Antioxidant properties of polyphenols are believed to underlie cocoa chemopreventive potential. However, it has been not recognized if these effects are mainly caused by the most abundant components or result from concerted action of major and minor cocoa bioactives as proposed by food synergy concept. This study was aimed at resolving this question. Initially, the cocoa extract composition was determined by HPLC-DAD-MS. Then, bioactivities of cocoa extract and a series of artificial mixtures of cocoa phytochemicals were tested to compare their redox properties in cell-free system and redox-associated biological effects in human colon cancer HT29 cells serving as a model of human alimentary tract. Under cell-free conditions, DPPH test as well as differential pulse voltammetry showed the highest antioxidant activity for cocoa powder extract (CE), but surprisingly, did not reveal any dose-dependent differences between mixtures despite growing concentration and complexity of antioxidants. Basically, to the same conclusion lead determinations of cellular antioxidant activity; CE was the most efficient in cell protection against ROS whereby concentration of catechins in studied solutions had to be above 10 μM to override cellular redox homeostasis. Cell growth inhibition was dose-dependent only for mixtures that consisted of main catechins at narrow range of low concentrations (0.01 – 1 μM C+EC). Neither clear relationship between composition of cocoa phytochemicals and nutrigenomic activity of CE and matching mixtures was spotted. Therefore, our study indicates that the bioactivity of non-toxic complex natural mixtures such as cocoa is strongly affected by interactions between their components, as predicted by food synergy.Nutraceuticals in balancing redox status in ageing and age-related diseases WGs Meeting of the NutRedOx COST Action CA16112 Belgrade, March 2-3, 202
