Synergistic Antioxidant Activities Of Eight Traditional Chinese Herb Pairs

Many Chinese therapeutic herbs widely used in functional food in the form of formula, and many of them are demonstrated significantly better pharmacological effects when used in the combination than when used alone. However, the pharmacological mechanism for this synergism is still not well understood. Researches show that pharmacologic effects of herbs are closely relevant to their antioxidant properties. Therefore, in the present study, the antioxidant activities of six common herbs ((Paeonia lactiflora (PL), Atractylodes macrocephala (AMA), Angelica sinensis (AS), Astragalus membranaceus (AME), Glycyrrhiza uralensis (GU) and Rheum officinale (RO)), which were historically combined into eight traditional Chinese herb pairs (TCHPs) (AME-AS, AME-AMA, AME-RO, AME-GU, AME-PL, PL-AS, PL-AMA and PL-GU), were investigated in vitro by assessing the 1,1-diphenyl-2-picryl hydrazine (DPPH)-radical scavenging abilities of the herbs. The results of this study showed that all eight TCHPs had a significantly larger scavenging capacity than would be expected from the theoretical sum of those of the respective constituent herbs (P<0.05).As phenolic and flavonoid compounds are excellent antioxidant in herbs, the changes in the total phenolic and flavonoid contents were also investigated. Our study showed a significant correlation between the rate of enhancement in antioxidant capacity and the rate of increase in flavonoid content ( the Spearman correlation coefficients were: RREAC-RIFC=0.559, P=0.024). Thus, the flavonoids are likely responsible for the synergistic effects present in the eight TCHPs.In order to further study the synergistic effect, we select three TCHPs (AME-GU, AME-PL and AME-AMA pairs) which showed a better synergistic effect in the DPPH scavenging assay for the hydroxyl radical and superoxide radical anion scavenging assays. Results demonstrated similar conclusions in hydroxyl radical and superoxide radical anion scavenging assays. Interestingly, the AME-AMA combination had a significantly higher superoxide anion (0.2 g/mL) and hydroxyl radical scavenging ability than the AME or AMA.During the assay of the effect of AME-PL on decrease of MRC-5 cell viability induced by CdCl2, we found that 20μmol/L CdCl2 can significantly result the reduction of MRC-5 cell viability (P<0.05) which can be inhibited by 10-3g/mL AME, 10-3g/mL PL have the weaker inhibited capacity and AME-PL have the middle capacity.We found in the assay of protective effect of the AME-PL on oxidative injury induced by CdCl2 in MRC-5 cells that CdCl2 can reduce the activities of Mn-SOD ,Cu/Zn-SOD and GSH-Px (P<0.05) and increase the content of MDA, while PL can increase the Cu/Zn-SOD and GSH-Px activities and have lower MDA content. AME can enhance all the activities of Mn-SOD, Cu/Zn-SOD and GSH-Px but have no significantly effect on MDA content. AME-PL can not only enhance all three enzymes activities especially Cu/Zn-SOD but also decrease the MDA content which lower than the theoretical sum of those of AME and PL (3.22<(6.85+2.66)/2, P<0.05). This also demonstrate the excellent synergistic effect of AME-PL on the basis of cell level, which lay a theoretical foundation for the further studies on the herbs-source functional foods.