Partial Chemical Characterization of Immunomodulatory Polysaccharides from Plantago palmata Hook. f. s. Leaves

Abstract EN

A previous work on Plantago palmata polysaccharides (PS) attributed immunomodulatory properties of leaves to a polysaccharide fraction (PS50) that stimulated NO and TNF-α production by interferon gamma- (IFN-γ-) activated macrophages.

The present work aims to elucidate the chemical structure of these immunomodulatory polysaccharides.

Size exclusion chromatography showed that the active polymers present an active fraction with a very high molecular weight (about 1200 kDa).

These polysaccharides are pectic in nature, with a predominantly unbranched galacturonan domain and with a domain bearing side chains that consist of highly branched arabinan, galactan, and/or arabinogalactan.

Comparatively to the well-known Plantago major biologically active PS, Plantago palmata PS50 contained less arabinogalactan-proteins (AGPs) and had a different composition in glucose, galactose, and galacturonic acid.

DNA contamination of the polysaccharide was estimated at about 0.04%, a concentration much lower than those reported immunomodulatory in hyaluronic acid preparations (3 to 15%).

Therefore, the eventuality of a contaminating DNA-mediated biological activity could be ruled out.