Isolation and partial characterization of a pectic polysaccharide from the fruit pulp of Spondias cytherea and its effect on peritoneal macrophage activation.

The total carbohydrate content of the intact pulp of Spondias cytherea was 41%. Polysaccharides were obtained via hot aqueous extraction after defatting with organic solvents. The aqueous extract was treated with excess ethanol to form a precipitate, which was then solubilized in water. The material precipitated upon acidification when HCl was removed. The resulting supernatant fraction was submitted to freeze-thawing treatment yielding a soluble fraction (sFTS). This fraction had Ara, Rha, Gal and GalA in its structure as determined by GC-MS. 13C NMR analysis showed signals assigned to alpha-L-Araf, beta-D-Galp, alpha-D-GalpA and alpha-L-Rhap units, in addition to galacturonic acid units, which were present also as methyl ester. These results suggest a type I rhamnogalacturonan with arabinogalactan branches. Cell eliciting activity in a dose-depending pattern was observed in vitro on peritoneal macrophages treated with sFTS.