Available online 29 March 2024, 100974

A novel polysaccharide with galactose backbone (SPR-1) was isolated from PRWB and the structural features were comprehensively elucidated.

SPR-1 could stimulate the RAW 264.7 production of immune response.

ITC and molecular docking indicated high-affinity binding between SPR-1 and MD2.

SPR-1 activated the immune response through TLR4 signaling and downstream responses.

SPR-1could be a promising TLR4 agonist candidate derived from PRWB.

A purified polysaccharide with a galactose backbone (SPR-1, Mw 3,622 Da) was isolated from processed Polygonati Rhizoma with black beans (PRWB) and characterized its chemical properties. The backbone of SPR-1 consisted of [(4)-β-D-Galp-(1]9→4,6)-β-D-Galp-(1→4)-α-D-GalpA-(1→4)-α-D-GalpA-(1→4)-α-D-Glcp-(1→4,6)-α-D-Glcp-(1→4)-α/β-D-Glcp, with a branch chain of R1: β-D-Galp-(1→3)-β-D-Galp-(1→ connected to the →4,6)-β-D-Galp-(1→ via O-6, and a branch chain of R2: α-D-Glcp-(1→6)-α-D-Glcp-(1→ connected to the →4,6)-α-D-Glcp-(1→ via O-6. Immunomodulatory assays showed that the SPR-1 significantly activated macrophages, and increased secretion of NO and cytokines (i.e., IL-1β and TNF-α), as well as promoted the phagocytic activities of cells. Furthermore, isothermal titration calorimetry (ITC) analysis and molecular docking results indicated high-affinity binding between SPR-1 and MD2 with the equilibrium dissociation constant (KD) of 18.8 μM. It was suggested that SPR-1 activated the immune response through Toll-like receptor 4 (TLR4) signaling and downstream responses. Our research demonstrated that the SPR-1 has a promising candidate from PRWB for the TLR4 agonist to induce immune response, and also provided an easily accessible way that can be used for PR deep processing.

Polygonati Rhizoma

Polysaccharide

Structural properties

Immunoregulatory

processed Polygonati Rhizoma with black beans

isothermal titration calorimetry

the equilibrium dissociation constant

traditional Chinese medicine

Polygonatum polysaccharide

high-performance gel permeation chromatography

Fourier-transform infrared

nuclear magnetic resonance

the partially methylated alditol acetates

gas chromatography–mass spectrometry

D-glucosamine hydrochloride

N-acetyl-D-glucosamine

D-galactosamine hydrochloride

high-performance ion exchange chromatography

Quantitative real-time polymerase chain reaction

the weight average molecular weight

the number average molecular weight

the total ion chromatograms

© 2024 Published by Elsevier B.V. on behalf of Xi’an Jiaotong University.