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BRIEF INTRODUCTION: During recent years, innumerable scientific studies have been focused on examination of bioactive compounds with antioxidant properties, aimed for their use in prevention and treatment of different health issues. However, research and final application has mostly been dedicated to single compounds, without taking into account the potential synergistic effects of a multi-component mixture of different bioactive compounds. MATERIALS AND METHODS: In this study, antioxidant properties of single and the combination of chemically different groups of bioactive compounds ; polyphenol quercetin, ascorbic acid, aminoacids lysine and carnitine were assesed to evaluate whether synergistic interactions and effects occur. For that purpose, in vitro methods of antioxidant capacity determination by free radical scavenging assays (ABTS and DPPH assays) and by cytotoxicity and reactive oxygen species (ROS) formation on model human laryngeal carcinoma (HEp2) and colon cancer (CaCo2) cell lines were employed. Electron paramagnetic resonance (EPR) spectroscopy was introduced as an advanced technique to confirm the kinetics of a model spin-probe (TEMPO) scavenging by the evaluated antioxidant mixture. RESULTS: The use of ascorbic acid enabled to adjust the pH and enhance the solubility of quercetin in water, resulting with formulation of multi-component aqueous mixture. Synergistic effect in terms of enhancement of antioxidant capacity of formulated mixture was achieved (with regard to theoretical values). The formulated mixture exhibited cytoprotective and antioxidant activity on HEp2 cells, which was attributed to the same effect of quercetin and ascorbic acid, while single amino acids lysine and carnitine exhibited no significant effect on the survival of HEp2 and CaCo2 cells. EPR measurements revealed that the enhanced antioxidant effect of bioactive mixture does not differ significantly from plain ascorbic acid, indicating that the ROS scavenging of the formulated mixture would most likely be attributed to ascorbic acid and its prominent antioxidant properties. CONCLUSIONS: Due to the prevalent activity of ascorbic acid, further dose-response optimization is required to allow the formulation of functional, nutraceutical antioxidant mixture. |
