Relative Reactivity of Vitamin a vs. a Mixture of Β-carotene Geometric Isomers with Electrochemically Generated Superoxide and Hydroperoxyl Radicals
The present study comprises a kinetic comparison of the reactivity of electrochemically generated superoxide, O2√−, and hydroperoxyl, HO2√, radicals toward a mixture of β-carotene geometric isomers versus all-trans-retinol (vitamin A). Rate constants were determined by computer simulation of experimental cyclic voltammetric data. It is reported that all-trans-retinol reacts more readily with both O2√− and HO2√ than a mixture of geometric β-carotene isomers. Specifically, the latter is unreactive at ≤25 mM with O2√− within the timescale of cyclic voltammetry, while it reacts with HO2√ at least an order of magnitude slower than all-trans-retinol. Our results indicate that all-trans-retinol is a better radical scavenger than a mixture of geometric β-carotene isomers and parallel the results of a recent epidemiological study which has shown that vitamin a may be a better anticarcinogenic agent than β-carotene.
C. M. Collins et al., "Relative Reactivity of Vitamin a vs. a Mixture of Β-carotene Geometric Isomers with Electrochemically Generated Superoxide and Hydroperoxyl Radicals," Electrochimica Acta, Elsevier, Nov 2001.
The definitive version is available at https://doi.org/10.1016/S0013-4686(01)00776-9
National Cancer Institiute
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