Polysaccharides from raw and cooked chayote modulate macrophage function

Abstract

Chayote (Sechium edule) pulp is consumed raw or cooked and is source of polysaccharides with potential immunomodulatory properties in macrophages, which are cells that play important roles in homeostasis and innate immune responses to pathogens; however, these immunomodulatory effects of chayote polysaccharides remain unknown. Therefore, polysaccharides from raw (SeR) and cooked (SeC) chayote and from the hot water extract obtained after heating (SeH) were analyzed for their composition and effects on macrophages. Chayote has a high- (340kDa) and a low- (46kDa) molecular weight (MW) polysaccharide fraction containing high amounts of galactose, arabinose and galacturonic acid. After cooking, SeC was enriched in high-MW galactose-rich fractions, whereas SeH was enriched in low-MW arabinans and homogalaturonans-rich fractions. The polysaccharides induced tumor necrosis factor alpha (TNF-α) and nitric oxide (NO) secretion in macrophages; however, only SeR and SeH reduced TNF-α, NO and interleukin-6 secretion in activated macrophages. Furthermore, SeR and SeCW, but not SeC, affected phagocytic activity. In conclusion, bioactive polysaccharides in chayote modulate macrophage functions, and minor changes in composition resulting from the solubilization of a small proportion of low-MW arabinans and homogalacturonans during cooking accounted for the different effects of raw and cooked chayote.