RESUMO
Glucokinase (GK, hexokinase IV) is a unique hexokinase that plays a central role in mammalian glucose homeostasis. Glucose phosphorylation by GK in the pancreatic ß-cell is the rate-limiting step that controls glucose-stimulated insulin secretion. Similarly, GK-mediated glucose phosphorylation in hepatocytes plays a major role in increasing hepatic glucose uptake and metabolism and possibly lowering hepatic glucose output. Small molecule GK activators (GKAs) have been identified that increase enzyme activity by binding to an allosteric site. GKAs offer a novel approach for the treatment of Type 2 Diabetes Mellitus (T2DM) and as such have garnered much attention. We now report the design, synthesis, and biological evaluation of a novel series of 2,5,6-trisubstituted indole derivatives that act as highly potent GKAs. Among them, Compound 1 was found to possess high in vitro potency, excellent physicochemical properties, and good pharmacokinetic profile in rodents. Oral administration of Compound 1 at doses as low as 0.03mg/kg led to robust blood glucose lowering efficacy in 3week high fat diet-fed mice.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Ativadores de Enzimas/química , Ativadores de Enzimas/uso terapêutico , Glucoquinase/metabolismo , Hipoglicemiantes/química , Hipoglicemiantes/uso terapêutico , Indóis/química , Indóis/uso terapêutico , Regulação Alostérica/efeitos dos fármacos , Animais , Glicemia/análise , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Desenho de Fármacos , Ativação Enzimática/efeitos dos fármacos , Ativadores de Enzimas/farmacocinética , Ativadores de Enzimas/farmacologia , Humanos , Hipoglicemiantes/farmacocinética , Hipoglicemiantes/farmacologia , Indóis/farmacocinética , Indóis/farmacologia , Insulina/sangue , Insulina/metabolismo , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Systemically acting glucokinase activators (GKA) have been demonstrated in clinical trials to effectively lower blood glucose in patients with type II diabetes. However, mechanism-based hypoglycemia is a major adverse effect that limits the therapeutic potential of these agents. We hypothesized that the predominant mechanism leading to hypoglycemia is GKA-induced excessive insulin secretion from pancreatic ß-cells at (sub-)euglycemic levels. We further hypothesized that restricting GK activation to hepatocytes would maintain glucose-lowering efficacy while significantly reducing hypoglycemic risk. Here we report the discovery of a novel series of carboxylic acid substituted GKAs based on pyridine-2-carboxamide. These GKAs exhibit preferential distribution to the liver versus the pancreas in mice. SAR studies led to the identification of a potent and orally active hepatoselective GKA, compound 6. GKA 6 demonstrated robust glucose lowering efficacy in high fat diet-fed mice at doses ⩾10mpk, with ⩾70-fold liver:pancreas distribution, minimal effects on plasma insulin levels, and significantly reduced risk of hypoglycemia.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Ativadores de Enzimas/farmacologia , Glucoquinase/metabolismo , Hipoglicemiantes/farmacologia , Piridinas/farmacologia , Animais , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Descoberta de Drogas , Ativadores de Enzimas/química , Ativadores de Enzimas/farmacocinética , Ativadores de Enzimas/uso terapêutico , Humanos , Hipoglicemiantes/química , Hipoglicemiantes/farmacocinética , Hipoglicemiantes/uso terapêutico , Insulina/sangue , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Pâncreas/efeitos dos fármacos , Pâncreas/metabolismo , Piridinas/química , Piridinas/farmacocinética , Piridinas/uso terapêuticoRESUMO
A method to detect and quantify a small amount crystalline material within a liquid solution of solubilized material is described. 19F CP-MAS ssNMR was investigated as a technique to detect low levels (0.2 mg/g) of crystalline sodium (2R)-7-{3-[2-chloro-4-(2,2,2-trifluoroethoxy)phenoxy]propoxy}-2-methyl-3,4-dihydro-2H-chromane-2-carboxylate (I) within a solid mixture (with microcrystalline cellulose) and a slurry with a liquid vehicle (capric and caprylic acid triglycerides). The results demonstrate that the area of the 19F CP/MAS signal obtained in 25 min at 25 degrees C is linearly dependent (R2=0.997) on the mass of I within the ssNMR rotor. Slopes of CP-MAS peak area versus mass of I in the rotor were nearly identical for the solid mixture and slurry suspension. Signal-to-noise ratio for the low potency slurry suggest detection and quantitation of 0.1 mg of crystalline I in the rotor, corresponding to 2 mg/g of crystalline material within the slurry suspension.
Assuntos
Benzopiranos/análise , Celulose/química , Espectroscopia de Ressonância Magnética/métodos , Éteres Fenílicos/análise , Polietilenoglicóis/química , Triglicerídeos/química , Benzopiranos/química , Cromatografia Líquida de Alta Pressão , Cristalização , Veículos Farmacêuticos , Éteres Fenílicos/química , SolubilidadeRESUMO
From poisoning caused by lead-based paint on domestic buildings to groundwater contamination by naturally occurring arsenic deposits in India, heavy-metal toxicity is a global health problem. Contaminated ground water and acute cases of heavy-metal poisoning are treated with chelators to remove the heavy metals from the contaminated site or person. This review discusses the effort to generate heavy-metal chelators through peptide de novo design. De novo design entails the design of a primary sequence that will precisely fold into a predetermined secondary and tertiary protein structure. The first-generation peptide chelator used to initiate this investigation is the three-stranded coild coil containing Cys. Cys provides a potential trigonal binding site with soft thiolate ligands, which has been proposed to provide specific interactions with heavy metals. This hypothesis derives from the observation that similar sites on natural proteins show selectivity for heavy metals over other essential metals, such as Zn or Mg. A description of two systems, the TRI series and the IZ-AC peptide, is given, highlighting the interaction of these peptides with Hg, Cd, As and Pb. Arguments are also presented for the potential use of three-helix bundles as a second-generation design.
Assuntos
Metais Pesados/metabolismo , Biossíntese Peptídica , Peptídeos/metabolismo , Tecnologia Farmacêutica/métodos , Sequência de Aminoácidos , Animais , Proteínas de Transporte/síntese química , Desenho de Fármacos , Humanos , Metais Pesados/sangue , Metais Pesados/química , Dados de Sequência Molecular , Peptídeos/químicaRESUMO
(1S,5R)-2-{[(4S)-azepan-4-ylamino]carbonyl}-7-oxo-2,6-diazabicyclo[3.2.0] heptane-6-sulfonic acid (Compound 1) is a ß-lactamase inhibitor for intravenous administration. The objective of this preformulation study was to determine the most appropriate form of the API for development. Compound 1 can exist as an amorphous solid and four distinct crystalline phases A, B, C, and D in the solid state. Slurry experiments along with analysis of physicochemical properties were used to construct a phase diagram and select the most suitable form of the API for development. In aqueous formulations, the dihydrate form of the API was predominant and, due to the more favorable solubility and dissolution profile required for preclinical and clinical studies, a metastable form of the API was selected, and the risks associated with developing this form were evaluated.
Assuntos
Química Farmacêutica , Injeções Intravenosas , Preparações Farmacêuticas/química , Solubilidade , beta-Lactamases/química , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Compostos Bicíclicos Heterocíclicos com Pontes/química , Fenômenos Químicos , Cristalização , Estabilidade de Medicamentos , Ligação de Hidrogênio , Estrutura Molecular , Peso Molecular , Tamanho da Partícula , Preparações Farmacêuticas/administração & dosagem , Água/química , Inibidores de beta-LactamasesRESUMO
A detailed kinetic analysis of metal encapsulation by a de novo-designed protein is described. The kinetic mechanism of Hg(II) encapsulation in the three-stranded coiled coil formed by the peptide CH(3)CO-G LKALEEK CKALEEK LKALEEK G-NH(2) (Baby L9C) is derived by global analysis. The mechanism involves rapid initial collapse of two peptides by Hg(II) forming Hg(Baby L9C(-H))(2) with a linear thiolato Hg(II) bound to the cysteine sulfur atoms. Here, Baby L9C(-H) denotes Baby L9C with the cysteine thiol deprotonated. Addition of the third peptide, forming the three-stranded coiled coil, is the rate-determining step and results in an intermediate state involving two separate species. One of the species, termed the properly folded intermediate, undergoes rapid deprotonation of the third cysteine thiol, yielding the desired three-stranded coiled coil with an encapsulated trigonal thiolato Hg(II). The other species, termed the misfolded intermediate, rearranges in an experimentally distinguishable step to the properly folded intermediate. The order of the reaction involving the addition of the third peptide with respect to the concentration of Baby L9C indicates that addition of the third helix only occurs through reaction of Hg(Baby L9C(-H))(2) and Baby L9C that is unassociated with a coiled coil. Temperature dependence of the reaction afforded activation parameters for both the addition of the third helix (deltaH = 20(2) kcalmol; deltaS= 40(5) calmol K) and the rearrangement of the misfolded intermediate steps (deltaH = 23(2) kcalmol; deltaS= 27(5) calmol K). The mechanism is discussed with regard to metalloprotein folding and metalloprotein design.
Assuntos
Mercúrio/metabolismo , Metaloproteínas/química , Metaloproteínas/metabolismo , Sequência de Aminoácidos , Cisteína/química , Cinética , Mercúrio/química , Modelos Moleculares , Dados de Sequência Molecular , Oligopeptídeos/química , Peptídeos/química , Dobramento de Proteína , Estrutura Secundária de Proteína , Espectrofotometria Ultravioleta , Compostos de Sulfidrila/química , TermodinâmicaRESUMO
Designed alpha-helical peptides of the TRI family with a general sequence Ac-G(LKALEEK)(4)G-CONH(2) were used as model systems for the study of metal-protein interactions. Variants containing cysteine residues in positions 12 (TRI L12C) and 16 (TRI L16C) were used for the metal binding studies. Cd(II) binding was investigated, and the results were compared with previous and current work on Hg(II) and As(III) binding. The metal peptide assemblies were studied with the use of UV, CD, EXAFS, (113)Cd NMR, and (111m)Cd perturbed angular correlation spectroscopy. The metalated peptide aggregates exhibited pH-dependent behavior. At high pH values, Cd(II) was bound to the three sulfurs of the three-stranded alpha-helical coiled coils. A mixture of two species was observed, including Cd(II) in a trigonal planar geometry. The complexes have UV bands at 231 nm (20 600 M(-1) cm(-1)) for TRI L12C and 232 nm (22 600 M(-1) cm(-1)) for TRI L16C, an average Cd-S bond length of 2.49 A for both cases, and a (113)Cd NMR chemical shift at 619 ppm (Cd(II)(TRI L12C)(3)(-)) or 625 ppm (Cd(II)(TRI-L16C)(3)(-)). Nuclear quadrupole interactions show that two different Cd species are present for both peptides. One species with omega(0) = 0.45 rad/ns and low eta is attributed to a trigonal planar Cd-(Cys)(3) site. The other, with a smaller omega(0), is attributed to a four-coordinate Cd(Cys)(3)(H(2)O) species. At low pH, no metal binding was observed. Hg(II) binding to TRI L12C was also found to be pH dependent, and a 3:1 sulfur-to-mercury(II) species was observed at pH 9.4. These metal peptide complexes provide insight into heavy metal binding and metalloregulatory proteins such as MerR or CadC.