INFLUENCE OF MOLECULAR WEIGHT AND PERIODATE-MODIFICATION OF β-D-GLUCANS FROM PORIA COCOS SCLEROTIUM ON ANTITUMOR ACTIVITIES*

In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysisor partially hydrolysis, the derivatives have obvious antitumor activities. The decreasein molecular weight of glucans after periodate modification hardly affects their antitumoractions, but on the other hand, the decrease of molecular weight without periodate modi-fication could lead to an enhancement of the antitumor activities. Moreover, the glucansand these derivatives have much higher enhancement ratios of body weight of mice thanthat of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.     

水溶性高支化多糖及硫酸酯衍生物抗癌活性研究

从虎奶菇菌核中提取出一种水溶性高支化葡聚糖,并用氯磺酸和吡啶在无水二甲亚砜中进行硫酸酯衍生化,制备出硫酸酯衍生物.用巴比赛小鼠动物实验研究该多糖及其硫酸酯衍生物的体内抗肉瘤S-180活性,以及用肝癌细胞株HepG2研究体外活性,同时讨论多糖分子尺寸与抗癌活性的关系.通过形态学、组织切片、以及酶联免疫法研究硫酸酯化对多糖抗肿瘤活性的影响.结果表明,支链多糖的均方根旋转半径在42.5~113 nm之间,显示出较高的体内和体外抗肿瘤活性,硫酸酯衍生物的均方根旋转半径在17.8~34.9 nm之间,抗癌活性随其分子尺寸的增大而逐渐提高.多糖及其硫酸酯衍生物能诱导人体肝癌HepG2细胞凋亡,且具有时间依赖性.它们对免疫反应的调节作用可通过肿瘤坏死因子TNF-α来介导.