绿茶阿拉伯半乳糖蛋白的分离、纯化及肝脏靶向性的初步研究

Separation, purification of green tea arabinogalactan proteins and preliminary study on its liver targeting

目的:从绿茶中分离纯化阿拉伯半乳糖蛋白(AGPs),对其肝脏靶向性进行初步研究。方法:将脱色后的绿茶粉末在80?℃加水(1:20,w/v)浸提1.5h,获得的上清浓缩后用乙醇沉淀,收集重新溶解后在离子交换色谱Q Sepharose Fast Flow柱(20mm×60cm)和SephadexG100柱(16mm×60cm)纯化,收集主要含糖组分,冷冻干燥后获得绿茶AGPs,对其进行单糖组成、氨基酸组成、蛋白含量、糖醛酸含量分析。分别以200、400和800mg/kg.d3种剂量的绿茶AGPs灌胃昆明小鼠,2周后处死,取肝脏测定湿重和肝糖元含量。结果:分离纯化获得的绿茶AGPs分子量约为100kDa,是一种主要单糖组成为阿拉伯糖和半乳糖、含有一定量糖醛酸、蛋白含量低于10%的水溶性糖蛋白。初步研究发现绿茶AGPs与其它来源的AGPs一样具有肝脏靶向性。结论:绿茶AGPs的安全性和肝脏靶向性使其在药品输送上具有良好的应用前景。

Objective: To separate and purify arabinogalactan proteins (AGPs) from green tea and preliminarily investigate its liver targeting. Methods: The discolored green tea powder was immersed in 80 ?℃ water for 1.5 h, and the obtained extracts were concentrated and precipitated by ethanol. The precipitates were resolved in water and loaded onto Q Sepharose Fast Flow column (20 mm×60 cm) and then onto Sephadex G100 column (16mm×60cm) for purification. The main polysaccharide part was collected and submitted to freeze-dry to yield green tea AGPs which monosaccharide composition, amino acid composition, protein content, and uronic acid content were analyzed. Kunming mice were gavaged with green tea AGPs at the dosage of 200、400 和 800 mg/kg.d. After 14 consecutive days infusion, the mice were sacrificed and their liver weight and liver glycogen content were determined. Results: The purified green tea AGPs, a soluble glycoprotein with molecular weight of 100 kDa, was mainly composed of arabinose and galactose, some uronic acids and no more than 10% protein. The preliminary study disclosed that green tea AGPs displayed liver targeting as other AGPs. Conclusions: The characters of safety and liver targeting of green tea AGPs made it a promising vector in drug transportation.