Synthesis and activity of di- or trisubstituted N-(phenoxyalkyl)- or N-{2-[2-(phenoxy)ethoxy]ethyl}piperazine derivatives on the central nervous system

Aim of the study was evaluation of anxiolytic, antidepressant, anticonvulsant and analgesic activity in a series of a consistent group of compounds. A series of eleven new N-(phenoxyalkyl)- or N-{2-[2-(phenoxy)ethoxy]ethyl}piperazine derivatives has been obtained. Their affinity towards 5-HT_1A, 5-HT_2A, 5-HT₆, 5-HT₇, D₂ and α₁ receptors has been assessed, and then functional assays were performed. The compounds were evaluated in mice, i.p. for their antidepressant-like (forced swim test), locomotor, anxiolytic-like (four-plate test) activities as well as – at higher doses – for anticonvulsant potential (MES) and neurotoxicity (rotarod). Two compounds (3, 6) were also evaluated for their analgesic activity in neuropathic pain models (streptozocin test, oxaliplatin test) and they were found active against allodynia in diabetic neuropathic pain at 30?mg/kg. Among the compounds, anxiolytic-like, anticonvulsant or analgesic activity was observed but antidepressant-like activity was not. One of the two most interesting compounds is 1-{2-[2-(2,4,6-trimethylphenoxy)ethoxy]ethyl}-4-(2-methoxyphenyl)piperazine dihydrochloride (9), exhibiting anxiolytic and anticonvulsant activity in mice, i.p. 30 min after administration (at 2.5?mg/kg and ED₅₀?=?26.33?mg/kg, respectively), which can be justified by the receptor profile: 5-HT_1A K_i?=?5?nM (antagonist), 5-HT₇ K_i?=?70?nM, α₁ K_i?=?15?nM, D₂ K_i?=?189?nM (antagonist). Another interesting compound is 1-[3-(2,4,6-trimethylphenoxy)propyl]-4-(4-methoxyphenyl)piperazine dihydrochloride (3), exhibiting anxiolytic, anticonvulsant and antiallodynic activity in mice, i.p., 30?min after administration (at 10?mg/kg, ED₅₀?=?23.50?mg/kg, at 30?mg/kg, respectively), which can be related with 5-HT_1A weak antagonism (K_i?=?146?nM), or other possible mechanism of action, not evaluated within presented study. Additionally, for the most active compound in the four-plate test (7), molecular modeling was performed (docking to receptors 5-HT_1A, 5-HT_2A, 5-HT₇, D₂ and α_1A).     

Design,physico-chemical properties and biological evaluation of some new N-[(phenoxy)alkyl]- and N-{2-[2-(phenoxy)ethoxy]ethyl}aminoalkanols as anticonvulsant agents

A series of thirty N-(phenoxy)alkyl or N-{2-[2-(phenoxy)ethoxy]ethyl}aminoalkanols has been designed, synthesized and evaluated for anticonvulsant activity in MES, 6 Hz test, and pilocarpine-induced status epilepticus. Among the title compounds, the most promising seems R-(−)-2N-{2-[2-(2,6-dimethylphenoxy)ethoxy]ethyl}aminopropan-1-ol hydrochloride (22a) with proved absolute configuration with X-ray analysis and enantiomeric purity. The compound is effective in MES test with ED₅₀ = 12.92 mg/kg b.w. and its rotarod TD₅₀ = 33.26 mg/kg b.w. The activity dose is also effective in a neurogenic pain model—the formalin test. Within high throughput profile assay, among eighty one targets, the strongest affinity of the compound is observed towards σ receptors and 5-HT transporter and the compound does not bind to hERG. It also does not exhibit mutagenic properties in the Vibrio harveyi test. Moreover, murine liver microsomal assay and pharmacokinetics profile (mice, iv, p.o., ip) indicate that the liver is the primary site of biotransformation of the compound, suggesting that both 22a and its metabolite(s) are active, compensating probably low bioavailability of the parent molecule.     

Novel naphthyloxy derivatives – Potent histamine H3 receptor ligands. Synthesis and pharmacological evaluation

A series of 1- and 2-naphthyloxy derivatives were synthesized and evaluated for histamine H₃ receptor affinity. Most compounds showed high affinities with K_i values below 100?nM. The most potent ligand, 1-(5-(naphthalen-1-yloxy)pentyl)azepane (11) displayed high affinity for the histamine H₃ receptor with a K_i value of 21.9?nM. The antagonist behaviour of 11 was confirmed both in vitro in the cAMP assay (IC₅₀?=?312?nM) and in vivo in the rat dipsogenia model (ED₅₀?=?3.68?nM). Moreover, compound 11 showed positive effects on scopolamine induced-memory deficits in mice (at doses of 10 and 15?mg/kg) and an analgesic effect in the formalin test in mice with ED₅₀?=?30.6?mg/kg (early phase) and ED₅₀?=?20.8?mg/kg (late phase). Another interesting compound, 1-(5-(Naphthalen-1-yloxy)pentyl)piperidine (13; H₃R K_i?=?53.9?nM), was accepted for Anticonvulsant Screening Program at the National Institute of Neurological Disorders and Stroke/National Institute of Health (Rockville, USA). The screening was performed in the maximal electroshock seizure (MES), the subcutaneous pentylenetetrazole (scPTZ) and the 6-Hz psychomotor animal models of epilepsy. Neurologic deficit was evaluated by the rotarod test. Compound 13 inhibited convulsions induced by the MES with ED₅₀ of 19.2?mg/kg (mice, i.p.), 17.8 (rats, i.p.), and 78.1 (rats, p.o.). Moreover, 13 displayed protection against the 6-Hz psychomotor seizures (32?mA) in mice (i.p.) with ED₅₀ of 33.1?mg/kg and (44?mA) ED₅₀ of 57.2?mg/kg.Furthermore, compounds 11 and 13 showed in vitro weak influence on viability of tested cell lines (normal HEK293, neuroblastoma IMR-32, hepatoma HEPG2), weak inhibition of CYP3A4 activity, and no mutagenicity. Thus, these compounds may be used as leads in a further search for histamine H₃ receptor ligands with promising in vitro and in vivo activity.     

Synthesis and evaluation of pharmacological properties of some new xanthone derivatives with piperazine moiety

A series of new xanthone derivatives with piperazine moiety [1–7] was synthesized and evaluated for their pharmacological properties. They were subject to binding assays for α₁ and β₁ adrenergic as well as 5-HT_1A, 5-HT₆ and 5-HT_7b serotoninergic receptors. Five of the tested compounds were also evaluated for their anticonvulsant properties. The compound 3a 3-methoxy-5-{[4-(2-methoxyphenyl)piperazin-1-yl]methyl}-9H-xanthen-9-one hydrochloride exhibited significantly higher affinity for serotoninergic 5-HT_1A receptors (K_i = 24 nM) than other substances. In terms of anticonvulsant activity, 6-methoxy-2-{[4-(benzyl)piperazin-1-yl]methyl}-9H-xanthen-9-one (5) proved best properties. Its ED₅₀ determined in maximal electroshock (MES) seizure assay was 105 mg/kg b.w. (rats, p.o.). Combining of xanthone with piperazine moiety resulted in obtaining of compounds with increased bioavailability after oral administration.     

Discovery of 1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazoles as novel class of corticotropin releasing factor 1 receptor antagonists

A new class of corticotropin releasing factor 1 (CRF₁) receptor antagonists characterized by a tricyclic core ring was designed and synthesized. Novel tricyclic derivatives 2a–e were designed as CRF₁ receptor antagonists based on conformation analysis of our original 2-anilinobenzimidazole CRF₁ receptor antagonist. The synthesized tricyclic derivatives 2a–e showed CRF₁ receptor binding activity with IC₅₀ values of less than 400?nM, and the 1,2,3,4-tetrahydropyrimido-[1,2-a]benzimidazole derivative 2e was selected as a lead compound with potent in vitro CRF₁ receptor binding activity (IC₅₀?=?7.1?nM). To optimize the pharmacokinetic profiles of lead compound 2e, we explored suitable substituents on the 1-position and 6-position, leading to the identification of compound 42c-R, which exhibited potent CRF₁ receptor binding activity (IC₅₀?=?58?nM) with good oral bioavailability (F?=?68% in rats). Compound 42c-R exhibited dose-dependent inhibition of [¹²⁵I]-CRF binding in the frontal cortex (5 and 10?mg/kg, p.o.) as well as suppression of locomotor activation induced by intracerebroventricular administration of CRF in rats (10?mg/kg, p.o.). These results suggest that compound 42c-R successfully binds CRF₁ receptors in the brain and exhibits the potential to be further examined for clinical studies.     

Discovery of (1R,6S)-5-[4-(1-cyclobutyl-piperidin-4-yloxy)-phenyl]-3,4-diaza-bicyclo[4.1.0]hept-4-en-2-one (R,S-4a): Histamine H3 receptor inverse agonist demonstrating potent cognitive enhancing and wake promoting activity

A series of fused cyclopropyl-4,5-dihydropyridazin-3-one (3,4-diaza-bicyclo[4.1.0]hept-4-en-2-one) phenoxypiperidine analogs was designed and synthesized, leading to the identification of (1R,6S)-5-[4-(1-cyclobutyl-piperidin-4-yloxy)-phenyl]-3,4-diaza-bicyclo[4.1.0]hept-4-en-2-one (R,S-4a) as a second-generation pyridazin-3-one H₃R antagonist. Compound R,S-4a was a potent H₃R functional antagonist in vivo in the rat dipsogenia model, demonstrated potent wake activity in the rat EEG/EMG model, and enhanced short-term memory in the rat social recognition memory model at doses as low as 0.03–0.3 mg/kg po.     

Synthesis and pharmacological evaluation of new arylpiperazines N-{4-[4-(aryl) piperazine-1-yl]-phenyl}-amine derivatives: Putative role of 5-HT1A receptors

In an attempt to design novel 5-HT_1A agonists/partial agonists, based on an arylpiperazine nucleus, a series of N-{4-[4-(aryl)piperazine-1-yl]-phenyl}-amine derivatives were synthesized and biologically tested. The anxiolytic effect of the compounds was investigated employing the Elevated plus Maze (EPM) task. On the basis of in vivo functional test, compound 1c (3 mg/kg) and 4c (3 mg/kg) induced significant increments in open arm entries and time on EPM as compared to Buspirone. The anxiolytic effects of compounds 1c and 4c were effectively antagonized by WAY-100635, a 5-HT_1A receptor antagonist (0.5 mg/kg). Furthermore, we have also evaluated the concentration of 5-HT in the brain tissue using HPLC with fluorescent detection. Our result showed that serotonin levels were significantly decreased by ～38% (p < 0.001) and ～32% (p < 0.001) after acute administration of compounds 1c and 4c, respectively. These findings suggest that the anxiolytic like activity of these new arylpiperazines is mediated via 5-HT_1A receptors in the brain.     

Design,synthesis, biological evaluation,homology modeling and docking studies of (E)-3-(benzo[d][1,3]dioxol-5-ylmethylene) pyrrolidin-2-one derivatives as potent anticonvulsant agents

A series of (E)-3-(benzo[d][1,3]dioxol-5-ylmethylene)pyrrolidin-2-one derivatives were designed, synthesized, and evaluated for their anticonvulsant activities. In the preliminary screening, compounds 5, 6a–6f and 6h–6i showed promising anticonvulsant activities in MES model, while 6f and 6g represented protection against seizures at doses of 100?mg/kg and 0.5?h in scPTZ model. The most active compound 6d had a high-degree protection against the MES-induced seizures with ED₅₀ value of 4.3?mg/kg and TD₅₀ value of 160.9?mg/kg after intraperitoneal (i.p.) injection in mice, which provided 6d in a high protective index (TD₅₀/ED₅₀) of 37.4 comparable to the reference drugs. Beyond that, 6d has been selected and evaluated in vitro experiment to estimate the activation impact. Apparently, 6d clearly inhibits the Na_v1.1 channel. Our preliminary results provide new insights for the development of small-molecule activators targeting specifically Na_v1.1 channels to design potential drugs for treating epilepsy. The computational parameters, such as homology modeling, docking study, and ADME prediction, were made to exploit the results.     

Synthesis,evaluation and docking of novel pyrazolo pyrimidines as potent p38α MAP kinase inhibitors with improved anti-inflammatory,ulcerogenic and TNF-α inhibitory properties

A series of nine new N-substituted-4-((1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl)amino)benzamides (6a-i) derivatives was synthesized. All the compounds were screened in-vitro for BSA anti-denaturation property, antioxidant assay and p38α MAP kinase inhibition. The in vitro anti-inflammatory assay results revealed that the compounds (6f-i) showed better activity than the compounds 6a-e. Compound 6f bearing the 4-chlorophenyl group showed in vitro anti-inflammatory activity (82.35 ± 4.04) comparable to standard drug diclofenac sodium (84.13 ± 1.63) and better p38α MAP kinase inhibitory activity (IC₅₀ = 0.032 ± 1.63 µM) than the prototypic inhibitor SB203580 (IC₅₀ = 0.041 ± 1.75 µM). The selected active compounds (6f-i) were further studied in animal models for anti-inflammatory activity, ulcerogenic liability, lipid peroxidation and TNF-α inhibition potential. Compound 6f showed promising anti-inflammatory potential with a percentage inhibition of 83.73% when compared to the standard, diclofenac sodium (78.05%). Compound 6f was also found to show reduced ulcerogenic liability and lipid peroxidation in comparison to the standard. This compound also potently inhibited the lipopolysaccharide (LPS)-induced TNF-α production in mice model (ID₅₀ = 8.23 mg/kg) in comparison to SB 203580 (ID₅₀ = 26.38 mg/kg). The molecular docking of compounds 6a-i against p38α MAP kinase receptor was also performed to understand ligand receptor interaction. Amongst all synthesized molecules compound 6f displayed highest docking score of −9.824. It showed hydrogen bonding interactions with Asn115 and pi-cation interaction with Lys53.     

Design and synthesis of pyrrolo[3,2-d]pyrimidine HER2/EGFR dual inhibitors: Improvement of the physicochemical and pharmacokinetic profiles for potent in vivo anti-tumor efficacy

During the course of our studies on a novel HER2/EGFR dual inhibitor (TAK-285), we found an alternative potent pyrrolo[3,2-d]pyrimidine compound (1a). To enhance the pharmacokinetic (PK) profile of this compound, we conducted chemical modifications into its N-5 side chain and conversion of the chemically modified compounds into their salts. Among them, 2cb, the tosylate salt of compound 2c, showed potent HER2/EGFR kinase inhibitory activity (IC₅₀: 11/11 nM) and cellular growth inhibitory activity (BT-474 cell GI₅₀: 56 nM) with a good drug metabolism and PK (DMPK) profile. Furthermore, 2cb exhibited significant in vivo antitumor efficacy in both mouse and rat xenograft models with transplanted 4-1ST gastric cancer cell lines (mouse, T/C = 0%, 2cb po bid at 100 mg/kg; rat, T/C: -1%, 2cb po bid at 25 mg/kg).     

Novel boronated chlorin e6-based photosensitizers: Synthesis,binding to albumin and antitumour efficacy

Chlorins, a class of plant porphyrins, are perspective as photosensitizing agents due to light absorption in the long wavelength spectral region and deeper photodamage of tissues. Aiming at optimization of antitumour properties of chlorins, we synthesized a series of boronated derivatives of chlorin e₆ and their complexes containing Zn(II), Pd(II) or Sn(IV). The compounds were synthesized by alkylation of amino or hydroxy derivatives of chlorin e₆ with 1-trifluoromethanesulfonylmethyl-o-carborane. Chlorin e₆ 13(1)-N-{2-[N-(o-carboran-1-yl)methyl]aminoethyl}amide-15(2), 17(3)-dimethyl ester (compound 5) formed complexes with serum albumin, a major porphyrin carrier. The binding constant of these complexes was ～4 times bigger than the respective value for the complexes of albumin with boron-free aminochlorin e₆. Compound 5 potently sensitized rat fibroblasts to illumination with monochromatic red light: >98% of cells were necrotic by 24 h post-illumination with 1 μM of 5. This compound demonstrated high efficacy in photodynamic therapy of rat M-1 sarcoma. After PDT with 25 mg/kg of 5 the residual tumours were significantly smaller than in animals subjected to PDT with equal concentration of boron-free aminochlorin e₆. No signs of general toxicity were detectable after PDT with 5. Thus, boronation can enhance the potency of chlorins in PDT, in particular, due to an increased binding to albumin. Our data expand the therapeutic applicability of boronated chlorins beyond boron neutron capture therapy; these agents emerge as dual efficacy photoradiosensitizers.     

Discovery of novel spiro[chromane-2,4′-piperidine] derivatives as potent and orally bioavailable G-protein-coupled receptor 119 agonists

Herein, we describe the discovery, synthesis, and evaluation of a novel series of spiro[chromane-2,4′-piperidine] derivatives as G-protein-coupled receptor 119 agonists. Their initial design exploited the conformational restriction in the linker-to-tail moiety, which was a key concept in this study, to give lead compound 11 (EC₅₀?=?369?nM, E_max?=?82%). An extensive structure–activity relationship study resulted in the identification of the optimized drug candidate (R)-29 (EC₅₀?=?54?nM, E_max?=?181%). The defining structural features of the series were a terminal benzyl-type bulky substituent and a methylene linker between the sulfonyl and phenyl groups, both of which were in the head moiety as well as the spiro-type scaffold in the linker-to-tail moiety. An in vivo oral glucose-tolerance test using C57BL/6N mice showed that (R)-29 reduced glucose excursion at a dose of 3?mg/kg in a dose-dependent manner.     

Synthesis and pharmacological evaluation of novel N-Mannich bases derived from 5,5-diphenyl and 5,5-di(propan-2-yl)imidazolidine-2,4-dione core

The aim of this study was to design and synthesize two series of N-Mannich bases with imidazolidine-2,4-dione core as a potential anticonvulsant with reduced toxicity and broad antiseizure activity. Preliminary screening revealed that the majority of synthesized compounds were effective in the maximal electroshock seizure (MES) and/or subcutaneous pentylenetetrazole (scPTZ) test. The most active in vivo compound, 18 (3-((4-methylpiperazin-1-yl)methyl)-5,5-diphenylimidazolidine-2,4-dione), exhibited an ED₅₀ value comparable to that of phenytoin in the MES test (38.5 mg/kg vs 28.1 mg/kg), and more importantly, it showed four times higher potency than phenytoin in the 6 Hz test (12.2 mg/kg vs > 60 mg/kg). Additionally, 18 exhibited antiallodynic properties in the von Frey test in neuropathic (oxaliplatin-treated) mice. Compound 18 also demonstrated a broader spectrum of anticonvulsant activity than phenytoin and showed statistically significant antinociceptive properties in selected models of chronic pain.     

Synthesis and structure-activity relationships of 4-oxo-1-phenyl-3,4,6,7-tetrahydro-[1,4]diazepino[6,7,1-hi]indoles: novel PDE4 inhibitors

A novel series of benzodiazepine derivatives have been discovered as inhibitors of PDE4 enzymes. We have found that our compounds are selective versus other PDE enzymes, and that the activity can be modulated by specific structural modifications. One compound exhibited a strong eosinophilic infiltration inhibiting action on sensitized Brown-Norway rats (compound 9, 5.1 mg/kg p.o.), moreover this compound is not emetic at 3 mg/kg i.v.     

Discovery of 4-ethoxy-7H-pyrrolo[2,3-d]pyrimidin-2-amines as potent,selective and orally bioavailable LRRK2 inhibitors

Inhibition of LRRK2 kinase activity with small molecules has emerged as a potential novel therapeutic treatment for Parkinson’s disease. Herein we disclose the discovery of a 4-ethoxy-7H-pyrrolo[2,3-d]pyrimidin-2-amine series as potent LRRK2 inhibitors identified through a kinase-focused set screening. Optimization of the physicochemical properties and kinase selectivity led to the discovery of compound 7, which exhibited potent in vitro inhibition of LRRK2 kinase activity, good physicochemical properties and kinase selectivity across the kinome. Moreover, compound 7 was able to penetrate into the CNS, and in vivo pharmacology studies revealed significant inhibition of Ser935 phosphorylation in the brain of both rats (30 and 100?mg/kg) and mice (45?mg/kg) following oral administration.     

Synthesis and biological evaluation of novel azole derivatives as selective potent inhibitors of brassinosteroid biosynthesis

Brassinosteroids (BRs) are phytohormones that control several important agronomic traits, such as flowering, plant architecture, seed yield, and stress tolerance. To manipulate the BR levels in plant tissues using specific inhibitors of BR biosynthesis, a series of novel azole derivatives were synthesized and their inhibitory activity on BR biosynthesis was investigated. Structure–activity relationship studies revealed that 2RS, 4RS-1-[4-(2-allyloxyphenoxymethyl)-2-(4-chlorophenyl)-[1,3]dioxolan-2-ylmethyl]-1H-[1,2,4]triazole (G₂) is a highly selective inhibitor of BR biosynthesis, with an IC₅₀ value of approximately 46 ± 2 nM, which is the most potent BR biosynthesis inhibitor observed to date. Use of gibberellin (GA) biosynthesis mutants and BR signaling mutants to analyze the mechanism of action of this synthetic series indicated that the primary site of action is BR biosynthesis. Experiments feeding BR biosynthesis intermediates to chemically treated Arabidopsis seedlings suggested that the target sites of this synthetic series are CYP90s, which are responsible for the C-22 and/or C-23 hydroxylation of campesterol.     

Synthesis and structure–activity relationship of fused-pyrimidine derivatives as a series of novel GPR119 agonists

A series of fused-pyrimidine derivatives have been discovered as potent and orally active GPR119 agonists. A combination of the fused-pyrimidine structure and 4-chloro-2,5-difluorophenyl group provided the 5,7-dihydrothieno[3,4-d]pyrimidine 6,6-dioxide derivative 14a as a highly potent GPR119 agonist. Further optimization of the amino group at the 4-position in the pyrimidine ring led to the identification of 2-{1-[2-(4-chloro-2,5-difluorophenyl)-6,6-dioxido-5,7-dihydrothieno[3,4-d]pyrimidin-4-yl]piperidin-4-yl}acetamide (16b) as an advanced analog. Compound 16b was found to have extremely potent agonistic activity and improved glucose tolerance at 0.1 mg/kg po in mice. We consider compound 16b and its analogs to have clear utility in exploring the practicality of GPR119 agonists as potential therapeutic agents for the treatment of type 2 diabetes mellitus.     

A novel,potent, and orally active VLA-4 antagonist with good aqueous solubility: trans-4-[1-[[2-(5-Fluoro-2-methylphenylamino)-7-fluoro-6-benzoxazolyl]acetyl]-(5S)-[methoxy(methyl)amino]methyl-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylic acid

We have carried out the optimization of substituents at the C-3 or the C-5 position on the pyrrolidine ring of VLA-4 antagonist 3 with 2-(phenylamino)-7-fluorobenzoxazolyl moiety for the purpose of improving in vivo efficacy while maintaining good aqueous solubility. As a result, we successfully increased in vitro activity in the presence of 3% human serum albumin and achieved an exquisite lipophilic and hydrophilic balance of compounds suitable for oral administrative regimen. The modification resulted in the identification of zwitterionic compound 7n with (5S)-[methoxy(methyl)amino]methylpyrrolidine, which significantly alleviated bronchial hyper-responsiveness to acetylcholine chloride at 12.5 mg/kg, p.o. in a murine asthma model and showed favorable aqueous solubility (JP1, 89 μg/mL; JP2, 462 μg/mL). Furthermore, this compound showed good oral bioavailability (F = 54%) in monkeys.     

Synthesis and in vitro anti-HIV activity of N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives using MTT method

A series of novel N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives has been synthesized. All the newly synthesized compounds were evaluated for their anti-HIV activity using MTT method. Most of these compounds showed moderate to potent activity against wild-type HIV-1 with an EC₅₀ ranging from >7 EC₅₀ [μg/ml] to <100 EC₅₀ [μg/ml]. Among them, N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide 6v was identified as the most promising compound (EC₅₀ = <7 μg/ml). Among all the compounds, three compounds 6m, 6v and 6u have been exhibits potent anti-HIV activity against MT-4 cells.     

Synthesis and evaluation of a potent,well-balanced EP2/EP3 dual agonist

A highly potent and well-balanced dual agonist for the EP₂ and EP₃ receptors is described. Optimization of the lead compound was accomplished in consideration of the relative agonist activity against each EP subtype receptor and the pharmacokinetic profile. As the result, 2-[(2-{(1R,2R)-2-[(1E,4S)-5-cyclopentyl-4-hydroxy-4-methyl-1-penten-1-yl]-5-oxocyclopentyl}eth-yl)thio]-1,3-thiazole-4-carboxylic acid (10) showed excellent potency (human EC₅₀ EP₂?=?1.1?nM, EP₃?=?1.0?nM) with acceptable selectivity over the EP₁ and EP₄ subtypes (>2000-fold). Further fine-tuning of compound 10 led to identification of ONO-8055 as a clinical candidate. ONO-8055 was effective at an extremely low dose (0.01?mg/kg, po, bid) in rats, and dose-dependently improved voiding dysfunction in a monkey model of underactive bladder (UAB). ONO-8055 is expected to be a novel and highly promising drug for UAB.