Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/6297
Title: Kinetics of oxidation of adenosine by <i>tert</i>-butoxyl radicals: Protection and repair by chlorogenic acid
Authors: Vijayalakshmi, G
Adinarayana, M
Rao, P Jayaprakash
Keywords: Chlorogenic acid
Adenosine repair
<i></i> <i>t</i>-BuO<b><sup>.</sup></b><b style=""><sup> </sup></b>radicals
Oxidation
Issue Date: Oct-2009
Publisher: CSIR
Abstract: The rates of oxidation of adenosine and chlorogenic acid by <i>tert</i>-butoxyl radicals (<i>t</i>-BuO<sup>-</sup>) were studied by measuring the absorbance of adenosine at 260 nm and chlorogenic acid at 328 nm spectrophotometrically.<i> t</i>-BuO<sup>-</sup><b><sup></sup></b> radicals were generated by the photolysis of <i>tert</i>-butyl hydroperoxide (<i>t</i>-BuOOH) in presence of tert-butyl alcohol to scavenge OH<sup>. </sup>radicals. The rates and the quantum yields(<img src='/image/spc_char/phi.gif'>) of oxidation of chlorogenic acid by <i>t</i>-BuO<sup>-</sup>radicals were determined in the absence and presence of varying concentrations of adenosine. An increase in the concentration of adenosine was found to decrease the rate of oxidation of chlorogenic acid, suggesting that adenosine and chlorogenic acid competed for <i>t</i>-BuO<b style=""><sup>.</sup></b> radicals. From competition kinetics, the rate constant of chlorogenic acid reaction with <i>t</i>-BuO<sup>-</sup><b><sup></sup></b> was calculated to be 3.20 <img src='/image/spc_char/cross.gif'> 10<sup>9</sup> dm<sup>3</sup> mol<sup>-1</sup> s<sup>-1</sup>. The quantum yields (<img src='/image/spc_char/phi.gif'><sub>expt</sub>) were calculated from the experimentally determined rates of oxidation of chlorogenic acid under different experimental conditions. Assuming that chlorogenic acid acts as a scavenger of <i>t</i>-BuO<sup>-</sup> radicals only, the quantum yields (<img src='/image/spc_char/phi.gif'><sub>cal</sub>) were theoretically calculated. <img src='/image/spc_char/phi.gif'><sub>expt</sub> and <img src='/image/spc_char/phi.gif'><sub>cal</sub> values suggested that chlorogenic acid not only protected adenosine from<i> t</i>-BuO<sup>-</sup> radicals, but also repaired adenosine radicals, formed by the reaction of adenosine with <i>t</i>-BuO<sup>-</sup><b><sup> </sup></b>radicals.
Description: 389-394
URI: http://hdl.handle.net/123456789/6297
ISSN: 0975-0959 (Online); 0301-1208 (Print)
Appears in Collections:IJBB Vol.46(5) [October 2009]

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