The core structure of a Dendrobium huoshanense polysaccharide required for the inhibition of human lens epithelial cell apoptosis.

The aim of this work was to investigate the core structure of a Dendrobium huoshanense polysaccharide DHPD1 required for the inhibition of lens epithelial cell apoptosis. In order to obtain the fragments containing the core domain, pectinase was employed to hydrolyze DHPD1. After 24h reaction, it is interesting that the hydrolyzation seemed to be stopped, leading to a final enzymatic fragment DHPD1-24 with molecular weight about 1552Da. Compared to DHPD1, although the bioactivity is decreased, DHPD1-24 remained the ability to inhibit the HO-induced apoptosis of human lens epithelial (HLE) cells via suppressing the MAPK signaling pathways. These results suggested that DHPD1-24 might be the core domain required for DHPD1 to inhibit HLE cell apoptosis. Methylation analysis showed DHPD1-24 was composed of (1→5)-linked-Araf, (1→3,6)-linked-Manp, 1-linked-Glcp, (1→4)-linked-Glcp, (1→6)-linked-Glcp, (1→4,6)-linked-Glcp, (1→6)-linked-Galp and 1-linked-Xylp in a molar ratio of 1.06:1.53:2.11:2.04:0.93:0.91:0.36:1.01. Moreover, the primary structural features of DHPD1-24 were characterized by NMR spectrum.