Human protein DDX3X: design, synthesis and biological evaluation of ATPase and RNA-helicase inhibitors

The human ATPase/RNA helicase X-linked DEAD-box polypeptide 3 (DDX3X) emerged as a novel therapeutic target in the fight against infectious disease. The aim of this work was the study of two new families of DDX3X inhibitors. The new compounds have been designed starting from the first ATPase DDX3X inhibitors discovered in 2008 from Prof. M. Botta’s research group and characterized by a rhodanine scaffold. Replacing their rhodanine moiety, already reported in the list of PAINS, with the 1,3,4-thiadiazole ring a new family of inhibitors was designed, synthesized and tested for its inhibitory action on the ATPase activity of the enzyme. The most promising derivatives has been investigated by evaluating their anti-HIV-1 effects revealing inhibitory activities in the low micromolar range. ADME analysis demonstrated high metabolic stability and aqueous solubility. All the results make these novel compounds a very good starting point for further development. When the inhibitors of RNA helicase were first discovered they showed activity against HIV-1 drug-resistant strains but their aqueous solubility limited bioavailability in preclinical models, causing its accumulation in fat tissues. A homology model-based virtual screening led to the identification of a new class characterized by sulfonamide moiety with better profile of aqueous solubility and specifically target the helicase activity of DDX3X, accordingly they were inactive in the ATPase assay.