We report a design strategy to obtain potent DPP-4 inhibitors by incorporating salt bridge formation with Lys554 in the S1' pocket. By applying the strategy to the previously identified templates, quinoline 4 and pyridines 16a, 16b, and 17 have been identified as subnanomolar or nanomolar inhibitors of human DPP-4. Docking studies suggested that a hydrophobic interaction with Tyr547 as well as the salt bridge interaction is important for the extremely high potency. The design strategy would be useful to explore a novel design for DPP-4 inhibitors having a distinct structure with a unique binding mode.
The design, synthesis, and structure-activity relationships of a new class of potent and orally active non-peptide dipeptidyl peptidase IV (DPP-4) inhibitors, 3-aminomethyl-1,2-dihydro-4-phenyl-1-isoquinolones, are described. We hypothesized that the 4-phenyl group of the isoquinolone occupies the S1 pocket of the enzyme, the 3-aminomethyl group forms an electrostatic interaction with the S2 pocket, and the introduction of a hydrogen bond donor onto the 6- or 7-substituent provides interaction with the hydrophilic region of the enzyme. Based on this hypothesis, intensive research focused on developing new non-peptide DPP-4 inhibitors has been carried out. Among the compounds designed in this study, we identified 2-[(3-aminomethyl-2-(2-methylpropyl)-1-oxo-4-phenyl-1,2-dihydro-6-isoquinolinyl)o xy]acetamide (35a) as a potent, selective, and orally bioavailable DPP-4 inhibitor, which exhibited in vivo efficacy in diabetic model rats. Finally, X-ray crystallography of 35a in a complex with the enzyme validated our hypothesized binding mode and identified Lys554 as a new target-binding site available for DPP-4 inhibitors.
Dipeptidyl peptidase IV (DPP-4) inhibition is a validated therapeutic option for type 2 diabetes, exhibiting multiple antidiabetic effects with little or no risk of hypoglycemia. In our studies involving non-covalent DPP-4 inhibitors, a novel series of quinoline-based inhibitors were designed based on the co-crystal structure of isoquinolone 2 in complex with DPP-4 to target the side chain of Lys554. Synthesis and evaluation of designed compounds revealed 1-[3-(aminomethyl)-4-(4-methylphenyl)-2-(2-methylpropyl)quinolin-6-yl]piperazine- 2,5-dione (1) as a potent, selective, and orally active DPP-4 inhibitor (IC(5)(0)=1.3 nM) with long-lasting ex vivo activity in dogs and excellent antihyperglycemic effects in rats. A docking study of compound 1 revealed a hydrogen-bonding interaction with the side chain of Lys554, suggesting this residue as a potential target site useful for enhancing DPP-4 inhibition.
We have previously discovered nicotinic acid derivative 1 as a structurally novel dipeptidyl peptidase IV (DPP-4) inhibitor. In this study, we obtained the X-ray co-crystal structure between nicotinic acid derivative 1 and DPP-4. From these X-ray co-crystallography results, to achieve more potent inhibitory activity, we targeted Arg125 as a potential amino acid residue because it was located near the pyridine core, and some known DPP-4 inhibitors were reported to interact with this residue. We hypothesized that the guanidino group of Arg125 could interact with two hydrogen-bond acceptors in a bidentate manner. Therefore, we designed a series of 3-pyridylacetamide derivatives possessing an additional hydrogen-bond acceptor that could have the desired bidentate interaction with Arg125. We discovered the dihydrochloride of 1-{[5-(aminomethyl)-2-methyl-4-(4-methylphenyl)-6-(2-methylpropyl)pyridin-3-yl]ac etyl}-l-prolinamide (13j) to be a potent and selective DPP-4 inhibitor that could interact with the guanidino group of Arg125 in a unique bidentate manner.
Inhibition of dipeptidyl peptidase IV (DPP-4) is an exciting new approach for the treatment of diabetes. To date there has been no DPP-4 chemotype possessing a carboxy group that has progressed into clinical trials. Originating from the discovery of the structurally novel quinoline derivative 1, we designed novel pyridine derivatives containing a carboxy group. In our design, the carboxy group interacted with the targeted amino acid residues around the catalytic region and thereby increased the inhibitory activity. After further optimization, we identified a hydrate of [5-(aminomethyl)-6-(2,2-dimethylpropyl)-2-ethyl-4-(4-methylphenyl)pyridin-3-yl]ac etic acid (30c) as a potent and selective DPP-4 inhibitor. The desired interactions with the critical active-site residues, such as a salt-bridge interaction with Arg125, were confirmed by X-ray cocrystal structure analysis. In addition, compound 30c showed a desired preclinical safety profile, and it was encoded as TAK-100.
Title: A novel dipeptidyl peptidase-4 inhibitor, alogliptin (SYR-322), is effective in diabetic rats with sulfonylurea-induced secondary failure Asakawa T, Moritoh Y, Kataoka O, Suzuki N, Takeuchi K, Odaka H Ref: Life Sciences, 85:122, 2009 : PubMed
AIMS: Loss of efficacy over time or secondary failure occurs somewhat often and remains a major concern of sulfonylurea (SU) therapy. In this study, we investigated the benefits of alogliptin, an oral, potent and highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, in a rat model exhibiting SU secondary failure. MAIN METHODS: Neonatally streptozotocin-induced diabetic rats (N-STZ-1.5 rats), a non-obese model of type 2 diabetes, were used in these studies. The effects of alogliptin on DPP-4 activity and glucagon-like peptide 1 (GLP-1) concentration were determined by measuring their levels in plasma. In addition, the effects of alogliptin on an oral glucose tolerance test were investigated by using an SU secondary failure model. KEY FINDINGS: Alogliptin dose dependently suppressed plasma DPP-4 activity leading to an increase in the plasma active form of GLP-1 and improved glucose excursion in N-STZ-1.5 rats. Repeated administration of glibenclamide resulted in unresponsiveness or loss of glucose tolerance typical of secondary failure. In these rats, alogliptin exhibited significant improvement of glucose excursion with significant increase in insulin secretion. By contrast, glibenclamide and nateglinide had no effect on the glucose tolerance of these rats. SIGNIFICANCE: The above findings suggest that alogliptin was effective at improving glucose tolerance and therefore overcoming SU induced secondary failure in N-STZ-1.5 rats.
Title: The dipeptidyl peptidase-4 inhibitor alogliptin in combination with pioglitazone improves glycemic control, lipid profiles, and increases pancreatic insulin content in ob/ob mice Moritoh Y, Takeuchi K, Asakawa T, Kataoka O, Odaka H Ref: European Journal of Pharmacology, 602:448, 2009 : PubMed
The combination of two agents with different but complementary mechanisms of action is a logical approach for treating patients with type 2 diabetes. Thus, we evaluated chronic combination therapy with alogliptin, a highly selective dipeptidyl peptidase-4 inhibitor that enhances the action of incretins, and pioglitazone, a thiazolidinedione that improves peripheral and hepatic insulin sensitivity. Studies were designed to investigate the chronic metabolic and pancreatic effects of alogliptin (0.03%) plus pioglitazone (0.003%) combination treatment in obese ob/ob mice. After 4-5 weeks of treatment, alogliptin significantly increased plasma active glucagon-like peptide-1 levels up to 4.1-fold and decreased plasma glucagon up to 25%, whereas pioglitazone significantly increased plasma adiponectin up to 1.3-fold. Combination treatment exhibited a complementary effect, increasing plasma insulin levels by 3.2-fold (alogliptin alone, 1.6-fold; pioglitazone alone, 1.5-fold) and decreasing glycosylated hemoglobin by 2.3% (alogliptin alone, 1.0%; pioglitazone alone, 1.5%), and non-fasting and fasting plasma glucose by 37% and 62% (alogliptin alone, 17% and 24%; pioglitazone alone, 30% and 45%), respectively. Combination treatment also decreased plasma triglycerides by 67% and non-esterified fatty acids by 25% (alogliptin alone, 24% and 11%; pioglitazone alone, 54% and 8%). Moreover, combination treatment increased pancreatic insulin content by 2.2-fold (alogliptin alone, 1.3-fold; pioglitazone alone, 1.6-fold), with no significant changes in body weight. These results indicate that combination treatment with alogliptin and pioglitazone improved glycemic control, lipid profiles and increased pancreatic insulin content in ob/ob mice by preventing incretin inactivation and improving insulin resistance. These results provide a strong argument for using alogliptin in combination with pioglitazone.
Title: Pharmacokinetic, pharmacodynamic, and efficacy profiles of alogliptin, a novel inhibitor of dipeptidyl peptidase-4, in rats, dogs, and monkeys Lee B, Shi L, Kassel DB, Asakawa T, Takeuchi K, Christopher RJ Ref: European Journal of Pharmacology, 589:306, 2008 : PubMed
The aim of the present research was to characterize the pharmacokinetic, pharmacodynamic, and efficacy profiles of alogliptin, a novel quinazolinone-based dipeptidyl peptidase-4 (DPP-4) inhibitor. Alogliptin potently inhibited human DPP-4 in vitro (mean IC(50), ~ 6.9 nM) and exhibited > 10,000-fold selectivity for DPP-4 over the closely related serine proteases DPP-2, DPP-8, DPP-9, fibroblast activation protein/seprase, prolyl endopeptidase, and tryptase (IC(50) > 100,000 nM). Absolute oral bioavailability of alogliptin in rats, dogs, and monkeys was 45%, 86%, and 72% to 88%, respectively. After a single oral dose of alogliptin, plasma DPP-4 inhibition was observed within 15 min and maximum inhibition was > 90% in rats, dogs, and monkeys; inhibition was sustained for 12 h in rats (43%) and dogs (65%) and 24 h in monkeys (> 80%). From E(max) modeling, 50% inhibition of DPP-4 activity was observed at a mean alogliptin plasma concentration (EC(50)) of 3.4 to 5.6 ng/ml (10.0 to 16.5 nM) in rats, dogs, and monkeys. In Zucker fa/fa rats, a single dose of alogliptin (0.3, 1, 3, and 10 mg/kg) inhibited plasma DPP-4 (91% to 100% at 2 h and 20% to 66% at 24 h), increased plasma GLP-1 (2- to 3-fold increase in AUC(0-20 min)) and increased early-phase insulin secretion (1.5- to 2.6-fold increase in AUC(0-20 min)) and reduced blood glucose excursion (31%-67% decrease in AUC(0-90 min)) after oral glucose challenge. Alogliptin (30 and 100 mg/kg) had no effect on fasting plasma glucose in normoglycemic rats. In summary, these data suggest that alogliptin is a potent and highly selective DPP-4 inhibitor with demonstrated efficacy in Zucker fa/fa rats and potential for once-daily dosing in humans.
Title: Chronic administration of alogliptin, a novel, potent, and highly selective dipeptidyl peptidase-4 inhibitor, improves glycemic control and beta-cell function in obese diabetic ob/ob mice Moritoh Y, Takeuchi K, Asakawa T, Kataoka O, Odaka H Ref: European Journal of Pharmacology, 588:325, 2008 : PubMed
Dipeptidyl peptidase-4 (DPP-4) inhibitors improve glycemic control in patients with type 2 diabetes by increasing plasma active glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide levels. However, the effects of chronic DPP-4 inhibition on in vivo beta-cell function are poorly characterized. We thus evaluated the chronic effects of the DPP-4 inhibitor alogliptin benzoate (formerly SYR-322) on metabolic control and beta-cell function in obese diabetic ob/ob mice. Alogliptin (0.002%, 0.01%, or 0.03%) was administered in the diet to ob/ob mice for 2 days to determine effects on plasma DPP-4 activity and active GLP-1 levels and for 4 weeks to determine chronic effects on metabolic control and beta-cell function. After 2 days, alogliptin dose-dependently inhibited DPP-4 activity by 28-82% and increased active GLP-1 by 3.2-6.4-fold. After 4 weeks, alogliptin dose-dependently decreased glycosylated hemoglobin by 0.4-0.9%, plasma glucose by 7-28% and plasma triglycerides by 24-51%, increased plasma insulin by 1.5-2.0-fold, and decreased plasma glucagon by 23-26%, with neutral effects on body weight and food consumption. In addition, after drug washout, alogliptin (0.03% dose) increased early-phase insulin secretion by 2.4-fold and improved oral meal tolerance (25% decrease in glucose area under the concentration-time curve), despite the lack of measurable plasma DPP-4 inhibition. Importantly, alogliptin also increased pancreatic insulin content up to 2.5-fold, and induced intense insulin staining of islets, suggestive of improved beta-cell function. In conclusion, chronic treatment with alogliptin improved glycemic control, decreased triglycerides, and improved beta-cell function in ob/ob mice, and may exhibit similar effects in patients with type 2 diabetes.
Alogliptin is a potent, selective inhibitor of the serine protease dipeptidyl peptidase IV (DPP-4). Herein, we describe the structure-based design and optimization of alogliptin and related quinazolinone-based DPP-4 inhibitors. Following an oral dose, these noncovalent inhibitors provide sustained reduction of plasma DPP-4 activity and a lowering of blood glucose in animal models of diabetes. Alogliptin is currently undergoing phase III trials in patients with type 2 diabetes.
The International Human Genome Sequencing Consortium (IHGSC) recently completed a sequence of the human genome. As part of this project, we have focused on chromosome 8. Although some chromosomes exhibit extreme characteristics in terms of length, gene content, repeat content and fraction segmentally duplicated, chromosome 8 is distinctly typical in character, being very close to the genome median in each of these aspects. This work describes a finished sequence and gene catalogue for the chromosome, which represents just over 5% of the euchromatic human genome. A unique feature of the chromosome is a vast region of approximately 15 megabases on distal 8p that appears to have a strikingly high mutation rate, which has accelerated in the hominids relative to other sequenced mammals. This fast-evolving region contains a number of genes related to innate immunity and the nervous system, including loci that appear to be under positive selection--these include the major defensin (DEF) gene cluster and MCPH1, a gene that may have contributed to the evolution of expanded brain size in the great apes. The data from chromosome 8 should allow a better understanding of both normal and disease biology and genome evolution.
