N-[1-(2-Phenylethyl)pyrrolidin-3-yl]-1-adamantanecarboxamides as novel 5-HT2 receptor antagonists

A series of 1-adamantanecarboxamides was synthesized and examined for their potency as a selective 5-HT2 receptor antagonist. We found (S)-N-[1-[2-(4-fluorophenyl)ethyl]pyrrolidin-3-yl]-1-adamantane carboxamide hydrochloride hydrate (10-(S), Y-39241) to have a high affinity and selectivity for 5-HT2 receptors, and this potent anti-platelet effect of Y-39241 was confirmed both in vitro and in vivo.     

Synthesis of trans-L/D-2-(tert-butoxycarbonyl-aminomethyl)-4-(thymin-1-yl) pyrrolidin-1-yl acetic acid

To delineate the binding preferences of stereochemically divergent pyrrolidine PNAs, synthesis of all four diastreomeric monomers of I and the systematic complexation studies of the resultant PNAs with complementary DNA/RNA is essential. We herein report the synthesis of trans-L/D-2-(tert-butoxycarbonyl-aminomethyl)-4-(thymin-1-yl) pyrrolidin-1-yl acetic acids I, their incorporation in PNA oligomers and DNA binding studies will be presented.     

Crystal structure and conformation of 8-(2-hydroxyethylamino) and 8-(pyrrolidin-1-yl) adenosines

In the course of investigation of 8-alkylamino substituted adenosines, the title compounds were synthesized as potential partial agonists for adenosine receptors. The structure determination of these compounds was carried out with the X-ray crystallography study. Crystals of 8-(2-hydroxyethylamino)adenosine are monoclinic, space group P 2(1); a = 7.0422(2), b = 11.2635(3), c = 8.9215(2) A, beta = 92.261(1) degrees, V = 707.10(3) A3, Z = 2; R-factor is 0.0339. The nucleoside is characterized by the anti conformation; the ribose ring has the C(2')-endo conformation and gauche-gauche form across C(4')-C(5') bond. The molecular structure is stabilized by intramolecular hydrogen bond of N-HO type. Crystals of 8-(pyrrolidin-1-yl)adenosine are monoclinic, space group C 2; a = 19.271(1), b = 7.3572(4), c = 11.0465(7) A, beta = 103.254(2), V = 1524.4(2) degrees A3, Z = 4; R-factor is 0.0498. In this compound, there is syn conformation of the nucleoside; the ribose has the C(2')-endo conformation and gauche -gauche form across C(4')- C(5') bond. The molecular structure is stabilized by intramolecular hydrogen bond of O-HN type. For both compounds, the branching net of intermolecular hydrogen bonds occur in the crystal structures.     

Discovery and preclinical profile of teneligliptin (3-[(2S,4S)-4-[4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl]pyrrolidin-2-ylcarbonyl]thiazolidine): A highly potent,selective, long-lasting and orally active dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes

Dipeptidyl peptidase IV (DPP-4) inhibition is suitable mechanism for once daily oral dosing regimen because of its low risk of hypoglycemia. We explored linked bicyclic heteroarylpiperazines substituted at the γ-position of the proline structure in the course of the investigation of l-prolylthiazolidines. The efforts led to the discovery of a highly potent, selective, long-lasting and orally active DPP-4 inhibitor, 3-[(2S,4S)-4-[4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl]pyrrolidin-2-ylcarbonyl]thiazolidine (8g), which has a unique structure characterized by five consecutive rings. An X-ray co-crystal structure of 8g in DPP-4 demonstrated that the key interaction between the phenyl ring on the pyrazole and the S₂ extensive subsite of DPP-4 not only boosted potency, but also increased selectivity. Compound 8g, at 0.03 mg/kg or higher doses, significantly inhibited the increase of plasma glucose levels after an oral glucose load in Zucker fatty rats. Compound 8g (teneligliptin) has been approved for the treatment of type 2 diabetes in Japan.     

Synthesis of 2-deoxy-2-(4-nitroimidazol-1-yl)-D-alditols

Small molecules possessing defined configuration at centres of chirality provide a valuable chiral pool. Among different strategies applied for modification of chiral compounds, the most common is to begin with a single stereoisomer and use a synthesis that does not affect the chiral centres. The ANRORC type reaction has been applied for conversion of unprotected 2-amino-2-deoxy-D-hexopyranoses into 2-deoxy-2-(4-nitroimidazol-1-yl)-D-hexopyranoses in a reaction of some 2-aminosugars with 1,4-dinitroimidazoles. The reaction occurs with retention of configuration at C-2 of sugar ring. The products of the reaction were obtained as anomeric mixtures and separated into anomers after acetylation followed by column chromatography. 2-Deoxy-2-(4-nitroimidazol-1-yl)-D-hexopyranoses treated with sodium borohydride in methanolic solution gave the corresponding 2-deoxy-2-(4-nitroimidazol-1-yl)-D-hexitols, characterised as per-O-acetylated derivatives.     

Characterization of cytochrome P450 2A4 and 2A5-catalyzed 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism

The tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is a potent lung carcinogen in the A/J mouse, and is believed to be a causative agent for human lung cancer. NNK requires metabolic activation by alpha-hydroxylation to exert its carcinogenic potential. The human P450, 2A6 is a catalyst of this reaction. There are two closely related enzymes in the mouse, P450 2A4 and 2A5, which differ from each other by only 11 amino acids. In the present study these two mouse P450s were expressed in Spodoptera frugiperda (Sf9) cells using recombinant baculovirus. The catalysis of NNK metabolism by Sf9 microsomal fractions containing either P450 2A4 or 2A5 was determined. Both enzymes catalyzed the alpha-hydroxylation of NNK but with strikingly different efficiencies and specificities. P450 2A5 preferentially catalyzed NNK methyl hydroxylation, while P450 2A4 preferentially catalyzed methylene hydroxylation. The KM and Vmax for the former were 1.5 microM and 4.0 nmol/min/nmol P450, respectively, and for the latter 3.9 mM and 190 nmol/min/nmol P450. The mouse coumarin 7-hydroxylase, P450 2A5 is a significantly better catalyst of NNK alpha-hydroxylation than is the closely related human enzyme, P450 2A6.     

Antioxidant activity and low toxicity of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one

The aim of the present study was to evaluate the potential pharmacological and toxicological properties of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one (compound 1), an organoselenium compound. In vitro experiments showed that compound 1 presented a reduction in the lipid peroxidation induced by Fe2? in thiobarbituric acid-reactive species (TBARS) production, and in the generation of reactive species caused by Fe2?/malonate in DCFH-DA oxidation. The high dose (500 mg/kg) induced an increase on ALT but not on AST activity. Hepatic, but not cerebral, δ-ALA-D activity from mice treated with 500 mg/kg presented a significant inhibition. Brain catalase activity was significantly inhibited by 100 mg/kg whereas hepatic catalase activity showed a significant increase at all doses. Hepatic lipid peroxidation was diminished only at lowest dose (100 mg/kg) whereas for brain tissue, all doses induced a significant reduction in TBARS levels. Brain and liver ascorbic acid contents were increased only at highest dose of compound 1. Urea and creatinine levels were not significantly altered by treatments. This is a promising compound with antioxidant activity and low toxicity, suggesting the potential beneficial activity of compound 1 against oxidative damage in many parameters studied in rats and mice.     

Synthesis of novel 5-(3-alkylquinolin-2-yl)-3-aryl isoxazole derivatives and their cytotoxic activity

The propargyl alcohol on reaction with aldoxime and NaOCl in DCM gave exclusively (3-arylisoxazol-5-yl) methanol 1. The compound 1 was oxidized to an aldehyde 2 followed by reaction with aniline resulted in Schiff’s base 3. The compounds 3 were further reacted with various aldehydes having α-hydrogen using molecular iodine as catalyst and which yielded 5-(3-alkylquinolin-2-yl)-3-aryl isoxazole derivatives 4. All the final compounds 4 were screened against four human cancer cell lines (A549, COLO 205, MDA-MB 231 and PC-3) and among these compounds 4n showed potent cytotoxicity against all the cell lines at IC₅₀ values of <12 μM.     

N-[[1-(2-phenylethyl)pyrrolidin-2-yl]methyl]cyclohexanecarboxamides as selective 5-HT1A receptor agonists

A series of benzamides was synthesized as selective agonists for the 5-HT1A receptor. It was found that (S)-N-[[1-(2-phenylethyl)pyrrolidin-2-yl]methyl]cyclohexanecarb oxamide(7-(S)) has potent and selective agonistic activity for the 5-HT1A receptor (5-HT1A; Ki 0.49 nmol/L, D2; IC50 = >1000 nmol/L, 5-HT2; Ki = 240 nmol/L).     

(3,3-Difluoro-pyrrolidin-1-yl)-[(2S,4S)-(4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl]-methanone: A potent,selective, orally active dipeptidyl peptidase IV inhibitor

A series of 4-substituted proline amides was synthesized and evaluated as inhibitors of dipeptidyl pepdidase IV for the treatment of type 2 diabetes. (3,3-Difluoro-pyrrolidin-1-yl)-[(2S,4S)-(4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl]-methanone (5) emerged as a potent (IC₅₀ = 13 nM) and selective compound, with high oral bioavailability in preclinical species and low plasma protein binding. Compound 5, PF-00734200, was selected for development as a potential new treatment for type 2 diabetes.     

Determination of free N-acetylneuraminic acid in urine by high-performance liquid chromatography using 3-[(1-[[4-(5,6-dimethoxy-1-oxoisoindolin-2-yl)-2-methoxyphenyl]sulfonyl]pyrrolidin-2-yl)carbonylamino]phenylboronic acid as a fluorescent labeling reagent

A highly sensitive high-performance liquid chromatography (HPLC) method for the determination of urinary N-acetylneuraminic acid (NeuAc) using 3-[(1-[[4-(5,6-dimethoxy-1-oxoisoindolin-2-yl)-2-methoxyphenyl]sulfonyl]pyrrolidin-2-yl)carbonylamino]phenylboronic acid as a fluorescent labeling reagent was developed. The labeling reaction was carried out at 30 degrees C for 30 min in the presence of pyridine. The derivative was monitored at Ex 314 nm and Em 388 nm. The detection limit of NeuAc was about 48 fmol per injection. The relative standard deviations of within-day and between-day precisions were 2.6-3.3 and 1.7-3.3%, respectively. Urine diluted 10 times with distilled water was analyzed by employing the standard-addition method. The concentrations were 8-89 nmol/mg creatinine (30+/-28 nmol/mg creatinine, n=9).     

Stereoselective bioreduction of 1-(5-phenylfuran-2-yl)-ethanones mediated by baker's yeast

Abstract

Baker's yeast mediated reduction of various phenylfuran-2-yl-ethanones has been studied. The influence of the reaction conditions, the type and position of the substituents, as well the presence of various additives on the enantiomeric composition of the products and the reaction yield are discussed. The absolute configuration of the reaction products was established using a retrosynthetic procedure.     

Enantioselective resolution of 2-(1-hydroxy-3-butenyl)-5-methylfuran by immobilized lipase

An efficient and convenient strategy for synthesis of enantiomerically pure S-2-(1-hydroxy-3-butenyl)-5-methylfuran was for the first time described utilizing a lipase-mediated asymmetric acylation in organic solvents. Rhizopus arrhizus lipase was chosen as the biocatalyst, and different immobilization methods including sol–gel encapsulation and covalent attachment were adopted to improve its catalytic characteristics. Various influential factors of the reaction were also investigated. Finally, the results showed that the lipase covalently attached onto epoxy resin exhibited the highest enantioselectivity and operational stability. Under optimized reaction conditions, i.e., n-hexane as the solvent, 5/1 (mol/mol) of vinyl acetate to 2-(1-hydroxy-3-butenyl)-5-methylfuran and 30 °C, the ee value of S-1 reached up to above 98% at 52% conversion with an E value of 99.     

Design and synthesis of 2-(3-alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones as potent antitumor agents

2-(3-Alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones 1–3 were synthesized and screened for anti-proliferative activity against three human cancer cell lines, as well as the normal cell line Detroit 551. All of the synthesized target compounds 1–3 demonstrated potent cytotoxic activity against the cancer cell lines, but weak inhibitory activity toward the normal cell line. 2-(3-Methyl aminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-one (1), one of the potent compounds in vitro, was also tested in an in vivo Hep3B xenograft nude mice model, and its significant anticancer activity was reconfirmed. Therefore, compound 1 merits further investigation as an antitumor clinical trial candidate and potential anticancer agent.     

5-(pyridinon-1-yl)indazoles and 5-(furopyridinon-5-yl)indazoles as MCH-1 antagonists

A new series of 5-(pyridinon-1-yl)indazoles with MCH-1 antagonist activity were synthesized. Potential cardiovascular risk for these compounds was assessed based upon their interaction with the hERG potassium channel in a mini-patch clamp assay. Selected compounds were studied in a 5-day diet-induced obese mouse model to evaluate their potential use as weight loss agents. Structural modification of the 5-(pyridinon-1-yl)indazoles to give 5-(furopyridinon-5-yl)indazoles provided compounds with enhanced pharmacokinetic properties and improved efficacy.     

Synthesis and biological activity of N6-(N[(4-azido-3,5,6-trifluoro)-pyridin-2-yl]-2-aminoethyl)-adenosine 5'-monophosphate, a new AMP photoactivatable derivative. Covalent modification of horse liver alcohol dehydrogenase

N6-(N-[(4-Azido-3,5,6-trifluoro)pyridin-2-yl]-2-aminoethyl)- adenosine 5'-monophosphate has been synthesized and evidence presented for its structural assignment by ultraviolet and 19F-NMR spectroscopies. Its photolysis was shown to occur within 5 min. This AMP derivative behaves as a competitive inhibitor of NAD+ in horse-liver-alcohol-dehydrogenase-promoted oxidation of ethanol, with a Ki (0.95 mM) comparable to the Ki of AMP (1.9 mM). Moreover it is an activator of the enzyme when nicotinamide ribose is used as the oxidation cofactor. This activation is as good as that promoted by AMP or by the well known 8-azido-AMP. Upon photolysis of this new derivative in the presence of horse liver alcohol dehydrogenase, a covalent enzyme--analogue complex was isolated and assayed as a catalyst in the oxidation of ethanol using nicotinamide ribose as the cofactor. The reaction took place without complementation of AMP, indicating clearly that the AMP analogue is mainly covalently bound in the AMP-binding site, and that the linkage formed between the enzyme and the azido derivative has not dramatically altered the active site of the enzyme. A similar experiment with 8-azido-AMP produced a completely inactive complex.     

New antiprotozoal agents: Synthesis and biological evaluation of different 4-(7-chloroquinolin-4-yl) piperazin-1-yl)pyrrolidin-2-yl)methanone derivatives

In an endeavor to develop efficacious antiprotozoal agents 4-(7-chloroquinolin-4-yl) piperazin-1-yl)pyrrolidin-2-yl)methanone derivatives (5–14) were synthesized, characterized and biologically evaluated for antiprotozoal activity. The compounds were screened in vitro against the HM1: IMSS strain of Entamoeba histolytica and NF54 chloroquine-sensitive strain of Plasmodium falciparum. Among the synthesized compounds six exhibited promising antiamoebic activity with IC₅₀ values (0.14–1.26 μM) lower than the standard drug metronidazole (IC₅₀ 1.80 μM). All nine compounds exhibited antimalarial activity (IC₅₀ range: 1.42–19.62 μM), while maintaining a favorable safety profile to host red blood cells. All the compounds were less effective as an antimalarial and more toxic (IC₅₀ range: 14.67–81.24 μM) than quinine (IC₅₀: 275.6 ± 16.46 μM) against the human kidney epithelial cells. None of the compounds exhibited any inhibitory effect on the viability of Anopheles arabiensis mosquito larvae.     

One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones using CuBr2 as catalyst

A simple, efficient procedure and improved conditions have been found to carry out the Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives. This synthesis was performed using CuBr2 as the catalyst in ethanol solution. The optimum conditions were as follows: the molar ratio of aldehyde to alpha,beta-diketone to urea or thiourea is 1:1:1:0.5, the molar ratio of catalyst to aldehyde is 25%, and the reaction time is 4 h.Under the above conditions, the highest yield of dihydropyrimidinones was up to 95%. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields and short reaction times.     

Discovery of 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) as a potent,selective and orally efficacious cannabinoid-1 receptor antagonist

Structure–activity relationship studies in a series of diarylpyrazolyl thiadiazoles identified cannabinoid-1 receptor antagonists with excellent potency and selectivity. Based on its exceptional in vivo efficacy in animal models and its favorable pharmacokinetic and toxicological profiles, 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) was selected as a preclinical candidate for the treatment of obesity.