1. Using mass spectrometry techniques for the elucidation of structural features of immunostimulatory polysaccharides from medicinal plantsaqueous extracts
- Author
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Martins, Vitor Manuel Ramalheira, Simões, Joana, Ferreira, Isabel, Cruz, Maria T., Domingues, Maria R.M., and Coimbra, Manuel A.
- Subjects
Mass spectrometry ,Polysaccharides - Abstract
Polysaccharides are well known for their immunostimulatory properties, which are closely related to structural fèatures, such as molecular weight, branching, acetylation degree and acetylation pattem, and presence of speciflc structures [1, 2]. TTie electrospray ionization-mass spectrometry (ESI-MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) have shown to be powerfül techniques that can provide detailed information regarding the structural features of polysaccharides and help to clarify its relation to some ofthe observed immunostimulatory properties [3-6]. TTie present work desenhes the use of ESI-MS and ESI-MS/MS in the confimation and elucidation of structural features of immunostimulatory polysaccharides present in lhe aqueous extracts of Fraxinus angustifolia dned leaws and Ptemapaitum tridentatum dried inflorescences. The polysaccharides present in the aqueous extracts of F. angustifolia dried leaves and P. fridentafum dried inflorescences were isolated and fractionated using dialysis, ethanol precipitation, and anionexchange chromatography. Sugar and linkage analysis suggested that the aqueous extracts of F. angustifolia were mostly composed of pectic polysaccharides, while those from P. tridentatum contained a mixture of pectic polysacchahdes, galactomannans, and also xyloglucans. Selected fractions isolated from lhe aqueous extracts of F. angustifolia and P. tridentatum evidenced an in vitro macrophage immunostimulatory activity, expressed through the production of nitric oxide (NO). Enzymatic hydrolysis of the isolated polysaccharides, fbllowed by size exclusion chromatography of the resulting oligosaccharides (OS), and ESI-MS and ESI-MS/MS characterization allowed to confirm the presence of pectic polysaccharides, possibly with xylogalaturonan domains, in the aqueous extracts of F. angustifolia. For the aqueous extracts of P. fridentatum it was possible to detect the presence of galactomannans acetylated at 0-2. Moreover, it was possible to identify acetylated OS that presented an acetylation pattem with much more acetyl groups than those observed for galactomannans from coffee infusions [3]. The saponification ofthe fraction isolated from the aqueous extracts of P. tridentatum dried inflorescences, which contained the acetylated galactomannans, caused a decrease in the NO macrophage production, confirming lhe galactomannans acetylation as an important structural feature for lhe expression of the in vitm macrophage immunostimulatory activity previously registered. info:eu-repo/semantics/publishedVersion
- Published
- 2017