cannot be overemphasized. In several cases, these plants are used in ethnomedicine without regard to their toxicity. The study evaluated the antioxidant activities of both methanol (MeOH) extract and the bulk alkaloidal fraction of Zanthoxylum zanthoxyloides leaves and determined their median lethal dose in mice. The extract was subjected to solvent-solvent partitioning to obtain the bulk alkaloids from the methanol extract. The antioxidant activity of both the methanol extract and the bulk alkaloid fraction was measured in-vitro using DPPH radical scavenging; FRAP assays, as well as total antioxidant capacity (TAC) quantitation models. The MeOH extract (IC 50 40.22 mg/L; EC 50 32.08 µg/mL) and bulk alkaloid fraction (IC50 19.46 mg/L; EC50 30.27 µg/mL) showed significant (p < 0.05) antioxidant activities comparable with ascorbic acid (IC50 20.62 mg/L; EC50 32.51 µg/mL). The methanol extract and alkaloid fraction are relatively safe. No death was recorded on the mice upon oral administration of the extract/fraction at maximum dose of 5000 mg/kg. In conclusion, alkaloids constituents of Z. zanthoxyloides leaves have the potential to mop up free radicals in-vitro suggesting its high antioxidant potentials.