Alogliptin is a potent, selective inhibitor of the serine protease dipeptidyl peptidase IV (DPP-4... more 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.
An angucycline series compound P371 A1 (1) from Streptomyces sp. P371 was established to have a n... more An angucycline series compound P371 A1 (1) from Streptomyces sp. P371 was established to have a novel structure comprising an ureido group at one of four sugar units on the basis of 2D NMR techniques. 1 exhibited an inhibitory activity against the pentagastrin-stimulated acid secretion as well as protective activities against HCl/ethanol- and indomethacin-induced gastric lesions.
We have previously discovered nicotinic acid derivative 1 as a structurally novel dipeptidyl pept... more 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]acetyl}-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.
The design, synthesis, and structure-activity relationships of a new class of potent and orally a... more 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)oxy]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.
Current protocols in toxicology / editorial board, Mahin D. Maines (editor-in-chief) ... [et al.], 2012
Bisphosphonates (BPPs) were developed as antiresorptive drugs capable of treating diseases relate... more Bisphosphonates (BPPs) were developed as antiresorptive drugs capable of treating diseases related to bone remodeling; however, they have untoward effects including ulceration in the upper gastrointestinal tract and worsen the healing-impairment action of nonsteroidal anti-inflammatory drugs, prescribed in patients with arthritis or osteoporosis. We produced ulcers in the antrum by administering BPPs to fasted rats, followed by refeeding, and confirmed their healing-impairment action on pre-existing gastric ulcers; the ulcerogenic effect is due to direct mucosal irritation and decrease in the mucosal anti-oxidative system, while the latter effect is due to dysregulation of growth factor expression, such as vascular endothelial growth factor and basic fibroblast growth factor, and angiogenesis in the ulcerated mucosa. In this article, we describe these two animal models for investigating BPP-related adverse reactions, including methods for the induction of antral ulcers and healing i...
Duodenal HCO3- secretion increases in response to luminal acid, mediated by endogenous nitric oxi... more Duodenal HCO3- secretion increases in response to luminal acid, mediated by endogenous nitric oxide (NO) as well as prostaglandins (PGs). In this study, we examined the effects of various inhibitors of cyclooxygenase (COX) or NO synthase (NOS) on the acid-induced HCO3- secretion in rats and determined the enzyme isoforms responsible for this response. A proximal duodenal loop was perfused with saline under urethane anesthesia, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Mucosal acidification was performed by exposing the loop to 10 mM HCl for 10 min. Indomethacin, SC-560 (a selective COX-1 inhibitor) and rofecoxib (a selective COX-2 inhibitor) were given intraduodenally 1 hr before exposure to 10 mM HCl, while N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) and aminoguanidine (a relatively selective inhibitor of iNOS) were given subcutaneously 3 hr before the acidification. The mucosal acidification increas...
A Gilles de la Tourette's syndrome (TS) patient is described who experienced a schizophre... more A Gilles de la Tourette's syndrome (TS) patient is described who experienced a schizophrenic episode 11 years after TS onset. Analogies and differences between the two syndromes are reviewed, leading to the conclusion that TS is a definite entity independent from schizophrenia, but that they share some common features of symptomatology and pathophysiology and have closely related anatomical lesions.
NSAID-induced enteropathy has been the focus of recent basic and clinical research subsequent to ... more NSAID-induced enteropathy has been the focus of recent basic and clinical research subsequent to the development of the capsule endoscope and double-balloon endoscope. We review the possible pathogenic mechanisms underlying NSAID-induced enteropathy and discuss the role of the inhibition of COX-1/COX-2 and the influences of food as well as various prophylactic treatments on these lesions. Studies were performed in experimental animals. Multiple factors, such as intestinal hypermotility, decreased mucus secretion, enterobacteria, and upregulation of iNOS/NO expression, are involved in the pathogenesis of NSAID-induced enteropathy, in addition to the decreased production of PGs due to the inhibition of COX. Enterobacterial invasion is the most important pathogenic event, and intestinal hypermotility, which was associated with this event, is essential for the development of these lesions. NSAIDs also upregulate the expression of COX-2, and the inhibition of both COX-1 and COX-2 is requ...
We examined the prophylactic effect of rebamipide on gastric bleeding induced by the perfusion of... more We examined the prophylactic effect of rebamipide on gastric bleeding induced by the perfusion of aspirin (acetylsalicylic acid [ASA]) plus clopidogrel under the stimulation of acid secretion in rats. Under urethane anesthesia, acid secretion was stimulated by the i.v. infusion of histamine (8 mg/kg/h), and the stomach was perfused with 25 mmol/L ASA at a rate of 0.4 mL/min. Gastric bleeding was evaluated as the concentration of hemoglobin in the perfusate. Clopidogrel (30 mg/kg) was given p.o. 24 h before the perfusion. Rebamipide (3-30 mg/kg) or other antiulcer drugs were given i.d. before the ASA perfusion. Slight gastric bleeding or damage was observed with the perfusion of ASA under the stimulation of acid secretion, whereas these responses were significantly increased in the presence of clopidogrel. Both omeprazole and famotidine inhibited acid secretion and prevented these responses to ASA plus clopidogrel. Rebamipide had no effect on acid secretion, but dose-dependently prev...
European journal of biochemistry / FEBS, Jan 2, 1987
Nitrile hydratase of Pseudomonas chlororaphis B23 was completely stabilized by the addition of 22... more Nitrile hydratase of Pseudomonas chlororaphis B23 was completely stabilized by the addition of 22 mM n-butyric acid. The enzyme was purified from extracts of methacrylamide-induced cells of P. chlororaphis B23 in eight steps. At the last step, the enzyme was crystallized by adding ammonium sulfate. The crystallized enzyme appeared to be homogeneous from analysis by polyacrylamide gel electrophoresis, analytical ultracentrifuge, and double diffusion in agarose. The enzyme has a molecular mass of about 100 kDa and consists of four subunits identical in molecular mass (approximately 25 kDa). The enzyme contained approximately 4 mol iron/mol enzyme. The concentrated solution of highly purified nitrile hydratase had a pronounced greyish green color and exhibited a broad absorption in visible range with a absorption maxima at 720 nm. A loss of enzyme activity occurred in parallel with the disappearance of the absorption in the visible range under a variety of conditions. The enzyme cataly...
The mucosal irritative action of alcoholic beverages such as white wine, Japanese sake and whisky... more The mucosal irritative action of alcoholic beverages such as white wine, Japanese sake and whisky was examined in rat stomachs in vivo and in vitro, in comparison with ethanol. The concentration of ethanol in these alcoholic beverages was 15%. Mucosal application of ethanol (15%) and whisky in the chambered stomach caused a decrease in gastric potential difference (PD), while that of Japanese sake and white wine caused a slight increase but not decrease in PD. Likewise, both ethanol and whisky markedly reduced the cell viability of RGM1 cells after 5 min incubation, whereas neither Japanese sake nor white wine had any effect. In addition, supplementation of glucose, one of the non-alcoholic ingredients of white wine and Japanese sake, antagonized a reduction in both PD and cell viability caused by ethanol. These results suggest that the mucosal irritative action of Japanese sake and white wine is much less than that of ethanol or whisky and that these properties may be, at least partly, due to the glucose contained in these alcoholic beverages.
We compared the HCO3- secretory responses induced by mucosal acidification at different HCl conce... more We compared the HCO3- secretory responses induced by mucosal acidification at different HCl concentrations (100 and 200 mM HCl) in the rat stomach. Under urethane anesthesia, the stomach was mounted on an ex vivo chamber and perfused with saline under inhibition of acid secretion by omeprazole (60 mg/kg, i.p.). TheHCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 2 mM HCl. The acidification was performed by exposure of the mucosa to 100 mMor 200 mM HCl for 10 min. The secretion of HCO3- was increased by acidification of the mucosa at both 100 and 200 mM of HCl, and the maximal HCO3- response was 1.5-times greater at the latter concentration. The HCO3- responses induced by 100 and 200 mM HCl were both totally inhibited by prior administration of indomethacin, an inhibitor of prostaglandin (PG) production. The HCO3- stimulatory effect of 200 mM HCl was also significantly attenuated by pre-treatment with N(G)-nitro L-arginine methyl ester (L-NAME), the inhibitor of nitric oxide (NO) synthase, as well as chemical ablation of capsaicin-sensitive afferent neurons, whereas that of 100 mM HCl was affected by neither of these treatments. We conclude that the mucosal acidification stimulates gastric HCO3- secretion in different mechanisms, depending on the concentration of acid; the response caused by 100 mM HCl is mediated only by PGs, while that caused by 200 mM HCl is mediated by both capsaicin-sensitive afferent neurons and NO, in addition to PGs.
Alogliptin is a potent, selective inhibitor of the serine protease dipeptidyl peptidase IV (DPP-4... more 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.
An angucycline series compound P371 A1 (1) from Streptomyces sp. P371 was established to have a n... more An angucycline series compound P371 A1 (1) from Streptomyces sp. P371 was established to have a novel structure comprising an ureido group at one of four sugar units on the basis of 2D NMR techniques. 1 exhibited an inhibitory activity against the pentagastrin-stimulated acid secretion as well as protective activities against HCl/ethanol- and indomethacin-induced gastric lesions.
We have previously discovered nicotinic acid derivative 1 as a structurally novel dipeptidyl pept... more 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]acetyl}-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.
The design, synthesis, and structure-activity relationships of a new class of potent and orally a... more 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)oxy]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.
Current protocols in toxicology / editorial board, Mahin D. Maines (editor-in-chief) ... [et al.], 2012
Bisphosphonates (BPPs) were developed as antiresorptive drugs capable of treating diseases relate... more Bisphosphonates (BPPs) were developed as antiresorptive drugs capable of treating diseases related to bone remodeling; however, they have untoward effects including ulceration in the upper gastrointestinal tract and worsen the healing-impairment action of nonsteroidal anti-inflammatory drugs, prescribed in patients with arthritis or osteoporosis. We produced ulcers in the antrum by administering BPPs to fasted rats, followed by refeeding, and confirmed their healing-impairment action on pre-existing gastric ulcers; the ulcerogenic effect is due to direct mucosal irritation and decrease in the mucosal anti-oxidative system, while the latter effect is due to dysregulation of growth factor expression, such as vascular endothelial growth factor and basic fibroblast growth factor, and angiogenesis in the ulcerated mucosa. In this article, we describe these two animal models for investigating BPP-related adverse reactions, including methods for the induction of antral ulcers and healing i...
Duodenal HCO3- secretion increases in response to luminal acid, mediated by endogenous nitric oxi... more Duodenal HCO3- secretion increases in response to luminal acid, mediated by endogenous nitric oxide (NO) as well as prostaglandins (PGs). In this study, we examined the effects of various inhibitors of cyclooxygenase (COX) or NO synthase (NOS) on the acid-induced HCO3- secretion in rats and determined the enzyme isoforms responsible for this response. A proximal duodenal loop was perfused with saline under urethane anesthesia, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Mucosal acidification was performed by exposing the loop to 10 mM HCl for 10 min. Indomethacin, SC-560 (a selective COX-1 inhibitor) and rofecoxib (a selective COX-2 inhibitor) were given intraduodenally 1 hr before exposure to 10 mM HCl, while N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) and aminoguanidine (a relatively selective inhibitor of iNOS) were given subcutaneously 3 hr before the acidification. The mucosal acidification increas...
A Gilles de la Tourette's syndrome (TS) patient is described who experienced a schizophre... more A Gilles de la Tourette's syndrome (TS) patient is described who experienced a schizophrenic episode 11 years after TS onset. Analogies and differences between the two syndromes are reviewed, leading to the conclusion that TS is a definite entity independent from schizophrenia, but that they share some common features of symptomatology and pathophysiology and have closely related anatomical lesions.
NSAID-induced enteropathy has been the focus of recent basic and clinical research subsequent to ... more NSAID-induced enteropathy has been the focus of recent basic and clinical research subsequent to the development of the capsule endoscope and double-balloon endoscope. We review the possible pathogenic mechanisms underlying NSAID-induced enteropathy and discuss the role of the inhibition of COX-1/COX-2 and the influences of food as well as various prophylactic treatments on these lesions. Studies were performed in experimental animals. Multiple factors, such as intestinal hypermotility, decreased mucus secretion, enterobacteria, and upregulation of iNOS/NO expression, are involved in the pathogenesis of NSAID-induced enteropathy, in addition to the decreased production of PGs due to the inhibition of COX. Enterobacterial invasion is the most important pathogenic event, and intestinal hypermotility, which was associated with this event, is essential for the development of these lesions. NSAIDs also upregulate the expression of COX-2, and the inhibition of both COX-1 and COX-2 is requ...
We examined the prophylactic effect of rebamipide on gastric bleeding induced by the perfusion of... more We examined the prophylactic effect of rebamipide on gastric bleeding induced by the perfusion of aspirin (acetylsalicylic acid [ASA]) plus clopidogrel under the stimulation of acid secretion in rats. Under urethane anesthesia, acid secretion was stimulated by the i.v. infusion of histamine (8 mg/kg/h), and the stomach was perfused with 25 mmol/L ASA at a rate of 0.4 mL/min. Gastric bleeding was evaluated as the concentration of hemoglobin in the perfusate. Clopidogrel (30 mg/kg) was given p.o. 24 h before the perfusion. Rebamipide (3-30 mg/kg) or other antiulcer drugs were given i.d. before the ASA perfusion. Slight gastric bleeding or damage was observed with the perfusion of ASA under the stimulation of acid secretion, whereas these responses were significantly increased in the presence of clopidogrel. Both omeprazole and famotidine inhibited acid secretion and prevented these responses to ASA plus clopidogrel. Rebamipide had no effect on acid secretion, but dose-dependently prev...
European journal of biochemistry / FEBS, Jan 2, 1987
Nitrile hydratase of Pseudomonas chlororaphis B23 was completely stabilized by the addition of 22... more Nitrile hydratase of Pseudomonas chlororaphis B23 was completely stabilized by the addition of 22 mM n-butyric acid. The enzyme was purified from extracts of methacrylamide-induced cells of P. chlororaphis B23 in eight steps. At the last step, the enzyme was crystallized by adding ammonium sulfate. The crystallized enzyme appeared to be homogeneous from analysis by polyacrylamide gel electrophoresis, analytical ultracentrifuge, and double diffusion in agarose. The enzyme has a molecular mass of about 100 kDa and consists of four subunits identical in molecular mass (approximately 25 kDa). The enzyme contained approximately 4 mol iron/mol enzyme. The concentrated solution of highly purified nitrile hydratase had a pronounced greyish green color and exhibited a broad absorption in visible range with a absorption maxima at 720 nm. A loss of enzyme activity occurred in parallel with the disappearance of the absorption in the visible range under a variety of conditions. The enzyme cataly...
The mucosal irritative action of alcoholic beverages such as white wine, Japanese sake and whisky... more The mucosal irritative action of alcoholic beverages such as white wine, Japanese sake and whisky was examined in rat stomachs in vivo and in vitro, in comparison with ethanol. The concentration of ethanol in these alcoholic beverages was 15%. Mucosal application of ethanol (15%) and whisky in the chambered stomach caused a decrease in gastric potential difference (PD), while that of Japanese sake and white wine caused a slight increase but not decrease in PD. Likewise, both ethanol and whisky markedly reduced the cell viability of RGM1 cells after 5 min incubation, whereas neither Japanese sake nor white wine had any effect. In addition, supplementation of glucose, one of the non-alcoholic ingredients of white wine and Japanese sake, antagonized a reduction in both PD and cell viability caused by ethanol. These results suggest that the mucosal irritative action of Japanese sake and white wine is much less than that of ethanol or whisky and that these properties may be, at least partly, due to the glucose contained in these alcoholic beverages.
We compared the HCO3- secretory responses induced by mucosal acidification at different HCl conce... more We compared the HCO3- secretory responses induced by mucosal acidification at different HCl concentrations (100 and 200 mM HCl) in the rat stomach. Under urethane anesthesia, the stomach was mounted on an ex vivo chamber and perfused with saline under inhibition of acid secretion by omeprazole (60 mg/kg, i.p.). TheHCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 2 mM HCl. The acidification was performed by exposure of the mucosa to 100 mMor 200 mM HCl for 10 min. The secretion of HCO3- was increased by acidification of the mucosa at both 100 and 200 mM of HCl, and the maximal HCO3- response was 1.5-times greater at the latter concentration. The HCO3- responses induced by 100 and 200 mM HCl were both totally inhibited by prior administration of indomethacin, an inhibitor of prostaglandin (PG) production. The HCO3- stimulatory effect of 200 mM HCl was also significantly attenuated by pre-treatment with N(G)-nitro L-arginine methyl ester (L-NAME), the inhibitor of nitric oxide (NO) synthase, as well as chemical ablation of capsaicin-sensitive afferent neurons, whereas that of 100 mM HCl was affected by neither of these treatments. We conclude that the mucosal acidification stimulates gastric HCO3- secretion in different mechanisms, depending on the concentration of acid; the response caused by 100 mM HCl is mediated only by PGs, while that caused by 200 mM HCl is mediated by both capsaicin-sensitive afferent neurons and NO, in addition to PGs.
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