Histone Deacetylase 2 (HDAC2) Inhibitors Containing Boron

Histone deacetylase enzymes (HDACs) are responsible for the global silencing of tumour-suppressor genes. Treatment with a histone deacetylase inhibitor (HDACi) can reverse this process and restore normal cell function. Herein, we report a small series of boron-based (boronic acid, boronate ester and closo-1,2-carborane) HDAC2 inhibitors with IC₅₀ values in the nanomolar range. The boronate ester 4 b was the most potent compound assessed in this study (IC₅₀ =40.6±1.5 nM), followed closely by the 1,2-closo-carborane (IC₅₀ =42.9±1.5 nM). Compound 4 b exceeds the potency of the related gold-standard HDAC pan-inhibitor vorinostat (1) toward this particular HDAC isoform.