Investigation of antioxidant interaction between Green tea polyphenols and acetaminophen using isobolographic analysis

The antioxidant interactions between acetaminophen (APAP) and green tea polyphenols were investigated using 1,1-diphenyl- 2-picryl-hydrazyl (DPPH) radicals and cupric reducing antioxidant capacity (CUPRAC). The results obtained experimentally for the mixtures were compared with theoretical values calculated by adding up the effects of both individual components analyzed separately. The potential antagonistic, additive or synergistic effects were also evaluated using the isobolographic analysis and interaction indexes. The results obtained for DPPH assays suggest the antagonistic type of interaction, while the results from CUPRAC method showed synergism. The observed differences in the type of interactions were probably a result of different reaction mechanisms between two used assays.