Characterization of aloeride, a new high-molecular-weight polysaccharide from Aloe vera with potent immunostimulatory activity

We have characterized a new immunostimulatory polysaccharide called Aloerid e from commercial aloe vera (Aloe barbadensis) juice. Aloeride is between 4 and 7 million Da, and its glycosyl components include glucose (37.2%), gal actose (23.9%), mannose (19.5%), and arabinose (10.3%). At 0.5 mug/mL Aloer ide increased NF-kappa B directed luciferase expression in THP-1 human mono cytic cells to levels 50% of those achieved by maximal concentrations (10 m ug/mL) of LPS. Aloeride induced the expression of the mRNAs encoding IL-1 b eta and TNF-alpha to levels equal to those observed in cells maximally acti vated by LPS. Acemannan, the major carbohydrate component from aloe, used a t 200 mug/mL in the macrophage assay resulted in negligible NF-kappa B acti vation. Analysis of acemannan and Aloeride using size-exclusion chromatogra phy 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 wei ght, its potency for macrophage activation accounts fully for the activity of the crude juice.