Purification, Structural Characterization and Immunomodulatory Effects of Polysaccharides from <i>Amomum</i><i>villosum</i> Lour. on RAW 264.7 Macrophages

• Main Authors: Yang Zhou, Chunguo Qian, Depo Yang, Cailin Tang, Xinjun Xu, E-Hu Liu, Jingtang Zhong, Longping Zhu, Zhimin Zhao
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Molecules
• Subjects: polysaccharide; <i>Amomum villosum</i> Lour.; structural analysis; immunomodulatory activity
• Online Access: https://www.mdpi.com/1420-3049/26/9/2672

<i>Amomum Villosum</i> Lour. (<i>A. villosum</i>) is a folk medicine that has been used for more than 1300 years. However, study of the polysaccharides of <i>A. villosum</i> is seriously neglected. The objectives of this study are to explore the structural characteristics of polysaccharides from <i>A. villosum</i> (AVPs) and their effects on immune cells. In this study, the acidic polysaccharides (AVPG-1 and AVPG-2) were isolated from AVPs and purified via anion exchange and gel filtration chromatography. The structural characteristics of the polysaccharides were characterized by methylation, HPSEC-MALLS-RID, HPLC, FT-IR, SEM, GC-MS and NMR techniques. AVPG-1 with a molecular weight of 514 kDa had the backbone of → 4)-α-<span style="font-variant: small-caps;">d</span>-Glc<i>p</i>-(1 → 3,4)-β-<span style="font-variant: small-caps;">d</span>-Glc<i>p</i>-(1 → 4)-α-<span style="font-variant: small-caps;">d</span>-Glc<i>p</i>-(1 →. AVPG-2 with a higher molecular weight (14800 kDa) comprised a backbone of → 4)-α-<span style="font-variant: small-caps;">d</span>-Glc<i>p</i>-(1 → 3,6)-β-<span style="font-variant: small-caps;">d</span>-Gal<i>p</i>-(1 → 4)-α-<span style="font-variant: small-caps;">d</span>-Glc<i>p</i>-(1 →. RAW 264.7 cells were used to investigate the potential effect of AVPG-1 and AVPG-2 on macrophages, and lipopolysaccharide (LPS) was used as a positive control. The results from bioassays showed that AVPG-2 exhibited stronger immunomodulatory activity than AVPG-1. AVPG-2 significantly induced nitric oxide (NO) production as well as the release of interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α), and upregulated phagocytic capacities of RAW 264.7 cells. Real-time PCR analysis revealed that AVPG-2 was able to turn the polarization of macrophages to the M1 direction. These results suggested that AVPs could be explored as potential immunomodulatory agents of the functional foods or complementary medicine.