Synthesis of phenylpyrimidinones as guanylyl cyclase C inhibitors.

Diarrhea is one of the most important causes of mortality in the developing world, being responsible for 2.5 million deaths each year. Many of these deaths are caused by enterotoxigenic strains of bacteria, like Escherichia coli, that produce enterotoxins that cause acute watery diarrhea, commonly defined as secretory diarrhea. Studies on symptomatic patients indicate a high prevalence of enterotoxigenic E. coli strains producing the heat-stable toxin, STa. STa is a small, cysteine-rich peptide that binds to the extracellular receptor domain of guanylyl cyclase C (GCC), located at the luminal membrane of intestinal epithelial cells. GCC and its endogenous peptide ligands, guanylin and uroguanylin, play a key role in balancing water absorption and hydration of the intestinal lumen, as exemplified by the finding that loss of GCC function causes severe dehydration of the intestinal lumen, culminating in intestinal obstruction. From a mechanistic viewpoint, reduction of GCC activity offers an efficient approach to limit enterotoxigenic E. coli- provoked secretory diarrhea. Inhibition of GCC-mediated cGMP production would not only reduce anion secretion, but would also restore NHE3 activity, resulting in a comprehensive antidiarrheal action. In the present study, two novel phenylpyrimidinone derivatives were simultaneously synthesized and tested for their ability to block STa-induced CFTR activity in T84 cells.

Microwave assisted synthesis: a new technology in drug discovery.

The interest in the microwave assisted organic synthesis has been growing during the recent years. It results from an increasing knowledge of fundamentals of the dielectric heating theory, availability of an equipment designed especially for the laboratory use as well as the discovery of the special techniques of the microwave syntheses. The efficiency of microwave flash-heating chemistry in dramatically reducing reaction times (reduced from days and hours to minutes and seconds) has recently been proven in several different fields of organic chemistry and this aspect is of great importance in high-speed combinatorial and medicinal chemistry. In this contribution, the current state of the art is summarized providing examples of the most recent applications in the field of microwave assisted synthesis of biologically active compounds both in heterocyclic and in peptide and peptidomimetic optimization.

Recent advances in synthesis of PAR ligands as therapeutic strategy for inflammatory diseases.

Several studies have been published on discovering involvement of PARs receptors in a number of disease states, including cancer and inflammation of the cardiovascular, respiratory, musculoskeletal, gastrointestinal and nervous systems. This mini-review will focus on recent advances in the synthesis of PAR ligands highlighting their therapeutic potential in the treatment of various inflammatory diseases.

Synthesis and in vitro pharmacological evaluation of a new series of 5-HT1A 5-HT2A and 5-HT2C receptor ligands containing a norbornene nucleus.

A series of 4-substituted piperazine derivatives bearing a norbornene nucleus have been prepared and their affinity for serotonin 5-HT1A, 5-HT2A and 5-HT2C receptors has been evaluated. Compounds showing the highest affinity have been selected and evaluated on dopaminergic (D1 and D2) and adrenergic (alpha1 and alpha2) receptors. The combination of structural elements (heterocyclic nucleus, oxyalkyl chain and 4-substituted piperazine) known to be critical in order to have affinity on serotonin receptors and the proper selection of substituents led to compounds with higher receptor specificity and affinity. In binding studies, several molecules showed affinity in nanomolar range towards 5-HT1A, 5-HT2A and 5-HT2C receptors and moderate to no affinity for other relevant receptors (D1, D2, alpha1 and alpha2). Compound 2q 4-[2-[4-(3,4-dichlorophenyl)piperazin-1-yl]ethoxy]-4-aza-tricyclo[5.2.1.02,6]dec-8-ene-3,5-dione (Ki = 1.13 nM), was the most active and selective derivative for the 5-HT2C receptor with respect to other serotonin, dopaminergic and adrenergic receptors. Moreover, compound 3p showed mixed 5-HT2A/5-HT2C activity with affinity values in nanomolar range.

Enhanced activity of a hydrogen sulphide-releasing derivative of mesalamine (ATB-429) in a mouse model of colitis.

BACKGROUND AND PURPOSE: Mesalamine is the first-line therapy for colitis, but it lacks potency and is only effective for mild-to-moderate forms of this disease. Hydrogen sulphide has been shown to be a potent, endogenous anti-inflammatory substance, modulating leukocyte-endothelial adhesion and leukocyte migration. The purpose of this study was to determine if an H(2)S-releasing derivative of mesalamine (ATB-429) would exhibit increased potency and effectiveness in a mouse model of colitis. EXPERIMENTAL APPROACH: Colitis was induced in mice with trinitrobenzene sulphonic acid and the effects of ATB-429 and mesalamine were compared in several treatment regimens. The severity of colitis was determined using several indices, including a disease activity score (comprised of scores for diarrhea, weight loss and fecal blood), colonic myeloperoxidase activity and macroscopic/microscopic scoring of tissue injury. KEY RESULTS: Irrespective of the treatment regiment, ATB-429 was more effective than mesalamine in reducing the severity of colitis. ATB-429 was particularly effective in reducing granulocyte infiltration into the colonic tissue (by approximately 70%), as well as reducing the expression of mRNA for several key proinflammatory cytokines/chemokines (e.g., TNFalpha, IFNgamma). Treatment with ADT-OH, the H(2)S-releasing moiety of ATB-429, did not affect severity of colitis. CONCLUSIONS AND IMPLICATIONS: ATB-429 exhibits a marked increase in anti-inflammatory activity and potency in a murine model of colitis, as compared to mesalamine. These results are consistent with recently described anti-inflammatory effects of H(2)S. ATB-429 may represent an attractive alternative to mesalamine for the treatment of inflammatory bowel disease.

Synthesis of 6beta-D-glucosyl and 6-nitroxy (-)-galanthamine derivatives as acetylcholinesterase inhibitors.

Galanthamine is an alkaloid approved for the treatment of Alzheimer's disease. In this paper the syntheses and the anticholinesterase activities of new glucosyl and nitroxy derivatives substituted on position 6 are reported. Compounds 2, 3 and 5 presented a percentage of inhibition of 35.22%, 47.48% and 67.89% respectively.

In vitro mutagenicity of anti-inflammatory parsalmide analogues PA7, PA10, and PA31 triggered by biotransformation into hydroxy derivatives.

In this study, the mutagenicity of the anti-inflammatory parsalmide [5-amino-N-butyl-2-(2-propynyloxy)-benzamide] analogues PA7 [5-amino-N-butyl-2-cyclohexyloxy-benzamide], PA10 [5-amino-N-butyl-2-phenoxy-benzamide] and PA31 [5-amino-N-butyl-2-(p-tolyloxy)-benzamide] was determined by an Ames Salmonella assay. The experiments were performed by preincubating the compounds in the absence and presence of a post-mitochondrial fraction (S9) of rat liver homogenate from phenobarbital/beta-naphtoflavone treated rats. No mutagenic effect was observed after direct testing (no S9 added) in Salmonella typhymurium strains TA98, TA100, TA102, TA1535 and TA1537. However, in the presence of S9, the test substances triggered mutagenic responses in strains TA100 and TA98. PA31 presented the strongest mutagenic potential. The reversion rates in the presence of PA31 were about 2-19 fold higher than spontaneous mutation rates. In the presence of PA7, the reversion increased 2-14-fold over spontaneous rates. While PA10 showed a relatively mild mutagenic potential, as the number of revertants did not exceed 2.5 times the number of spontaneous mutations. Mass spectrometric analysis of the in vitro biotransformation showed that S9 converted (%), regioselectively, PA7 (19%), PA10 (7%) and PA31 (12%) into hydroxy-derivatives.

Comparative bioavailability of two losartan formulations in healthy human volunteers after a single dose administration.

OBJECTIVE: To compare the bioavailability of two potassic losartan immediate release tablet (50 mg) formulations (Losartan from Laboratórios Cristália Ltd., Brazil, as a test formulation and Cozaar from Merck Sharp & Dohme Farmacêutica Ltd., Brazil, as a reference formulation) in 25 volunteers of both sexes. MATERIAL AND METHODS: The study was conducted in an open, randomized, 2-period crossover design and a 1-week washout period. Plasma samples were obtained over a 24-hour interval. The concentrations of losartan and its active metabolite losartan acid were analyzed by combined reversed phase liquid chromatography and tandem mass spectrometry (LC-MS-MS) with negative ion electrospray ionization using a selected ion monitoring method. From the losartan and losartan acid plasma concentrations vs. time curves the following pharmacokinetic parameters were obtained: AUClast, AUC0-inf and Cmax. RESULTS: The geometric mean and respective 90% confidence interval (CI) of Losartan/Cozaar losartan percent ratios were 92.9% (82.2-105.0%) for Cmax, 99.0% (92.5-105.9%) for AUClast, and 99.1% (92.7-105.8%) for AUC0-inf. Furthermore, the geometric mean and respective 90% CI of Losartan/Cozaar losartan acid percent ratios were 98.5% (91.5-106.0%) for Cmax, 97.9% (93.3 102.7%) for AUClast, and 98.1% (93.6-102.9%) for AUC0-inf. CONCLUSION: Since the 90% CI for Cmax, AUClast and AUC0-inf were within the 80-125% interval proposed by the US Food and Drug Administration, it was concluded that the potassic losartan immediate release 50 mg tablet was bioequivalent to the Cozaar immediate release 50 mg tablet, according to both the rate and extent of absorption. While there were no significant differences in the bioequivalence assessed by either losartan or losartan acid, future bioequivalence studies on losartan may be performed by quantifying losartan alone as the parent compounds are more discriminative.

Synthesis and hydrolysis by cathepsin B of fluorogenic substrates with the general structure benzoyl-X-ARG-MCA containing non-natural basic amino acids at position X.

We synthesized one series of fluorogenic substrates for cathepsin B derived from the peptide Bz-F-R-MCA (Bz=benzoyl, MCA=7-methyl-coumarin amide) substituting Phe at the P(2) position by non-natural basic amino acids that combine a positively charged group with aromatic or aliphatic radicals at the same side chain, namely, 4-aminomethyl-phenylalanine, 4-guanidine-phenylalanine, 4-aminomethyl-N-isopropyl-phenylalanine, 3-pyridyl-alanine, 4-piperidinyl-alanine, 4-aminomethyl-cyclohexyl-alanine, 4-aminocyclohexyl-alanine, and N(im)-dimethyl-histidine. Bz-F-R-MCA was the best substrate for cathepsin B but also hydrolyzed Bz-R-R-MCA with lower efficiency, since the protease accepts Arg at S(2) due to the presence of Glu(245) at the bottom of this subsite. The presence of the basic non-natural amino acids at the P(2) position of the substrate partially restored the catalytic efficiency of cathepsin B. All the kinetic parameters for hydrolysis of the peptides described in this paper are in accordance with the structures of the S(2) pocket previously described. In addition, the substrate with 4-aminocyclohexyl-alanine presented the highest affinity to cathepsin B although the peptide was obtained from a mixture of cis/trans isomers of the amino acid and we were not able to separate them. For comparison all the obtained substrates were assayed with cathepsin L and papain.

Derivatives as 5HT1A receptor ligands--past and present.

Serotonin is a neuromediator, well-know for its implication in mood regulation, anxiety, depression and, insomnia as well as in normal human function such as sleep, sexual activity and appetite. In this way, serotonin (5-hydroxytryptamine, 5-HT) is one of the most attractive targets for medicinal chemists and pharmaceutical companies. Among 5-HTRs, the 5-HT1A subtype is the best studied, and it is generally accepted that it is involved in psychiatric disorders such as anxiety and depression. Several structurally different compounds are known to bind 5-HT1A receptor sites such as aminotetralins, ergolines, arylpiperazines, indolylalkylamines, aporphines and aryloxyalkyl-amines. In this review, we report an overview of the 5-HT1A receptor ligands, belonging to different chemical classes.

Diffusion weighted MR imaging of primary and recurrent middle ear cholesteatoma: an assessment by readers with different expertise.

INTRODUCTION AND PURPOSE: Diffusion weighted imaging (DWI) has been proven to be valuable in the diagnosis of middle ear cholesteatoma. The aims of our study were to evaluate the advantage of multi-shot turbo spin echo (MSh TSE) DWI compared to single-shot echo-planar (SSh EPI) DWI for the diagnosis of cholesteatoma. MATERIAL AND METHODS: Thirty-two patients with clinical suspicion of unilateral cholesteatoma underwent preoperative MRI (1.5T) with SSh EPI and MSh TSE. Images were separately analyzed by 4 readers with different expertise to confirm the presence of cholesteatoma. Sensitivity, specificity, diagnostic accuracy, and positive (PPV) and negative predictive values (NPV) were assessed for each observer and interrater agreement was assessed using kappa statistics. Diagnosis was obtained at surgery. RESULTS: Overall MSh TSE showed higher diagnostic accuracy and lower negative predictive value (NPV) compared to conventional SSh EPI. Interreader agreement between the observers revealed the superiority of MSh TSE compared to SSh EPI. Interrater agreement among all the four observers was higher by using MSh TSE compared to SSh EPI. CONCLUSION: Our findings suggest that MSh TSE DWI has higher sensitivity for detection of cholesteatoma and lower probability of misdiagnosis. MSh TSE DWI is useful in guiding less experienced observers to the diagnosis.

The application of microwave irradiation as new convenient synthetic procedure in drug discovery.

Heterocyclic compounds hold a special place among pharmaceutically important natural and synthetic materials. The remarkable ability of heterocyclic nuclei to serve both as biomimetics and reactive pharmacophores has largely contributed to their unique value as traditional key elements of numerous drugs. In both lead identification and lead optimization processes there is an acute need for new organic small molecules. Traditional methods of organic synthesis are orders of magnitude too slow to satisfy the demand for these compounds. The fields of combinatorial and automated medicinal chemistry have been developed to meet the increasing requirement of new compounds for drug discovery, within these fields, speed is of the essence. The efficiency of microwave flash-heating chemistry in dramatically reducing reaction times (reduced from days and hours to minutes and seconds) has recently been proven in several different fields of organic chemistry. We believe that the time saved by using focused microwaves is potentially important in traditional organic synthesis but could be of even greater importance in high-speed combinatorial and medicinal chemistry. In this review, it is impossible to cover all significant developments in the area of microwave-assisted organic synthesis (MAOS). Rather, outlines the basic principles behind the technology and summarizes the areas in which microwave technology has made an impact, to date. Specific attention is given to application of microwave irradiation in liquid systems, and in the solid state as well of several representative biologically interesting nuclei. In addition we report some of the most recently disclosed applications in combinatorial chemistry.

Conformational analysis of three NK1 tripeptide antagonists: a proton nuclear magnetic resonance study.

Two new peptides, tailored after Ac-Thr-D-Trp(CHO)-Phe-NMeBzl (TRI), namely, Ac-Thr-D-Trp(CHO)-Phe-NMe alpha MeBzl (TRA) and Ac-Thr-D-Trp(CHO)-Oic-NMeBzl (TOI), in which Phe is replaced by (3aS, 7aS)-octahydroindole-2-carboxylic acid, proved more potent and selective NK1 antagonists. The conformational properties of all three compounds were investigated in solution by NMR spectroscopy and those of TRI analyzed in greater detail by means of systematic computer-assisted modeling. All conformers whose energy differs by less than 9 kcal/mol from the absolute minimum are different from the conformer proposed in a previous molecular modeling study by the discovers of TRI. Parallel calculations for TRA and TOI yield low-energy conformers similar to those of TRI but in a slightly different order. Comparison of the shapes of low-energy conformers of all three peptides with those of four typical rigid NK1 antagonists shows that putative bioactive conformations are indeed present in solution.

Synthesis and pharmacological activity of deltorphin and dermorphin-related glycopeptides.

The solid phase procedure, based on the Fmoc chemistry, was used to prepare some opioid deltorphin (H-Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2, DEL C) and dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2, DER) analogues in which a D-glucopyranosyl moiety is beta-O-glycosidically linked to a Thr4 or Thr7 side chain. Their activities were determined in binding studies based on displacement of mu- and delta-receptor selective radiolabels from rat brain membrane synaptosomes, in guinea pig ileum and rabbit jejenum bioassays, and, in vivo, by a mouse tail-flick test after intracerebroventricular (icv) and subcutaneous (sc) administrations. The glyco analogues modified at position 4 displayed low opioid properties, while Thr7-glycosylated peptides retained high delta- or mu-selectivity and remarkable activity in vivo. In particular, as systemic antinociceptive agents, the latter glucoside-bearing compounds were more potent than the parent unglycosylated peptide counterparts, showing a high blood to brain rate of influx which may be due to the glucose transporter GLUT-1.

Pyrrolobenzoxazepinone derivatives as non-nucleoside HIV-1 RT inhibitors: further structure-activity relationship studies and identification of more potent broad-spectrum HIV-1 RT inhibitors with antiviral activity.

Pyrrolobenzoxazepinone (PBO) derivatives represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTs) whose prototype is (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)- one (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis and biological evaluation of novel derivatives and analogues of 6 featuring a meta-substituted phenyl or a 2-thienyl ring at C-6 and a pyridine system in place of the fused-benzene ring to yield pyrrolopyridooxazepinones (PPOs). Compared with the lead 6 and nevirapine, several of the synthesized compounds (PBOs 13a-d and PPOs 13i-k) displayed higher inhibitory activity against wild-type RT and clinically relevant mutant RTs containing the single amino acid substitutions L100I, K103N, V106A, Y181I, and Y188L. The most potent inhibitors were further evaluated for in vitro antiviral activity on lymphocytes and monocyte-macrophages, for cytotoxicity on a panel of cell lines, and for potential synergistic antiviral activity with AZT. Pharmacokinetic studies performed on 13b, 13c, and 13i showed that these compounds achieve high concentrations in the brain. The results of the biological and pharmacokinetic experiments suggest a potential clinical utility of analogues such as 13b-d, 13i, and 13j, in combination with nucleoside RT inhibitors, against strains of HIV-1 bearing those mutations that confer resistance to known NNRTI.

Benign idiopathic partial seizures in the velocardiofacial syndrome: report of two cases.

We describe two children with the velocardiofacial syndrome and benign partial-onset seizures. Both presented with slight dysmorphic traits, mild to moderate mental delay, and high-arched palate. A cardiac defect was present in only one of them. In each patient, sporadic rolandic or occipital partial-onset seizures with the clinical and electroencephalographic features of benign idiopathic childhood epilepsy manifested at age 3 and 5 years, respectively. Treatment was started only in one patient, with complete seizure control. These two cases show that benign partial epilepsy can be a component manifestation of the central nervous system-related symptoms of the velocardiofacial syndrome.

Determination of 21-hydroxydeflazacort in human plasma by high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry. Application to bioequivalence study.

A liquid chromatographic atmospheric pressure chemical ionization tandem mass spectrometric method is described for the determination of 21-hydroxydeflazacort in human plasma using dexamethasone 21-acetate as an internal standard. The procedure requires a single diethyl ether extraction. After evaporation of the solvent under a nitrogen flow, the analytes are reconstituted in the mobile phase, chromatographed on a C18 reversed-phase column and analyzed by mass spectrometry via a heated nebulizer interface where they are detected by multiple reaction monitoring. The method has a chromatographic run time of less than 5 min and a linear calibration curve with a range of 1-400 ng ml(-1) (r>0.999). The between-run precision, based on the relative standard deviation for replicate quality controls, was < or =5.5% (10 ng ml(-1)), 1.0% (50 ng ml(-1)) and 2.7% (200 ng ml(-1)). The between-run accuracy was +/-7.1, 3.8 and 4.8% for the above concentrations, respectively. This method was employed in a bioequivalence study of two DFZ tablet formulations (Denacen from Marjan Industria e Comercio, Brazil, as a test formulation, and Calcort from Merrell Lepetit, Brazil, as a reference formulation) in 24 healthy volunteers of both sexes who received a single 30 mg dose of each formulation. The study was conducted using an open, randomized, two-period crossover design with a 7-day washout interval. The 90% confidence interval (CI) of the individual geometric mean ratio for Denacen/Calcort was 89.8-109.5% for area under the curve AUC(0-24 h) and 80.7-98.5% for Cmax. Since both the 90% CI for AUC(0-24 h) and Cmax were included in the 80-125% interval proposed by the US Food and Drug Administration, Denacen was considered bioequivalent to Calcort according to both the rate and extent of absorption.

Perfusion of rat colon with sennosides, rhein and rheinanthrone. Concentration-related histamine release.

Rat colon perfused intraluminally in vitro and in vivo released histamine into the perfusates. Histamine release was increased by rhein 0.1-10 micrograms/ml and much more by rheinanthrone 0.1-10 micrograms/ml but not by sennosides A or B 1-10 micrograms/ml. The effect of rhein and rheinanthrone was reduced by tritoqualine 20 mg/kg. This raises the possibility that laxation by senna and its derivatives involves histamine formation.

Topiramate in refractory partial-onset seizures in children, adolescents and young adults: a multicentric open trial.

PURPOSE: This study was to evaluate the efficacy and safety of topiramate (TPM) in refractory partial epilepsy in children, adolescents and young adults. METHODS: We performed a prospective open label add-on study in 55 patients (age 2-30 years, mean 15 years) with refractory partial seizures. Topiramate was added to one or two other baseline drugs and the efficacy was rated according to seizure type and frequency. RESULTS: TPM was initiated at a daily dose of 0.5-1 mg/kg, followed by a 2-week titration at increments of 1-3 mg/kg/24h, up to a maximum daily dose of 12 mg/kg. After 9 months of treatment, 11 patients (20%) had 100% fewer seizures and 25 patients (45%) had a more than 50% seizure reduction. TPM appeared to be effective both in cryptogenic (76.2%) and symptomatic (58.8%) partial epilepsies. Mild to moderate adverse events were present in 25 patients (45.4%), mostly represented by drowsiness, nervousness and hyporexia with or without weight loss. CONCLUSION: TPM was an overall effective and safe add-on drug both in cryptogenic and symptomatic childhood refractory partial seizures, the adverse reactions being generally mild or moderate.

Cardiac drug and psychotropic drug interactions: significance and recommendations.

Understanding cardiac drug interactions with concurrent psychotropic prescriptions is essential for the practicing cardiologist and primary care physician, as well as for the psychiatrist. There has been an explosive use of new drugs in both psychiatry and cardiology without widespread knowledge of their potential interactions. The increasing tendency toward poly-pharmacy, the use of psychotropic medications by cardiologists and primary care physicians caring for cardiac patients, and the growth of the aging population present major challenges for the practitioner. Finally, there is a need to have models/paradigms for predicting potential drug interactions--e.g., the Cytochrome p450 schema. This paper describes a method to identify, understand, and codify the interactions between psychotropic and cardiac drugs, a systematic approach for updating this key database and specific cardiac-psychotropic drug interactions. Specifically, this paper 1) details the interactions, 2) addresses the level of their clinical significance, 3) describes the potential mechanism(s) of the interactions, and 4) offers recommendations to the clinician. Since the majority of the original clinical trials, either for cardiac medications or psychotropic drugs, do not include studies comparing these two drug domains contemporaneously, their interactions often become known only with their combined use in the clinical arena, using the patient as "guinea pig," and through subsequent reporting.