Free And Bound Phenolic Contents Detemination And Bioactivities Assay In Grape

Grape widely planted and grown in China, mainly used for making grape wine and juice. Peels and seeds were the main by-products in the processing process of graps, but those by-products are not effectively utilized. Free polyphenols(FP) and bound polyphenols(BP) were main bioactive compounds in these by-products. In order to improve the utilization of by-products from grape, FP and BP in peels and seeds were extracted from kyoho grapes. The main compounds of FP and BP were analyzed by high performance liquid chromatography(HPLC). Functional evaluation was carried out by antioxidant assays and anti-inflammatory experiment of macrophages. This study will provide a strong support for the use of by-products from grapes.1. Extraction of FP in grape peels and seeds with ultrasonic method. The factors of ultrasonic time, ultrasonic power, solid-liquid ratio, extraction solvent of FP was determined by single factor test. And extraction parameters were optimized by response surface method. The optimized extraction conditions of FP in grape peels were as follows, solid/liquid 1:30, ultrasonic time 1.6h, ultrasonic power 430 W, ethanol concentration 33%, and 29.16 mg/g yield of polyphenols was obtained. The optimized extraction conditions of FP in grape seeds were as follows, solid/liquid 1/45, ultrasonic time 1h, ultrasonic power 425 W, ethanol concentration 60%, and 71.29 mg/g yield of polyphenols was obtained.2. Extraction of BP in grape peels and seeds using alkaline hydrolysis. The factors of hydrolysis time, alkali concentration, solid-liquid ratio of the three factors were determined by single factor test. And extraction parameters were optimized by response surface method. The optimized extraction conditions of FP in grape peel were as follow: extraction time 3h, solid-liquid ratio 1/40, extraction concentration of 1mol/L, and 37.33mg/g yield of polyphenols was obtained; The optimized extraction conditions of FP in grape seeds were as follow: extraction time 1.4h, solid-liquid ratio 1/31, extract concentration 2mol/L, and 5.29mg/g yield of polyphenols was obtained.3. The main compounds of FP and BP were analyzed by HPLC. The results showed that catechin was the major compound of FP from grape peels. Epicatechin and catechin were the major compounds of FP from grape seeds. Chlorogenic acid and epicatechin were the major compounds of BP in seeds and peels.4. Through functional evaluation, research results show that four kinds of grape polyphenols have antioxidant. The order of antioxidant activity was as following: FP in grape seeds> FP in grape peels > BP in grape peels > BP in grape seeds.5. The effects of four kinds of grape polyphenols on the secretion of COX-2, PGE2, NO and iNOS in LPS-prestimulated macrophage were studied. The results showed that the secretion of COX-2, PGE2, NO and iNOS can be decreased by four kinds of grape polyphenols in the LPS-induced macrophage. Research results show that four kinds of grape polyphenols have anti-inflammatory effect, and the inhibitory effect of FP was better than BP.In summary, the results show that the major phenolic compounds in grape were catechin, chlorogenic acid; Four kinds of grape polyphenols have antioxidant and anti-inflammatory properties, and the inhibitory effect of FP was better than that of BP.