Antioxidant potential of aqueous plant extracts assessed by the cellular antioxidant activity assay

Several teas and herbal infusions are asserted as health promoters due to their content in antioxidant compounds. However the chemical methods of analysis to assess the antioxidants content do not give information regarding the biological activity of the studied substances. In the present study eight medicinal plants (3 C. Sinensis, R. Canina, Menta Piperita, S. Officinalis, I. Paraguariensis and C. Arabica, C. Robusta blend) as well as various antioxidant compounds naturally contained in these plants were screened to their antioxidant capacities, through chemical and cellular assays. Such medicinal plants were selected due to their wide utilization, both as infusions and as ingredients in cosmetics products and in food formulations. The main purpose was to assess their biological antioxidative capability measured in human cells, to assess their efficiency of protection against peroxyl radicals under physiological conditions, and later predict their in vivo activity. The plant extracts and antioxidant compounds here tested were found to be successfully absorbed, at different proportions, into human cells. However a lack of correlation between the chemical assay and the cell-based assay was observed. Care should be taken when assessing the antioxidant power with purely chemical methods. Unlike chemical assays, cell-based assays better reflect the complexity of in vivo models, considering some important aspects of uptake, cellular distribution and metabolism of the antioxidants in a cellular environment, and thus could sustain the research on antioxidants prior to animal studies or clinical trials.