Extraction, Purification And Effect Of Scavenging Free Radicals Of Trans-resveratrol From Grape Pomace

This study used the grape byproducts after brewing (grape pomace) as material and extracted trans-resveratrol which had many kinds of physiological functions from it. In order to provide theory supports to the exploitation of grape pomace, extrcation conditions, purification methods and scavenging free radicals of trans-resveratrol were researched.The determinations of trans-resveratrol were detected by ultraviolet spectrophotometry and HPLC. When detected by ultraviolet spectrophotometry, the optimal absorption wavelength was 306nm and the regression equation of standard curve was y=0.1122x-0.0132(R2=0.9991) in the range of 0~8μg/mL. When detected by HPLC, the chromatography conditions were obtained with the flow phase being methanol/water (50:50, v/v), the flow ratio being 0.8mL/min and the column temperature being room temperature. Under these conditions, the chromatogram's peak shape of standard preparation was good and the regression equation of standard curve was y=60297x-10418(R2=0.9997). The linear relationship was excellent with concentration in the range of 0.5~20μg/mL and the minimum detection limit was 0.5μg/mL.The grape pomace was extracted by organic solvents such as 80% methanol, 80% alcohol, 80% acetone and acetidin. The results showed that 80% alcohol was the optimal extraction solvent.Response surface analysis with there factors and there levels was applied to optimize the conditions of extraction. The optimal conditions were temperature being 69℃, extraction time being 61min and ratio between solvent and dreg being 46mL/g. Its theory maximum extraction content was 104.39μg/g, while its practical content was 103.86μg/g which was obtained through the probation experiment. The order that the there factors effected the contents was ratio > extraction time > temperature.The macroporous resins method and the alkali extraction and acid precipitation method were used to purify trans-resveratrol. AB-8 resin was selected to purification and adsorbed trans-resvertrol mostly in 4h. When the concentration of trans-resvertrol was 70.6μg/mL, AB-8 resin absorbed it well. The absorbed AB-8 resin was desorbed by 75% alcohol with flow ratio being 0.75BV/h and volume being 5.5BV. The purity quotient of trans-resveratol by resins method was 26.32%. In the method of alkali extraction and acid precipitation, the pH value of NaOH solution was 12 when extracting and the pH value of extraction solution was 3, regulating by HCl solution. The product contained trans-resveratrol which was determined after the qualitative and quantitative study and its purity quotient was 59.88% detected by HPLC.Scavenging hydroxy free radical and DPPH free radical by trans-resveratrol were researched. The results showed that trans-resveratrol had some effects to free radicals and these effects depended on the concentration of trans-resveratrol solution. In this study, the higher the concentration, the stronger the effect.