老鹰茶(Litsea coreana Lvl.var.lanuginosa)多酚类化合物的提取纯化及EGCG含量测定

Extraction and purification of polyphenolic compounds and determination of EGCG from eagle tea (Litsea coreana Lévl. var. lanuginosa)

以老鹰茶(Litseacoreana Lvl.var.lanuginosa)粉末为原料,运用回流提取和聚酰胺树脂柱层析方法从中提取和纯化多酚类化合物.先用80%乙醇对老鹰茶粉末进行3次回流粗提,即提取温度100℃,提取时间30、20和10min,料液比1:20、1:10和1:10,多酚粗提率为31.46%;然后调节粗提液pH至2.0,12000r?min-1离心10min,得上清液,上清液中多酚得率为93.59%;用去离子水将上清液稀释到2mg?mL-1,调pH值至2.0,作为上样液,再利用聚酰胺树脂对上样液中的多酚类化合物进行纯化.结果表明:在柱高与直径比22,上样液体积1.5BV,吸附平衡1h,洗脱液依次为少量去离子水和80%乙醇,洗脱液流速6mL?min-1条件下,多酚洗脱率达到97.20%;洗脱液经浓缩后,冷冻真空干燥得到纯度为92.80%的多酚类化合物,多酚提取率为18.06%.高效液相色谱(HPLC)测定多酚类化合物中表没食子儿茶素没食子酸酯(EGCG)含量为49.82%.

The polyphenolic compounds were prepared using reflux extraction and polyamide chromatography from the powder of eagle tea（Litsea coreana Lévl.var.lanuginosa）.Polyphenolic compounds were extracted with the 80% ethanol for three times at 100 ℃,of which,the extraction time was 30,20,10 min and the ratio of material to liquid was 1：20,1：10,1：10 respectively,and the crude extraction rate reached 31.46%.Then,the supernatant was collected after adjusting the pH of crude extract to 2.0 and centrifugating at 12 000 r·min^-1 for 10 min,the yield rate of polyphenolic compounds from which was 93.59%.Finally,the supernatant was diluted to 2 mg·mL^-1 and its pH was adjusted to 2.0 as the sample solution,the optimum conditions for purification of polyphenolic compounds using polyamide resin were as follows：the ratio of column height to diameter was 22 with sample volume at 1.5 BV and 1 h of adsorption equilibrium time,and the eluent was little deionized water and 80% ethanol successively with 6 mL·min^-1 of eluent flow rate.Under the optimal conditions,the desorption rate of polyphenolic compounds reached 97.20%.The purity and extraction rate of polyphenolic compounds which were attained by freeze vacuum drying from concentrated eluent reached 92.80% and 18.06%,respectively.The epigallocatechin gallate（EGCG） content of polyphenolic compounds measured by HPLC was 49.82%.