Structural Characterization and Anti-inflammatory Activity of a Galactorhamnan Polysaccharide From Citrus medica L. var. sarcodactylis

Bi Luo; Jia Lv; Kejie Li; Peiran Liao; Peng Chen

doi:10.3389/fnut.2022.916976

Structural Characterization and Anti-inflammatory Activity of a Galactorhamnan Polysaccharide From Citrus medica L. var. sarcodactylis

Front Nutr. 2022 Jun 9:9:916976. doi: 10.3389/fnut.2022.916976. eCollection 2022.

Authors

Bi Luo^{1

2

3}, Jia Lv^{1

2

3}, Kejie Li^{1

2

3}, Peiran Liao^{1

2

3}, Peng Chen⁴

Affiliations

¹ School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China.
² Key Laboratory of State Administration of Traditional Chinese Medicine for Production & Development of Cantonese Medicinal Materials, Guangzhou, China.
³ Comprehensive Experimental Station of Guangzhou, Chinese Materia Medica, China Agriculture Research System, Guangzhou, China.
⁴ School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China.

Abstract

This study aimed to extract polysaccharides from Citrus medica L. var. sarcodactylis (finger citron fruits) and analyze their structures and potential bioactivities. A new polysaccharide named K-CMLP was isolated and purified by Diethylaminoethylcellulose (DEAE)-Sepharose Fast Flow and DEAE-52 cellulose column chromatography with an average molecular weight of 3.76 × 10³ kDa. Monosaccharide composition analysis revealed that K-CLMP consisted of rhamnose, galactose, and glucose, with a molar ratio of 6.75:5.87:1.00. Co-resolved by methylation and two-dimensional nuclear magnetic resonance (NMR), K-CLMP was alternately connected with 1, 2-Rha and 1, 4-Gal to form the backbone, and a small number of glucose residues was connected to O-4 of rhamnose. The results of DPPH⋅ and ABTS⁺⋅ radical scavenging assays indicated that both crude polysaccharide Citrus medica L. var. polysaccharide (CMLP) and K-CLMP exhibited strong free-radical-scavenging properties in a dose-dependent manner. In addition, K-CMLP significantly inhibited the production of pro-inflammatory cytokines (IL-6 and TNF-α) and reactive oxygen species (ROS) in RAW 264.7 cells treated with LPS. These results provide a basis for further use as one of the potential functions of food or natural medicine.

Keywords: Citrus medica L. var. sarcodactylis; anti-inflammatory activity; antioxidant activity; galactorhamnan polysaccharide; structure characterization.