Design, synthesis, docking, and biological evaluation of novel diazide-containing isoxazole- and pyrazole-based histone deacetylase probes.

The design, synthesis, docking, and biological evaluation of novel potent HDAC3 and HDAC8 isoxazole- and pyrazole-based diazide probes suitable for binding ensemble profiling with photoaffinity labeling (BEProFL) experiments in cells is described. Both the isoxazole- and pyrazole-based probes exhibit low nanomolar inhibitory activity against HDAC3 and HDAC8, respectively. The pyrazole-based probe 3f appears to be one of the most active HDAC8 inhibitors reported in the literature with an IC(50) of 17 nM.

Binding ensemble profiling with photoaffinity labeling (BEProFL) approach: mapping the binding poses of HDAC8 inhibitors.

A binding ensemble profiling with (f)photoaffinity labeling (BEProFL) approach that utilizes photolabeling of HDAC8 with a probe containing a UV-activated aromatic azide, mapping of the covalent modifications by liquid chromatography-tandem mass spectrometry, and a computational method to characterize the multiple binding poses of the probe is described. By use of the BEProFL approach, two distinct binding poses of the HDAC8 probe were identified. The data also suggest that an "upside-down" pose with the surface binding group of the probe bound in an alternative pocket near the catalytic site may contribute to the binding.