基于实验动物和胃肠细胞模型研究荔枝原花青素的吸收、转运、排泄及构效关系

Nowadays, procyanidins are considered a kind of dietary supplement by several developed countries to evaluate the physical conditions of citizens, since the science and technology is changing more and more quickly. In this research, litchi chinensis will be studied, which is a typical fruit in south of China and is used to prepare the representative procyanidin oligomers by multilevel column chromatography, including flavanol monomers, A- and B-type procyanidin oligomers. Depending on experimental animals, the bioavailability of main procyanidins in litchi pericarp will be discussed, in which we determine the peak time, maximum concentration, half-life and reduction rate of the compounds in rat plasma, and the composition of procyanidin metabolites in urine, in order to obtain the absorption, transport and excretion patterns of procyanidins, as well as their quantitative structure activity relationship (QSAR). Based on the results of in vivo experiment, we will establish an MNK-28 and a Caco-2 cell monolayer model to study the absorption and transport of different procyanidins through gastrointestinal epithelium cell. In the cell models, we will focus on the effect of pH gradient between apical and basolated side of cell, period of transport, concentration of samples and exogenous nutrients on the transport of procyanidins. At last, according to the statistical analysis and comparative molecular field analysis, a QSAR function will be calculated to describe the key factor of spatial structures, which intervenes the absorption and metabolism of procyanidins significantly.

随着科学技术的日新月异，某些发达国家开始将原花青素作为一种重要的膳食补充剂来衡量国民的健康。本项目以南方特色水果荔枝为研究对象，联合多级柱层析色谱高效制备了其特有的原花青素低聚体，包括不同构象的黄烷醇单体、A-和B-型原花青素低聚物等。基于大鼠模型，研究荔枝果皮中主要的5种原花青素在生物体内的达峰时间、最大血药浓度、半衰期和消减速率，同时明确不同原花青素尿液代谢物的基本组成和靶标分配，以初步获取其吸收、转运、排泄的规律及构效关系。在体内试验的基础上，建立胃癌MKN-28和肠癌Caco-2细胞模型，模拟不同原花青素通过胃和小肠上皮细胞的吸收和转运。分别比较膜两侧pH梯度、转运时间、上样浓度和外源营养物质（乙醇、低聚糖）等因素对不同结构原花青素跨膜转运的影响；结合统计学分析，采用比较分子力场法（CoMFA）构建定量构象关系模拟函数，最终确定影响荔枝原花青素吸收和代谢的关键因素。

原花青素是一种公认的具有极高抗氧化活性的膳食补充剂。本项目以南方特色水果荔枝为研究对象，基于双酶解耦合超声辅助绿色提取技术，得到了纯度较高的原花青素提取物（得率13.5%）；并联合多级柱层析色谱制备了三种高纯度的A-型原花青素低聚体。基于SD大鼠模型，研究了荔枝果皮中A-型原花青素在生物体内的达峰时间、最大血药浓度、半衰期和消减速率，并明确了其主要的尿液代谢产物，其中4-羟基苯丙酸和莽草酸是最具代表的酚酸。通过构建MKN-28单层胃细胞模型，研究了荔枝果皮中四种主要原花青素（EC、CC、A2和B2）的毒性和吸收转运特性；结果表明，样品浓度、跨膜pH值和转运时间均会对透过率产生影响；除B2外，其他三种原花青素均被不同程度的吸收，EC的转运率最高可达20%，A2可达16%。荔枝果皮花色苷与麦醇溶蛋白分子间的主要作用力表现为氢键和范德华力，二者复合后对其抗氧化能力影响不大；荔枝果皮原花青素与菊粉相互作用可形成稳定的复合物，复合物的抗氧化活性与混合物相比显著提高。