紫苏花青素及其同系物的神经保护作用及构效关系研究

Anthocyanins can pass the blood-brain barrier and arrive at the nerve center. They can play a neuroprotective activity by reducing the damage made by oxidative stress and β- Amyloid. So they are expected to become the new generation of natural anti-aging function pigment. The antioxidant activity of malonylshisonin, a major anthocyanin from Perilla frutescens, is twice of its aglycone - cyanidin. It suggests that Perilla anthocyanins may possess a stronger neuroprotective activity which is based on alleviating oxidative stress, and the activity is related with its chemical structure. In this study, firstly, 9 anthocyanins of Perilla frutescens will be seperated, and then the neuroprotective activity of perilla anthocyanins and other anthocyanins standard will be evaluated by testing on oxidative stress injury PC12 cells and Aβ-induced damage PC12 cells. The activity-structure relationship will be studied and 1-2 the most activated anthocyanins will be selected to test in rats. The study may provide a theoretical basis for the use of anthocyanins in elderly health food. .

花青素类化合物能通过血脑屏障，作用于神经中枢，通过抗氧化及减轻Aβ对神经细胞的损伤，起到神经保护作用，可望成为新一代天然抗衰老功能性色素。紫苏花青素-丙二酰紫苏宁的抗氧化能力是其苷元的2倍，提示紫苏花青素可能具有更强的基于减轻氧化应激的神经保护活性，且活性与其结构存在相关性。本研究拟对紫苏花青素中所含9种花青素进行分离，分别建立氧化应激损伤和Aβ诱导损伤的PC12神经细胞模型，评价并对比各紫苏花青素分别对两种损伤的神经保护作用，同时与市售常见花青素活性进行比较，讨论其构效关系，分析其活性基团，并将活性较高的1-2种花青素在整体动物水平进行神经保护活性验证，为花青素在老年保健食品中应用提供理论依据。

紫苏是一种传统的药食两用植物,富含花青素等多种多酚类成分.本课题对紫苏花青素及多酚类成分的提取进行了优化,发现加入低浓度硫酸的甲醇-水(1:1)的溶液不仅能获得较高的花青素提取率,也能减少提取过程中花青素的降解. 鉴定了紫苏中花青素类化合物7个：malonylshisonin, cafeoylmalonylcyanin, cyanine, cafeoylcyanin，cis-shisonin, shisonine, 和malonyl-cis-shisonin； 8种黄酮：vicenin-2, apigenin-7-O-diglucuronide, scutellarein-7-O-diglucuronide, scutellarein-7-O-glucuronide, luteoline-7-O-diglucuronide, luteolin-7-O- glucuronide, apigenin及luteolin；及三种苯丙素：咖啡酸，迷迭香酸和coutaric acid。在细胞水平研究了紫苏提取物及分离所得的单体shisonin，迷迭香酸，咖啡酸和luteolin的抗氧化应激活性，发现仅有luteolin能少量提高H2O2损伤的PC12细胞的存活率，其它化合物及提取物没有活性。shisonin在能提高Aβ损伤的PC12细胞的存活率，在100-300μg/mL的浓度下呈量效关系；而紫苏粗提物没有明显抗Aβ活性。100μg/mL紫苏提取物能有效保护RAW264.7细胞免受氧化损伤，保护效果在10-100μg/mL浓度范围内呈量效关系。低浓度迷迭香酸也显示出抗氧化损伤RAW264.7细胞的活性，但随着浓度升高细胞存活率反而下降。以DPPH法进行了31个不同结构的黄酮样品的抗氧化活性研究，发现3’，4’位有羟基取代基的黄酮抗氧化活性明显增加，其活性相当于Trolox的10倍以上，其次3-OH取代也能增强黄酮的抗氧化活性，而2’，5有羟基取代时明显使抗氧化活性降低。而甲氧基取代的黄酮均未显示出抗氧化活性。在对红花苯丙素提取研究中，发现一个新化合物2-hydroxy-1-(3-hydroxy-3-(2-(2-methoxy-2-oxoethyl) phenyl) propanoyloxy) pentan-3-yl benzoate