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PubMed2002

Revisiting the mechanism of P450 enzymes with the radical clocks norcarane and spiro[2,5]octane.

Norcarane (1) and spiro[2.5]octane (2) yield different product distributions depending on whether they are oxidized via concerted, radical, or cationic mechanisms. For this reason, these two probes were used to investigate the mechanisms of hydrocarbon hydroxylation by two mammalian and two bacterial cytochrome P450 enzymes. Products indicative of a radical intermediate with a lifetime ranging from 16 to 52 ps were detected during the oxidation of norcarane by P450(cam) (CYP101), P450(BM3) (CYP102), CYP2B1, and CYP2E1. Trace amounts of the cation rearrangement product were observed with norcarane for all but CYP2E1, while no cation or radical rearrangement products were observed for spiro[2.5]octane. The results for the oxidation of norcarane with a radical rearrangement rate of 2 x 10(8) s(-1) are consistent with the involvement of a two-state radical rebound mechanism, while for the slower (5 x 10(7) s(-1)) spiro[2,5]oct-4-yl radical rearrangement products were beyond detection. Taken together with earlier data for the hydroxylation of bicyclo[2.1.0]pentane, which also suggested a 50 ps radical lifetime, these three structurally similar and functionally simple substrates show a consistent pattern of rearrangement that supports a radical rebound mechanism for this set of cytochrome P450 enzymes.

Animals↗
PubMed2003

Synthesis and pharmacology of site specific cocaine abuse treatment agents: 8-substituted isotropane (3-azabicyclo[3.2.1]octane) dopamine uptake inhibitors.

A series of 8-substituted-3-azabicyclo[3.2.1]octanes (isotropanes) were synthesized and tested for inhibitor potency using [(3)H]WIN 35,428 binding at the dopamine (DA) transporter, [(3)H]citalopram binding at the serotonin (5-HT) transporter, and [(3)H]DA uptake assays. The synthesis started with a Mannich condensation of cyclopentanone, benzylamine, and fomaldehyde to afford N-benzyl-3-azabicyclo[3.2.1]octan-8-one (6). The 8-phenyl group was introduced by Grignard addition to ketone 6 or nucleophilic displacement via a triflate of the corresponding alcohol 7a. The 8beta-phenyl-8alpha-alcohols from Grignard addition generally have low affinity for the two transporters and do not effectively inhibit the uptake of [(3)H]DA. The 8beta-phenyl compound (14) without the hydroxyl group at C-8 was much more potent (22-fold) for [(3)H]WIN 35,428 binding inhibition than the corresponding 8beta-phenyl-8alpha-hydroxy compound (7a). The 8alpha-phenyl compound 8a was almost as potent as cocaine in binding to the DA transporter (IC(50) = 234 nM vs 159 nM for cocaine), whereas the C-8 epimer, compound 14, was somewhat less potent (IC(50) = 785 nM). The lower potency of 14 (beta-orientation of 8-phenyl group) as compared to 8a (alpha-orientation) was unexpected, based on modeling studies comparing the new compounds to WIN 35,065-2, an analogue of cocaine. The benzhydryl ethers at C-8 (17), analogous to the benztropines, had better selectivity than the corresponding phenyl compounds, 8a and 14, for the DA transporter as compared to the 5-HT transporter. The isotropane and benzisotropine analogues seem to bind in a manner that is more similar to that of the benztropine compounds 5 rather than those of cocaine and WIN 35,065-2.

Animals↗
PubMed2005

Stereoselectivity and substrate specificity in the kinetic resolution of methyl-substituted 1-oxaspiro[2.5]octanes by Rhodotorula glutinis epoxide hydrolase.

The kinetic resolution of a range of methyl-substituted 1-oxaspiro[2.5]octanes by yeast epoxide hydrolase (YEH) from Rhodotorula glutinis has been investigated. The structural determinants of substrate specificity and stereoselectivity of YEH toward these substrates appeared to be the configuration of the epoxide ring and the substitution pattern of the cyclohexane ring. For all compounds tested, O-axial epoxides were hydrolyzed faster than the corresponding O-equatorial compounds. In concern of the ring substituents, YEH preferred methyl groups on the Re side of the ring. Placement of substituents close to the spiroepoxide carbon decreased the reaction rate but increased enantioselectivity. YEH-catalyzed kinetic resolutions of 4-methyl 1-oxaspiro[2.5]octane epimers were most enantioselective (E > 100).

Epoxide Hydrolases↗
PubMed1983

Characterization of intracellular inclusions formed by Pseudomonas oleovorans during growth on octane.

The growth of Pseudomonas oleovorans on n-octane was characterized by the formation of intracellular structures. These inclusions were isolated and characterized. Morphologically, they resembled the poly-beta-hydroxybutyrate granules found in Bacillus cereus, as shown by freeze-fracture electron microscopy. The elemental analysis of isolated granules showed, however, that they do not contain poly-beta-hydroxybutyric acid. Instead, the analysis was consistent with a C8 polyester, which interpretation was supported by the fatty acid analysis of hydrolyzed granules. From the evidence presented here, we conclude that P. oleovorans forms poly-beta-hydroxyoctanoate granules when grown on n-octane.

Caprylates↗
PubMed1982

The effect of configuration of the sulphate moiety on the metabolism of potassium octan-2-sulphate in the rat.

1. A comparison was made of the metabolism of potassium D-(+)-octan 2-[35S]sulphate and potassium L-(-)-octan-2-[35S]sulphate in the rat. 2. Following administration of either enantiomer orally or i.v. the major proportion of the radioactivity was excreted in the urine within 24 h. When either enantiomer was administered i.v. to rats with bile-duct and ureter cannulae, the majority of the radioactivity was eliminated in the urine within six hours with only small amounts in bile. 3. Both enantiomers were extensively degraded in vivo. The metabolic products were identical with those previously reported (Maggs et al. 1982). 4. The major difference in the metabolite patterns was with respect to the relative amounts of hexanoate-5-sulphate: male and female urines contained approx. twice as much of this metabolite when the D-(+)-isomer was administered. In addition, isomer and sex-linked differences were observed with respect to the amounts of octanoate-7-sulphate.

Animals↗
PubMed2004

[Investigation of fuzzy-clustering in octane number prediction model based on detailed hydrocarbon analysis data].

A method to establish octane number prediction model based on detailed hydrocarbon analysis (DHA) data is presented. The techniques of fuzzy-clustering and the Euclidian distance are employed to select the samples needed in pattern establishment. One hundred and fifty gasoline samples and an amount of 140 characteristic components in the DHA chromatogram of each sample are used for the fuzzy-clustering research. It is found that the 3 - 10 samples, which have the nearest Euclidian distance ( < 1.5) to the prediction sample in the same cluster, are enough to build the octane number prediction model. The experimental results proved that the model obtained according to the above method has more predictable accuracy, wider application range and higher data resource utility compared with the current prediction method.

Cluster Analysis↗
PubMed1989

[Synthesis of derivatives of 2,4-bis(arylmethino)-8-butyl-8- azabicyclo[3.2.1]octan-3-one].

In the frame-work of continued search for novel compounds with potential cholagogic or antitumour activity, some derivatives of 2,4-bis-(arylmethino)-8-butyl-8-azabicyclo[3.2.1]octan-3-one were synthesized. 8-Butyl-8-azabicyclo[3.2.1]octan-3-one was condensed with selected tolualdehydes, methoxybenzaldehydes and chlorobenzaldehydes, as well as with piperonal, furfural, dimethylaminobenzaldehyde, 3-pyridine-carboxaldehyde and 4-pyridine-carboxaldehyde. Products of these reactions were isolated in the form of free bases or their hydrochlorides. The obtained compounds were subjected to pharmacological studies. Two as yet investigated compounds failed to induce statistically significant increase in the volume of secreted bile, but one of them was found to display cholinergic activity.

Animals↗
PubMedDate not supplied

[Catalysis by enzymes entrapped into reversed micelles of surfactants in organic solvents. Peroxidase in the aerosol OT-water-octane system].

Spectral and catalytic parameters of peroxidase solubilized in the aerosol OT-water-octane system have been studied. The spectrum of peroxidase solubilized in octane with AOT reversed micelles, a degree of surfactant hydration being above 12, is actually identical to that of the enzyme aqueous solution. On the other hand, significant spectral changes have been detected when transferring the enzyme from water to the reversed micelle medium at low degrees of surfactant hydration, precisely [H2O]/[AOT] less than 12. The reversed micelle-entrapped peroxidase catalyses the oxidation of pyrogallol with hydrogen peroxide much more actively (at [H2O]/[surfactant] approximately 13) than that in aqueous solution. The entrapment of peroxidase into surfactant reversed micelles increases precisely the catalytic constant of the reaction, i.e. the virtual reactivity of the enzyme increases ten and hundred times depending on degrees of surfactant hydration and concentration. The systems of reversed micelles may be considered as models of biomembranes. Our findings hence show that enzymes in vivo can be much more catalytically active then it appears possible to reveal in conventional experiments in vitro in aqueous solutions.

Catalysis↗
PubMed1994

[Regulation of catalytic activity and supramolecular structure of angiotensin-converting enzyme in reversed micelles of aerosol OT in octane].

Regulation of the catalytic activity and the supramolecular structure of the angiotensin-converting enzyme isolated from bovine lungs has been studied in a system of reversed micelles of aerosol OT (AOT) in octane. The curve for the dependence of the enzyme catalytic activity on the degree of the surfactant hydration (micellar size) has two maxima at the hydration degrees of [H2O]/[AOT] 27 and 31. Data from velocity sedimentation suggest that depending on the hydration degree, the angiotensin-converting enzyme occurs in the system of reversed micelles in both monomeric and dimeric forms, the latter being catalytically active. In contrast with aqueous media, in the reversed micelle system the angiotensin-converting enzyme does not require chloride anions for its catalytic activity. In the system of reversed micelles of AOT in octane the holoenzyme is stable, while the apoenzyme rapidly and irreversibly loses its activity. Under these conditions the apoenzyme shows an ability to incorporate the Zn2+ ions into the enzyme active center; however, only in the presence of a substrate or an inhibitor.

Adenosine Diphosphate↗
PubMed1996

[Polarization fluoroimmunoassay of propazine in reversed micelles of aerosol OT in octane].

The interaction between fluorescein-labeled propazine and antibodies against this hapten was studied in the reversed micelles of Aerosol OT in n-octane by a polarization fluoroassay. The effect of the hydration degree of micelles W0 (W0=[H2O]/[Surf]), which determines their size and surfactant concentration, on the binding of the antigen with antibodies was studied. A high hydration degree of the reversed micelles (W0 = 15-30) and low concentration of the surfactant (less than 50 microM) are optimal for binding. The binding efficacy depends upon the structure of the fluorescein-labeled hapten, particularly upon the length of the bridge binding fluorescein with propazine. It was shown that the polarization fluoroimmunoassay of propazine may be carried out in a reversed micellar system in nonpolar organic solvent (octane) with a detection limit of about 100 nM (20 microns/l). This is an order of magnitude higher than that achievable upon analysis in aqueous medium. The proposed polarization fluoroimmunoassay in a reversed micellar system makes it possible to detect haptens that are poorly soluble in water directly in organic extracts, e.g. in chloroform solutions.

Dioctyl Sulfosuccinic Acid↗
PubMed2002

Inductive effects in isolated molecules: 4-substituted bicyclo[2.2.2]octane-1-carboxylic acids.

Energies of sixteen 4-substituted bicyclo[2.2.2]octane-1-carboxylic acids, their anions, and pertinent 1-substituted bicyclo[2.2.2]octanes were calculated within the framework of density functional theory at the B3LYP/6-311 + G(d,p) level. Substituent effects were evaluated separately in the acid molecule and in the anion in terms of isodesmic homodesmotic reactions. In both cases, the substituent effects are proportional and of opposite sense, that in the anion being eight times greater; in the effect on acidity they are summed. The calculated acidities are in agreement with experimental values with a standard deviation of 1.1 kJ mol-1, and are recommended as a model for evaluating the inductive effect of various substituents, whether they are experimentally accessible or not. The resulting values are closely related to other scales but can be determined more reliably, particularly when compared with the previous quantum chemical method. We also checked electrostatic calculations and confirmed their very approximate character, particularly in the case of unsymmetrical substituents or of substituents with zero dipole moment.

Journal Article↗
PubMed2003

Synthesis and structure-activity relationship of di-(3, 8-diazabicyclo[3.2.1]octane) diquaternary ammonium salts as unique analgesics.

Based on the structure characteristics of the lead compounds, 1, 1' octanedioyl-4, 4'-dimethyl-4, 4'-dibenzyl dipiperazinium dibromide (2) and 3, 8-disubstituted-3, 8-diazabicyclo [3.2.1]octanes (DBO), di-(3, 8-diazabicyclo [3.2.1]octane) diquaternary ammonium salts 3 a-c were designed and synthesized through a highly practical procedure. Target compounds 3 a-c and the hydrochloride salts of their precursors 10 a-c were evaluated for their in vivo analgesic and sedative activities. Interestingly, the introduction of an endoethylenic bridge in the piperazine of lead compound 2 causes loss of the analgesic activity and increases the toxicity dramatically. This result shows that the flexible conformation of piperazine in compound 2 is favorable for interaction with the receptor, and the quaternization of compounds 10 a-c is the main reason for the toxicity increase.

Analgesics↗
PubMed1982

N-Phenyl-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-cis-amine derivatives with hypotensive and other activities.

The synthesis of N-phenyl-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-cis-amine (III) starting from 6-nitrimino-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane, as well as of a series of amides (IV) and ureas (VI) derived from (III), is described. A number of compounds (IV) showed strong hypotensive and bradycardic activity in rats, whereas the urea (IVb) showed infiltration anesthesia in mice similar to that of lidocaine. Antiarrhythmic activity in mice and antiacetylcholine activity in vitro are also reported.

Acetylcholine↗
PubMed1983

N-monosubstituted urethanes and esters of 6-cis-dimethylamino-1,3,3-trimethyl-2-oxabicyclo-[2.2.2]octan-5-trans-ol with hypotensive and other activities.

The synthesis of 6-cis-dimethylamino-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-5-trans-ol (III) starting from 1,3,3-trimethyl-6-nitrimino-2-oxabicyclo[2.2.2]octane is described. Starting from aminoalcohol (III), a series of N-substituted urethanes (IV) and esters (V), as well as the rigid analogue of acetylcholine (VII), were prepared. A number of compounds (V) and particularly (IV) showed remarkable hypotensive and bradycardic activities in rats, whereas the p-aminobenzoate (V h) showed infiltration anesthesia in mice comparable to that of lidocaine. Antiarrhythmic activity in mice and antiacetylcholine activity in vitro are also reported.

Acetylcholine↗
PubMed1984

Esters and N-substituted urethanes of 6-cis-dimethylamino-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-5-cis-ol with hypotensive and other activities.

The synthesis of 6-cis-dimethylamino-1,3,3-trimethyl-2-oxabicyclo [2.2.2] octan-5-cis-ol (III) starting from 6-cis-dimethylamino-1,3,3-trimethyl-2-oxabicyclo [2.2.2] octan-5-trans-ol (I) is described. Starting from aminoalcohol (II), a series of esters (IV) and N-substituted urethanes (V) was prepared. Benzoate (IV e) showed a remarkable hypotensive and bradycardic activity in rats, whereas acetate (IV a) showed infiltration anesthesia and antiarrhythmic activity in mice slightly inferior to those of lidocaine. Antiacetylcholine activity in vitro is also reported.

Acetylcholine↗
PubMed1991

Synthesis and structural, conformational, and pharmacological study of some of esters derived from 3-phenethyl-3-azabicyclo[3.2.1]octan-8-beta-ol and the corresponding N-endo-methyl quaternary derivatives.

A series of 8-beta-acyloxy-3-phenethyl-3-azabicyclo[3.2.1]octane and its N-endo methiodides were synthesized and studied by 1H and 13C NMR spectroscopy, and the crystal structure of 8-beta-p-chlorobenzoyloxy-3-phenethyl-3-azabicyclo[3.2.1]octane methiodide (2c) was determined by X-ray diffraction. In CDCl3 solution, 1b-1e display the same preferred conformation. The cyclopentane and piperidine rings adopt an envelope conformation flattened at C-8 and a distorted chair conformation puckered at C-8 and flattened at N-3, respectively, with the N-substituent in the equatorial position with respect to the piperidine ring. In all cases, methylation takes place from the endo position. The ability of the title compounds to antagonize the acetylcholine-induced contraction of guinea pig ileum is also reported. An initial structure-activity relationship is proposed.

Animals↗
PubMed1996

Synthesis and muscarinic M3 pharmacological activities of 1-azabicyclo[2.2.2]octan-3-one oxime derivatives.

A series of 1-azabicyclo[2.2.2]octan-3-one oximes and related 1-azabicyclo-[2.2.2]-octan-3-one hydroxylamines were synthesized and tested for muscarinic M3 activity. All compounds showed at least some muscarinic binding properties, however, only one member of the series demonstrated mucarinic M3 agonistic properties in vitro (contraction of guinea pig ileum) and in vivo (mydriasis, salivation). In addition, this compound partially reversed the cognitive deficit induced by central cholinergic depletion in two procedures testing memory in the rat, namely the delayed matching to position and swim maze tasks of spatial memory in the rat.

Animals↗