Design and Synthesis of Dihydroxamic Acids as HDAC6/8/10 Inhibitors.

We report the synthesis and evaluation of a class of selective multi-target agents for the inhibition of HDAC6, HDAC8 and HDAC10. The concept for this study grew out of a structural analysis of the two selective inhibitors Tubastatin A (HDAC6/10) and PCI-34051 (HDAC8), which we recognized share the same N -benzylindole core. Hybridization of the two inhibitor structures resulted in dihydroxamic acids with benzyl-indole and -indazole core motifs. These substances exhibit potent activity on HDAC6, HDAC8 and HDAC10, while retaining selectivity over HDAC1, HDAC2 and HDAC3. The best substance inhibited viability of the SK-N-BE(2)C neuroblastoma cell line with an IC 50 value similar to a combination treatment with Tubastatin A and PCI-34051. This compound class establishes proof of concept for such hybrid molecules and may serve as a starting point for the further development of enhanced HDAC6/8/10 inhibitors.