%0 Journal Article
%T Acetylation at the O-6 position of t-Glc improved immunoactivity of α-1,6-glucan from longan by additionally activating Dectin-1 and CD14 receptors.
%A Liu L
%A Lan H
%A Wang Y
%A Zhao L
%A Liu X
%A Hu Z
%A Wang K
%J Carbohydr Polym
%V 320
%N 0
%D 2023 Nov 15
%M 37659806
%F 10.723
%R 10.1016/j.carbpol.2023.121199
%X Acetylation is an important approach to improve the bioactivity of polysaccharides; however, the mechanisms have not been fully understood. As a key component of longan for exerting health promoting function, longan polysaccharide was hypothesized may achieve elevated immunoregulatory activity after acetylation. A bioactive longan polysaccharide (LP) composed of (1 → 6)-α-d-glucan (84.1 %) and with an average Mw of 9.68 × 104 kDa was acetylated to different degree of substitutions (DS) in this study. Key structural changes responsible for improvement in immunoregulatory activity were identified, and underlying mechanisms were investigated. Acetylated LP (Ac-LP) with DS 0.37, 0.78 and 0.92 were obtained. Structural characterization identified the substitution of acetyl groups occurs at O-6 positions of t-Glc non-selectively, while the backbone structure was not apparently changed. This resulted in increased expression of cytokines (IL-10, IL-6 and TNF-α) and ROS production in RAW264.7 macrophages, indicating improved immune activity which is positively related to the DS of Ac-LP. This is attribute to additional cellular receptors for Ac-LP (CD14 and Dectin-1) apart from receptors for LP (TLR4 and Ca2+ receptors), as well as the relative higher protein expression of TLR4-MyD88 signaling pathways. These results would provide guidance for the utilization of acetylated polysaccharides with improved immunoactivity.