Comparative Analysis of Free Radical Scavenging Potential of Pyrroloquinoline Quinone (PQQ) and Several Plants Extracts by in-vitro Methods

In-vitro lipid peroxidation (LPO) was induced by ferrous sulphate (FeSO4), hydrogen peroxide (H2O2) and carbon tetrachloride (CCl4) and then the effects of five different concentrations (10, 20, 40, 80 and 160 µM) of pyrroloquinoline quinone (PQQ) were evaluated in liver, the major target organ of a drug. A comparison was made with the effects of some known antioxidative plant extracts and vitamin C. For this different concentrations of PQQ, vitamin C and herbal extracts of Annona squamosa (AS), Rauvolfia serpentina (RS), Withania somnifera (WS), Commiphora mukul (CM), Syzygium cumini (SC) and Gymnema sylvestre (GS) were considered and examined through different in-vitro antioxidant potential assays such as Azino-bisethylbenzothiazoline-6-sulphonic acid (ABTS) scavenging assay; Diphenylpicrylhydrazyl (DPPH) scavenging assay; Metal (FeCl2) chelating assay; Hydrogen peroxide (H2O2) scavenging assay and Superoxide (SO) radical scavenging assay. While FeSO4, H2O2 and CCl4 markedly enhanced the hepatic LPO; simultaneous administration of PQQ reduced it in a concentration dependent manner. This effect was observed in all three, FeSO4, H2O2 and CCl4 induced hepatic LPO. Out of five different concentrations of PQQ, 20 µM and 80 µM showed the maximum inhibition in LPO, suggesting its beneficial/antioxidative activity. While comparing the antioxidative potential of PQQ with some known antioxidative herbal extracts and vitamin C, the test drug exhibited highest antioxidative activity in all the above free radical scavenging assays, further consolidating very high antioxidative potential of PQQ. PQQ exhibited better antioxidative potential than some known plant extracts. Therefore, its therapeutic use may prove to be advantageous in ameliorating oxidative stress associated diseases