Acetyl-glucomannan from Dendrobium officinale: Structural modification and immunomodulatory activities

Xiaoyu Guo; Mingguan Yang; Changlu Wang; Shaoping Nie; Steve W Cui; Qingbin Guo

doi:10.3389/fnut.2022.1016961

Acetyl-glucomannan from Dendrobium officinale: Structural modification and immunomodulatory activities

Front Nutr. 2022 Sep 29:9:1016961. doi: 10.3389/fnut.2022.1016961. eCollection 2022.

Authors

Xiaoyu Guo¹, Mingguan Yang², Changlu Wang¹, Shaoping Nie³, Steve W Cui⁴, Qingbin Guo¹

Affiliations

¹ State Key Laboratory of Food Nutrition and Safety, College of Food Science and Technology, Tianjin University of Science and Technology, Tianjin, China.
² College of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China.
³ State Key Laboratory of Food Science and Technology, China-Canada Joint Laboratory of Food Science and Technology (Nanchang), Nanchang University, Nanchang, China.
⁴ Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada.

Abstract

To understand the mechanisms of immunomodulatory effect, Dendrobium Officinale polysaccharides (DOP) were treated by ultrasound and mild base separately to generate fractions of various weight-average molecular weight (Mw) and degrees of acetylation (DA). The structural features, conformational properties, functional properties and immunomodulatory activities of original and modified DOPs were investigated. Ultrasonic treatment decreased the Mw and apparent viscosity and improved the water solubility of DOP. Mild base treatment remarkably reduced the DA and the water solubility, while the overall apparent viscosity was increased. Conformational analysis by triple-detector high performance size-exclusion chromatography showed that the molecular chain of DOP turned more compact coil conformation with decreased DA. Results from the macrophages RAW 264.7 analysis showed that samples sonicated for 200 min (Mw 34.2 kDa) showed the highest immune-regulation effects. However, the immunomodulatory effects of the samples after de-acetylation were all compromised compared to the original DOP. This study inspires further research to establish the structural-immunomodulatory relationships, which promote the application of DOP in both the food and medicine fields.

Keywords: Dendrobium officinale polysaccharide; O-acetylation; glucomannan; immunomodulatory; structural modification.