Extraction,Antioxidant And Antibacterial Properties Of Polyphenols From Chestnut Shell

Chestnut shell is one of the main by-products in the chestnut processing,which contains rich polyphenols.At present,chestnut shell is mainly discarded by burning,throwing away and other ways,and has not been used efficiently.The study on the extraction,antioxidant and antibacterial properties of polyphenols from chestnut shell has theoretical and practical significance to promote its further processing and utilization.In this study,polyphenols from chestnut shell were extracted by solvent extraction and purified by microporous resin.The constituents of polyphenols from chestnut shell were identified by high performance liquid chromatography-quadruple time-of-flight mass spectrometer.Then,the antioxidant activity and antibacterial properties of the polyphenols from chestnut shell were investigated.The main research results were as follows:(1)The optimal extraction conditions were determined by single factor test and response surface test as follows:liquid-solid ratio 39:1,extraction temperature 74?,extraction time 91min,ethanol concentration 65%.Under these conditions,the yield of polyphenols from chestnut shell was 6.09%.(2)AB-8 microporous resin was selected from six microporous resin as the purification resin of polyphenols from chestnut shell,and the optimal purification conditions were determined:the concentration of polyphenols was 4 mg/m L,the p H was 3,the loading flow rate was 1 m L/min,the loading volume was 60 m L,the concentration of eluent ethanol was45%,the eluent flow rate was 1 m L/min,the eluent volume was 100 m L.The purity of polyphenols in the extract was increased from 30.60%to 71.10%.(3)Using high performance liquid chromatography-quadruple time-of-flight mass spectrometer,the mass spectrum information of four compounds in the polyphenols extract were obtained.According to the mass spectrometry information,three compounds were identified as:Isorhamnetin,Eupatilin,Jaceosidin.(4)There was a dose-effect relationship between the concentration and total reducing power,DPPH radical and ABTS radical scavenging ability of polyphenols from chestnut shell.The total reducing power of purified polyphenols was greater than that of unpurified polyphenols.The scavenging ability of DPPH free radical was as follows:purified polyphenols>VC>unpurified polyphenols,IC₅₀ values were 0.014 mg/m L,0.025 mg/m L,0.035 mg/m L,respectively.The scavenging ability of ABTS free radicals was as follows:purified polyphenols>VC>unpurified polyphenols,IC₅₀ values were 0.024 mg/m L,0.035 mg/m L,0.066 mg/m L,respectively.(5)The antibacterial effect of polyphenols from chestnut shell against Staphylococcus aureus and Bacillus subtilis was better than that on Escherichia coli.The polyphenols from chestnut shell could cause damage to the cell wall and membrane of S.aureus and B.subtilis,destroy the integrity of cell membrane,increase the permeability of cell membrane,and not only cause the leakage of intracellular ions,but also cause the leakage of biological macromolecules such as nucleic acid and protein,so as to achieve the antibacterial effect.