Identification of substituted 3-hydroxy-2-mercaptocyclohex-2-enones as potent inhibitors of human lactate dehydrogenase

A novel class of 3-hydroxy-2-mercaptocyclohex-2-enone-containing inhibitors of human lactate dehydrogenase (LDH) was identified through a high-throughput screening approach. Biochemical and surface plasmon resonance experiments performed with a screening hit (LDHA IC₅₀ = 1.7 μM) indicated that the compound specifically associated with human LDHA in a manner that required simultaneous binding of the NADH co-factor. Structural variation of this screening hit resulted in significant improvements in LDHA biochemical inhibition activity (best IC₅₀ = 0.18 μM). Two crystal structures of optimized compounds bound to human LDHA were obtained and explained many of the observed structure–activity relationships. In addition, an optimized inhibitor exhibited good pharmacokinetic properties after oral administration to rats (F = 45%).