Polyphenol Compounds And Hypoglycemic Effects Of Diospyros Lotus L.Fermented With Endophyte And Lactobacillus

Diospyros lotus as an edible food can also be a traditional medicine which has abundant nutritional value.The phenolic compounds in Diospyros lotus fruit have remarkable effects on many diseases.In recent years,microbial fermentation technology has been used as a biological means to improve the biological utilization of substrate.In this study,the endophytes isolated from wild Diospyros lotus fruit and Lactobacillus were selected to ferment the Diospyros lotus fruit.The nutrients and bioactivity during the microbial fermentation were determined.The main functional components of hypoglycemia in extract were analyzed.The protective mechanism of Microbacterium flavum and Lactobacillus plantarum fermentation Diospyros lotus L polyphenol extract(MLDPE)on glucose damaged Min6 cells in the high glucose environment was investigated.The results are as follows:M.flavum and L.plantarum as the fermentative strain were selected by the Colony-Forming Units(CFU)and pH.Random Centroid Optimization(RCO)optimization results were showed as follow:The optimum fermentation conditions of M flavum was 3.5%inoculation amount,30? and 106 revolutions per minute.The optimum fermentation conditions of L.plantarum was 2%inoculation amount,35.5?,97 revolutions per minute.The optimum fermentation conditions of mix strain fermentation was 4%inoculation amount,32.5? and 105 revolutions per minute.After 24 h of fermentation,the total phenol content of M flavum fermented Diospyros lotus extract,L.plantarum fermented Diospyros lotus extract and the mixed strain fermented Diospyros lotus extract increased by 6.37%,7.35%and 7.26%respectively.23 kinds of phenolic compounds were identified by Liquid Chromatography Electrospray ionization Quadrupole-Time of Flight mass spectrometry(HPLC-ESI-Q-TOF/MS).Mixed strain fermentation showed stronger advantages than the unfermented one in the improvement of nutrient composition.The content of myricetin has been increased by 13 times compared to which unfermented,and gallic acid,quercetin and salicylic acid increased by 4,7 and 3 times,respectively.The results of antioxidant activity showed that compared with the single strain fermentation group,the mix strain fermentation group had more significant effect on DPPH(IC50=115.26±1.55 ?g/mL)and ABTS(IC50=61.32 ± 1.54 ?g/mL)radical scavenging ability.The results of hypoglycemic capacity showed that the mixed bacteria fermentation had the best a-glucosidase inhibition ability(IC50=28.81±1.05 ?g/mL)and the lowest trypsin inhibition ability(IC50=288.25 ±2.70 ?g/mL).In addition,the results of a-glucosidase inhibitory ability of four monomers as follow:Myricetin>acarbose>quercetin>gallic acid>salicylic acid.Myricetin has the highest ?-glucosidase inhibitory ability(IC50=4.52±0.13?g/mL)and its a-glucosidase inhibitory ability is greater than the positive control of acarbose.The results of correlation analysis showed that quercetin and myricetin were significantly correlated with the inhibitory ability of a-glucosidase.It is speculated that quercetin and myricetin may be the components of a-glucosidase inhibitory ability in the extract,and myricetin may play a major role.Methyl thiazolyl tetrazolium(MTT),flow cytometry,Euzymelinked immunosorbent assay(ELISA),and Real time Polymerase Chain Reaction(RT-PCR)were used to explore the protective mechanism of MLDPE on damaged Min6 cells in the high glucose environment.The results showed that MLDPE can promote the expression of insulin mRNA and the release of insulin on damaged Min6 cells in the case of high glucose condition,and myricetin played a important role.MLDPE could increase the gene expression of Bcl-2/Bax,reduce the protein expression of Cytochrome C(Cyt C)and Apoptosis inducing factor(AIF),thus it improved the viability of cells and reduced apoptosis rate.Finally,the normal secretion of insulin was maintained and the normal growth of Min6 cells was protected.The results provided a solid foundation for the deeply development and application of Diospyros lotus.This study also provided new resources and approach for the development and utilizaxion of Diospyros lotus polyphenols.In the future,the polyphenols of Diospyros lotus may have the potential to be widely used in the food and pharmaceutical industries.