Antioxidant Activity of Melanoidins from Different Sugar/Amino Acid Model Systems: Influence of the Enantiomer Type
The effect of amino acid enantiomers on the antioxidant activity of melanoidins was examined. For this purpose, antioxidant activities were evaluated on the basis of ferric reducing/antioxidant power (FRAP) and free radical scavenging activity including 1, 1-diphenyl-2-picryl-hydrazil (DPPH) and 2, 2'-azinobis (3-ethylbenothiazoline-6-sulfonic acid), diammonium salt (ABTS) and ferrous ion chelating activity. Ethylene diamine tetraacetate and trolox, a water-soluble analog of tocopherol, were used as the reference antioxidant compounds. Melanoidins formed from D-isomers were found to be effective antioxidants in different in vitro assays with regard to the ferrous ion chelating activity, ABTS and DPPH radical scavenging activities, and FRAP. In particular, the antioxidant activities of melanoidins formed from fructose systems were higher than those of melanoidins formed from glucose systems. In addition, the results showed that melanoidins formed from D-isomers had antioxidant activities, similar to those of melanoidins formed from L-isomers.