Structural elucidation and immunomodulatory evaluation of a polysaccharide from Stevia rebaudiana leaves

Stevia rebaudiana, a sweetener with medicinal functions, has attracted extensive attention due to its application in food and pharmaceutical fields. However, a few studies were performed to explore polysaccharides in this plant. Herein, SRP70-1 was derived from S. rebaudiana. Structural analysis (monosaccharide composition analysis, high-performance liquid chromatography-multi-angle light scattering detection, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy) revealed that SRP70-1 was composed of mannose, glucose, galactose, and arabinose at the molar ratio of 1.35:1.00:3.23:3.47, with an absolute molecular weight of 7698 Da. SRP70-1 was found to contain -> 5)-alpha-L-Araf-(1 ->, -> 2,3,5)-alpha-L-Araf-(1 ->, -> 4)-beta-L-Arap-(1 ->, -> 4)-beta-D-Galp-(1 ->, -> 6)-beta-D-Galp-(1 ->, -> 4)-beta-D-Manp-(1 ->, -> 6)-beta-D-Manp-(1 ->, and terminal alpha-L-Araf, beta-D-Galp, and beta-D-Glcp residues. Cell experiments showed that SRP70-1 could significantly promote phagocytosis and increase the release of nitric oxide and cytokines including IL-1 beta, IL-6, and TNF-alpha. Further zebrafish experiments confirmed the immunological enhancement effects of SRP70-1. This study revealed that SRP70-1 may be useful for the development of functional foods.

Automated summary

This study extracted a polysaccharide SRP70-1 from Stevia rebaudiana, analyzed its structure and immunological functions, and found that it may be helpful for the development of functional foods.