Red-beet betalain pigments inhibit amyloid-β aggregation and toxicity in amyloid-β expressing Caenorhabditis elegans

ABSTRACT BACKGROUND Betalain pigments are mainly produced by plants in the order Caryophyllales. Recent interest in the biological functions of betalain pigments has increased with antioxidant, anti-inflammatory, and anticancer activities reported. RESULTS We investigated the effects of betalain pigments derived from red-beet on amyloid-β (Aβ) aggregation, a cause of Alzheimer’s disease. Inhibition of Aβ aggregation against Aβ40 and Aβ42 by betalain pigments in vitro was demonstrated by the Thioflavin T fluorescence assay, circular dichroism spectroscopy analysis and transmission electron microscopic observations. Moreover, we examined the ability of betalain pigments to interfere with Aβ toxicity by using the transgenic Caenorhabditis elegans strain CL2006, which expresses the human Aβ42 protein intracellularly within the body wall muscle and responds to Aβ-toxicity with paralysis. Treatment with 50 μM betalain pigments significantly delayed the paralysis of Caenorhabditis elegans. CONCLUSION These results suggest that betalain pigments reduce Aβ-induced toxicity by inhibiting Aβ aggregation and may lead to their use as inhibitors of Aβ aggregation.