Preliminary Study On Antioxident Activity Of Ginkgo Biloba Endophytic Fungi

Endophytic fungi is a kind of special fungus that growth in health plant tissues, its variety and the source is widespread, they are one of main sources of new natural active products. At present, scholars already isolated a varity of bioactive endophytic fungi from all kinds of plants. Such as, antitumor activity, antibacterial, plant growth regulators and antioxidant activity, etc. Because of its special growth environment, endophytic fungus have a broad prospect of application in the pharmaceutical development, industrial, agricultural prodution and environmental protection.In this paper, we isolated32strains endophytic fungus from Ginkgo biloba, use DPPH antioxident model to test its antioxident antivity. To screen out eight strains which antioxident are relatively stable and high. The antioxident activity for multiple screen. Using measurement antioxident activity of eight strains’endophytic funguns mycelium as secondary screen, provide further reference to obtain good strains. The results revealed that, GCZX015has higher antioxidant activity, carry on the further research.By use of combined classical morphology with the method of molecular biology to identified GCZX015. The result showed that, GCZX015has the higher homology with Chaetomium globosum, reached99%, its morphological characteristics of the comparison results are consistent, preliminary definition that this strain is Chaetomium globosum.One-factor-at-a-time method was used to determine the suitable conditions for the growth and antioxident activity of GCZX015. The optimal temperature is25℃, rotate speed is170r/min, incubation time is8d, inoculum size is5%, liquid medium volume is100mL/250mL, its growth of pH range is wide, at pH6.5, the product activity is the highest. In addition, investigated the impact of nutritional factors on strain GCZX015product antioxident activity. According to Plackett-Burman experimental results, MgSO4, potato and pH has signification influence. Used reponse surface methodology to optimize potato, MgSO4and the initial pH. Achieved the best combination of three conditions:potato contents is209.542g/L, the concentration of MgSO4is0.0019mg/mL, pH is6.4132. On this condition, the theoretical values of free radical scanvenging activity is96.51%.Centrifugation and alcohol were used to deal with large-scale fermentation broth of strain GCZX015.Lyophilized powder was dissolved with methanol, the solution was separated by silica gel column chromatography. Merged the six samples which obtained from silica gel column chromatography by thin layer chromatography, measured antioxidant activity of the six samples, the highest is sample2, reached97.03%. On this basis, used preparative chromatography for further separation, obtained2-1component, its antioxidant activity is97.37%. Qualitative analysis of2-1component by high performance liquid chromatography and mass spectrometry, preliminary sure that the antioxidant component of the fermentation broth is quercetin.