Targeting human adenylate kinase 1 (hAK1) with phenylcyanomethylenequinone oximes: a novel scaffold of non-competitive inhibitors – synthesis, kinetic studies, SAR and QSAR analysis

Adenylate kinases (AKs) are a family of highly conserved enzymes that catalyze the reversible phosphotransfer between two ADP molecules to generate ATP and AMP, thereby maintaining nucleotide homeostasis and supporting cellular energy dynamics. Among the 9 human isoenzymes, AK1 is one of the most extensively studied and is implicated in both neurodegeneration and inflammation. Elevated AK1 activity has been associated with tau pathology and retinal inflammation, suggesting that its inhibition may help restore nucleotide homeostasis and alleviate these pathological conditions. In pursuit of potent AK1 modulators, we investigated derivatives of phenylcyanomethylenequinone oxime (4-AN), a scaffold previously reported as an ATP-competitive inhibitor of protein kinases. A library of 25 compounds was examined: 9 with synthesis previously reported and 16 newly synthesized by introducing substituents on the phenyl and methylenequinone rings and by O-functionalizing the oxime group with various alkyl and acyl chains. Several phenylcyanomethylenequinone oxime derivatives exhibited moderate to strong inhibition of human AK1 (hAK1), with the most active compounds demonstrating IC₅₀ values around 15 μM. Structure-activity analysis revealed that hydrophobic, bulky groups at the oxime position enhance inhibition, likely through allosteric interactions. The tested compounds were found to act via a non-competitive mechanism, binding near the LID domain, which plays a key role in the catalytic process. Chemometric and QSAR analyses indicated that the most active compounds share common physicochemical features, supporting the potential of 4-AN derivatives as a novel scaffold for potent, non-competitive AK1 inhibitors.