Characterization and Histone Deacetylase Inhibitory Activity of Three Novel Fluorescent Benzamide Derivatives

New fluorescent benzamide derivatives were developed by using four different aromatic groups with expanding sizes from thiophene to naphthalene, anthracene, and pyrene in an attempt to identify a novel histone deacetylase (HDAC) inhibitor. The compounds exhibited red shift absorption and emission dependent on the size of the aromatic group as well as a high fluorescence efficiency with high quantum yields. However, the HDAC binding affinity of the compounds with polyaromatic modification of the substituent was very low (IC50 ranging from 46 to 101 μM) in contrast to that of the monoaromatic substituted compound (