A novel combined bioactivity / chemoactivity holistic approach for the evaluation of dietary supplements.

Abstract There is increased evidence that the excessive production of free radicals in the human body plays a major role in the pathophysiology and development of various diseases, closely associated with oxidative damage. In this frame, the consumption of antioxidant nutrients through food or dietary supplements may prevent free radicals from harming human cells. This work proposes a holistic approach consisting of distinct methodologies, suitable to evaluate the antioxidant and chemoprotective activity of three novel dietary supplements, each one containing active substances with complementary properties. In one step, this approach includes in vitro studies to evaluate the antioxidant activity of the dietary supplements by measuring the parameters of free radical scavenging capacity, of reductive power activity, as well as, their ability to protect biomolecules from oxidation. Furthermore, their antimutagenic and antigenotoxic evaluation is also presented. In another step, the specific effects of the dietary supplements were examined in three cancer cell lines (HepG2, HeLa, MKN45), by measuring redox biomarkers such as glutathione, reactive oxygen species and thiobarbituric acid reactive substances, using flow cytometry and spectrophotometry. Our results indicatthat all the dietary supplements exhibit high antioxidant, antimutagenic, antigenotoxic and lipid protective activity. The most prominent result is their capability to induce the damage caused by cancer cells due to critical downregulation of the levels of their intracellular glutathione as well as increase of ROS and lipid peroxidation levels after the administration of non-cytotoxic concentrations. We suggest that the proposed methodology could constitute a valuable tool for the characterization of dietary supplements based on their chemical and functional properties.