Synthesis of novel pyridine-carboxylates as small-molecule inhibitors of human aspartate/asparagine-β-hydroxylase

The human 2-oxoglutarate (2OG)-dependent oxygenase aspartate/asparagine-β-hydroxylase (AspH) is a potential medicinal chemistry target for anti-cancer therapy. AspH is overexpressed on the cell surface of invasive cancer cells and accepts epidermal growth factor-like domain (EGFDs) substrates with a non-canonical ( i.e. Cys 1-2, 3-4, 5-6) disulfide pattern. We report a concise synthesis of C-3 substituted derivatives of pyridine-2,4-dicarboxylic acid (2,4-PDCA) as 2OG competitors for use in SAR studies on AspH inhibition. AspH inhibition was assayed using a mass spectrometry based assay employing a stable thioether-analogue of a natural EGFD AspH substrate. Certain C-3 substituted 2,4-PDCA derivatives were potent AspH inhibitors, manifesting selectivity over some, but not all, other tested human 2OG oxygenases. The results raise questions about the use of pyridine-carboxylate related 2OG analogues as selective functional probes for specific 2OG oxygenases, and should aid the development of AspH inhibitors suitable for in vivo use.