Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.4, No.3, 2014 1 In-vitro antioxidant activities of the stem bark extract fractions of Bridelia ferruginea Olaide Olarewaju 1* , Omotade Oloyede 1 , Olufemi Ojo 2 , Amos Onikanni 2 and Bashir Ajiboye 2 1 Department of Biochemistry, Ekiti State University, Ado Ekiti, Ekiti State, Nigeria. 2 Department of Chemical Sciences, Biochemistry Unit, Afe Babalola University, Afe Babalola way, Ado Ekiti, Ekiti State, Nigeria. * Corresponding author’s e-mail: lydeolarewaju@yahoo.com Phone no: +2348036400146 ABSTRACT Bridelia ferruginea stem bark generally used in Indigenous folk medicine for diverse uses was evaluated scientifically to elucidate the antioxidant activity of various fractions in-vitro to validate its folkloric usage. In vitro antioxidant properties of the extract fractions were evaluated using the free radical scavenging activities by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) with ascorbic acid as control. The total antioxidant activity results indicated that, the inhibition percent of aqueous extract was significantly higher than the inhibition percent of ethanol and ethyl acetate in the DPPH methods. A higher IC 50 (0.85 mg/ml compared to 1.34 mg/ml ethanolic extract and 1.41mg/ml of Ethyl acetate) value was observed. The aqueous extract was better in Fe 2+ chelating activity and higher in the content of total phenol as compared to ethanolic and ethyl acetate extracts. However, the ethyl acetate extract had significantly higher (P < 0.05) hydroxyl radical scavenging activity with the concentration for 50% inhibition (IC) value of 0.86 mg/mL, 1.24 mg/mL for ethanolic extract and 2.16 mg/mL for aqueous extract. The results indicated that all the extracts showed excellent Nitric oxide scavenging activities with a close range of IC 50 values of 0.83, 0.99 and 1.83 mg/mL for aqueous, ethanolic and ethyl acetate extract. The results suggest that Bridelia ferruginea stem bark possesses varied degrees of antioxidant activity in vitro and has the potential to be developed into dietary supplements and synergically modified with synthetic antioxidants. Keywords: Ethanolic extract, Aqueous extract, Ethyl acetate extract, Bridelia ferruginea, and Antioxidant activity. INTRODUCTION Antioxidants have been found to play a major role in protecting the human body against damage induced by reactive free radicals (Halliwell and Gutteridge, 1990; Mates et al., 1999) by reacting with free radicals, chelating and also by acting as oxygen scavenger (Shahidi and Wanasundara, 1992; Buyukokuroglu et al., 2001). Antioxidant compounds play an important role in our body due to favorable effects on human health. Consumption of food containing phytochemicals with potential antioxidant properties can reduce the risk of human diseases (Temple, 2000) since Overproduction of free radicals in certain conditions can cause an imbalance, leading to oxidative damage to large biomolecules such as lipids, DNA, and proteins (Liu,2002). Natural antioxidants that are present in plants and herbs are responsible for inhibiting or preventing the deleterious consequences of oxidative stress since synthetic antioxidants have been limited because of their toxicity (Valentao et al., 2002). Bridelia ferruginea belongs to the family Euphorbiaceae which is commonly found in Savannah regions (Ekanem et al., 2008). It is usually a gnarled shrub which sometimes reaches the size of a tree in suitable condition. Its common names are Kizni (Hausa), Marehi (Fulani), Iralodan (Yoruba), Ola (Igbo); and Kensange Abia (Boki). Its habitat is the Savannah, especially in the moister regions extending from Guinea to Zaire and Angola. The tree is 6 - 15 m high, up to 1.5 m in girth and bole crooked branching low down. The bark is dark grey, rough and often marked scaly (Rashid et al., 2000). A decoction of the leaves has been used to treat diabetes. It is also used as purgative and a vermifuge (Cimanga et al., 1999). The bark extract has been used for the coagulation of milk and also lime juice for the formulation of a traditional gargle “egun efu” (Orafidiya et al., 1990). It is also reported of having potential for water treatment (Kolawole and Olayemi, 2003). In Togo, the roots of the plant are used as chewing sticks and the root bark is used for intestinal and bladder disorder remedies as well as skin diseases (De Bruyne et al., 1997). Other reported activities of the bark extract include typanocidal (Iwu, 1984), molluscidal ( Adeoye et al., 1988), antimicrobial (Olajide et al., 1999) and anti-inflammatory (Ndukwe et al., 2005). Antimicrobial properties of stem bark of B. ferruginea against facultative Gram negative rods have been reported by (Ndukwe et al., 2005). The plant was found to contain Alkaloids, Tannins, Terpenoids, Glycosides, Flavonoids, Saponins, Anthraquinones and Steroids. The activities of the methanol, petroleum ether and chloroform bark extracts of the B. ferruginea against some potential pathogenic organisms have been extensively investigated (Iwu, 1984); (Adeoye et al., 1988); (Olajide et al., 1999). Bridelia ferruginea has a great antioxidant potential which can be used to protect the body against damage caused by free radicals which is regularly produced in vivo and oxidative stress induce these free radicals (Oloyede and Babalola, 2012).