An inhibitor of polyQ aggregation (IC50s = 25 and 0.05 μM for recombinant HDQ51 and in PC12 cells, respectively); inhibits polyQ aggregation in organotypic hippocampal slice cultures isolated from R6/2 transgenic mice and reduces neurodegeneration in a dose-dependent manner in a Drosophila model of Huntington's disease; reduces huntingtin aggregate size, reduces neuronal atrophy, and improves motor performance in a rotarod test in the R6/2 transgenic mouse model of Huntington's disease (100 and 200 mg/kg),