Antioxidant and mineral nutrients evaluation of methanol stem bark extract and fractions of Pentaclethra macrophylla (Benth.)

Abstract

Many important drugs used in medicine today are directly or indirectly derived from plants and plant products. This study aimed to evaluate the antioxidant activity and mineral nutrient constituents of methanol stem bark extract and fractions of Pentaclethra macrophylla. The powdered stembark of Pentaclethra macrophylla was extracted by maceration in methanol. The extract was fractionated into n-hexane, dichloromethane, ethyl acetate, and aqueous methanol fractions by solvent-solvent extraction. The crude extract and fractions were evaluated for their total phenol and flavonoid contents. The antioxidant activity of the extract and fractions was determined using the DPPH radical scavenging assay. The mineral nutrients were determined according to standard procedure, while acute toxicity was evaluated using the Lorke method. Phytochemical screening of P. macrophylla stem bark showed the presence of flavonoids, terpenoids, and phenolic compounds. Tannins, anthraquinone, and alkaloids were absent. The aqueous methanol fraction had the highest total phenol and flavonoid content of 132.364.03 mg GAE/g and 31.503.47 mg QE/g, respectively. The extract and fractions exhibited strong antioxidant activity, with the aqueous methanol fraction having the highest activity (IC₅₀ = 0.439 μg/mL). The mineral nutrient investigation showed the presence of Potassium, Calcium, Sodium, Copper, Zinc, Iron, Lead, Nickel, Cadmium, Magnesium. Acute toxicity screening showed that the extract is relatively safe at low and moderate doses, but may be toxic at high doses (LD₅₀ = 3,800 mg/kg). This study has shown that the stem bark of P. macrophylla has excellent antioxidant properties, with rich mineral content, and is relatively safe when consumed at low – moderate doses.