The effect of selected phenolic compounds on antioxidant and antimicrobial activity of resveratrol in binary phenolic mixtures

U ovom radu određen je učinak odabranih fenolnih spojeva (fenolnih kiselina, flavonoida, stilbena) na antioksidacijsku i antimikrobnu aktivnost resveratrola. Antioksidacijska aktivnost fenolnih spojeva i binarnih fenolnih smjesa s resveratrolom određena je korištenjem FRAP, DPPH i BR metoda, dok je antimikrobna učinkovitost na test modelima odabranih gram-pozitivnih i gram-negativnih bakterija kvantificirana mikrodilucijskom metodom. Rezultati istraživanja ukazuju na razlike u biološkoj aktivnosti testiranih fenolnih spojeva, kao i binarnih fenolnih smjesa. Na osnovu rezultata dobivenih ovom studijom, može se zaključiti da interakcija pojedinih fenolnih spojeva s resveratrolom u ekvimolarnim binarnim smjesama, rezultira sinergijskim, aditivnim ili čak antagonističkim antioksidacijskim učinkom. Sinergijsko djelovanje između katehina i resveratrola dokazano je svim korištenim antioksidacijskim metodama. Sinergijsko antimikrobno djelovanje prema gram-pozitivnim ili prema gram-negativnim bakterijama potvrđeno je za pojedine binarne fenolne smjese. Rezultati istraživanja ukazuju na potencijalnu povezanost molekularne strukture i aktivnosti fenolnih spojeva što doprinosi boljem razumijevanju mehanizama biološkog učinka prirodnih fenolnih spojeva.The effect of selected phenolic compounds (phenolic acids, flavonoids, stilbenes) on antioxidant and antimicrobial activity of resveratrol has been researched in this study. Antioxidant activity of phenolic compounds, and their binary mixtures with resveratrol has been evaluated using FRAP, DPPH and BR methods, while antimicrobial effectiveness against selected gram-positive and gram-negative bacterial strains has been quantified using broth microdilution method. The results have shown certain differences in the biological activity of tested phenolic compounds, as well as their binary phenolic mixtures. Based on the results obtained in this study it can be concluded that the mutual interactions among the studied phenolic compounds and resveratrol result in synergistic, additive or even antagonistic effect with respect to their antioxidant capacity. The synergistic interaction between catechin and resveratrol has been proven using all three antioxidant methods. The synergistic antimicrobial effect on selected gram-positive or gram-negative bacteria strains has been confirmed for some of the phenolic binary mixtures. Obtained results point out the possible influence of molecular structure on the activity of the phenolic compounds, which contributes significantly to a better understanding of mechanisms of biological effect of natural phenolic compounds