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Results for “Norbornanes”

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At least 19 recordsLinked to original sources
PubMed1997

Mobility of norbornane-type substrates and water accessibility in cytochrome P-450cam.

The behaviour of norbornane-type substrates bound to oxidised cytochrome P-450cam (CYP 101) in 60% (w/w) glycerol-containing phosphate buffer was investigated using electronic absorption spectroscopy. The high-pressure dependence study revealed that the value of the spin-state reaction-volume change decreased from -70 to -22.8 cm3/mol with decreasing high-spin state content from 99 to 63%. Simultaneously, the values for the enthalpy and entropy determined from the low-temperature dependence of the spin-state transition decreased from 73.7 to 24.3 kJ/mol and from 310.4 to 88.9 J/mol K, respectively. Under our experimental conditions the pH-value of the buffer remained at low temperatures and high pressures in the range of pH 7-8, in which no pH-value-induced spin-state conversion occurred. Therefore, the secondary effect of the temperature and pressure-induced pH change can be disregarded as being responsible for the observed spin-state transition effects. Substrate dissociation constants were determined. From the temperature-jump experiments (297 K to 180 K) we found a higher mobility in the active site for the substrates in the sequence (1R)-camphor, (1S)-camphor, camphane, (1R)- and (1S)-camphorquinone, norcamphor, and norbornane. Our findings can be explained by the incomplete fit of the methyl groups of the norbornane-type substrate to the protein, in particular to the I-helix, predominantly determining the substrate mobility and water accessibility to the protein.

Binding Sites↗
PubMed1995

Investigation of cytotoxic effects of 8 norbornane derivatives on 4 human cancer cell lines using the MTT assay.

A group of 8 structurally modified norbornane analogs, selected on basis of water solubility, was tested for its potential cytotoxic effects using a modified MTT assay. Four tumor cell lines, three hematological and a hepatocellular one were used as an experimental model system. Some analogs exhibited an antitumor effect which was shown to be tissue specific. The cytotoxic effect is most likely due to the nature of the side chains rather than to the basic bicyclic norbornane structure of the molecule. These results not only provide a basis for the synthesis of derivatives with effective antitumor activity, but also give some indication of the the molecular target of these compounds.

Antineoplastic Agents↗
PubMedDate not supplied

Development of neural network simulator for structure--activity correlation of molecules (NECO). Prediction of endo/exo substitution of norbornane derivatives and of carcinogenic activity of PAHs from 13C-NMR shifts.

A perceptron type neural network simulator for structure--activity correlation of molecules has been developed with two different learning methods, i.e., back-propagation and reconstruction methods. First by use of the back-propagation method the exo/endo branching of norbornane and norbornene derivatives was correctly predicted from the set of 13C NMR chemical shifts for various ring carbon atoms. Then the obtained correlation was analyzed by the reconstruction learning method. It was shown in this case that the NMR shifts for two carbon atoms out of seven have strong correlation with the exo/endo branching. Further, structure--activity correlation between the 13C NMR chemical shifts and carcinogenicity of 11 polycyclic aromatic hydrocarbons was also analyzed using the reconstruction method. It was demonstrated that neural network analysis is suitable for the elucidation of complicated structure--activity problems where many factors are nonlinearly entangled.

Animals↗
PubMed1983

[Norbornane compounds in pharmaceutical research].

This review compiles the literature about norbornanes which already are used as medicaments and such bicyclo [2.2.1]heptanes, which are connected with drug research in some way. As is shown for the period from 1967 until 1980 the occupation with these bicyclic compounds has gained some importance in drug research, not only because they are used medicinally but also because they are used as suitable test molecules for studying structure-activity-relationships by reason of their special molecular shape, their voluminous, bicyclic carbon skeleton and the sterically fixed position of their substituents.

Amines↗
PubMed1990

[Synthesis of the isocamphene series. 33. The synthesis of fungicidal norbornane derivatives].

Starting from the corresponding amines the syntheses of various norbornyl ureas with potential fungicidal activity are described. These new compounds possess a tricyclo[5.2.1.0(2,6)]decane, or an isocamphenilane, a camphenilane, an exo- and endo- dimethylnorbornane or a bicyclo[2.2.2]octane carbon skeleton. With the exception of the first class all other derivatives bear a geminal dimethyl group--important because of its shielding effect--at C-3 of the bicyclus. Some ureas, especially 6 and the acetamide 5, are active against phytopathogenic fungi.

Ascomycota↗
PubMed1978

[Glycinamide derivatives of norbornane].

Three groups of glycinamides derivatived respectively from 4-aminomethyl-2,2,3-trimethylnorbornane, from 1-aminomethyl-2,2-dimethyl-3-methylennorbornane and from 1-aminomethyl-2,2,3-trimethylnorbornane are prepared and described.

Amides↗
PubMed1981

Importance of the aromatic ring in adrenergic amines. 6. Nonaromatic analogues of phenylethanolamine as inhibitors of phenylethanolamine N-methyltransferase: role of pi-electronic and steric interactions.

To probe the importance of pi-electronic and steric interactions of nonaromatic analogues of phenylethanolamine as inhibitors of phenylethanolamine N-methyltransferase (PNMT), a series of norbornane and norbornene ethanolamines was prepared and evaluated as inhibitors of PNMT (liquid chromatographic-electrochemical detector assay). Previous studies indicated a major importance of hydrophobic interaction of the ring moiety attached to the ethanolamine side chain, but a possible importance of pi-complex formation could have been obscured by conformational differences among the analogues. In this study, norbornane and norbornene substituted with an ethanolamine side chain at positions 1,2-exo, and 2-endo were prepared from the corresponding aldehydes by addition of trimethylsilyl cyanide (Me3SiCN) and lithium aluminum hydride reduction. The saturated (norbornane) analogues were two times more potent as inhibitors of the enzyme than were the norbornene analogues, thus suggesting that pi-complex formation is not an important contribution to binding and, as previously proposed, a hydrophobic interaction is the significant binding interaction of the ring moiety. The hydrophobic binding area has a critical size that requires the hydrophobic moiety to be of sufficient length (the bridgehead-substituted norbornane and norbornene ethanolamines being too "'short" for optimal binding). The 2-exo orientation of the ethanolamine side chain was preferred to the 2-endo orientation, supporting our earlier hypothesis that the ring moiety prefers to be oriented away from the side chain.

2-Hydroxyphenethylamine↗
PubMed1980

Energization of amino acid transport in energy-depleted Ehrlich cells and plasma membrane vesicles.

We redirect attention to contributions to the energization, of the active transport of amino acids in the Ehrlich cell, beyond the known energization, by down-gradient comigration of Na+, beyond possible direct energization by coupling to ATP breakdown, and beyond known energization by exchange with prior accumulations of amino acids. We re-emphasize the uphill operation of System L, and by prior depletion of cellular amino acids show that this system must receive energy beyond that made available by their coupled exodus. After this depletion the Na+-indepdendent accumulation of the norbornane amino acid, 2-aminobicycloheptane-2-carboxylic acid becomes strongly subject to stimulation by incubation with glucose. Energy transfer between Systems A and L through the mutual substrate action of ordinary amino acids was minimized although not entirely avoided by the use of amino acid analogs specific to each system. When 2,4-dinitrophenol was included in the depleting treatment, and pyruvate, phenazine methosulfate, or glucose used for restoration, recovery of uptake of the norbornane amino acid was independent of external Na+ or K+ levels. Restoration or the uptake of 2-(methylamino)isobutyric acid was, however, decreased by omission of external K+. Contrary to an earlier finding, restoration of uptake of each of these amino acids was associated with distinct and usually correlated rises in cellular ATP levels. ATP addition failed to stimulate exodus of the norbornane amino acid from plasma membrane vesicles, although either NADH or phenazine methosulfate did stimulate exodus. ATP production and use is thus associated with transport energization although evidence for a direct role failed to appear.

Adenosine Triphosphate↗