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Proceedings of the 31 st European Peptide SymposiumMichal Lebl, Morten Meldal, Knud J. Jensen, Thomas Hoeg-Jensen (Editors)European Peptide Society, 2010Radical Scavenging Activity of Hydroxycinnamoylamides ofAmino Acids - Precursors of Biogenic AminesMaya G. Chochkova 1 , Hristina G. Nikova 1 , Galya I. Ivanova 2 ,Lyubomir N. Georgiev 1 , and Tsenka S. Milkova 11 South-West University “Neofit Rilski”, Blagoevgrad, 2700, Bulgaria; 2 Requimte, Polo daUniversidade do Porto, Departamento de Química, Rua do Campo Alegre,Porto, 4169-007, PortugalIntroductionOxygen is a molecule that humans and the other aerobics require to maintain their lives.However, it creates a paradox, because this molecule is essential for the survival, being atthe same time potentially harmful. During normal metabolism, unconsumed oxygenmolecules could be changed to free radicals such as superoxide (O2 - , OOH•), hydroxyl(OH•) and peroxyl (ROO•) radicals. Excessive production of these species beyond theantioxidant defense system of the body can cause oxidative stress [1,2]. This phenomena isa key factor to the pathogenesis of various disorders in human body, including cancer,atherosclerosis, malaria, and rheumatoid arthritis and neurodegenerative diseases [3,4].Thus, the development of different type antioxidants, which can block the production orscavenge the obtained free radicals, has attracted the attention in the recent years. Amongstthe various groups of antioxidants, our attention was focused on hydroxycinnamic acidamides, because more of these compounds are naturally occuring and have a stablestructure after the free radicals are quenched.Results and DiscussionIn order to estimate the influence of different incorporatated amino components inhydroxycinnamoylamides towards DPPH radical, two type of amides were obtained(Table 1).Table 1. Synthesized hydroxycinnamic acid amidesSubstituentCompoundR` R`` Y1 ОH H HO Y2R'NOCH 3 OCH 3 H3HOCH 3 H HHO4 R''OCH 3 OCH 3 COOBu t5 OCH 3 H COOBu t6 OH H H7 O YNHOCH 3 OCH 3 H8R'NHOCH 3 H H9 HOОH H COOМеR''10 OCH 3 OCH 3 COOМе11 OCH 3 H COOМеThe free radical scavenging activities (RSA) of amides (1–11) and standards such asferulic, sinapic, caffeic acids were determined using a DPPH method [5] (Table 2). Themethod is based on the reduction of alcoholic DPPH* solution in the presence of ahydrogen-donating antioxidant due to the formation of the non-radical form DPPH-H.56