Atmospheric implications of hydration on the formation of methanesulfonic acid and methylamine clusters: A theoretical study

The effect of hydration on the formation mechanism of clusters consisting of methanesulfonic acid (MSA) and methylamine (MA) is investigated by quantum chemistry (Density Functional Theory, DFT) and kinetics simulation (Atmospheric Chemical Dynamic Code, ACDC) methods. The results showed that the process of hydration is favorable from the thermodynamic point of view, and the presence of water molecules can promote proton transfer significantly. Although MA has a significant influence on the formation rate of MSA-based clusters at the parts per trillion (ppt) levels, the effective nucleation of MSA-MA anhydrous clusters hardly seems to occur under common typical atmospheric conditions. The high concentrations of precursors ([MSA] > 6 × 10⁷ molecules·cm^-3 and [MA] > 1 ppt or [MSA] > 1 × 10⁶ molecules·cm^-3 and [MA] > 100 ppt) is necessary for the effective nucleation of the MSA-MA system. The formation rate of the MSA-MA system is enhanced significantly by hydration. The formation rate increases with the relative humidity (RH) and reached up to a factor of 2700 at RH = 40%. The formation mechanism of the hydrous system is different from the anhydrous system. The formation of (MSA)₂ and (MSA)(MA) dimers is the rate-determining step of the anhydrous and hydrous systems, respectively. In addition, the growth pathway of clusters was complicated by low temperature and simplified by high humidity, respectively. In general, although humidity is a very favorable factor for the formation of the MSA-MA system, the involvement of other species (such as sulfuric acid) may be more effective to promote the nucleation of the MSA-MA system under typical atmospheric environment.

Design, Synthesis, and Biological Evaluation of N,N-Disubstituted-4-Arylthiazole-2-Methylamine Derivatives as Cholesteryl Ester Transfer Inhibitors

Cholesteryl ester transfer protein (CETP) has been identified as a potential target for cardiovascular disease (CVD) for its important role in the reverse cholesteryl transfer (RCT) process. In our previous work, compound 5 was discovered as a moderate CETP inhibitor. The replacement of the amide linker by heterocyclic aromatics and then a series of N,N-substituted-4-arylthiazole-2-methylamine derivatives were designed by utilizing a conformational restriction strategy. Thirty-six compounds were synthesized and evaluated for their CETP inhibitory activities. Structure-activity relationship studies indicate that electron donor groups substituted ring A, and electron-withdrawing groups at the 4-position of ring B were critical for potency. Among these compounds, compound 30 exhibited excellent CETP inhibitory activity (IC₅₀ = 0.79 ± 0.02 μM) in vitro and showed an acceptable metabolic stability.

PRELIMINARY EVALUATION OF CENTRAL NERVOUS SYSTEM ACTIVITY OF (E)-N-2-METHYL-3-PHENYLPROP-2-ENYL ((E)-N- α-METHYLCINNAMYL) DERIVATIVES OF SELECTED AMINOALKANOLS

A series of (E)-α-methylcinnamyl derivatives of selected aminoalkanols was synthetized and evaluated for activity in central nervous system. All compounds were tested as anticonvulsants and one additionally in antidepressant- and anxiolytic-like assays. The compounds possessed pharmacophoric elements regarded as beneficial for anticonvulsant activity: hydrophobic unit and two hydrogen bonds donor/acceptor features. The compounds were verified in mice after intraperitoneal (i.p.) administration in maximal electroshock (MES) and subcutaneous pentetrazole (scPTZ) induced seizures as well as neurotoxicity assessments. Eight of the tested substances showed protection in MES test at the dose of 100 mg/kg. The derivative of 2-aminopropan-1-ol was also tested in 6-Hz test in mice i.p. and showed anticonvulsant activity but at the same time the neurotoxicity was noted. The derivative of 2-amino-1-phenylethanol which possessed additional hydrophobic unit in aminoalkanol moiety was tested in other in vivo assays to evaluate antidepressant- and anxiolytic-like activity. The compound proved beneficial properties especially as anxiolytic agent remaining active in four-plate test in mice at the dose of 2.5 mg/kg (i.p.). In vitro biotransformation studies of 2-amino-1-phenylethanol derivative carried out in mouse liver microsomal assay indicated two main metabolites as a result of aliphatic and aromatic hydroxylation or aliphatic carbonylation. To identify possible mechanism of action, we evaluated serotonin receptors (5-HT1A, 5-HT6 and 5-HT7) binding affinities of the compounds but none of them proved to bind to any of tested receptors.

Synthesis, growth, crystalline perfection of 4-bromo-4'dimethylamino benzylideneaniline (BDMABA) and photons absorption of BDMABA crystal

One of the Schiff base 4-bromo-4'dimethylamino benzylideneaniline (BDMABA) compounds was synthesized and single crystal of the material was grown by solvent evaporation method at room temperature. Molecular structure of BDMABA was confirmed by (1)H nuclear magnetic resonance and the presence of functional groups was confirmed by Fourier Transform Infrared and Fourier Transform Raman spectral analyses. Cell parameters were determined using single crystal X-ray diffraction analysis and crystalline perfection of the grown BDMABA crystal was evaluated using high-resolution X-ray diffraction analysis. Thermal analyses indicated that the material is thermally stable up to 215 °C and its melting point is 161.5 °C. Vickers microhardness study was carried out to estimate the mechanical hardness of BDMABA crystal which shows that the crystal belongs to the class of soft materials. Linear and nonlinear optical studies were carried out using UV-vis-NIR spectrum and open aperture Z-scan technique respectively.

Diazonium salt-derived 4-(dimethylamino)phenyl groups as hydrogen donors in surface-confined radical photopolymerization for bioactive poly(2-hydroxyethyl methacrylate) grafts

In this paper we describe a novel methodology for grafting polymers via radical photopolymerization initiated on gold surfaces by aryl layers from diazonium salt precursors. The parent 4-(dimethylamino)benzenediazonium salt was electroreduced on a gold surface to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; free benzophenone in solution was used as a photosensitizer to strip hydrogen from the grafted DMA. This system permitted efficient surface initiation of photopolymerization of 2-hydroxyethyl methacrylate. The resulting poly(2-hydroxyethyl methacrylate) (PHEMA) grafts were found to be very adherent to the surface as they resist total failure after being soaked in the well-known paint stripper methyl ethyl ketone. The PHEMA grafts were reacted with 1,1'-carbonyldiimidazole to yield carbamate groups that are able to react readily with amino groups from proteins. The final surface consisted of protein-functionalized PHEMA grafts where bovine serum albumin (BSA) protein is specifically linked to the grafts by covalent bonds. We used X-ray photoelectron spectroscopy to monitor the chemical changes at the gold surface all along the process from the neat gold to the end-protein-functionalized polymer grafts: the PHEMA graft thickness ranged from 7 to 27 nm, and the activation by 1,1'-carbonyldiimidazole reached 37% of the OH groups, which was sufficient for 90% surface coverage of the grafts by BSA. This work conclusively provides a new approach for bridging reactive and functional polymers to surfaces via aryl diazonium salts in a simple, fast, and efficient approach of importance in biomedical and other applications.

Indatraline: synthesis and effect on the motor activity of Wistar rats

A new approach for the synthesis of indatraline was developed using as the key step an iodine(III)-mediated ring contraction of a 1,2-dihydronaphthalene derivative. Behavioral tests were conducted to evaluate the effect of indatraline and of its precursor indanamide on the motor activity of Wistar rats. Specific indexes for ambulation, raising and stereotypy were computed one, two and three hours after i.p. drug administration. Indatraline effects on motor activity lasted for at least three hours. On the other hand, no significant differences in motor activity were observed using indanamide. The results suggest that indatraline has a long lasting effect on motor activity and add evidence in favor of the potential use of that compound as a substitute in cocaine addiction.

Synthesis and evaluation of indatraline-based inhibitors for trypanothione reductase

The search for novel compounds of relevance to the treatment of diseases caused by trypanosomatid protozoan parasites continues. Screening of a large library of known bioactive compounds has led to several drug-like starting points for further optimisation. In this study, novel analogues of the monoamine uptake inhibitor indatraline were prepared and assessed both as inhibitors of trypanothione reductase (TryR) and against the parasite Trypanosoma brucei. Although it proved difficult to significantly increase the potency of the original compound as an inhibitor of TryR, some insight into the preferred substituent on the amine group and in the two aromatic rings of the parent indatraline was deduced. In addition, detailed mode of action studies indicated that two of the inhibitors exhibit a mixed mode of inhibition.

Soft alkyl ether prodrugs of a model phenolic drug: the effect of incorporation of ethyleneoxy groups on transdermal delivery

Two different types of soft alkyl ether prodrugs incorporating ethyleneoxy groups into the promoiety have been synthesized for a model phenol (acetaminophen, APAP): alkyloxycarbonyloxymethyl type (AOCOM) and N-alkyl-N-alkyloxycarbonyl-aminomethyl type (NANAOCAM). The solubilities in isopropyl myristate, S_IPM, and water, S_AQ, partition coefficients between IPM and pH 4.0 buffer, K_IPM:4.0, and the delivery of total species containing APAP through hairless mouse skin from IPM, J_MMIPM, have been measured for the prodrugs. The J_MMIPM values were accurately predicted by the Roberts-Sloan (RS) equation. Only modest increases in J_MMIPM were realized (about 1.4 times) by each type. The only prodrug that was more water soluble and more lipid soluble than APAP did not improve J_MMIPM of APAP. This result may be due to the strong association of water molecules with the ethyleneoxy groups, and especially the triethyleneoxy derivative, which dramatically increases the molecular weight and depresses J_MMIPM.

Cyclic nucleotide phosphodiesterase type 4 inhibitors: evaluation of pyrazolo[1,5-a]-1,3,5-triazine ring system as an adenine bioisostere

A series of 8-substituted pyrazolo[1,5-a]-1,3,5-triazines were considered as a bioisosteric replacement for the 9-substituted adenine derivatives resulting in the discovery of 8-(2-methoxybenzyl)-4-(N-methylamino)-2-n-propylpyrazolo[1,5-a]-1,3,5-triazine (14d) and 2-trifluoromethyl-8-(2-methoxybenzyl)-4-(N-methylamino)pyrazolo[1,5-a]-1,3,5-triazine (14e) as a new structural class of potent phosphodiesterase type 4 inhibitors (IC(50)=13 nM and 11 nM, respectively) with high isoenzyme selectivity. An original tandem of reactions involving a palladium-mediated cross-coupling reaction (PMCCR) of the readily available 8-iodo-2-methyl-4-(N-methyl-N-phenylamino)pyrazolo[1,5-a]-1,3,5-triazine (11a) and arylboronic acids or alkynes followed by the displacement of the N-methyl-N-phenylamino group constitute the key steps in a novel synthetic approach developed herein. The treatment of 11a-c with n-BuLi and selected aldehydes represents an interesting alternative to the PMCCR for the synthesis of benzylic derivatives 14a-i. Preliminary biological testing has shown that compounds 14d and 14e strongly inhibit LPS-induced TNFalpha release from human mononuclear cells from healthy subjects. These two compounds were selected for further biological evaluation.

Iodine(III)-Promoted Ring Contraction of 1,2-Dihydronaphthalenes: A Diastereoselective Total Synthesis of (±)-Indatraline

[reaction: see text] A new approach for the synthesis of (+/-)-indatraline, which is a 3-phenyl-1-indanamine that displays several biological activities, is described. The strategy features as the key step a diastereoselective ring contraction of a 1,2-dihydronaphthalene promoted by PhI(OTs)OH, to construct the indan ring system. The oxidative rearrangement of other 1,2-dihydronaphthalenes was also investigated, generalizing this method to obtain indans.

Design, synthesis and biological activity of selective and orally available TF/FVIIa complex inhibitors containing non-amidine P1 ligands

We found the novel selective and orally available non-amidine TF/FVIIa complex inhibitor 21e, 4-({[(1S)-(aminocarbonyl)-3-methylbutyl]amino}carbonyl)-2'-({[4- (aminomethyl)phenyl]amino}carbonyl)-4'-(methylamino)biphenyl-2- carboxylic acid. The derivatives were synthesized by conversions of the isobutyl moiety and the introduction of alkylamino groups to 4'-position of the central phenyl ring of compounds 2a and 2b reported previously. Some compounds show increased in vitro anti-TF/FVIIa and PT prolongation activities. Among them, compound 21e reached and sustained micromolar plasma concentration levels of up to 2h after oral administration in mice. Moreover, compound 21e did not prolong the bleeding time even at the highest dose level in cynomolgus monkeys, while PT was prolonged 3.7-fold increases at this dose.

WB4101-Related Compounds: New, Subtype-Selective α1-Adrenoreceptor Antagonists (or Inverse Agonists?)

Our previous structure-affinity relationship study had considered the enantiomers of the naphthodioxane, tetrahydronaphthodioxane, and 2-methoxy-1-naphthoxy analogues (compounds 1, 3, and 2, respectively) of 2-(2,6-dimethoxyphenoxyethylaminomethyl)-1,4-benzodioxane, the well-known alpha1-adrenoceptor (alpha1-AR) antagonist WB4101, showing that such modifications significantly modulate the affinity and selectivity profile for alpha1-AR subtypes and 5-HT1A receptor. Here, we extend investigations to antagonist activity enclosing new enantiomeric pairs, namely those of the methoxytetrahydronaphthoxy and methoxybiphenyloxy WB4101 analogues (4 and 5-7, respectively) and of a double-modified WB4101 derivative (8) resulting from hybridization between 2 and 3. We found that (S)-2 is a very potent (pA2 10.68) and moderately selective alpha1D-AR antagonist and the hybrid (S)-8 is a potent (pA2 7.98) and highly selective alpha1A-AR antagonist. Both of these compounds and (S)-WB4101 seem to act as inverse agonists in a vascular model. The results, which generally validate the logic we followed in designing these eight compounds, are acceptably rationalized by comparative SAR analysis of binding and functional affinities.

Novel ligands for the human histamine H1 receptor: Synthesis, pharmacology, and comparative molecular field analysis studies of 2-dimethylamino-5-(6)-phenyl-1,2,3,4-tetrahydronaphthalenes

This paper reports the synthesis of a novel series of (+/-)-2-dimethylamino- 5- and 6-phenyl-1,2,3,4-tetrahydronaphthalene derivatives (5- and 6-APTs), and, corresponding affinity, functional activity, and, molecular modeling studies with regard to drug design targeting the human histamine H1 receptor. The 5-APTs have 2- to 4-fold higher H1 receptor affinity than the endogenous agonist histamine. The chemical nature of a meta-substituent on the 5-APT pendant phenyl moiety does not significantly affect H1 affinity. In contrast, analogous meta-substitution for the 6-APTs increases H1 affinity up to 100-fold. The new APTs do not activate H1 receptor-linked intracellular signaling and apparently are competitive H1 antagonists. A new model that establishes structural parameters for binding to the human H1 receptor by APTs and other ligands was developed using 3-D QSAR (CoMFA). The model predicts H1 ligand binding with a higher degree of external predictability compared to a previously reported model. The APTs also were examined for activity at human serotonin 5-HT2A and 5-HT2C receptors, which are phylogenetically closely related to the H1 receptor. 5-APT and m-Cl-6-APT were identified as novel agonists that selectively activate 5-HT2C receptors. It is concluded that the lipophilic (brain-penetrating) APT molecular scaffold may have pharmacotherapeutic potential in neuropsychiatric diseases.

1-Aminomethylbenzocycloalkanes: conformationally restricted hallucinogenic phenethylamine analogues as functionally selective 5-HT2A receptor agonists

A series of conformationally restricted analogues of the hallucinogenic phenethylamine 1 (2,5-dimethoxy-4-bromophenethylamine, 2C-B) was synthesized to test several hypotheses concerning the bioactive conformation of phenethylamine ligands upon binding to the 5-HT(2A) receptor. These benzocycloalkane analogues were assayed for their receptor binding affinity and ability to activate downstream signaling pathways, and one exceptional compound was selected for testing in an in vivo drug discrimination model of hallucinogenesis. All compounds were examined in silico by virtual docking into a homology model of the 5-HT(2A) receptor. On the basis of these docking experiments, it was predicted that the R enantiomer of benzocyclobutene analogue 2 would be the most potent. Subsequent chemical resolution and X-ray crystallography confirmed this prediction, as (R)-2 proved to be equipotent to LSD in rats trained to discriminate LSD from saline. Thus, we propose that the conformation of 2 mimics the active binding conformation of the more flexible phenethylamine type hallucinogens. In addition, (R)-2 is one of the most potent and selective compounds yet discovered in the in vivo drug discrimination assay. Further, 2 was found to be a functionally selective agonist at the 5-HT(2A) receptor, having 65-fold greater potency in stimulating phosphoinositide turnover than in producing arachidonic acid release. If hallucinogenic effects are correlated with arachidonic acid production, such functionally selective 5-HT(2A) receptor agonists may lack the intoxicating properties of hallucinogens such as LSD.

C-(4,5,6-Trimethoxyindan-1-yl)methanamine: A Mescaline Analogue Designed Using a Homology Model of the 5-HT2A Receptor

A conformationally restricted analogue of mescaline, C-(4,5,6-trimethoxyindan-1-yl)-methanamine, was designed using a 5-HT(2A) receptor homology model. The compound possessed 3-fold higher affinity and potency than and efficacy equal to that of mescaline at the 5-HT(2A) receptor. The new analogue substituted fully for LSD in drug discrimination studies and was 5-fold more potent than mescaline. Resolution of this analogue into its enantiomers corroborated the docking experiments, showing the R-(+) isomer to have higher affinity and potency and to have efficacy similar to that of mescaline at the 5-HT(2A) receptor.

Kinetics and mechanistic studies of the hydrolysis of diisocyanate-derived bis-thiocarbamates of cysteine methyl ester

Diisocyanates (dNCOs) are the most commonly reported cause of chemically induced occupational asthma, but the ultimate antigenic form is unknown. Reactions of the three most common monomeric dNCOs, hexamethylene dNCO (HDI), methylene diphenylisocyanate (MDI), and toluene dNCO (TDI), with cysteine methyl ester (CME) gave the corresponding bis-dithiocarbamates (HDI-CME, TDI-CME, and MDI-CME). The dissociation kinetics of these bis-thiocarbamates, in aqueous conditions, was followed spectrophotometrically under varying pH and temperature conditions. Reaction of the adducts with methylamine or human serum albumin (HSA) produced diurea, monourea, and diamine products, and this was consistent with the base-catalyzed elimination reaction (E1cB) pathway being the dominant, but not exclusive, dissociation mechanism. The hydrolysis of the adducts was first-order with respect to OH(-) concentration and overall second-order (HDI-CME, k = 3.36 x 10(2) M(-)(1) min(-)(1); TDI-CME, k = 2.49 x 10(4) M(-)(1) min(-)(1); and MDI-CME, k = 5.78 x 10(4) M(-)(1) min(-)(1) at pH 7.4) with deviation from second-order when the dNCO had an aromatic functional group. Arrhenius plots gave activation energies (HDI-CME, E(a) = 70.6 kJ/mol; TDI-CME, E(a) = 46.1 kJ/mol; and MDI-CME, E(a) = 44.5 kJ/mol) that were consistent with the following order of stability: HDI-CME > TDI-CME > MDI-CME. Therefore, the stability of different dNCO-derived thiocarbamates in aqueous environments can vary greatly. Thiocarbamate dissociation rates and type of products formed may potentially influence antigenicity and subsequent hypersensitivity/toxic reactions following dNCO exposures.

Palladium-Catalyzed Insertion of Isocyanides into P(O)−H Bonds: Selective Formation of Phosphinoyl Imines and Bisphosphinoylaminomethanes

Palladium and rhodium catalyzed the addition of H-phosphine oxides to isocyanides to selectively generate alpha-iminophosphine oxides and bisphosphinoylaminomethanes, respectively.

An Access to 3,4-(Aminomethano)proline in Racemic and Enantiomerically Pure Form

Protected racemic and enantiomerically pure 3,4-(aminomethano)prolines rac-9 and (2S,2'R,3R,4R)-9 have been prepared applying a titanium-mediated reductive cyclopropanation as a key step. Thus, cyclopropanations of N,N-dibenzylformamide with titanacyclopropanes generated in situ from racemic or enantiomerically pure tert-butyl N-Boc-3,4-dehydroprolinates rac-8 or (S)-8 proceed diastereoselectively, and furnish the protected racemic and enantiomerically pure diamino acid 9. The latter was incorporated into three tripeptides containing glycyl, alanyl and phenylalanyl moieties.

Biological evaluation and structure-activity relationships of bis-(3-aryl-3-oxo-propyl)-methylamine hydrochlorides and 4-aryl-3-arylcarbonyl-1-methyl-4-piperidinol hydrochlorides as potential cytotoxic agents and their alkylating ability towards cellular glutathione in human leukemic T cells

Various bis (3-aryl-3-oxo-propyl)methylamine hydrochlorides 1 and their corresponding structural and non-classical isomers 4-aryl-3-arylcarbonyl-1-methyl-4-piperidinols 3 were evaluated against human leukemic T (Jurkat) cells and found to possess significant cytotoxicity. Among the series 1 (bis-Mannich bases) and 3 (corresponding piperidinols), compounds la, 1c and 1e showed cytotoxic potency which was approximately 1.6, 3.7 and 3.4 times that of the reference drug 5-fluorouracil, respectively. Except for compound 1d, conversion of bis-Mannich bases to their corresponding piperidinols 3a, 3b and 3e lowered the potency. Besides chloro derivative 1d, bis-Mannich bases displayed greater cytotoxicity compared with their mono-Mannich bases, series 5. Representative bis-Mannich bases (1a, 1e) and piperidinols (3a, 3e) decreased the glutathione level of Jurkat cells. Molecular modeling was utilized in order to evaluate whether the shape, size, critical volume, solvent accessible area and partition coefficient of the different compounds had contributed to the varying potencies observed. Bis-Mannich bases 1a, 1c and 1e may serve as candidate anticancer agents for future development.

Oxidation of a Dimethylthiourea Metabolite by Iodine and Acidified Iodate: N,N‘-Dimethylaminoiminomethanesulfinic Acid ()

The two major metabolites after S-oxygenation of dimethylthiourea (dimethylaminoiminomethane sulfinic acid, DMAIMSA, and dimethylaminoiminomethane sulfonic acid, DMAIMSOA) were synthesized and tested for their reactivities in the presence of mild oxidants, aqueous iodine and acidic iodate. The stoichiometry of the iodate-DMAIMSA reaction is 2IO3- + 3NHCH3(=NCH3)CSO2H + 3H2O --> 3SO4(2-) + 2I- + 3CO(NHCH3)2 + 6H+ (A). The reaction commences with immediate formation of aqueous iodine, which is produced from the reaction between the iodide product of stoichiometry (A) and reactant iodate. The instant accumulation of aqueous iodine is due to the very slow reaction of iodine with both DMAIMSA and DMAIMSOA. In excess iodate over that required for stoichiometry (A), the stoichiometry of the reaction is 4IO3- + 5NHCH3(=NCH3)CSO2H + 3H2O --> 5SO4(2-) + 2I2 + 5CO(NHCH3)2 + 6H+ (B). Even though excess DMAIMSA solutions do not afford iodine, the initial rapid formation of iodine is still observed, which reaches a peak and then decays to conform to stoichiometry (A). The maximum transient iodine concentrations obtained are directly proportional to the acid concentrations because acid catalyzes formation of iodine and retards reactions that consume iodine. The zwitterionic forms of DMAIMSA and DMAIMSOA are very stable in acid, and DMAIMSOA, especially, is very inert and unreactive in low pH environments. The predominant pathway for the oxidation of DMAIMSOA is through an initial hydrolysis reaction to yield bisulfite and dimethylurea, while the oxidation of DMAIMSA proceeds through DMAIMSOA as well as through an early heterolytic cleavage of the C-S bond to produce a highly reducing sulfoxylate species, SO2(2-), which is later rapidly oxidized to sulfate. In aerobic conditions, the sulfoxylate species reacts with molecular oxygen to produce superoxide anion radical, which in turn will form hydrogen peroxide and hydroxyl radicals which will bring with them inadvertent genotoxicity.

Synthesis and biological activity of analogues of the antimicrotubule agent N,beta,beta-trimethyl-L-phenylalanyl-N(1)-[(1S,2E)-3-carboxy-1-isopropylbut-2-enyl]- N(1),3-dimethyl-L-valinamide (HTI-286)

Hemiasterlin, a tripeptide isolated from marine sponges, induces microtubule depolymerization and mitotic arrest in cells. HTI-286, an analogue from an initial study of the hemiasterlins, is presently in clinical trials. In addition to its potent antitumor effects, 2 has the advantage of circumventing the P-glycoprotein-mediated resistance that hampers the efficacy of other antimicrotubule agents such as paclitaxel and vincristine in animal models. This paper describes an in-depth study of the structure--activity relationships of analogues of 2, their effects on microtubule polymerization, and their in vitro and in vivo anticancer activity. Regions of the molecule necessary for potent activity are identified. Groups tolerant of modification, leading to novel analogues, are reported. Potent analogues identified through in vivo studies in tumor xenograft models include one superior analogue, HTI-042.

Stereoselectivity and Regioselectivity in Nucleophilic Ring Opening in Derivatives of 3-Phenylisoxazolo[2,3-a]pyrimidine. Unpredicted Dimerization and Ring Transformation. Syntheses of Derivatives of Pyrimidinylmethylamine, Pyrimidinylmethylamino Acid Amides, and α-Amino-2-pyrimidinylacetamides1

The nucleophilic ring opening of the isoxazolone ring in 2-oxo-3-phenylisoxazolo[2,3-a]pyrimidine derivatives by optically active amino acid amides and ephedrine led to pyrimidinylmethylamino acid amides. Using amides of different L-amino acids and (-)-ephedrine resulted in different degrees of stereoselectivity. The degree of streoselectivity depended mostly on the nucleophile used. When applying hydroxy amines such as ephedrine, the attack via the secondary amino group was found as the favored regioselectivity. Upon replacement of the oxo group in position 2 in the phenylisoxazolo[2,3-a]pyrimidine system by an imino group, it was expected that the spontaneous decarboxylation that follows the ring opening would not take place, thus achieving amino acid amide derivatives of 2-pyrimidinylacetamide, which are closely related to pyrimidoblamic acid, an important constituent of Bleomycins, used in cancer therapy. However, by heating 5,7-dimethyl-2-imino-3-phenylisoxazolo[2,3-a]pyrimidine in solution, it underwent an unprecedented dimerization process that involved both the phenyl and the imino group. After protecting the imino group by acetylation, the ring opening by nucleophiles was possible, resulting in the formation of derivatives of 2-pyrimidinylacetamide. 2-Acetylimino-5,7-dimethyl-3-phenylisoxazolo[2,3-a]pyrimidine also underwent a ring transformation, yielding an interesting indolone derivative. Selectivity in ring opening and mechanisms of dimerization and ring transformation are discussed.

Multivariable optimization of a multiproduct continuous chemicals facility

Multivariable optimization (MVO) is a powerful nonlinear steady-state flowsheet simulation technique used widely in the chemical process industry to optimize plant performance by increasing plant capacity and/or reducing energy usage. The user supplies the objective function(s), constraints, and variable limits based on operating heuristics, prior experience, and observed process behavior. In this paper we describe how we used MVO in conjunction with improved automation and statistical process monitoring to increase capacity and reduce energy consumption. This project was conducted over a two-year period in a methylamines facility that produces three products: monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA). It led to a 14% improvement in MMA capacity and a 7% improvement in TMA capacity. Energy consumption per pound of main product decreased by approximately 20% for the six-month period (April-September, 2000) when compared to a three-year average (1997-2000). It was accompanied by a 60% improvement in process capability and 31% improvement in product quality. We attribute this improvement to several factors: smoother transition between optimum set points determined by the process optimizer, improved disturbance rejection due to controller installation and tuning, and reduced operator intervention because of controlled operation at or near the optimum set points.

N-acetyl-N'-methylamide derivative of (2S,3S)-1-amino-2,3-diphenylcyclopropanecarboxylic acid: theoretical analysis of the conformational impact produced by the incorporation of the second phenyl group to the cyclopropane analogue of phenylalanine

The intrinsic conformational preferences of (2S,3S)-1-amino-2,3-diphenylcyclopropanecarboxylic acid, a phenylalanine cyclopropane analogue bearing two phenyl substituents, have been examined theoretically. For this purpose, its N-acetyl-N'-methylamide derivative, Ac-(2S,3S)c(3)diPhe-NHMe, has been investigated by using ab initio HF and DFT methods. Results have been compared with those previously reported for other cyclopropane analogues of phenylalanine, and with experimental data available for c(3)diPhe-containing peptides.

Design, synthesis, and monoamine transporter binding site affinities of methoxy derivatives of indatraline

A series of methoxy-containing derivatives of indatraline 13a-f and 17 were synthesized, and their binding affinities for the dopamine, serotonin, and norepinephrine transporter binding sites were determined. Introduction of a methoxy group to indatraline affected its affinity and selectivity greatly. Except for the 4-methoxy derivative 13a,which had the same high affinity at the dopamine transporter binding site as indatraline, the other methoxy-containing analogues (13b-f and 17) exhibited lower affinity than indatraline for the three transporter binding sites. However, some of the analogues were more selective than indatraline, and the 6-methoxy derivative 13c displayed the highest affinity for both the serotonin and norepinephrine transporters. This compound retained reasonable affinity for the dopamine transporter and is a promising template for the development of a long-acting inhibitor of monoamine transporters. Such inhibitors have potential as medications for treatment, as a substitution medication, or for prevention of the abuse of methamphetamine-like stimulants.

Substituted 1-phenyl-2-cyclopropylmethylamines with high affinity and selectivity for sigma sites

A series of 1-phenyl-2-cyclopropylmethylamines structurally related to (+)- and (-)-MPCB were synthesized and their binding affinities for sigma1, sigma2, opioid and dopamine (D2) receptors were evaluated. Substitution of the cis-N-normetazocine with different aminic moieties provided compounds with high affinity and selectivity for sigma binding sites with respect to opioid and dopamine (D2) receptors. The observed increase in sigma2 affinity as compared to the parent (+)-MPCB, supports the idea that the particular stereochemistry of (+)-cis-N-normetazocine affects sigma1 selectivity but does not affect sigma1 affinity. The (+/-)-cis isomers of methyl 2-[(1-adamantylamino)methyl]-1-phenylcyclopropane-1-carboxyl ate (18) displayed a higher affinity and selectivity for the sigma1 and sigma2 receptor subtypes compared to the (+/-)-trans 19. Interestingly, the enantiomer (-)-cis 18 displayed a preference for sigma1 receptor subtype whereas the (+)-cis 18 did for sigma2. These results prompt us to synthesize compounds with modification of nitrogen and carboxyl groups. The compounds obtained showed high affinities and selectivity for sigma sites. Moreover, modifications of carboxyl groups provided compounds with the highest affinities in the series. In particular, compound 25 with reverse-type ester showed a Ki of 0.6 and 4.05 nM for sigma1 and sigma2 binding sites, respectively.

Design, synthesis, and activity of a series of pyrrolidine-3-carboxylic acid-based, highly specific, orally active ET(B) antagonists containing a diphenylmethylamine acetamide side chain

The endothelin (ET)-B receptor subtype is expressed on vascular endothelial and smooth muscle cells and mediates both vasodilation and vasoconstriction. On the basis of the pharmacophore of the previously reported ET(A)-specific antagonist 1, (ABT-627), we are reporting the discovery of a novel series of highly specific, orally active ET(B) receptor antagonists. Replacing the dibutylaminoacetamide group of 1 with a diphenylmethylaminoacetamide group resulted in antagonist 2 with a complete reversal of receptor specificity. Structure-activity relationship studies revealed that ortho-alkylation of the phenyl rings could further increase ET(B) affinity and also boost the ET(A)/ET(B) activity ratio of the resulting antagonists. A similar antagonism selectivity profile could also be achieved when one of the phenyl rings of the acetamide side chain was replaced with an alkyl group, preferably a tert-butyl group (10h). Combining these features with modification of the 2-aryl group of the pyrrolidine core, we have identified a potent antagonist (9k, A-308165) with over 27 000-fold selectivity favoring the ET(B) receptor and an acceptable pharmacokinetic profile (F = 24%) in rats.

Antibacterial activities of new synthetic divalent cation chelators

A series of new synthetic ligand compounds which chelate divalent cations was examined for the antibacterial activities of the compounds. Only 2 of 14 synthetic chelators, 9-trans-anthryl-1, 4, 8, 11-tetraaza-tetradecane (No. 6) and bis(2-pyridyl)methylamine (No. 13) showed antibacterial activities, whereas none of the diamines, hydrophilic triamines nor tetramines showed antibacterial activities. Chelators No. 6 and No. 13 inhibited the growth of both Gram-negative and -positive bacteria at doses of 25-200 microg/ml, comparable to those of common antibiotics such as polymixin B, fosfomycin and macrolides. Ethylenediaminetetraacetate (EDTA) potentiated these antibacterial activities, whereas an inhibitory effect of Mg2+ on the MICs of these chelators was observed. Moreover, these chelators enhanced the leakage of periplasmic beta-lactamase. It is therefore suggested that chelators No. 6 and No. 13 disrupt both the membranes and cytoplasmic functions of bacteria, resulting in cell death.

Design and synthesis of a series of 6-substituted-2-pyridinylmethylamine derivatives as novel, high-affinity, selective agonists at 5-HT1A receptors

A search for novel, selective agonists with high intrinsic activity at the 5-HT1A subtype of serotonin (5-HT) receptors was undertaken. Mechanistic and thermodynamic considerations led to the design of 6-substituted-2-pyridinylmethylamine as a potential 5-HT1A pharmacophore. Various adducts derived from the 6-substituted-2-pyridinylmethylamine moiety were tested for their affinity at 5-HT1A, alpha1-adrenergic, and D2-dopaminergic receptors. Compounds with high affinity for 5-HT1A receptors (pKi >/= 8) were examined for agonist properties by measuring their ability to inhibit forskolin-stimulated cAMP production in HA7 cells (i.e., HeLa cells permanently transfected with the h5-HT1A receptor gene and expressing the h5-HT1A receptor protein). Several compounds of the type aryl¿4-[(6-substituted-pyridin-2-ylmethylamino)methyl]piperidin -1-yl¿ methanone had nanomolar affinity for 5-HT1A binding sites and were more than 500-fold selective with respect to alpha1 and D2 sites. Importantly, their 5-HT1A agonist properties were demonstrated in HA7 cells where they behaved as potent inhibitors of cAMP accumulation. In particular, (3, 4-dichlorophenyl)¿4-[(6-oxazol-5-ylpyridin-2-ylmethylamin o)methyl]pip eridin-1-yl¿methanone (70) and (3, 4-dichlorophenyl)¿4-[(6-azetidinopyridin-2-ylmethylamino)met hyl]piper idin-1-yl¿methanone (36) appeared to be more potent than, and at least as efficacious as, the prototypical 5-HT1A agonist (+/-)-8-OH-DPAT. SAR studies revealed that the pyridine nitrogen atom and the nature and the position of the substituents on the pyridine ring were critically involved in the ability of the compounds to recognize and activate 5-HT1A receptors. Structural modifications of the nonpharmacophoric part of the molecule showed, however, that the entire structure was required for affinity at 5-HT1A binding sites.

Synthesis and biological activities of (R)-5,6-dihydro-N,N-dimethyl-4H-imidazo[4,5,1-ij]quinolin-5-amine and its metabolites

The imidazoquinoline (R)-5,6-Dihydro-N,N-dimethyl-4H-imidazo[4,5,1-ij]quinolin-5-amine [(R)-3] is a potent dopamine agonist when tested in animals but surprisingly shows very low affinity in in vitro binding assays. When incubated with mouse or monkey liver S9 microsomes, (R)-3 is metabolized by N-demethylation and oxidation to (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5,1-ij]quinolin-2(1H) -one [(R)-6], intermediate metabolites, where N-demethylation to the imidazoquinoline (R)-4 and where oxidation to the imidazoquinolinone (R)-5 has taken place, are also observed in these incubates. A cross-species study on the metabolism of (R)-3 in vitro has shown large variations in the extent of metabolism from species to species. Imidazoquinolinones (R)-5 and (R)-6 have comparable activity to (R)-3 in animals and also show good dopaminergic (D2) and serotonergic (5HT1A) activities in binding assays. It is probable that these metabolites account at least in part for the in vivo activity found for (R)-3. Efficient syntheses for compounds 3-6 as single enantiomers from quinoline are presented together with information on the biological activities and metabolic stabilities of these compounds.

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XVIII: Oligoamines with fluorescent properties, Part B: Fluorophores in the molecular periphery

Seventeen N,N'-benzene-1,3-dimethane and nine N,N',N''-benzene-1,3,5-trimethane derivatives with fluorescent properties have been synthesized. Three of them show antiplatelet activities (inducer collagen, IC50 Born-test) in concentrations < 10 mumol/L. They are suitable for interaction studies with biological macromolecules and synthetical and biological membranes. Structure activity relationships demonstrate that heteropolycyclic fluorophores i.e. quinoline, dibenzofurane, or carbazole are favorable substituents for this purpose.

Carcinogenesis and mutagenesis by N-nitroso compounds having a basic center

Two N-nitroso compounds that are derivatives of N,N-dimethylethylenediamine and are therefore strongly basic, were tested for carcinogenic activity. They were methylnitrosamino-N,N-dimethylethylamine (MNDMEA) and N,N-dimethylaminoethylnitrosoethylurea (DMENEU). Each was administered orally to male and female F344 rats by gavage. MNDMEA was also given by gavage to Syrian hamsters and to rats as a solution in drinking water. The response of rats treated with MNDMEA was almost the same by the two modes of treatment and all developed tumors of the esophagus and died in less than 40 weeks; many also had tumors of the nasal mucosa. Hamsters were less susceptible to the nitrosamine than rats, since they survived longer following a larger dose and the tumor incidence was small; several hamsters had tumors of the nasal mucosa, some males also had tumors of the liver and lung and one male and two females had a tumor of the colon. Although it is a strong directly acting mutagen, dimethylaminoethylnitrosoethylurea was weakly carcinogenic in rats, giving rise to tumors of the uterus and mammary gland in females, but having no particular target organ in male rats. The presence of a basic center in these N-nitroso compounds does not prevent their absorption nor their entry into cells, which they can transform to tumors.

5-(Aminomethyl)-3-aryldihydrofuran-2(3H)-ones, a new class of monoamine oxidase-B inactivators

Both cis- and trans-5-(aminomethyl)-3-aryldihydrofuran-2(3H)-one hydrochloride salts (9 and 10) were synthesized efficiently in a 5-step sequence from arylacetic acids. Both compounds were found to be irreversible inactivators of monoamine oxidase B. These compounds constitute the first members of a new class of monoamine oxidase inactivators.

The cytotoxicity of amine-cyanoboranes, amine-cyanoalkylboranes and aminomethyl-phosphonate cyanoborane adducts against the growth of murine and human tissue culture cells

The amine-cyanoboranes, the amine-cyanoalkylboranes and the aminomethyl-phosphonate-N-cyanoborane adducts proved to be active antineoplastic agents. These compounds were more effective against single cell cultured cell growth rather than solid tumors. The following amine-cyanoboranes, (CH3)2(C18H37)NBH2CN (5), (CH3)2NHBH[CH(CH3)2]CN (7) and (CH3)3NB(CN)2.CH3 (10), were the most active in vivo and in vitro. A related phosphine-cyanoborane was also very active in both in vivo and in vitro model screens. Of the amino-methyl-phosphonate-N-cyanoborane adducts, (CH3O)2.P(O)CH2N(C2H5)2BH2CN (13) proved to be the most active. The amine-cyanoalkylboranes had the poorest in vivo activity; the in vitro cytotoxicity, however, was similar to that of other cyanoboranes.

Interaction of amine oxides and quaternary ammonium salts with membrane and membrane-associated processes in E. coli cells: mode of action

The antimicrobials (1-methyldodecyl)dimethylamine oxide and (1-methyldodecyl)trimethylammonium bromide affect the cytoplasmic membrane of E. coli. The interaction results in release of intracellular material (K+, 260nm-absorbing material), an effect on dehydrogenase enzyme activity and inhibition of respiration. The final effect of both substances is the same; they differ only in their dynamics. The effect of the membrane was correlated with parameters characterizing these surfactants i.e. critical micelle concentration (c.m.c.) minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) over the concentration range of 10(-4) to 10(-1) mmol/dm3 of active substance. The three stage mode of action model can be summarized as follows: 1-polar (coulombic) interactions, 2-polar and hydrophobic interactions, 3-hydrophobic interactions (extraction and solubilization). The polar and hydrophobic interactions (1st and 2nd stage) are discussed also in relation to model membranes.

Acetylenic and allenic derivatives of 2-(1-methylindolyl) methylamine as selective inhibitors of the monoamine oxidases A and B

This paper reports the synthesis of a new series of acetylenic and allenic derivatives of 2-(1-methylindolyl) methylamine as well as the preliminary results of their study as selective inhibitors of the A and B forms of the mitochondrial monoamine oxidase from bovine brain. The compounds were obtained from 2-(1-methylindole)carboxylic acid which, as its acyl halide, reacts with amines to give the respective amides. The latter compounds were reduced with lithium aluminium hydride to the respective amines (II a-c) and then N-alkylated by reaction with 2-propynyl-, 2-butynyl- or 2,3-butadienyl bromides to the corresponding amines (III a-j).

Poly-N-acryloyl-Tris gels as anticonvection media for electrophoresis and isoelectric focusing

We describe in detail the synthesis of an acrylic monomer, N-acryloyl-tris(hydroxy-methyl)aminomethane (NAT), which was successfully used for the preparation of gels for electrophoresis and isoelectric focusing. The polymerization kinetics and transparency of the poly(NAT) gels crosslinked by N,N'-methylenebisacrylamide (Bis) are also shown. Poly(NAT)-Bis gradient (4-24%) gel resolves proteins according to their size. The exclusion limit of this gel is slightly over 3 X 10(6), which is more than threefold higher than the exclusion limit of the polyacrylamide gradient gel of the same concentration. The gel made of 6% NAT and 3% Bis represents a suitable matrix for isoelectric focusing. These results demonstrate that poly(NAT)-Bis gels could be advantageously used in those applications where the extensive sieving by the polyacrylamide matrix is not desir desirable.

Conformationally defined adrenergic agents. 4. 1-(aminomethyl)phthalans: synthesis and pharmacological consequences of the phthalan ring oxygen atom

The synthesis of a series of 1-(aminomethyl)phthalans 1b is reported. The radioligand binding to alpha 1- and alpha 2-receptors and the in vitro pharmacology in alpha 1 (rabbit aorta) and alpha 2 (phenoxybenzamine-pretreated dog saphenous vein) tissues were determined and were compared to the activity of the corresponding 1-(aminomethyl)indans. The activity of this series of phthalans was found to be consistent with the electrostatic repulsion hypothesis that was used to design the parent indan (ERBCOP) compounds. The effect of the phthalan ring oxygenation was to somewhat improve alpha 1-receptor potency relative to the 6-ERBCOP indans without having a general effect on the alpha 2-receptor potency. We conclude from the overall pattern of activity that while the norepinephrine type beta-hydroxyl group may be beneficial for binding to the alpha 1-adrenoceptor, it is not required for strong binding to or full stimulation of the alpha 2-adrenergic receptor, provided that the conformational mobility associated with the phenylethylamine is restricted and maintained in a favorable conformation for receptor interaction.

Reaction of N,N-disubstituted alpha-aminomethyleneketones with tosyl isocyanate. Synthesis of amino-disubstituted 2-acyl-3-amino-N-tosylpropenamides, N,N-(3-amino-1-alkyl-2-propenylidene) and N,N-[2-(aminomethylene)cyclohexylidene]tosylamides

The reaction of N,N-disubstituted open-chain and cyclohexane alpha-aminomethyleneketones (I) and (II) with p-toluenesulfonyl (tosyl) isocyanate gave amino-disubstituted 2-acyl-3-amino-N-tosylpropenamides (III) and/or N,N-(3-amino-1-alkyl-2-propenylidene) and N,N-[2-(aminomethylene)-cyclohexylidene] tosylamides (IV) and (V), the final product being related to the carbon and nitrogen substituents of the enaminone. The evaluation of the hypoglycemic activity concerning some of the above compounds gave no interesting results.

Synthesis of alpha-aminomethyl derivatives of beta-phenyltetrahydrofuran-2-one

beta-Phenyltetrahydrofuran-2-one-alpha-carboxylic acid 1 was transformed in the Mannich reaction into alpha-aminomethyl derivatives of beta-phenyltetrahydrofuran-2-one 2-6. The obtained alpha-aminomethyllactones, in reaction of ammono- and hydrazinolysis yield alpha-aminomethyl-beta-phenyl gamma-hydroxybutyric acid derivatives 7-12. Compounds 4, 5, 8, 9, and 10 depress the central nervous system, and compound 12 shows analgesic properties.

[(Aminomethyl)arloxy]acetic acid esters. A new class of high-ceiling diuretics. 3. Variation in the bridge between the aromatic rings to complete mapping of the receptor

Continued structural evaluation of the [(aminomethyl)aryloxy]acetic ester diuretics has produced a series of compounds in which the functional group that bridges the two aromatic rings has been varied. Diuretic screening of these analogues in rats indicates that the keto group can be effectively replaced with an ether or thio ether function with a slight increase in potency, whereas the methylene and sulfoxide linking groups lead to diminished saluretic potency. Replacement with either -SO2-, -COCO-, -CH2O-, -CONH- or direct bond results in a loss of activity. Although the series was designed according to QSAR criteria, the traditional linear free-energy properties of these compounds do not correlate with diuretic potency. However, conformational analysis of the series by potential energy calculations indicates that all active compounds have an accessible conformation that matches the bridge atom-carboxylate distance of the very potent dihydrobenzofuran analogue 56. Conformational calculations of several compounds in which the aminomethyl group was varied suggests that the active conformation is probably a low-energy conformation. Consideration of rotation about the bridge could not distinguish between two possible orientations of the aminomethyl ring in the active conformation. However, there is a quantitative negative linear correlation between diuretic potency and the protrusion into space of the group that bridges the two aromatic rings.

[(Aminomethyl)aryloxy]acetic acid esters. A new class of high-ceiling diuretics. 2. Modifications of the oxyacetic side chain

The discovery of high-ceiling natriuretic activity from a series of aminomethyl derivatives of ethyl [2,3-dichloro-4-(4-hydroxybenzoyl)phenoxy]acetate prompted our continued investigation of this new class of (aryloxy)acetic acid diuretics. Systematic alteration of the oxyacetic side chain has shown that the carboxylic acid function is the active species in vivo and that the ethyl ester group serves as a prodrug to enhance oral absorption. Side-chain functional groups that are incapable of generating the carboxylic acid in vivo failed to impart diuretic activity to the target compounds. Additional side-chain modifications including homologation, methyl substitution, and heteroatom replacement are also described. Ring annelation of the oxyacetic side chain to a dihydrobenzofuran-2-carboxylic acid produced compound 32, which displayed the highest level of saluretic activity for this series.

[(Aminomethyl)aryloxy]acetic acid esters. A new class of high-ceiling diuretics. 1. Effects of nitrogen and aromatic nuclear substitution

A series of Mannich bases and aminomethyl derivatives of ethyl [2,3-dichloro-4-(4-hydroxybenzoyl)phenoxy]acetate were synthesized and tested for saluretic and diuretic activities. The effects of nitrogen and aromatic nuclear substitution, reorientation of the aminomethyl group relative to that of the phenolic hydroxyl group, and replacement of either the phenolic hydroxyl or the aminomethyl group by other functional groups are described. Ethyl [2,3-dichloro-4-[3-(aminomethyl)-4-hydroxybenzoyl]phenoxy]acetate (27) was found to be a very potent, high-ceiling diuretic.

Nuclear magnetic resonance study of side-chain conformation of tyrosyl residue in [Met5]-enkephalin. Solvent and temperature dependence

[Met5]-Enkephalin and tyrosine methylamide containing (2S, 3S)-[2,3-2H]-tyrosine and [Met5]-enkephalin containing (2S, 3R)-[3-2H]tyrosine were synthesized. 270 MHz 1H-NMR spectra of the normal species and selectively deuterated species were analyzed. The lower field and higher field beta-proton signals of the Tyr1 residues of [Met5]-enkephalin (and tyrosine methylamide) were unambiguously assigned to the pro-S and pro-R protons, respectively, in organic solvents, but the alternative assignments apply in 1H2O. For [Met5]-enkephalin and tyrosine methylamide (model for N-terminal tyrosyl residue), the rotamer populations around the Calpha-Cbeta bond of tyrosyl residue were determined in a variety of solvents. Rotamer populations of the tyrosyl residue depend on solvent polarity. In aqueous solution, the rotamers I and II are predominant while in weakly polar solvents the rotamer I becomes predominant. For the tyrosyl residue of the dipolar form of [Met5]-enkephalin in (C2H3)2SO solution, anomalous temperature dependences of rotamer populations are observed. This anomaly is suggested to be due to the equilibrium of the folded and extended conformations of the main chain. In fact, the temperature dependences of rotamer populations become normal in the presence of 2 M NH4ClO4, which weakens the attraction between the N-terminal and C-terminal groups of the dipolar form and thus reduces the population of the folded form in (C2H3)2SO solution.

Specific deuteromethylation by the Eschweiler-Clarke reaction. Synthesis of differently labelled variants of trimethylamine and their use for the preparation of labelled choline and acetylcholine

Reductive methylation (the Eschweiler-Clarke reaction) was used as a route for the synthesis of differently deuterium labelled variants of trimethylamine with the ultimate aim of preparing labelled variants of choline and acetylcholine. Combinations of unlabelled and labelled formaldehyde and formic acid yielded symmetrically labelled trimethylamines of high isotopic purity. The labelled congeners to acetylcholine and choline that were prepared subsequently provide suitable internal standards and tracers to be used in mass spectral analysis and in the evaluation of the pharmacokinetics of the parent compounds.

alpha-Aminomethylglutarate, a beta-amino analog of glutamate that interacts with glutamine synthetase and the enzymes that catalyze glutathione synthesis

The glutamate analog, alpha-aminomethylglutaric acid, was synthetized by Michael addition of ammonia to 2-methylene glutaronitrile followed by hydrolysis of the intermediate alpha-aminomethylglutaryl nitrile; the analog cyclizes readily on heating to 2-piperidone-5-carboxylic acid. Sheep brain glutamine synthetase utilizes one isomer of DL-alpha-aminomethylglutarate at about 10% of the rate with L-glutamate. gamma-Glutamylcysteine synthetase uses both isomers of DL-alpha-aminomethylglutarate, preferentially acting on the same isomer used by glutamine synthetase. gamma-(alpha-Aminomethyl)glutaryl-alpha-aminobutyrate, prepared enzymatically with gamma-glutamylcysteine synthetase, was found to be a substrate and an inhibitor of glutathione synthetase. alpha-Aminomethylglutarate does not inhibit gamma-glutamyl cyclotransferase and gamma-glutamyl transpeptidase appreciably. When alpha-aminomethylglutarate was administered to mice, there were substantial decreases in the levels of glutamine, glutathione, glutamate, and glycine in the kidney, and of glutamine and glutamate in the liver, indicating that this glutamate analog is effective as an inhibitor of glutamine and glutathione synthesis in vivo, and suggesting that it may also inhibit other enzymes.

Oxidation of N-methyl-gamma-tocopheramine to a nitroxide

An unstable nitroxide identified by electron paramagnetic resonance spectra was obtained by oxidation of N-methyl-gamma-tocopheramine with peroxide and also by ultraviolet photooxidation.

[Synthesis and biological trial of 1-methylene-4-naphthylazo polymer derivates]

With the purpose of preparing latent forms of six naphthylazoderivatives (five of them are schistosomicidal agents), polymers of these chemotherapeutic agents were synthesized in a two-step reaction. First, polymeric 1-methyleneaminonaphthalene (II) was synthesized by condensing 1-naphthylamine with formaldehyde. Subsequently, coupling of II with five sulfonamides (of which four are moieties of schistosomicidal agents) and 5-aminouracil (which is a part of another schistosomidical agent) yielded polymeric 1-methyleneamino-4-naphthylazoderivaties (IIIa-f). In bioligical tests in mice experimentally infected by Schistosoma mansoni, the six new polymers were found inactive.