An inulin-type polysaccharide from Atractylodis Macrocephalae Rhizoma can relieve psoriasis.

Atractylodis Macrocephalae Rhizoma (AMR), an herb often found in compounded remedies for psoriasis, is rich in polysaccharides. However, the beneficial effects of AMR polysaccharides on psoriasis remain obscure. In this study, an inulin-type fructan-labelled AMP was extracted from the AMR. AMP has a molecular weight of 5.84 kDa and comprises fructose, glucose, and arabinose at a molar ratio of 93:5:2. Methylation and NMR analyses revealed that AMP comprises a linear backbone of 2,6-linked Fruf or 1,2-linked Fruf with branching 1,2,6-linked Fruf and terminates in T-Glcp. Animal studies verified that AMP can improve imiquimod-induced psoriasis-like skin lesions and downregulate the Il-17a, Il-23, Il-22, Il-6, Il-12, and Tnf-α gene expression. Furthermore, we elucidated the underlying mechanisms using cellular experiments. The ability of AMP to inhibit hyperproliferation and the overexpression of TNF-α, IL-6, and IL-23 genes in human immortal keratinocyte cells (HaCaT) stimulated by lipopolysaccharide was demonstrated. These results indicate that AMP may directly target keratinocytes to suppress excessive proliferation and contribute to anti-inflammatory responses, potentially by blocking the activation of the PI3K/AKT/mTOR pathway. In summary, AMP has demonstrated potential as a prospective treatment strategy for psoriasis.