红莲外皮原花青素各级分的分析鉴定

Analysis of Proanthocyanidin Fractions from Red Skin of Lotus Seed

以分级分离得到的4种红莲外皮原花青素级分(F1、F2、F3、F4)为原料,分别进行平均聚合度的测定,通过红外光谱、反相-高效液相色谱以及反相高效液相色谱和电喷雾质谱联用分析,以揭示不同级分的组成和化学结构特征。结果表明F1、F2、F3、F4的平均聚合度分别为2.12、7.27、7.85、8.16。F1、F2、F3和F4的红外光谱图均表现出明显的原花青素特征骨架振动,并推测出红莲外皮原花青素的主要结构单元是原花青定。F1的反相高效液相色谱和电喷雾质谱联用分析检测出3种单体、4种二聚体和2种四聚体,其中3种单体分别为棓儿茶素、儿茶素、表儿茶素,4种二聚体和2种四聚体都是由儿茶素或表儿茶素聚合而成。F2、F3和F4的反相高效液相色谱分析均检测出儿茶素单体和表儿茶素单体。通过与F1的高效液相色谱图对比,推断出F2、F3和F4均含有3种二聚体,并且其中1种二聚体含量较多。同时F2、F3、F4中还存在一种含量较多的未知组分。

Four proanthocyanidin fractions(F1, F2, F3 and F4) from the red skin of lotus seed were measured for mean degree of polymerization, and analyzed for chemical composition and structure by infrared spectroscopy, reversed phase high performance liquid chromatography(RP-HPLC) and reversed phase high performance liquid chromatography coupled with electrospray ionization mass spectrometry(RP-HPLC-ESI-MS). The results of measurement showed that the mean degrees of polymerization of F1, F2, F3 and F4 were 2.12, 7.27, 7.85 and 8.16, respectively. Their infrared spectra exhibited obviously the characteristic stretching vibration of proanthocyanidins, indicating that these proanthocyanidin fractions are mainly composed of procyanidins. By RP-HPLC-ESI-MS, three types of monomers, four types of dimmers, and two types of tetramers were tentatively identified in F1. The three types of monomers were catechin, epicatechin, and gallocatechin and both the four types of dimmers and two types of tetramers were composed of catechin or epicatechin through polymerization. In addition, the monomers of catechin and epicatechin were identified in F2, F3 and F4 by RP-HPLC. By comparing the HPLC chromatogram of F1 with those of F2, F3 and F4, it can be speculated that F2, F3 and F4 contain three types of dimmers, and the content for one of which was higher than those of the others. Meanwhile, an unknown component with relatively high content existed in F2, F3 and F4.