ISSN 2462-2052 DOI: https://doi.org/10.37134/jsml.vol11.1.4.2023 Journal of Science and Mathematics Letters Volume 11, Issue 1, 30-38, 2023 30 | Page RESEARCH ARTICLE Comparative Phytochemical and Antioxidant Analysis of the Leaf Extracts of Two Nigerian Medicinal Plants Afolayan Michael Olalekan Chemistry Advanced Research Centre, Sheda Science and Technology Complex (SHESTCO), P.M.B. 186, Garki, Abuja, Nigeria *Corresponding author: mo.afolayan@shestco.gov.ng Received: 17 January 2023; Accepted: 21 February 2023; Published: 28 February 2023 ABSTRACT Bridelia ferruginea (Benth., Euphorbiaceae), prominently found in Savannah regions, is commonly used as an ethnomedicine for the treatment of several ailments in many parts of Africa. Piliostigma thonningii (Schum., Fabaceae) is used for various medicinal purposes in African countries with some pharmacological activities established from the crude extracts including antibacterial, antihelminthic, antiinflammatory and antilipidemic activities. In the present study, crude methanolic extract and fractions of B. ferruginea and P. thonningii were examined for their phytochemical constituents and antioxidant activity using standard protocols. Qualitative phytochemical screening of B. ferruginea crude extract revealed the presence of tannins, saponins, phlobatanins, flavonoids, steroids, alkaloids, glycosides, phenols and resins while it tested negative for triterpenoids, carbohydrates, terpenoids and anthraquinones; the quantitative phytochemical analysis showed that it contained 1.5% saponins, 5.3% flavonoids, 1.2% alkaloids and 0.9% phenols. P. thonningii crude extract tested positive for saponins, flavonoids, terpenoids, steroids, alkaloids, and phenols while tannins, phlobatanins, glycosides, triterpenoids, carbohydrates, resins and anthraquinones were absent. It contains 3.2% saponins, 1.6% flavonoids, 1.8% alkaloids, and 0.7% phenols. The concentration of the crude extract required for 50% inhibition of DPPH radical scavenging effect (IC50) is 0.018 and 0.020 mg/ml for B. ferruginea and P. thonningii, respectively, compared to 0.015 mg/ml for vitamin C as a standard antioxidant. Both extracts showed potent inhibition of DPPH radical scavenging activity comparable to that of the Vitamin C standard and would be valuable sources of antioxidant compounds. Keywords: antioxidant, Bridelia ferruginea, DPPH, Piliostigma thonningii, phytochemical 1. INTRODUCTION Plants have been traditionally used as a source for secondary metabolites which play a significant role as medicines, flavoring, and recreational drugs in different parts of the world. This use contributes immensely to the enhancement of primary health care delivery (Usman et al., 2018). Plants continue to be an integral part of human survival, and this has made ethnobotany a necessary, interesting, and important research field (Thambi and Cherian, 2023). Bridelia ferruginea is a shrub commonly growing up to a height of 45 feet in the Savannah or in open spaces of coastal districts (Ngueyem et al., 2009). The plant is usually a