Structure and Bioactivities of a Novel Polysaccharide Extracted From Dendrobium huoshanense by Subcritical Water

Abstract

In this study, the polysaccharide was extracted by subcritical water from <i>Dendrobium huoshanense</i>. A novel polysaccharide (DHPs-1) was obtained through several purification steps and its structure and bioactivity were investigated. Structural analysis indicated that the weight-average molecular weight of DHPs-1 was 5.0 × 10⁴ Da and it was mainly composed of glucose (65.04%), mannose (14.23%), galactose (8.17%), galacturonic acid (6.41%), rhamnose (2.34%), and xylose (1.25%). 1,4-Glc<i>p</i>, and 1,4,6-Gal<i>p</i> were existed in the backbone of DHPs-1. The residues of 1,3,4-Gal<i>p</i>, 1,4-Man<i>p</i>, 1,4-Gal<i>p</i>, and 1,3,4,6-Gal<i>p</i> could be in the backbone or the side chains with the non-reducing terminal of α-Man<i>p</i>. Bioactivity tests indicated that DHPs-1 had immunomodulatory activity in that it significantly enhanced transcript levels of cytokines [Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), and Interleukin-10 (IL-10)]. DPPH and hydroxyl radical scavenging tests showed that it had good antioxidant activity. These results reveal that DHPs-1 could be developed as a safe immunomodulatory agent and antioxidant for pharmacological or functional food applications.