Design, synthesis and evaluation of novel BRD4 and RIPK3 dual inhibitors as potential anti-inflammatory agents and antidotes for arsenicals.

Arsenicals and other vesicant chemical weapons are highly reactive, toxic substances capable of causing severe and painful blistering and inflammation following topical exposure. These effects can also lead to a wide range of systemic organ damage resulting in significant morbidity and death. Two major proteins, Bromodomain 4 (BRD4) and receptor-interacting protein kinase-3 (RIPK3), are associated with the arsenicals-mediated inflammatory and tissue wounding responses in the skin and in other organs. The downstream pathway of these two proteins also leads to induction of various cytokines and chemokines, including interleukin-6 (IL-6). Our medicinal chemistry efforts were focused on the identification and lead optimization of potent small-molecule dual inhibitors of BRD4 and RIPK3with consequent dampening of the activation of IL-6. The initial hit compound, 5a was identified from a high-throughput screening (HTS) campaign of 4 K compounds which inhibited all three proteins, BRD4 (IC50 = 22.40 μM), RIPK3 (IC50 = 0.56 μM), and IL6 (IC50 = 12.60 μM), and had moderate metabolic stability (MLM t1/2 = 23.7 min, HLM t1/2 = 14.6 min), but was insoluble at pH 7.4 (solubility <1 μM). A structure-activity relationship (SAR) campaign led to the discovery of a new potent inhibitor, 12 m, 6-[[4-(2-fluoro-N-methyl-anilino)pyrimidin-2-yl]amino]-3-methyl-1,4-dihydroquinazolin-2-one, which had improved potency against BRD4 (IC50 = 5.91 μM), RIPK3 (IC50 = 1.32 μM), and IL6 (IC50 = 0.22 μM), and similar metabolic stability (MLM t1/2 = 11.0 min, HLM t1/2 = 33.2 min). Herein, we report a hit-to‑lead optimization study that led to the discovery of novel BRD4 and RIPK3 dual inhibitors.