Isolation of antioxidant constituents from Combretum apiculatum subsp. apiculatum

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dc.contributor.author Aderogba, M.A. (Mutalib)
dc.contributor.author Kgatle, Dimakatso Thomas
dc.contributor.author McGaw, Lyndy Joy
dc.contributor.author Eloff, Jacobus Nicolaas
dc.date.accessioned 2012-01-13T06:18:31Z
dc.date.available 2012-01-13T06:18:31Z
dc.date.issued 2012
dc.description.abstract Species of the family Combretaceae are used extensively in traditional medicine against inflammation and infections, and although antibacterial activity has been reported in non-polar extracts, further rationale for the widespread use of the Combretaceae is expected to exist. Methanol extracts of leaves of ten different Combretum species were evaluated for antioxidant activity by spraying TLC chromatograms of each leaf extract with 2, 2-diphenyl-1- picrylhydrazyl (DPPH). Compounds with antioxidant activity were detected by bleaching of the purple DPPH colour. Leaf extracts of Combretum apiculatum subsp. apiculatum had the most antioxidant compounds. This species was consequently selected for phytochemical investigation. A DPPH assay-directed fractionation of the leaf extracts of C. apiculatum led to the isolation of four antioxidant compounds from the ethyl acetate and butanol soluble fractions. The structures of the compounds were determined by spectroscopic analyses (1H-NMR, 13CNMR and MS) and identified as: cardamonin (1), pinocembrin (2), quercetrin (3) and kaempferol (4). In a quantitative antioxidant assay, the more polar fractions (ethyl acetate and butanol) obtained by solvent-solvent fractionation had the highest antioxidant activity among the solvent fractions obtained from C. apiculatum, with EC50 values of 3.91 ± 0.02 and 2.44 ± 0.02 μg/mL respectively. Of the four isolated compounds, quercetrin (4) and kaempferol (3) had the strongest antioxidant activity, with EC50 values of 11.81 ± 85 and 47.36 ± 0.03 μM respectively. Cardamonin (1) and pinocembrin (2) did not demonstrate strong activity. L-ascorbic acid was used as standard antioxidant agent (EC50 = 13.37 ± 0.20 μM or 2.35 μg/mL). The cytotoxicity of cardamonin and pinocembrin was evaluated on Vero kidney cells using the MTT (3-(4, 5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide) assay with berberine as positive control. At concentrations higher than 50 μg/ml of cardamonin or pinocembrin, the cells were not viable. Cardamonin was more toxic (LC50 = 1.97 μg/ml) than pinocembrin (LC50 = 29.47 μg/ml) and even the positive control, berberine (LC50 = 12.35 μg/ml). en
dc.description.librarian mn2012 en
dc.description.sponsorship Funding for this project was provided by the National Research Foundation (NRF), South Africa. en
dc.description.uri http://www.elsevier.com/locate/sajb en
dc.identifier.citation Aderogba, M.A., et al., Isolation of antioxidant constituents from Combretum apiculatum subsp. apiculatum, South African Journal of Botany (2012), doi:10.1016/j.sajb.2011.10.004 en
dc.identifier.issn 0254-6299 (print)
dc.identifier.issn 1727-9321 (online)
dc.identifier.other 10.1016/j.sajb.2011.10.004
dc.identifier.other 55952645400
dc.identifier.other 7005589445
dc.identifier.uri http://hdl.handle.net/2263/17771
dc.language.iso en en
dc.publisher Elsevier en
dc.rights © 2011 SAAB. Published by Elsevier B.V. All rights reserved. en
dc.subject Combretaceae en
dc.subject Combretum apiculatum en
dc.subject Antioxidants en
dc.subject Cytotoxicity en
dc.subject.lcsh Veterinary medicine -- Research en
dc.subject.lcsh Medicinal plants -- South Africa en
dc.subject.lcsh Materia medica, Vegetable en
dc.title Isolation of antioxidant constituents from Combretum apiculatum subsp. apiculatum en
dc.type Postprint Article en


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