This study was conducted to evaluate selected phytochemicals (antioxidant potentials of aqueous, methanol and ethanol stem bark extracts of Simarouba glauca) relative to standard antioxidants. Sample was harvested, air dried, pulverized and extracted with aqueous and absolute methanol and ethanol; freeze dried at the National Energy Commission Centre, University of Benin. Alkaloids, phenols and tannins were identified, and also flavonoid was detected. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, reducing power activity, total antioxidant activity, hydroxyl radical activity, trolox equivalent antioxidant activity and nitric oxide (NO•) radical scavenging activity of stem bark extracts of S. glauca were evaluated, and all the experiment were conducted in a dose dependent manner. Butylated hydroxytuolene (BHT), ascorbate and trolox were introduced as positive controls (antioxidant). DPPH radical scavenging activity of stem bark extracts did not exhibit anti-radical activity at 50% inhibition but demonstrated less anti-radical activity at percentage inhibition lower than 50%. Extracts yielded significant reducing power and total antioxidant activities (FRAP). Hydroxyl radical scavenging activities of extracts was substantial; extracts exhibited significant anti-radical activity when trolox was introduced as positive antioxidant control, while nitric oxide scavenging activities was unprecedented. The presence of phytochemicals and antioxidant principles proffer high medicinal value to S. glauca.
Key words: Simarouba glauca, stem bark, oxidants, radical scavenging properties.