Abstract: In order to explore the synergistic antioxidant effects of procyanidins from Litchi chinensis pericarp (LPPC) and vitamin C (VC) or vitamin E (VE), the antioxidant capacity of LPPC in the presence of VC or VE was evaluated by DPPH radical scavenging assay coupled with isobologram method. The results indicated that the IC50 of LPPC, VC and VE were 9.98, 9.21mg/L, and 27.96 mg/L, respectively, which suggested that LPPC had significant DPPH radical scavenging effect. The effect-response points of LPPC combined with VC or VE were observed below the addition line with 95% confidence interval in isobolographic plots. Meanwhile, a significant difference between theoretical IC50add value and experimental IC50mix value was achieved. The interaction index of each combination was less than 1. These findings indicate that there is a synergistic antioxidant effect between LPPC and VC or VE, which will reveals promising prospects in practical applications.

Key words: procyanidins from Litchi chinensis pericarp (LPPC), antioxidation, isobologram, synergistic effect