Structural characterization of an alkali-extracted polysaccharide from Dioscorea opposita Thunb. with initial studies on its anti-inflammatory activity

Abstract

An alkali-extracted polysaccharide (HY-B) was isolated and purified from Dioscorea opposita Thunb. (Huai Yam). Its chemical structure was analyzed with FT-IR, GC-MS and 1 D, 2 D-NMR spectrometry. It was proved that HY-B is mainly composed of α-1,4-linked glucose, which is similar to starch, but the starch-iodine color test proved that it was not starch. The chain conformation of HY-B was analyzed by SEC-MALLS-RI and TEM, indicated that HY-B exists in a random coil conformation. Its molecular weight is 18.7 kDa, and the molecular size is about 100 nm. MTT assays indicated that HY-B was nontoxic to RAW 264.7 cells in vitro. The results of anti-inflammatory studies showed that HY-B could inhibit the production of NO and TNF-α in RAW 264.7 macrophage stimulated by lipopolysaccharides (LPSs). This work provided the important information about the anti-inflammatory active component of Huai Yam and its potential applications in the food and health industries.

Graphical Abstract

Keywords:

• Anti-inflammation
• Dioscorea opposita Thunb.
• NO
• polysaccharide
• TNF-α

Disclosure statement

The authors declared that they have no conflicts of interest in this work.

Additional information

Funding

We gratefully acknowledge the financial supports from the Program for Innovative Research Team (in Science and Technology) at the University of Henan Province [Grant No. 20IRTSTHN022], Major Public Welfare Projects in Henan Province [201300110200] and Yunnan Key Laboratory of Tobacco Chemistry [2019539200340167].