葡萄籽原花青素结构单元的红外光谱分析

对葡萄籽原花青素粗提物及其纯化物的红外光谱分析发现，在1520～1540cm。有一个峰，从而推断其基本结构单元主要为原花青定（即B环为邻苯二酚）。由于采用体积分数30％乙醇洗脱纯化物除原花青素外还含有一定量的酚酸，而体积分数50％和70％乙醇洗脱纯化物以原花青素（结构单元主要为花青定）为主，因此乙醇洗脱纯化物的红外光谱图在1380～1100cm^-1和750～850cm。有一定差别，而体积分数70％和50％的乙醇洗脱纯化物红外光谱图比较相近，仅在1000～1200cm。处有细微差别．将葡萄籽原花青素在热酸条件下进行醇解，用LC-MS测定其醇解后的基本结构单元，结果表明葡萄籽原花青素醇解产物为矢车菊素，从而证明葡萄籽原花青素基本结构单元为花青定，这与其红外光谱图特征峰的推断相吻合。

The Analysis of the Infrared Spectra of Grape Seed Proanthocyanidins

By analysis of the Infrared Spectra of crude proanthocyanidin and purified proanthocyanidin extracted from grape seed, a single peak at 1 520~1 540 cm~(-1) region was observed, which could be used to verify the fact that, the basic structural unit of grape seed proanthocyanidin mainly contains two hydroxyls on B ring. Meanwhile, there are some difference between purified extract No.1 (the elutes in big hole resin by 30% ethanol) and the purified extract No.2 (the elutes in big hole resin by 50% ethanol)or No.3(the elutes in big hole resin by 70% ethanol) in the Infrared Spectra of 1 380~1 100 cm~(-1) and 750~850 cm~(-1). The purified extracts No.1 possessed some phenolic acid, which has different structure from proanthocyanidin, the purified extracts No.2 and No.3 are all proanthocyanidin with the basic structural unit of procyanidin. The infrared spectra of purified extract No.2 and No.3 is very similar except little difference in the 1 000~1 200 cm~(-1)region. The result of depolymerization of the grape seed proanthocyanidin under hot acidic alcohol. and analysis with LC-MS, showed that they are all cyanidins. The result verified that the basic structural unit of grape seed proanthocyanidin is cyanidin. That is consistent with the conclusion deduced from the infrared characteristic peaks.