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Articles by Patricia A. Onocha
Total Records ( 1 ) for Patricia A. Onocha
  Patricia A. Onocha , Ganiyat K. Oloyede and Qasim O. Afolabi
  The cytotoxicity using Brine shrimp lethality assay and free-radical scavenging activities of fractions obtained from chromatographic separation of Dacryodes edulis (G.Don) H.J. Lam (African Pear) were investigated. The hexane extract was separated into smaller fractions by using a mixture of hexane, ethylacetate and methanol and silica gel 70-230 mesh as adsorbent in a gradient elution-column chormatographic technique. The in vitro antioxidant assay involved determination of the effect on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and spectrophotometric determination of D. edulis is the scavenging effect on hydrogen peroxide carried out at 285 nm. The free radical scavenging activities were compared with the activities of known antioxidants such as Ascorbic Acid (AA), Butylated hydroxyanisole (BHA) and α-Tocopherol. Fractions obtained were pooled based on Rf values obtained from Thin Layer Chromatography (TLC). Cytotoxicity analysis revealed that out of the five pooled fractions (D1-D5) screened, fractions D1, D3, and D4 were not toxic as their LC50 values were all greater than 1,000 μg mL-1, D2 (LC50 = 0.0000 μg mL-1) and D5 (LC50 = 116.6931 μg mL-1) were toxic at varied degrees with reference to 1,000 μg mL-1. None of the fractions showed significant free radical scavenging activity when compared to standards Butylated hydroxylanisole (BHA), Ascorbic acid (AA) and α-Tocopherol. At 1.0 mg mL-l when screened with 2,2-diphenyl-1-picrylhydrazyl radical, D4 (17.7%) and D5 (17.6%) both scavenged better than α-Tocopherol(15.4%). Fractions D2 (14.2%), D4 (14.8%) and D5 (17.5%), at 500 μg mL-1 exhibited better activities than α-Tocopherol (12.4%) and at 250 μg mL-1, only D4 (14.0%) was better than α-Tocopherol (12.4%), these %inhibition values are however lower than values obtained for BHA and AA. None of the samples scavenged better than α-Tocopherol (12.1%) at 125 μg mL-1 and only D4 (10.6%) exhibited greater scavenging capacity than α-Tocopherol (10.4%) at the least concentration of 62.5 μg mL-1. The activity was also low with scavenging effects on Hydrogen peroxide (H2O2) measured at 285 nm. Interestingly, α-Tocopherol showed an exceptionally high antioxidant activity in scavenging OH radical when compared to its activity in DPPH. The ability to scavenge hydroxyl radical which is known to cause cellular damage justifies the ethno medicinal application of D. edulis.
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