Yacon fructans (Smallanthus sonchifolius) extraction, characterization and activation of macrophages to phagocyte yeast cells.

Yacon (Smallanthus sonchifolius) originates from the Andean region and has spread across South America, Europe and Japan. In contrast with most roots, yacon stores its carbohydrates in fructooligosaccharides (FOS) and contains approximately 37% of FOS in its root dry matter. Aqueous extracts of yacon were characterized through TLC, methylation, NMR, and ESI-MS. FOS of yacon showed as linear fructooligosaccharides containing almost exclusively (2→1)-linked ß-fructofuranosyl units, with terminal α-glucopyranosyl and ß-fructofuranosyl units. ESI-MS analyses indicated a wide degree of polymerization (DP) ranging from 2 to 10. The effect of the isolated FOS on non-specific immune activity by THP-1 cells was evaluated through phagocytic activity against heat-killed yeast (Saccharomices cerevisiae). The stimulant effect of yacon FOS was dose- and time-dependent, showing results more effective than branched FOS observed in previous studies. The results reinforce the use of linear yacon FOS as immunomodulators.