RESUMEN
In the liver, citrate is a key metabolic intermediate involved in the regulation of glycolysis and lipid synthesis and reduced expression of the hepatic citrate SLC13A5 transporter has been shown to improve metabolic outcomes in various animal models. Although inhibition of hepatic extracellular citrate uptake through SLC13A5 has been suggested as a potential therapeutic approach for Type-2 diabetes and/or fatty liver disease, so far, only a few SLC13A5 inhibitors have been identified. Moreover, their mechanism of action still remains unclear, potentially limiting their utility for in vivo proof-of-concept studies. In this study, we characterized the pharmacology of the recently identified hydroxysuccinic acid SLC13A5 inhibitors, PF-06649298 and PF-06761281, using a combination of 14C-citrate uptake, a membrane potential assay and electrophysiology. In contrast to their previously proposed mechanism of action, our data suggest that both PF-06649298 and PF-06761281 are allosteric, state-dependent SLC13A5 inhibitors, with low-affinity substrate activity in the absence of citrate. As allosteric state-dependent modulators, the inhibitory potency of both compounds is highly dependent on the ambient citrate concentration and our detailed mechanism of action studies therefore, may be of value in interpreting the in vivo effects of these compounds.
Asunto(s)
Malatos/farmacología , Fenilbutiratos/farmacología , Piridinas/farmacología , Succinatos/farmacología , Simportadores/antagonistas & inhibidores , Regulación Alostérica/efectos de los fármacos , Radioisótopos de Carbono , Ácido Cítrico/metabolismo , Células HEK293 , Humanos , Activación del Canal Iónico/efectos de los fármacos , Malatos/química , Modelos Biológicos , Técnicas de Placa-Clamp , Fenilbutiratos/química , Piridinas/química , Especificidad por Sustrato/efectos de los fármacos , Succinatos/química , Simportadores/metabolismoRESUMEN
A novel series of potent thioether benzenesulfonamide inhibitors of carbonic anhydrases II and IV was discovered using structure-based drug design. Synthesis, structure-activity relationship, and optimization of physicochemical properties are described. Low nanomolar potency was achieved, and selected compounds with improved thermodynamic solubility showed promising in vitro inhibition of carbonic anhydrase activity in rabbit iris ciliary body homogenate.