Abstract
Medicinal plants remain an important source of bioactive compounds with significant therapeutic potential due to their diverse phytochemical constituents and biological activities. Polyherbal formulations, which combine multiple medicinal plants, have gained increasing scientific interest because of their potential synergistic effects. This study investigated the quantitative phytochemical composition, mineral content and in vitro antioxidant activities of selected medicinal plants used in traditional healthcare: Vernonia amygdalina, Greenwayodendron suaveolens, Euphorbia heterophylla and Xylopia aethiopica. The phytochemical constituents, including phenolic compounds, flavonoids, tannins, saponins, alkaloids and other secondary metabolites, were evaluated using standard analytical procedures. Mineral elements comprising essential macro-elements and trace elements such as calcium, magnesium, potassium, iron, manganese, copper, chromium and nickel, as well as potentially toxic elements including lead and cadmium, were determined using flame photometry and atomic absorption spectrophotometry. The antioxidant potentials of the plant extracts were assessed through established in vitro models, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay, hydroxyl radical scavenging assay and ferric reducing antioxidant power (FRAP) assay. Results indicated the presence of important phytochemical constituents capable of contributing to biological activities. The extracts demonstrated concentration-dependent antioxidant effects, with increased radical scavenging and reducing abilities at higher extract concentrations. Variations observed among the plant species may be attributed to differences in phytochemical composition and mineral profiles. The findings suggest that the investigated medicinal plants possess considerable antioxidant potential and may provide a scientific basis for their traditional applications. However, further studies involving isolation of active compounds, toxicity evaluation and in vivo investigations are recommended before therapeutic applications.
Keywords: medicinal plants, polyherbal formulation, phytochemicals, antioxidant activity, mineral composition, free radical scavenging