ABSTRACT
We have prepared a series of quinazolinone derivatives linked with piperazinylquinoline for the treatment of irritable bowel syndrome (IBS). Using pharmacophore analysis, we designed and synthesized compounds which bind to both serotonin receptor subtype 1A (5-HT(1A)) and subtype 3 (5-HT(3)). Quinazolinone derivatives with a sulfur atom in the linker showed high affinity in in vitro assays, but low in vivo activity. Focusing on the linker to improve the pharmacokinetic profile, the sulfur atom in the linker was replaced with a methylene group. Further optimization led to the discovery of compound 17m (TZB-30878) ( J. Pharmacol. Exp. Ther. 2007 , 322 , 1315 - 1323 , Patent WO2005082887 (A1), 2005 ), a novel 5-HT(1A) agonist/5-HT(3) antagonist in the 3-aminoquinazolinone series. In in vivo functional assays, 17m dose dependently inhibited the Bezold-Jarisch reflex and induced 5-HT(1A)-mediated behaviors, and in an IBS animal model, 17m significantly inhibited stress-induced defecation. Pretreatment by WAY-100635 (5-HT(1A) antagonist) significantly attenuated but did not abolish the inhibitory effects of 17m. These results suggested that 17m exerted inhibitory effects via both 5-HT(1A) agonistic and 5-HT(3) antagonistic activities and that 17m would be useful as a therapeutic agent for IBS.
Subject(s)
Irritable Bowel Syndrome/drug therapy , Quinazolinones/chemical synthesis , Quinolines/chemical synthesis , Serotonin 5-HT1 Receptor Agonists/chemical synthesis , Serotonin 5-HT3 Receptor Antagonists/chemical synthesis , Administration, Oral , Animals , Biological Availability , Brain/metabolism , Cell Line , Cricetinae , Cricetulus , Guinea Pigs , Humans , Ileum/drug effects , Ileum/physiology , In Vitro Techniques , Irritable Bowel Syndrome/physiopathology , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Muscle, Smooth/physiology , Piperazines/pharmacology , Pyridines/pharmacology , Quinazolinones/chemistry , Quinazolinones/pharmacology , Quinolines/chemistry , Quinolines/pharmacology , Radioligand Assay , Rats , Receptor, Serotonin, 5-HT1A/metabolism , Receptors, Serotonin, 5-HT3/metabolism , Reflex/drug effects , Serotonin 5-HT1 Receptor Agonists/chemistry , Serotonin 5-HT1 Receptor Agonists/pharmacology , Serotonin 5-HT1 Receptor Antagonists/pharmacology , Serotonin 5-HT3 Receptor Antagonists/chemistry , Serotonin 5-HT3 Receptor Antagonists/pharmacology , Stereoisomerism , Structure-Activity RelationshipABSTRACT
We have prepared a series of piperazinylpyridine derivatives for the treatment of irritable bowel syndrome (IBS). These compounds, which were designed by pharmacophore analysis, bind to both serotonin subtype 1A (5-HT1A) and subtype 3 (5-HT3) receptors. The nitrogen atom of the isoquinoline, a methoxy group and piperazine were essential to the pharmacophore for binding to these receptors. We also synthesized furo- and thienopyridine derivatives according to structure-activity relationship analyses. Compound 17c (TZB-20810) had high affinities to these receptors and exhibited 5-HT1A agonistic activity and 5-HT3 antagonistic activity concurrently, and is a promising drug for further development in the treatment of IBS.
Subject(s)
Irritable Bowel Syndrome/drug therapy , Piperazines , Pyridines/therapeutic use , Receptors, Serotonin, 5-HT3/chemistry , Serotonin Antagonists , Serotonin Receptor Agonists , Animals , CHO Cells , Cricetinae , Cricetulus , Guinea Pigs , Humans , Molecular Structure , Piperazines/chemical synthesis , Piperazines/chemistry , Piperazines/therapeutic use , Pyridines/chemical synthesis , Pyridines/chemistry , Serotonin Antagonists/chemistry , Serotonin Antagonists/therapeutic use , Serotonin Receptor Agonists/chemistry , Serotonin Receptor Agonists/therapeutic useABSTRACT
3-Amino-5,6,7,8-tetrahydro-2-{4-[4-(quinolin-2-yl)piperazin-1-yl]-butyl}quinazolin-4(3H)-one (TZB-30878), a novel 5-hydroxytryptamine (5-HT)(1A) agonist/5-HT(3) antagonist, is currently under development for the treatment of irritable bowel syndrome. The objective of this investigation was to obtain information on the biotransformation of TZB-30878. This compound has quinazoline, piperazine, and quinoline rings. Metabolites of [quinazoline-2-(14)C]TZB-30878 were determined using radio high-performance liquid chromatography on samples obtained after incubation with human hepatic microsomes. Eight metabolites were detected in the microsomal incubation mixture, and their structures were proposed by mass spectrometry techniques using TZB-30878 and two stable labeled TZB-30878 analogs, [quinoline-deuterium (D)(6)]TZB-30878 and [piperazin-D(8)]TZB-30878. Liquid chromatography/tandem mass spectrometry analyses suggested that the eight metabolites consisted of a cyclic metabolite (M6), four hydroxylated metabolites (M1, M2, M3, and M4) (three on quinoline ring and one on quinazoline ring), a deaminated metabolite (M5), and two metabolites (M7 and M8) that were presumably intermediates leading to the formation of the cyclic metabolite M6. Hydroxylation sites in the quinoline and quinazoline rings were predicted by electron density calculations and confirmed by comparison with authentic standards. To the best of our knowledge, N-deamination by microsomes leading to the formation of M5 appears to be novel. In addition, in vitro experiments in human liver microsomes with cytochrome P450 (P450)-specific inhibitors revealed that CYP3A4 was the major enzyme responsible for the metabolism of TZB-30878. Other P450 enzymes, such as a CYP2D6, played a minor role in its metabolism.
Subject(s)
Microsomes, Liver/metabolism , Quinazolinones/metabolism , Quinolines/metabolism , Serotonin 5-HT1 Receptor Agonists , Serotonin 5-HT3 Receptor Antagonists , Serotonin Agents/metabolism , Biotransformation , Cytochrome P-450 Enzyme System/metabolism , HumansABSTRACT
3-Amino-5,6,7,8-tetrahydro-2-[4-[4-(quinolin-2-yl)piperazin-1-yl]butyl]quinazolin-4(3H)-one (TZB-30878) is a novel compound with both 5-hydroxytryptamine (5-HT)(1A) agonism and 5-HT(3) antagonism effects. We hypothesized that TZB-30878 might have benefits from these dual effects as a medication for diarrhea-predominant irritable bowel syndrome (d-IBS), and these studies were designed to confirm the pharmacological properties of TZB-30878 and its efficacy in an IBS-like animal model. The binding assays demonstrated that [(3)H]TZB-30878 selectively binds to human 5-HT(1A) and 5-HT(3) receptors, with K(d) values of 0.68 +/- 0.03 and 8.90 +/- 1.73 nM, respectively. Systemic administration of TZB-30878 inhibited 5-HT-induced bradycardia in a dose-dependent manner in rats. In behavioral assays TZB-30878 produced signs of 5-HT syndrome in rats. These results suggest that TZB-30878 has dual effects as a 5-HT(1A) receptor agonist and a 5-HT(3) receptor antagonist. Finally, we evaluated the effects of TZB-30878 on wrap restraint stress-induced defecation in an IBS-like model in rats. TZB-30878 (1-10 mg/kg p.o.) normalized stress-induced defecation in a dose-dependent manner, whereas the 5-HT(1A) agonist tandospirone (30 and 100 mg/kg p.o.) and the 5-HT(3) antagonist alosetron (1-10 mg/kg p.o.) did not show such effects. Furthermore, this efficacy of TZB-30878 was partly antagonized by a 5-HT(1A) antagonist, [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride (WAY-100635). These results suggest that 5-HT(1A) receptor agonism and 5-HT(3) receptor antagonism contribute to the efficacy of TZB-30878 in the IBS-like model. The efficacy of TZB-30878 supports the concept that the presence of both actions, namely 5-HT(1A) receptor agonism and 5-HT(3) receptor antagonism, could be an important mechanism in the treatment of d-IBS.
