Novel Mannich Bases, 5‐Arylimidazolidine‐2,4‐dione Derivatives with Dual 5‐HT1A Receptor and Serotonin Transporter Affinity

A computer aided ligand design study of imidazolidine‐2,4‐dione derivatives was conducted in order to obtain compounds with dual 5‐HT_1A receptor and serotonin transporter (SERT) affinity. According to molecular modeling results, series of Mannich bases were chosen and synthesized. Investigated compounds were tested for 5‐HT_1A, 5‐HT_2A, α₁ and SERT affinity. Two selected compounds ( 5 , 9 ) were characterized in functional experiments and possessed a pharmacological profile which may enhance SERT blocking efficacy – 5‐HT_1A partial agonism and 5‐HT_2A antagonism in one molecule. Furthermore these compounds displayed satisfactory selectivity over adrenergic α₁ receptors. The most promising compounds, 5‐arylimidazolidine‐2,4‐dione derivatives with 4‐(3‐chlorophenyl)piperazinylmethyl moiety were tested for antidepressant and anxiolytic activity. In particular, compound 5 (5‐(2‐methoxyphenyl)‐3‐{1‐[4‐(3‐chlorophenyl)piperazin‐1‐yl]methyl}‐imidazolidine‐2,4‐dione), tested in the forced swim test in mice, exhibited a favorable antidepressant‐like profile without affecting spontaneous locomotor activity.     

New Arylpiperazines with Flexible versus Partly Constrained Linker as Serotonin 5‐HT1A/5‐HT7 Receptor Ligands

A series of new long‐chain arylpiperazine (LCAP) derivatives with flexible and partly constrained alkyl linker were synthesized and investigated in vitro as potential serotonin 5‐HT_1A and 5‐HT₇ receptor ligands. The compounds were prepared by a two‐step procedure using naphthalimide and 2H‐1,3‐benzoxazine‐2,4(3H)‐dione as imides, and 1‐(2‐methoxyphenyl)piperazine (o‐OMe‐PhP) and 1,2,3,4‐tetrahydroisoquinoline (THIQ) as amine pharmacophores. Modifications of the spacer structure included introduction of flexible penta‐ and hexamethylene chains as well as partly constrained m‐ and p‐xylyl moieties. In general, the new compounds were more active at the 5‐HT_1A than at the 5‐HT₇ receptor, and the o‐OMe‐PhP derivatives displayed higher affinities than their respective THIQ analogs. The spacer modifications had little effect on the observed in vitro activities. Within the o‐OMe‐PhP series, except for a small binding reduction for ligands containing the m‐xylyl moiety, there was no substantial change in the compounds' potency at both receptors, while for the THIQ derivatives a clear structure–activity relationship was visible only for the interaction of the compounds with the 5‐HT₇ receptor, which strongly favored flexible analogs.     

Solid‐Supported Synthesis and 5‐HT7/5‐HT1A Receptor Affinity of Arylpiperazinylbutyl Derivatives of 4,5‐dihydro‐1,2,4‐triazine‐6‐(1H)‐one

A series of arylpiperazinylbutyl derivatives of 4,5‐dihydro‐1,2,4‐triazine‐6(1H)‐ones was designed and synthesized according to the new solid‐supported methodology. In this approach, triazinone scaffold was constructed from the Fmoc‐protected glycine. The library representatives showed different levels of affinity for 5‐HT₇ and 5‐HT_1A receptors; compounds 13 , 14 and 18 – 20 were classified as dual 5‐HT₇/5‐HT_1A receptors ligands. The structure–affinity relationship analysis revealed that the receptor affinity and selectivity of the tested compounds depended on the kind of substituent in position 3 of triazinone fragment as well as substitution pattern of the phenylpiperazine moiety.     

Fully automated synthesis and purification of 4‐(2′‐methoxyphenyl)‐1‐[2′‐(N‐2″‐pyridinyl)‐p‐[18F]fluorobenzamido]ethylpiperazine

We have developed an efficient synthesis method for the rapid and high‐yield automated synthesis of 4‐(2′‐methoxyphenyl)‐1‐[2′‐(N‐2″‐pyridinyl)‐p‐[¹⁸F]fluorobenzamido]ethylpiperazine (p‐[¹⁸F]MPPF). No‐carrier‐added [¹⁸F]F^? was trapped on a small QMA cartridge and eluted with 70% MeCN(aq) (0.4 mL) containing Kryptofix 222 (2.3 mg) and K₂CO₃ (0.7 mg). The nucleophilic [¹⁸F]fluorination was performed with 3 mg of the nitro‐precursor in DMSO (0.4 mL) at 190 °C for 20 min, followed by the preparative HPLC purification (column: COSMOSIL Cholester, Nacalai Tesque, Kyoto, Japan; mobile phase: MeCN/25 mm AcONH₄/AcOH = 200/300/0.15; flow rate: 6.0 mL/min) to afford p‐[¹⁸F]MPPF (retention time = 9.5 min). p‐[¹⁸F]MPPF was obtained automatically with a radiochemical yield of 38.6 ± 5.0% (decay corrected, n = 5), a specific activity of 214.3 ± 21.1 GBq/µmol, and a radiochemical purity of >99% within a total synthesis time of about 55 min. Copyright © 2012 John Wiley & Sons, Ltd.     

Quinolinesulfonamides of Aryloxy‐/Arylthio‐ethyl Piperidines: Influence of an Arylether Fragment on 5‐HT1A/5‐HT7 Receptor Selectivity

The solid‐phase synthesis of a new series of 19 biomimetics of long‐chain arylpiperazines, namely flexible quinoline sulfonamides of aryl(heteroaryl)oxy‐/heteroarylthio‐ethyl 4‐aminomethylpiperidines, is reported. Various structural modifications applied followed by biological evaluation for 5‐HT_1A, 5‐HT₆, and 5‐HT₇ receptors gave further support of a possible replacement of arylpiperazine with aryloxy‐/arylthio‐ethyl derivatives of alicyclic amines and control of receptor selectivity upon diversification in the aryl(heteroaryl)oxy‐/heteroarylthio‐ethyl fragment.     

Synthesis,docking studies,and pharmacological evaluation of 5HT2C ligands containing the N′‐cyanoisonicotinamidine or N′‐cyanopicolinamidine nucleus

N′‐Cyanoisonicotinamidine and N′‐cyanopicolinamidine derivatives, linked to an arylpiperazine moiety, were prepared and their affinities to the 5‐HT_1A, 5‐HT_2A, and 5‐HT_2C receptors were evaluated. Several of the newly synthesized compounds, tested by binding studies, showed nanomolar affinity at the 5‐HT_1A and 5‐HT_2C receptors and moderate or no affinity for other relevant receptors (D₁, D₂, α₁, and α₂). Compound 8e (K_i = 21.4 nM) was the most affine for the 5‐HT_2C receptor, showing, at the same time, a high selectivity with respect to the other receptors analyzed. Compounds 4a and 4c , instead, showed an interesting mixed 5‐HT_1A/5‐HT_2C activity with K_i values of 21.3/11.5 and 23.2/6.48 nM, respectively. The compounds with better affinity and selectivity binding profiles toward 5‐HT_2C ( 4a , 4c , 8b , and 8e ) were selected for further in vivo assays to determine their functional activity. Finally, to rationalize the obtained results, molecular docking studies were performed. The results of the pharmacological studies showed that compounds 4a , 8b , and 8e exerted antidepressant‐like effects and 4a and 8e revealed also significant anxiolytic properties. Among the developed derivatives, the most promising compound seems to be 4a , which displayed antipsychotic‐, antidepressant‐ and anxiolytic‐like properties. No side effects, like catalepsy, motor‐impairment or ethanol‐potentiating effects, were observed after the injection of the tested compounds.     

Synthesis and Evaluation of a Series of 3,4,5‐Trimethoxycinnamic Acid Derivatives as Potential Antinarcotic Agents

A series of 3,4,5‐trimethoxycinnamic acid derivatives was prepared and evaluated for antinarcotic effects on morphine dependence in mice and binding affinities on serotonergic receptors. The key synthetic strategies involve generation of ketones 6–7 , esters 9–12 through condensation reaction, and amides 13–19 via coupling reaction using 1‐hydroxybenzotriazole/ethyl(dimethylaminopropryl)carbodiimide system in high yield. We found that the naloxone‐induced morphine withdrawal syndrome was significantly suppressed by new synthetic 3,4,5‐trimethoxycinnamic acid derivatives (20 mg/kg/day). Most of 3,4,5‐trimethoxycinnamic acid derivatives were found to have high affinity to 5‐HT_1A receptor. The naloxone‐induced morphine withdrawal syndrome was attenuated by (+)8‐OH‐DPAT (0.1 mg/kg/day, i.p.), a 5‐HT_1A receptor agonist. In cortical neuronal cells, (+)8‐OH‐DPAT (1 μm ) produced an elevation of the pERK 1/2 expression, and the elevated pERK levels were inhibited by WAY 100635, a 5‐HT_1A receptor‐specific antagonist. Interestingly, the pERK levels were increased by the 3,4,5‐trimethoxycinnamic acid derivatives and the derivatives‐mediated changes in pERK levels were blocked by the WAY 100635. These results suggested that new synthetic 3,4,5‐trimethoxycinnamic acid derivatives have a potential antinarcotic effect through acting as a 5‐HT_1A receptor agonist in mice.     

Synthesis of Novel 3‐aryl‐1‐oxa‐2,8‐diazaspiro[4.5]dec‐2‐ene Derivatives and Their Biological Evaluation Against Protein Tyrosine Phosphatase 1B

A series of novel 3‐aryl‐1‐oxa‐2,8‐diazaspiro[4.5]dec‐2‐ene derivatives were designed, synthesized, and evaluated as a new class of inhibitors against protein tyrosine phosphatase 1B. Among them, compound 6f displayed moderate inhibitory activity with IC₅₀ of 2.87 ± 0.24  μ m and can be used as a novel lead compound for the design of inhibitors of protein tyrosine phosphatase 1B.     

Design,Synthesis and Biological Evaluation of Imidazo[1,2‐a]pyridine Derivatives as Novel DPP‐4 Inhibitors

A new series of DPP‐4 inhibitors with imidazo[1,2‐a]pyridine scaffold were designed by exploiting scaffold hopping strategy and docking study. Based on docking binding model, structural modifications of 2‐benzene ring and pyridine moieties of compound 5a led to the identification of compound 5d with 2, 4‐dichlorophenyl group at the 2‐position as a potent (IC₅₀ = 0.13 μm ), selective (DPP‐8/DPP‐4 = 215 and DPP‐9/DPP‐4 = 192) and in vivo efficacious DPP‐4 inhibitor. Further, molecular docking revealed that compound 5d could retain key binding features of DPP‐4 with the pyridine moiety of imidazo[1,2‐a]pyridine ring providing an additional π?π interaction with Phe357 of DPP‐4. Compound 5d might be a promising lead for further development of novel DPP‐4 inhibitor treating T2DM.     

Synthesis and in‐vitro Cytotoxic Evaluation of Novel Pyridazin‐4‐one Derivatives

A new series of N‐aryl‐4‐oxo‐1,4‐dihydro‐pyridazine‐3‐carboxylic acids has been synthesized by condensation of aryldiazonium with 4‐hydroxy‐6‐methyl‐2‐pyrone. Some of these compounds exhibited in‐vitro cytotoxic activity with moderate to excellent growth inhibition against the murine P815 mastocytoma cell line. Compound 5b showed an important cytotoxic activity against cell line P815 (IC₅₀ = 0.40 μg/mL).     

Synthesis,radiosynthesis and preliminary in vivo evaluation of [123I]‐(4‐fluorophenyl) {1‐[2‐(2‐iodophenyl)ethyl]piperidin‐4‐yl}methanone,a potential 5‐HT2A‐antagonist for SPECT brain imaging

Many people suffer from psychiatric illnesses like depression and anorexia. Relevant to these diseases is amongst others a malfunctioning of brain 5‐HT_2A‐receptors. To allow in vivo quantification of these receptors with Single Photon Emission Computerized Tomography (SPECT), a radiolabelled ligand with high 5‐HT_2A affinity is needed. This work reports the radiosynthesis of [¹²³I]‐(4‐fluorophenyl) {1‐[2‐(2‐iodophenyl)ethyl]piperidin‐4‐yl}methanone, the synthesis of its precursor, (4‐fluorophenyl) {1‐[2‐(2‐bromophenyl)ethyl]piperidin‐4‐yl}methanone, and the preliminary in vivo evaluation of the tracer. The precursor was synthesized with a total yield of 40%. Radiolabelling was performed using a halogen exchange reaction and the yield was 70%. Radiochemical purity was >95%, and specific activity was at least 2.4 Ci/µmol. Log P was measured to be 2.52. The tracer showed uptake in mice brain (3.5% I.D./g tissue at 3 min post injection) and therefore will be evaluated further by regional brain biodistribution and displacement studies in rabbits. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and Evaluation of Biological and Antitumor Activities of Tetrahydrobenzothieno[2,3‐d]Pyrimidine Derivatives as Novel Inhibitors of FGFR1

A series of tetrahydrobenzothieno[2,3‐d]pyrimidine derivatives were designed, synthesized, and evaluated as inhibitors of FGFR1. These analogs were synthesized via Gewald's reaction under mild conditions. The structures of the synthesized compounds were characterized by spectroscopic data (IR, ¹H NMR and MS). Their antitumor activities were evaluated against H460, A549 and U251 cell lines in vitro. Results revealed that the tested compounds showed moderate antitumor activities. Structure–activity relationship analyses indicated that compounds with an aromatic ring substituted in the C‐2 position or with larger molecules such as 3g , 4c , and 7 were more effective than others. The compound, 3g (78.8% FGFR1 inhibition at 10 μ m ), was identified to have the most potent antitumor activities, with IC₅₀ values of 7.7, 18.9, and 13.3 μ m against the H460, A549, and U251 cell lines, respectively. Together, the results suggested that tetrahydrobenzothieno[2,3‐d]pyrimidine derivatives may serve as a potential agent for the treatment of FGFR1‐mediated cancers.     

Evaluation of 2‐benzylidene‐1‐tetralone derivatives as antagonists of A1 and A2A adenosine receptors

Antagonists of the adenosine receptors (A₁ and A_2A) are thought to be beneficial in neurological disorders, such as Alzheimer's and Parkinson's disease. The aim of this study was to explore 2‐benzylidene‐1‐tetralone derivatives as antagonists of A₁ and/or A_2A adenosine receptors. In general, the test compounds were found to be selective for the A₁ adenosine receptor, with only three test compounds possessing affinity for both the A₁ and A_2A adenosine receptor. The 2‐benzylidene‐1‐tetralones bearing a hydroxyl substituent at either position C5, C6 or C7 of ring A displayed favourable adenosine A₁ receptor binding, while C5 hydroxy substitution led to favourable A_2A adenosine receptor affinity. Interestingly, para‐hydroxy substitution on ring B in combination with ring A bearing a hydroxy at position C6 or C7 provided the 2‐benzylidene‐1‐tetralones with both A₁ and A_2A adenosine receptor affinity. Compounds 4 and 8 displayed the highest A₁ and A_2A adenosine receptor affinity with values below 7 μm . Both these compounds behaved as A₁ adenosine receptor antagonists in the performed GTP shift assays. In conclusion, the 2‐benzylidene‐1‐tetralone derivatives can be considered as lead compounds to design a new class of dual acting adenosine A₁/A_2A receptor antagonists that may have potential in treating both dementia and locomotor deficits in Parkinson's disease.     

2‐Amino‐3‐(1‐(4‐(4‐(2‐methoxyphenyl) piperazine‐1‐yl)butyl)‐1H‐1,2,3‐triazol‐4‐yl) propanoic acid: synthesized, 99mTc‐tricarbonyl labeled,and bioevaluated as a potential 5HT1A receptor ligand

To develop a novel 5HT_1A receptor imaging agent, a new methoxyphenyl piperazine derivative was synthesized and radiolabeled with ^99mTc‐tricarbonyl precursor. We used the Cu (I)‐catalyzed cycloaddition of azide and terminal alkynes to synthesize 1, 2, 3 triazole as the metal chelating system. This synthesis provided reliable and reproducible method to attach technetium to the methoxyphenyl piperazine moiety. ^99mTc‐tricabonyl labeling of ligand was performed at high radiochemical purity (greater than 95%). The radiolabeled compound was stable at least 24 h in room temperature. In vitro stability study in human serum albumin showed more than 90% stability in 37 °C incubation for 6 h. Biodistribution studies in rat have shown brain hippocampus uptake of 0.31 ± 0.02 %ID/g at 5‐min post‐injection. The favorable in vitro/in vivo stability, lipophilicity, and biodistribution profiles suggest that this radioconjugate is a good candidate for further exploration of its potential clinical application. Copyright © 2012 John Wiley & Sons, Ltd.     

4‐amino‐6‐alkyloxy‐2‐alkylthiopyrimidine derivatives as novel non‐nucleoside agonists for the adenosine A1 receptor

Three 4‐amino‐6‐alkyloxy‐2‐alkylthiopyrimidine derivatives ( 4 – 6 ) were investigated as potential non‐nucleoside agonists at human adenosine receptors (ARs). When tested in competition binding experiments, these compounds exhibited low micromolar affinity (K_i values comprised between 1.2 and 1.9 μm ) for the A₁ AR and no appreciable affinity for the A_2A and A₃ ARs. Evaluation of their efficacy profiles by measurement of intracellular cAMP levels revealed that 4 and 5 behave as non‐nucleoside agonists of the A₁ AR with EC₅₀ values of 0.47 and 0.87 μm , respectively. No clear concentration‐response curves could be instead obtained for 6 , probably because this compound modulates one or more additional targets, thus masking the putative effects exerted by its activation of A₁ AR. The three compounds were not able to modulate A_2B AR‐mediated cAMP accumulation induced by the non‐selective AR agonist NECA, thus demonstrating no affinity toward this receptor.     

Discovery of Novel 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole Derivatives as Potential Anti‐Inflammatory Agents

A novel 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole derivative 5 with good anti‐inflammatory activity was identified from our in‐house library. Based on hit compound 5 , two series of 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole derivative 6a – g and 7a – h were designed and synthesized as novel anti‐inflammatory agents. Most of synthesized compounds exhibited good inhibitory activity on NO and TNF‐α production in LPS‐stimulated RAW 264.7 macrophages, in which the compound 6e showed most potent inhibitory activity on NO (IC₅₀ = 0.86 μm ) and TNF‐α (IC₅₀ = 1.87 μm ) production. Further evaluation revealed that compound 6e displayed more potent in vivo anti‐inflammatory activity than ibuprofen did on xylene‐induced ear oedema in mice. Additionally, Western blot analysis revealed that compound 6e could restore phosphorylation level of IκBα and protein expression of p65 NF‐κB in LPS‐stimulated RAW 264.7 macrophages.