Exploring the Antioxidant Potential of Nigerian Medicinal Plants: A comparative study of Phytochemical Constituents and Biological Activities

Oxidative stress plays a crucial role in the pathogenesis and progression of a wide range of chronic diseases, which include cardiovascular disorders, neurodegenerative disorders, Diabetes mellitus, and various cancers. Plant-derived natural antioxidants from medicinal plants have received increasing attention recently as result of their relative safety, affordability, and widespread availability, especially in biodiversity-rich areas like Nigeria where ethnomedicinal plants are abundant. This research offers a comparative analysis of five medicinal plants from Nigeria: Piper guineense, Bridelia ferruginea, Nauclea diderrichii, Ziziphus spina-christi, and Caesalpinia pulcherrima, with focus on their phytochemical profiles, specifically total flavonoid and phenolic content, as well as their in vitro antioxidant activities, which were assessed using DPPH and FRAP assays. The analysis revealed marked interspecies variation: plants with higher phenolic and flavonoid contents demonstrated stronger ferric-reducing and radical-scavenging abilities. Bridelia ferruginea demonstrated an exceptional total phenolic content (~347.8 mg GAE/g extract) and a very potent DPPH scavenging action (LC₅₀ ≈ 11.46 µg/mL). Correlation analysis confirmed a robust positive relationship between phytochemical abundance and antioxidant efficacy (r ≈ 0.8, p < 0.01). Overall, these results emphasize the promising antioxidant potential of these medicinal plants and identify key candidates for further study that includes chemical separation, bioavailability assessment, and in vivo validation.