Study of the participation of caffeine and polyphenols on the overall antioxidant activity of mate (Ilex paraguariensis)

The aim of this work was to investigate the participation of the main bioactive compounds (caffeine, caffeic acid derivatives and rutin) on the antioxidant activity (DPPH free radical scavenging activity and the prevention of lipid peroxidation) of the crude extracts of Ilex paraguariensis. Green and commercial products were used to prepare aqueous extracts. The main bioactive compounds were identified and quantified by HPLC-DAD. The antioxidant activities of the pure compounds in the concentrations present in the extracts were also analyzed. Results demonstrated that chlorogenic acid, caffeic acid and rutin contribute to the antioxidant activity. On the contrary, caffeine induced lipid peroxidation of linoleic acid acting as a pro-oxidant compound. The caffeine content in the green extracts was lower when compared to the commercial extracts. The antioxidant and pro-oxidant antagonistic effects of the compounds in the amounts present in the extracts resulted in higher antioxidant potency of the green extracts when compared to the commercial ones, as demonstrated by the EC50 values and without affecting the maximum efficiency displayed by the extracts.