Background: Potentilla fruticosa, also called ââ?¬Å?Jinlaomeiââ?¬Â and ââ?¬Å?Gesanghuaââ?¬Â, is widely used as folk herbs in traditional\nTibetan medicine in China to treat inflammations, wounds, certain forms of cancer, diarrhoea, diabetes and other\nailments. Previous research found P. fruticosa leaf extract (C-3) combined with Ginkgo biloba extracts (EGb) showed\nobvious synergistic effects in a variety of oxidation systems. The aim of the present study was to further confirm the\nsynergy of P. fruticosa combined with EGb viewed from physiological bioavailability and explore the related bioactive\nmechanism behind the synergism.\nMethods: The microbial test system (MTS) was adopted to evaluate the related bioactive mechanism. The synergistic\neffects were evaluated by isobolographic analysis. The H2O2 production rate and antioxidant enzyme (Catalase (CAT),\nPeroxidase (POD), Superoxide dismutase (SOD), Glutathione peroxidase (GSH-PX)) activities were determined by the\ncolorimetric method. Enzyme gene (CAT, SOD) expression was measured by real time-PCR.\nResults: The MTS antioxidant activity results showed the combination of C-3 + EGb exhibited synergistic effects\nespecially at the ratio 5:1. Components of isorhamnetin and caffeic acid in C-3 and EGb displayed strong\nantioxidant activities on MTS and their combination also showed significant synergy in promoting H2O2\nproduction. The combinations of C-3 + EGb and isorhamnetin + caffeic acid promoted CAT and SOD enzyme\nactivities and the ratio 1:1 exhibited the strongest synergy while no obvious promotion on POD and GSH-PX\nenzyme activities was found. Both combinations above promoted gene expression of CAT and SOD enzymes\nand the ratio 1:1 exhibited the strongest synergy.\nConclusions: Antioxidant activity results in MTS further confirmed the significant synergy of C-3 combined\nwith EGb and isorhamnetin combined with caffeic acid. The synergy of C-3 combined with EGb may be\nattributed to the combination of isorhamnetin + caffeic acid, which promoted CAT and SOD enzyme gene\nexpression and further promoted the enzyme activities in E. coli. This study could further provide rational basis\nfor optimizing the physiological bioavailability of P. fruticosa by using natural and safe antioxidants in low\ndoses to produce new medicines and functional products.
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