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[The growth-inhibiting activity of mixed complexes of platinum(II) with ammonia and cycloalkylamines].

The effect was studied of mixed cys- and 3-, 4-, 5-, 6-nomial cycloalkylamines or substituted 2-, 3-, 4-methyl- and 4-hydroxycyclohexylamines as well as similar carboxylatocomplexes containing anions of malonic hydroxymalonic, succinic and malic acids on the growth of corn sprout roots. Complexes with non-substituted cycloalkylamines possessed the most pronounced cytostatic activity. Complexes with substituted cyclohexylamines were less active than their non-substituted analogue as well as other complexes with lesser size of cyclic substitute. The cytostatic activity of carboxylatocomplexes, as compared to that of chlorocomplexes, generally manifested itself at ten times higher concentraiton and depended not only on the size of cycloalkylamine but also on the nature of acidoligand.

Amines↗

Synthesis and antibacterial activity of novel 1beta-methyl carbapenems with cycloalkylamine moiety at the C-2 position.

Novel 1beta-methyl carbapenems with a cycloalkylamine moiety as a side chain were synthesized and their structure-activity relationships were studied. These carbapenems showed potent antibacterial activities against a wide range of Gram-positive and Gram-negative bacteria, and moderate urinary recovery when administered intraperitoneally in mice.

Anti-Bacterial Agents↗

Oxidation of cycloalkylamines by cytochrome P-450. Mechanism-based inactivation, adduct formation, ring expansion, and nitrone formation.

Mechanism-based destruction of cytochrome P-450 (P-450) and P-450 heme is observed during the oxidation of N-cyclopropyl and N-cyclobutyl benzylamines. The slower inactivation by the cyclobutylamines relative to cyclopropylamines is consistent with known relative rates of ring opening of cycloalkyl-substituted aminium radicals. Evidence was found that porphyrin meso adducts of the type reported for horseradish peroxidase and cyclopropanone hydrate (Wiseman, J. S., Nichols, J. S., and Kolpak, M. X. (1982) J. Biol. Chem. 257, 6328-6332) were not formed. Radiolabels from cyclopropylamine substrates were covalently attached to protein but essentially only from the cyclopropyl portion and not the benzylic portion. Neither label appeared to be bound to extractable heme; however, during oxidations with cyclopropylamines, labeled P-450 heme became covalently attached to protein. Oxidation of 1-phenylcyclobutylamine by P-450 yielded 2-phenyl-1-pyrroline and 2-phenylpyrrolidine, and the ring expansion is interpreted as evidence for the existence of aminium radicals based on precedents with monoamine oxidase (Silverman, R. B., and Zieske, P. A. (1985) Biochemistry 24, 2128-2138). In addition, purified P-450PB-B oxidized N-(1-phenylcyclobutyl)-benzylamine to N-(1-phenyl)cyclobutyl phenyl nitrone, identified using spectral techniques. This transformation involves two sequential oxidations with either a hydroxylamine or benzylidene intermediate. While P-450 oxidized the amine to both compounds, only the hydroxylamine was rapidly oxidized to give the nitrone. The ring expansion and nitrone products are interpreted in the context of aminium radical intermediates involved in the mechanism of P-450-catalyzed amine oxidation.

Animals↗

Analogues of torasemide--structure function relationships--experiments in the thick ascending limb of the loop of Henle of rabbit nephron.

The aim of the present study was to examine compounds related to torasemide with respect to their ability to block the equivalent short circuit current, corresponding to the rate of chloride reabsorption, in isolated in vitro perfused cortical thick ascending limbs of Henle of the rabbit. The torasemide molecule was modified with respect to the anionic sulfonylurea group, and the secondary amine linked to the pyridine ring. Our results indicate that only few of the tested 48 torasemide-related compounds were able to inhibit from both epithelial sides like torasemide. Only few of the tested compounds were equally effective as torasemide from the lumen side. Some analogues were acting only from the luminal side and some only from the peritubular side. The correlations between structure and potency of inhibition from the luminal side allow the following conclusions: The secondary amine moiety linked to the pyridine ring (toluidine in case of torasemide) can be replaced by a cycloalkylamine or, with some loss of inhibitory potency, by alkylamines. The inhibitory potency is increased with the number of C-atoms in the cycloalkylamine substituted compounds (optimum C7 to C8) and is also depending on the length of the alkylamines (optimum C4). The secondary amine seems to be required since nitrogen cannot be replaced by -S- or -SO2-. The sulfonylurea group cannot be substituted by other anionic groups such as -SO-3 or -COO-. If the pyridine ring is replaced by a NO2-substituted phenyl ring, the inhibitory potency from the luminal side is lost. However, these compounds act still (with some loss of potency) from the peritubular side.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

N6-cycloalkyl-2-phenyl-3-deaza-8-azaadenines: a new class of A1 adenosine receptor ligands. A comparison with the corresponding adenines and 8-azaadenines.

Several 9-benzyl-N6-cycloalkyl-2-phenyladenines, 9-benzyl-N6-cycloalkyl-2-phenyl-8-azaadenines and 4-cycloalkylamino-1-benzyl-6-phenyl-1H-1,2,3-triazolo[4,5-c]pyridines were prepared and assayed as A1 adenosine receptor ligands. The 1H-1,2,3-triazolo[4,5-c]pyridines were obtained starting from N,N-diethyl-1-benzyl-4-carboxyamido-5-methyl-1H-1,2,3-triazole by lithiation in anhydrous tetrahydrofurane in the presence of benzonitrile. The usual work up afforded the isolation of 1-benzyl-6-phenyl-1H-1,2,3-triazolo[4,5-c]pyridin-4-one which was treated with phosphorous oxychloride and cycloalkylamines. Some compounds showed high affinity and selectivity and the trend of Ki values corresponds to the series of 9-benzyl-N6-cycloalkyl-2-phenyladenines and 9-benzyl-N6-cycloalkyl-2-phenyl-8-azaadenines, therefore they can be considered bioisosteres. The affinity data permitted us to ascertain the role and the importance of the N3 in the adenine or 8-azaadenine moiety in the receptor binding and to study the dimension of the receptor lipophilic pocket which is filled by the N6 substituent of adenosine derivatives.

Adenine↗

Adenine and deazaadenine nucleoside and deoxynucleoside analogues: inhibition of viral replication of sheep MVV (in vitro model for HIV) and bovine BHV-1.

A series of N(6)-cycloalkyl-2',3'-dideoxyadenosine derivatives has been prepared by coupling of 2,6-dichloropurine to protected 2,3-dideoxyribose, followed by reaction with appropriate cycloalkylamines. Synthesized compounds, along with other purine nucleoside analogues previously synthesized in our laboratory, have been tested for their antiviral activity against Bovine herpesvirus 1 (BHV-1) and sheep Maedi/Visna Virus (MVV), the latter being an in vitro and in vivo model of Human Immunodeficiency Virus (HIV). All compounds showed good antireplicative activity against MVV, with the N(6)-cycloheptyl-2',3'-dideoxyadenosine (5b) being the most active [effective concentration (EC(50)) causing 50% reduction of cytopatic effects (CPE)=27 nM]. All compounds showed also a from low to very low cell toxicity, resulting in a cytotoxic dose 50 (CD(50))/EC(50) ratio in some cases higher than 1000.

Animals↗

Transport of the highly charged myo-inositol hexakisphosphate molecule across the red blood cell membrane: a phase transfer and biological study.

To address the problem of delivering highly charged small molecules, such as phytic acid (InsP(6) or IHP), across biological membranes, we investigated an approach based on a non-covalent interaction between transport molecule(s) and IHP. Thus, we synthesized a collection of compounds containing IHP ionically bound to lipophilic (but non-lipidic) ammonium or poly-ammonium cations. First, we assessed the ability of these water-soluble salts to cross a biological membrane by measuring the partition coefficients between human serum and 1-octanol. In view of the ability of IHP to act as potent effector for oxygen release, the O(2)-hemoglobin dissociation curves were then measured for the most efficient salts on whole blood. From both the biological and the physical properties of IHP-ammonium salts we determined that cycloalkylamines (or poly-amines) were the best transport molecules, especially cycloheptyl- and cyclooctylamine. Indeed, the octanol/serum partition coefficient of IHP undecacyclooctylammonium salt, is superior to 1, which is very favorable for potential uptake into the red blood cell membrane. A qualitative correlation was found between the partitioning experiments and the biological evaluations performed on whole blood.

1-Octanol↗

Adsorption behavior of surface chemically pure N-cycloalkylaldonamides at the air/water interface.

Equilibrium surface tension (sigma(e)) and electric surface potential (DeltaV(e)) versus concentration isotherms of the homologous series of N-cycloalkylaldonamides synthesized from cycloalkylamines (from cyclopentyl- to cyclododecylamine) and D-glucono-1,5-lactone (c-C(n)GA) or D-glucoheptono-1,4-lactone (c-C(n)GHA) (c-n(C) = 5-12) were investigated at the air/water interface. The measurements were performed with aqueous, surface chemically pure surfactant solutions. Equilibrium surface tension vs concentration isotherms were evaluated to get the adsorption parameters, i.e., standard free energy of adsorption, DeltaG degrees (ads), saturation surface concentration, Gamma(infinity), minimum surface area demand per molecule adsorbed, A(min), and interaction parameter, H(s). Increasing the size of the cycloalkyl moiety leads to a significant increase of the minimum surface area demand per molecule adsorbed. This fact, together with a decrease of the intermolecular interaction parameter suggests that the introduction of a more bulky cycloalkyl ring (c-n(C) = 7 and 8) causes an attenuation of the hydrogen-bond network. This goes in line with the exceptional finding that the higher homologues revealed improved solubility in water. In addition, surface tension investigations suggest occurrence of a phase transition for the N-cyclooctylaldonamides at relatively small surface coverage. This observation is well supported by the surface potential measurements, for which the effect of possible changes in the molecules' surface orientation is even more pronounced. Moreover, the concentration intervals of N-cyclooctylaldonamide in which the change in orientation is observed for either the surface tension or the surface potential isotherms are in very good agreement.

Adsorption↗

Radical cation intermediates in N-dealkylation reactions.

1. A number of mechanistic possibilities exist for P450-catalysed N-dealkylation and have been considered over the years, including C- and N-hydroxylation and sequential electron transfer (SET). With peroxidases the evidence strongly favours SET and free radicals can be detected. Any mechanism must account for lack of incorporation of label from H218O into product by P450s and the high kinetic deuterium isotope effects that are seen in N-dealkylation reactions catalysed by peroxidases but not P450s. 2. Several lines of evidence support a role for SET in P450 amine oxidations, including Hammett analysis, products of dihydropyridine oxidations, and products of mechanism-based inhibition by strained cycloalkylamines. 3. The hypothesis was considered that the P450s act via base catalysis to deprotonate the aminium radical generated by SET, since the pKa has been estimated to be approximately 9. Dihydropyridine aminium radicals have low pKa (< 4) and are generally considered to have considerable kinetic acidity. None of the haemoproteins under consideration (including the peroxidases and haemoglobin) showed high kinetic hydrogen isotope effects for the oxidation of [4-2H]- or [4-3H]-labelled 1,4-dihydropyridines. These results are consonant with the view that P450s catalyse the deprotonation of N,N-dialkylaniline aminium radicals. 4. Since low isotope effects were seen with biomimetic metalloporphyrin models as well as P450s, the deprotonation is attributed to the (FeO)2+ entity, expected to be a strong base, and not the apoprotein. Thus, the FeO moiety of peroxidases is shielded, consistent with evidence by others that SET occurs through the porphyrin edge. Both P450s and peroxidases catalysed the oxidative N-demethylation of aminopyrine and N,N-dimethylaminothioanisole; however, only the peroxidases generated the stable coloured aminium radicals. 5. The rates of N-demethylation of variously para-substituted N,N-dimethylanilines can be used to undertake Hammett or Marcus analysis. The former yields rho = -0.6 and the latter an apparent E1/2 of approximately 1.8 for the formal (FeO)3+ entity of P4502B1. 6. Even in the oxidation of N,N-dialkylanilines, a finite rate of N-oxidation is seen (approximately 0.1% of N-dealkylation). The simplest paradigm has N-oxygenation and N-dealkylation both proceeding from a common aminium radical intermediate.

Animals↗

Poststatin, a new inhibitor of prolyl endopeptidase. VII. N-cycloalkylamide analogues.

Poststatin analogues containing (S)-2-oxo-2-(2-pyrrolidinyl)acetyl moiety in P1 were synthesized and examined for their inhibitory activity against prolyl endopeptidase and cathepsin B in vitro. Introduction of non-peptidyl cycloalkylamine component in P1, was effective and P3-acyl groups must be widely modifiable for prolyl endopeptidase inhibition. Acyl-L-phenylalanyl-(S)-2-oxo-2-(2-pyrrolidinyl)acetyl-cycloalkylamid e type compounds showed IC50 value of nano to subnano g/ml as prolyl endopeptidase inhibitor and were shown no significant inhibitory activities against cathepsin B, a cysteine protease.

Cathepsin B↗

Axial ligands and alicyclic ring size modulate the activity and biochemical pharmacology of ammine/cycloalkylamine-platinum(IV) complexes in tumor cells resistant to cis-diamminedichloroplatinum(II) or trans-1R,2R-1S,2S-diaminocyclohexanetetrachloroplatinum(IV).

A platinum(II) and 3 platinum(IV) ammine/cycloalkylamine homologous series were evaluated for cytotoxicity and biochemical pharmacology in murine leukemia L1210/0, cis-diamminedichloroplatinum(II)- resistant L1210/DDP, and diaminocyclohexaneplatinum-resistant L1210/1,2-diaminocyclohexane (DACH) cells. Within each series, which contained 4 homologues with differing alicyclic (cycloalkyl) ring size (cyclopropane, cyclobutane, cyclopentane, or cyclohexane), cytotoxicity increased with increasing ring size. This appeared to be due to an increase in partition coefficient, and the resulting increase in drug accumulation and intracellular DNA adducts in ascending each of the series. There were exceptions to this generalization, predominantly in L1210/DACH cells, where the biochemical pharmacology was not entirely consistent with the cytotoxic response and suggested that other factors may be at play. The relationship between structure and ability to circumvent cis-diamminedichloroplatinum(II) and/or trans-1R,2R-1S,2S- diaminocyclohexanetetrachloroplatinum(IV) resistance was complex. Ascending the platinum(II) series caused resistance factors to decrease in L1210/DDP cells but increase in L1210/DACH cells. An increase in resistance factors was also observed in ascending the axial chloroplatinum(IV) series in the L1210/DACH line. In contrast, ascending the axial chloroplatinum(IV) series in the L1210/DDP line and axial acetatoplatinum(IV) and axial hydroxoplatinum(IV) series in both cell lines resulted in increases in resistance factors for the first stepwise increase in the cycloalkylamine ring size, but resistance factors then decreased progressively with further increases in ring size. Reduction of the platinum(IV) analogues to the platinum(II) congener appears to be necessary for binding to DNA. The similarity in biological actions between the platinum(II) and axial chloroplatinum(IV) series is likely due to the rapid reduction of tetravalent members to platinum(II) forms. The axial acetatoplatinum(IV) and axial hydroxoplatinum(IV) complexes were reduced more slowly, which may explain their lower potency, but not the ability of the higher member to circumvent both cis-diamminedichloroplatinum(II) and trans-1R,2R-1S,2S- diaminocyclohexanetetrachloroplatinum(IV) resistances. Explanation for this will require additional studies. The results have demonstrated high dependencies on ring size of the carrier amine ligand, valence state of platinum, and the nature of the axial ligand for modulation of potency, cross-resistance property, and biochemical pharmacology of ammine/cycloalkylamine complexes.

Animals↗