Characterization of Aloeride, a New High-Molecular-Weight Polysaccharide from Aloe vera with Potent Immunostimulatory Activity

We have characterized a new immunostimulatory polysaccharide called Aloeride from commercial aloe vera (Aloe barbadensis) juice. Aloeride is between 4 and 7 million Da, and its glycosyl components include glucose (37.2%), galactose (23.9%), mannose (19.5%), and arabinose (10.3%). At 0.5 μg/mL Aloeride increased NF-kappa B directed luciferase expression in THP-1 human monocytic cells to levels 50% of those achieved by maximal concentrations (10 μg/mL) of LPS. Aloeride induced the expression of the mRNAs encoding IL-1β and TNF-α to levels equal to those observed in cells maximally activated by LPS. Acemannan, the major carbohydrate component from aloe, used at 200 μg/mL in the macrophage assay resulted in negligible NF-kappa B activation. Analysis of acemannan and Aloeride using size-exclusion chromatography suggests that the low activity of acemannan is due to trace amounts of Aloeride. Although Aloeride comprises only 0.015% of the aloe juice dry weight, its potency for macrophage activation accounts fully for the activity of the crude juice.

Keywords: Polysaccharide; aloe vera; immunostimulatory; nuclear factor kappa B; THP-1 human monocytic cells; acemannan; macrophage