Natural flavonol antioxidant properties

Synthetic analogues or derivatives of a-tocopherol which have better antioxidant properties can be introduced. Many natural antioxidants such as flavonols, flavones, tea leaf catechins, rosemary antioxidants and spice extracts have been reported to be more active than BHA, BHT or the tocopherols in model systems. The food applications of these compounds need to be explored further. 

This new strategy consists of the synthesis of molecules that possess hydroxyl groups in such positions that a radical species can be stabilized by mesomery. This feature is found in natural flavonol such as kaemferol that possesses undeniable antioxidant properties. The first published example is a lipophilic analogue of vitamin C, Fig (13) [40]. In this paper, we have proved that the synthesised substituted 2-hydroxyfuran-2-one is a true ascorbic acid analogue. A radical anion that gives very similar data has been generated under the same conditions as for ascorbic acid with a stability somewhat lower and a redox potential lower than those of ascorbyl radical. Its antioxidant properties are also similar to that of ascorbic acid but it inhibits LDL peroxidation induced by Cu2+ or AAPH more efficiently probably due to a higher lipophilicity. 

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