Abstract:

The effects of Polygonati Odorati Rhizoma (POR) with milk processing in traditional Mongolian medicine, was evaluated on polysaccharide composition, immunomodulatory activity and intestinal flora. In this study, polysaccharides were extracted from POR and Polygonati Odorati Rhizoma Lactum (PORL) using the water extraction and alcohol precipitation method. The total sugar content was determined by the phenol-sulfuric acid method. The molecular weight distribution of the polysaccharides was analyzed using high-performance gel permeation chromatography, and the monosaccharide composition was determined by ion chromatography. The immunomodulatory effects of POR and PORL were evaluated on a cyclophosphamide-induced immunosuppressed mouse model and its effects on the intestinal flora of immunosuppressed mice were analyzed using 16S rRNA high throughput sequencing. The results showed that the sugar content of POR was decreased after milk processing, and the polysaccharides with weight average molecular weight (M_W) of 438.752 kDa was degraded and the radio of M_W of 4.236 kDa was increased. The contents of galactose, galacturonic acid, rhamnose, and arabinose increased (P<0.05 or P<0.01), while the levels of glucose, xylose, and mannose decreased (P<0.01) after milk processing. Pharmacological experiments demonstrated that, compared to the model group, both POR and PORL significantly up-regulated the indices of immune organs in immunosuppressed mice (P<0.05) and significantly elevated the serum levels of immunoglobulin A (IgA), IgG, IgM and tumor necrosis factor-alpha(TNF-α), interleukin-2(IL-2) compared to the model group (P<0.05). In here, the PORL group significantly increased the spleen index (P<0.05) and IgM, TNF-α, and IL-2 levels (P<0.05) compared to the POR group. The intestinal flora analysis revealed that, compared with the model group,the alpha diversity of high-dose PORL group (1 400 mg/kg) was increased as indicated by the Chao1 and Shannon indices (P<0.05); the microbial diversity also tended to normalize; the ratio of the Firmicutes to Bacteroidetes was down-regulated and the relative abundance of Lactobacillus was up-regulated in both POR and PORL groups. This study preliminarily elucidated the changes in polysaccharide composition and the synergism effect on immunomodulatory effects of POR after milk processing, as well as its impact on intestinal flora. The findings provide valuable experimental evidence for the potential application of PORL.

Key words: Polygonati Odorati Rhizoma, milk processing, polysaccharide, immune regulation, intestinal flora