枸杞子糖缀合物LbGp4糖链的结构及其免疫活性的研究

枸杞子糖缀合物LbGp4经β--消除、柱层析分离后得到一条分子量高达180800的分支多糖化合物LbGp4-OL.LbGp4-OL糖基组成为n(Rha):n(Ara):n(Gal)=0.05:1.33:1.根据甲基化、部分酸水解及¹HNMR、¹³CNMR分析,确定了其主要的结构,并对LbGp4和LbGp4-OL的免疫活性进行了研究.

Structure Elucidation and Immunoactivity Studies of Glycan of Glycoconjugate LbGp4 Isolated from the Fruit of Lycium barbarum L

Glycan was isolated on Sephadex G-100 column after glycoconguate LbGp4 was released by β-elimination, then desalted on Sephadex G-25 and named LbGp4-OL. The linkage between the glycan and the core protein backbone was O-linkage. The molecular weight of LbGp4-OL was 180 800. The result of its elemental analysis was C 39.1%, H 5.72%, N 0％. Component analysis showed that it was composed of Rha, Ara and Gal in a molar ratio of 0.05∶1.33∶1. The structure of repeat unit of LbGp4-OL was deduced by methylation analysis, partial acid hydrolysis and 1H, 13C NMR spectroscopy of the original glycan and products of its partial hydrolysis. Methylation analysis of LbGp4-OL indicated that highly branching unit in LbGp4-OL was →3,4)Gal(1→, the major non-reducing end was Ara(1→. LbGp4-OL was obtained by partial acid hydrolysis. Comparing the results of methylation analysis of Lb Gp4 with that of LbGp4-OL, we can deduced that the main chain of LbGp4-OL was composed of →4)Gal(1→. 1H and \{13C\} NMR spectra of LbGp4-OL and LbGp4-OL indicate d that Ara(1→ was α-furanose, →3)Ara(1→ and →5)Ara(1→ were β-furanose, all the Gal were β-pyranose, Rha(1→ was α-pyranose, →3)Arap(1→ was α-pyranose. Immunoactivity studies of LbGp4 and its glycan showed that LbGp4 and LbGp4-OL not only enhanced the splenocyte proliferation in normal mouse, but also improved the reducing immune function in the senescense-accelerated mouse. It demonstrated that LbGp4 and LbGp4-OL possess a direct effect of splenocytl proliferation. In addition, the direct elevating action of LbGp4-OL on splencyte prolifexration was stronger than that of LbGp4. So it pointed out that the glycan play an important role in the immunopharmcological activity of glycoconjugate.