Structural analysis of a soluble polysaccharide from the root of Atractylodis Macrocephala Rhizoma and its mechanism in alleviating ulcerative colitis in mice.

Abstract

A newly identified polysaccharide, designated AMRP, was extracted and purified from traditional Chinese medicinal plant Atractylodes Macrocephalae Rhizoma (the rhizome of Atractylodis macrocephala Koidz.) collected from Qimen, Anhui Province. The structural characteristic of AMRP, its efficacy in alleviating ulcerative colitis (UC), and the underlying mechanisms regarding the enhancement of short-chain fatty acids (SCFAs) transport were thoroughly investigated. After purification, the structural formula of AMRP was identified as β-d-Fruf-[(2 → 1)-β-d-Fruf] n-(2 → 1)-α-d-Glcp. In vivo studies demonstrated that AMRP effectively mitigated colitis symptoms, including weight reduction, disease activity index, colon length, as well as pathological alterations within the colon. Further analyses showed that AMRP significantly reduced the concentrations of pro-inflammatory cytokines, including interleukin (IL)-6, IL-1β, and tumor necrosis factor-alpha, as well as the number of CD68+ inflammatory cells. With AMRP treatment, the content of the tight junction protein Claudin-1 was increased. Mechanistic investigations indicated that AMRP alleviates colitis symptoms by increasing SCFAs levels, upregulating the expression of monocarboxylate transporter 1 to facilitate the transport of butyric acid, and inhibiting the expression of histone deacetylase 2. Overall, these effects served to regulate the homeostasis of the colon immune system, achieving anti-inflammatory effects and improving the condition of UC.