2-O-Acetyl-20-hydroxyecdysone is an ecdysone steroid hormone that has been found in plants and animals. It completely inhibits the growth of the bacteria S. aureus, E. coli, and P. vulgaris, as well as the fungi C. albicans, A. alternata, and F. solani when used at a concentration of 10 μg/ml. 2-O-Acetyl-20-hydroxyecdysone (50 μM) increases aggregation of amyloid-β (1-42) (Aβ42), increases fibril formation by 60%, and decreases oligomer levels in cell-free assays. It reduces Aβ42-induced cytotoxicity of SH-SY5Y cells when used at concentrations of 5 and 10 μM.