| Proanthocyanidins is a generic term for a large class of polyphenols, with a variety of physiological effects, which is one of the safe and effective natural antioxidants. Xinjiang is an important grape growing areas with a mass of grape vines abandoned every year, in which contain a certain amount of proanthocyanidins. If people can take advantage of these wastes and improve their additional benefits, it not only increases the income of local farmers, but also plays a significant role in promoting the healthy development of grape industry. The paper collects the abandoned vines of different grape varieties as raw material, analyzing and comparing the content of the main chemical components. Based on comparing different analytical methods of proanthocyanidins content in grape vines, extraction process and separation and purification conditions were optimized on proanthocyanidins extracts from the abandoned vines, and its antioxidant activities were evaluated.Besides, the dates of composition and content of the extracts obtained by High Performance Liquid Chromatographic method are further analyzed. The main contents are as follows:Different methods, namely ferric ion catalytic colorimetric method,H2SO4-vanillin, HCl-vanillin assay method and UV spectrophotometry method, were adopted to analyze the content of proanthocyanidin in various kinds of grape vines.The advantages and disadvantages of above-mentioned analyzing ways of proanthocyanidins in varieties of grape vines were discussed by means of methodological and statistical analysis, and different proanthocyanidin reference substances were used to compare the results in UV methods. The research shows that the measurement results of UV spectrophotometry method were significantly higher than those of the other three methods, while the calculated content of the references in proanthocyanidin B2 is the highest among total proanthocyanidins through UVmethod, nearly twice the measurement value of proanthocyanidins UV reference. The calculated content of the references in proanthocyanidin B1 is between the other twos.The ferric ion catalytic colorimetric method and vanillin assay method are with great specificity, but the former requires a long reaction time and the latter is unstable.However, UV spectrophotometry method enjoys good stability, high precision, simple in operation these advantages.The crude fat, crude protein, polysaccharides, flavonoids and polyphenols and other chemical constituents in grape vines were analyzed, and a four factors and three level orthogonal test(L9(34)) was designed to optimize extraction technology of proanthocyanidins from grape vines on the basis of single factor experiments(seedless white grape was acted as material). The optimum parameters obtained were as follows:temperature 65 ℃, ethanol concentration 50%, solid-liquid ratio 1:30,ultrasonic-assisted time of 15 min, extraction time 90 min, and under the optimum conditions proanthocyanidins extraction rate of 5.41%.These two products of high polymer and oligomeric proanthocyanidins, which can be called PPCs and OPCs for short, were fractionated with ethyl acetate and N-butyl alcohol from proanthocyanidins crude extract with liquid-liquid extraction process, and its contents were futher compared. Meanwhile, the antioxidant activity of PPCs and OPCs on scavenging activity of DPPH radical and hydroxyl radical were evaluated a sun protection factor(SPF) were determined. The results showed that the total proanthocyanidin contents of different varieties of grape vines are between3.68%~6.85%. After separation, the extraction rate of PPCs is much higher than that of OPCs. The extraction rates of PPCs and OPCs are respectively 26.91%~47.65%and 24.14%~31.58%, but its purity is lower than oligomeric proanthocyanidins. The purity of PPCs and OPCs is separately 44.09%~68.17% and 90.98%~132.53%. PPCs and OPCs all have strong antioxidant activity and UV activity, and UV activity of the latter is stronger than the previous one. By F-test and shortest significant ranges(SSR)test for significance analysis, when it finds that the proanthocyanidins concentration comes in 0.02 mg/m L, it is related to DPPH radical scavenging activity and the species of grape vines but irrelevant to the degree of polymerization of proanthocyanidins. It is related to the degree of polymerization proanthocyanidins but unrelated to scavenging activity and grape varieties of hydroxyl radicals. When the concentration is increased to 0.05 mg/m L, its scavenging ability of hydroxyl radicals is also related to grape vines varieties, but it is without obvious correlation with polymerization degree of proanthocyanidins.The composition and content of proanthocyanidins in different varieties of grape vines and proanthocyanidins extract were futher analyzed by high performance liquid chromatography method in this study. It found that grape vines contain catechin,epicatechin and resveratrol. However, the type and content of various kinds of grape vines proanthocyanidins monomers were also different. The content of three extracted proanthocyanidin monomers also significantly got enriched. Proanthocyanidin B1 and proanthocyanidin B2 have not been detected in the extracts of grape vines among testing species, but this is the most common dimers in grape skin and seeds. |
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