Locust bean gum galactomannan hydrolyzed by thermostable beta-d-mannanase may reduce the secretion of pro-inflammatory factors and the release of granule constituents.

作者：Chen Wei Lin; Chen Huan Ling; Guo Gui Wen; Huang Yu Chun; Chen Cheng Yu; Tsai Yu; Huang Keh Feng; Yang Chao Hsun^*

来源：International Journal of Biological Macromolecules, 2018.

DOI：10.1016/j.ijbiomac.2018.03.097

• Allergy
• Inflammation
• Locust bean gum
• Thermobifida fusca
• beta-d-Mannanase

Locust bean gum (LBG) galactomannan has been claimed to have applications in the biopharmaceutical field. However, the effects of LBG galactomannan on immunomodulatory aspects are not yet clear. The purpose of this study was to over-express thermostable beta-d-mannanase from the thermophilic actinomycete Thermobifida fusca BCRC 19214 using a Pichia pastoris expression system. The maximum intracellular beta-d-mannanase activity obtained from the cell-free extract was approximately 40.0U/mL after 72h of cultivating a P. pastoris transformant (pPICZ-man) induced with methanol. Hydrolysis of native LBG galactomannan with 8U/mL beta-d-mannanase for 24h significantly decreased the weight-average molecular weight of LBG galactomannan from 5,580,010 to 3188. Native and hydrolyzed LBG galactomannan in a range of 0-0.2% did not trigger significant cytotoxicity after 24h of treatment compared with the control. The native LBG galactomannan stimulated RAW 264.7 cells to produce cytokine TNF-alpha dose-dependently, but there was no significant IL-1beta or nitric oxide production. The native LBG galactomannan also stimulated beta-hexosaminidase secretion in RBL-2H3 cells. After the native LBG galactomannan was hydrolyzed with beta-d-mannanase, all of the immunological properties disappeared. These results suggest the possible immunomodulatory effects of native LBG galactomannan.