Abstract: This study aimed to analyze the main chemical constituents of ethanol extracts of grape, mango and strawberry by high performance liquid chromatography-mass spectrometry (HPLC-MS) and compare the antioxidant interactions among the three extracts using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) radical scavenging assays. The isobolographic analysis method was used to analyze the differences in the antioxidant activity of mixtures in various proportions of the extracts. Results demonstrated that the grape extract had the highest contents of total phenols and total flavonoids among three fruit extracts. Gallogen, pelargonidin-3-glucoside, pelargonidin-3-acetylglucoside and pelargonidin-3-rutinoside were the main compounds of the strawberry extract. Gallogen, mangiferin and maclurin were the main compounds of the mango extract. Trans-resveratrol and anthocyanin were the main compounds of the grape extract. The same combination showed different antioxidant activities in different antioxidant models. The strawberry extract had the highest antioxidant capacity followed by the mango extract and the grape extract. In the same antioxidant model, the highest synergistic antioxidant effect of the strawberry extract was achieved when combined with the mango extract at a ratio of 1:9 and 1:1 (V/V) for scavenging of DPPH and ABTS radicals, respectively.

Key words: antioxidant interactions, isobolographic analysis, synergistic effect, fruit combination