Purification, characterization and immunomodulatory activity of a polysaccharide from Celosia cristata.

A polysaccharide CP1-1 was isolated and purified from Celosia cristata. Its average molecular weight was 2.3kDa and it was composed of glucose and galactose in a ratio of 1.00:2.03, and traces of mannose. Chemical characterization of CP1-1 was elucidated by methylation analysis. CP1-1 was a branched glucogalactan which was mainly composed of 1,6-linked Galp and 1,6-linked Glcp with a ratio of 5.6:3.8. The branches were at the O-3 of the main chain and might be composed of single terminal (1→)-linked glucopyranose and galactopyranose. CP1-1 also significantly promoted the proliferation and neutral red phagocytosis of RAW 264.7 macrophage cells in vitro. In addition, CP1-1 promoted cell proliferation by enhancing the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β. These results suggested that the polysaccharide from C. cristata could be used as a potential immunostimulator.