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Digitale Medien

Enkephalin analogues containing β-naphthylalanine at the fourth position (1990)

Mierke, Dale F. ; Said-Nejad, Odile E. ; Schiller, Peter W. ; [weitere]

New York : Wiley-Blackwell

Biopolymers 29 (1990), S. 179-196

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ISSN: 0006-3525

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: To examine the importance of the aromatic side chains of enkephalin on opiate activity, we report the synthesis and conformational analysis of a series of analogues related to enkephalin with β-naphthylalanine in place of phenylalanine at the fourth position. Three linear analogues (Tyr-D-Ala-Gly-(L and D)-β Nal(1)-Leu-NH2 and Tyr-D-Ala-Gly-β Nal(2)-Leu-NH2) were initially synthesized to examine the effect of the substitution on biological activity. The increased activity of these peptides at the μ-opiate receptor, compared to native Leu-enkephalin, prompted us to examine the more conformational constrained analogues, Tr-c[D-A2bu-Gly-(L and D)-β Nal(1)-Leu], incorporating a α,γ-diaminobutyric acid at the second position and cyclization to the carboxylic end of the leucine. These two cyclic analogues provide insight into the necessity for the L chirality of the aromatic residue at position 4. The Tyr-c[D-A2bu-Gly-L-β Nal(1)-Leu] analogue is highly potent and displays a slight preference for the μ receptor. The conformational analysis indicates that despite the high flexibility of the tyrosine side chain, the aromatic rings of the tyrosine and naphthylalanine are relatively distant from each other. The presence of two intramolecular hydrogen bonds help maintain the conformation of the 14-membered backbone ring that keeps the side chains directed away from each other. These findings are in agreement with our model of an extended structure required for μ selectivity and a folded form with close aromatic ring placement for δ selectivity.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bip.360290123

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Digitale Medien

Sur une tentative d'unification des théaories quantiques de la cancèrisation par les polyacènes: I. Thèorie des règions M, L, et B (1990)

Gayoso, Jose ; Kimri, Said

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 38 (1990), S. 461-486

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ISSN: 0020-7608

Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: This study is a unified approach to quantum theories of polyacen carcinogenesis. Part I discusses the M, L, and B regions theory. Although the M region of polyacens is much less reactive than is the K region, the chemical reactivity of these two regions parallels each other. Consequently, the K-L Pullman's theory may be reformulated by replacing the K region by the M region. The M-L regions theory improves all the quantum structure-carcinogenic activity relationships obtained previously in the K-L framework. Moreover, it would appear that in these correlations, the most important role is played by nonconcerted electrophilic reactions. We suggest that the M-L modified Pullman's theory and the Bay (B) region theory, proposed by Jerina et al., are related to different steps of the metabolic activation mechanism leading to ultimate carcinogen: the first step for the Pullman's theory and the carbocation step for the theory of the Bay region. We have termed the “M, L and B regions theory” as this unified approach to the problem of polyacens carcinogenesis.

Zusätzliches Material: 8 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/qua.560380308

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Digitale Medien

Competitive hydrodesulfurization and hydrogenation in a monolithic reactor (1990)

Irandoust, Said ; Gahne, Olof

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 36 (1990), S. 746-752

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Competitive liquid-phase hydrodesulfurization of thiophene and hydrogenation of cyclohexene on a monolithic CoMo/γ-Al2O3 catalyst were studied. The flow pattern in the monolithic catalyst reactor was segmented gas-liquid flow (slug flow). The hydrogen pressure and the temperature were varied between 30-40 bar and 509-523 K, respectively. The experimental data are consistent with rate expressions of the Langmuir-Hinshelwood type where the reactions proceed on two different types of active sites. This kinetic model is based on hydrogenation of the thiophene ring prior to sulfur elimination.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690360511

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Digitale Medien

Cyclocondensation of 4-Benzyl-1-hydrazinophthalazine (1990)

El-Feky, Said ; Bayoumy, Bashner E.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1041-1048

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ISSN: 0021-8383

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: 1-Hydrazino-4-benzylphthalazine 1 underwent closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride, trifluoroacetic anhydride, ortho esteres, aldehydes, urea or carbon disulphide to afford the N-formyl 3a, N-acyl 3b, and the appropriate 3-substituted-6-benzyl-s-triazolo [3,4-a] phthalazines 4a, c, 7, 8. Alkylation of the obtained s-triazolo[3,4-a]-phthalazine-3-thione 7 and s-triazolo [3,4-a] phthalazin-3-one 8 with N-substituted chloroacetamides gave the thioether 9 and N-substitution products 10, respectively. Likewise, applying Mannich conditions of the previously mentioned intermediates 7 and 8 yielded the N-Mannich bases (11 and 12). The new products were characterized by their elemental and spectral data.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/prac.19903320622

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Digitale Medien

Synthesis of polyfunctionally substituted pyridazines (1990)

Ghozlan, Said Ahmed Soliman ; Mohamed, Mona Hassan ; Fakhr, Yehia ; [weitere]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1990 (1990), S. 293-296

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ISSN: 0170-2041

Schlagwort(e): Pyridazine, derivatives ; Pyrazolo-pyridazine, derivative ; Pyrido-pyridazine, derivative ; Isoxazolo-pyridazine, derivative ; Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The pyridazines 3, 4, 5, and 7 were obtained by reaction of the hydrazone derivatives 2 with several reagents. By treatment of 5 with acetic acid/hydrochloric acid, the pyrazolo[4,3-c]-pyridazine 6 was formed. The pyrido-pyridazine derivatives 8 and 9 were obtained by reaction of 2 and 3 with malononitrile and ethyl cyanoacetate, respectively, and the isoxazolo-pyridazines 11 by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium ethoxide solution. The intermediate 9 was separated by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium acetate solution.

Zusätzliches Material: 2 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jlac.199019900153

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Digitale Medien

Synthesis of 2-alkyl-3-vinyloxaziridines as potential antitumor agents (1990)

Said, Samy B. ; Młochowski, Jacek ; Skarżewski, Jacek

Weinheim : Wiley-Blackwell

Liebigs Annalen 1990 (1990), S. 461-464

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ISSN: 0170-2041

Schlagwort(e): Antitumor agents ; Oxaziridines ; Aldimines, unsaturated ; Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: A convenient method for the synthesis of previously unknown oxaziridines having unsaturated substituents at the 3-position (3a-k) is based on the selective oxidation of the imino group of α,β-unsaturated aldimines 2 with m-chloroperbenzoic acid. The title compounds and 2-tert-butyl-3-(phenylethynyl)oxaziridine (3k) exhibit potent activity against experimental tumor cells in vitro.

Zusätzliches Material: 4 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jlac.199019900187

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Digitale Medien

Sur une tentative d'unification des théaories quantiques de la cancérisation par les polyacènes. II: Le rôle de la rèagion K dans le processus d'activation metabolique conduisant au cancérogène ultime. Théorie des régions M, L, et BK (1990)

Gayoso, Jose ; Kimri, Said

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 38 (1990), S. 487-495

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ISSN: 0020-7608

Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: This study is a unified approach to quantum theories of polyacen carcinogenesis. Part II is on the role of the K-region in metabolic activation process leading to ultimate carcinogen and discusses the M, L, and BK theory. The saturation of the polyacen K-region, or the transformation into a quinoid one, deactivates the carcinogenic process going through a diol epoxyde, which results in Bay-region carbocation. K and B regions must be considered as two interdependent parts of the same structural entity, which may be termed the BK-region. The M, L, and BK theory achieves a complete unification of the Pullman and Jerina and other theories.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/qua.560380309

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