| Plant polyphenol has the biological activities such as antioxidant, anticancer, antimicrobial, inhibition of cardiovascular and cerebrovascular diseases and so on, which makes it the hot spot of food and biomedical research. China’s acorn resource is so rich that to fully make use of acorn, the research optimized the extraction method of acorn nutlet polyphenol, analyzed the polyphenol components of acorn nutlet using HPLC-MS/MS and evaluated the biological activities such as antioxidant, antimicrobial, cell toxicological activity of acorn nutlet polyphenol extracts. The main results are as follows:The research used ultrasonic-assisted organic solvent extraction method to extract the polyphenol from acorn nutlet and optimized the extraction parameters such as extraction solvent concentration, extraction time, extraction temperature and solid-liquid ratio. The single factor experiments and orthogonal test indicated that extraction time, extraction temperature and solid-liquid ratio had significantly effect on extraction rate. Otherwise, the influence of four factors on extraction rate was: solid-liquid ratio> extraction time> extraction temperature> extraction solvent concentration. The response surface analysis results indicated that the interaction effect between extraction time and temperature was the most significant which3D surface was the steepest. The ridge analysis gave the optimal extraction parameters, that were:extraction solvent concentration50.7%, solid-liquid ration1:49.8, extraction time31.2min, extraction temperature48.9℃, the theoretical extraction rate was17.73%.The acorn nutlet polyphenol components were analyzed mainly to be quercetin derivatives by HPLC-MS/MS.8compounds were identified by mass spectra and literatures. They were:quercetin-3-O-glucosyl-rhamnosyl-hexosyl-hexoside, vescalin (castalin), quercetin-3-O-glucoside (quercetin-3-O-galactoside), quercetin-3-O-xyloside (quercetin-3-O-arabinoside), quercetin-3-O-rhamnoside, ellagic acid, quercetin-3-O-galloylarabinopyranoside and ellagitannin.The antioxidant activity of acorn nutlet poliphenol was evaluated by reducing power, DPPH radical scavenging rate and OH radical scavenging rate. The results showed that the reducing power of acorn polyphenol was not so strong as Vc and the DPPH radical scavenging activity of acorn polyphenol and Vc were almost the same. But different from DPPH, the OH radical scavenging activity of acorn polyphenol was much weaker than that of Vc, presumably due to the different reaction sites between DPPH-polyphenol and OH-polyphenol.The antimicrobial research showed that the acorn polyphenol had inhibition effect on Escherichia coli. and Tichoderma spp. The lowest antimicrobial concentrations of acorn polyphenol to Escherichia coli. was25g/L. It could also inhibite the growth of Tichoderma spp.’s spore when the concentration was33.33g/L.The acorn nutlet polyphenol had the growth inhibition effect on SF9cell evaluated by MTT experiment. The inhibition effect got strong when the polyphenol concentration increased. When the concentration was120mg/L, the cell growth inhibition rate was83.62%. The results showed that acorn nutlet polyphenol had cell toxicological activity.The polyphenol concentration of acorn starch changed little after heat treatment for2hours and it still had antioxidant activity. Especially for the DPPH radical scavenging activity, heat treatment had less effect on it compared with OH radical. So acorn starch could be developed and used as functional food. After polyphenol-off treatment, acorn starch became whiter and the polyphenol removal rate was nearly90%. |
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