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  • 1
    Electronic Resource
    Electronic Resource
    Structure determination of the adduct formed between the signal nucleotide diadenosine 5′, 5‴-P1, P4-tetraphosphate (Ap4A) and cis-[Pt(NH3)2Cl2] (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1623-1635 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diadenosine 5′,5‴-P1,P4-tetraphosphate (Ap4A), an intracellular regulatory nucleotide, has been found to react with the antitumor drug cis-diamminedichloroplatinum(II) and its aqua derivative to form a single complex. This complex has been purified by high-performance liquid chromatography and characterized by 1H-nmr and CD spectroscopy. In this complex, Ap4A takes a very particular conformation. It is an N7-N7 chelate of the metal with the two adenines in a head-to-head arrangement and an anti-anti conformation of the adenosines. Platinum chelation leads to a large decrease of the Ap4A conformational flexibility.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230902
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of the 1H and 13C NMR spectra of the novel macrolide antibiotic roxithromycin. Structure and conformation in solution (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 846-855 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; 13C NMR ; Roxithromycin ; Solution-state conformation ; Macrolide Antibiotic ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A complete assignment of the 1H and 13C NMR spectra of roxithromycin in deuteriochloroform, methanol-d4 and D2O was made using different two-dimensional (2D) chemical shift correlation methods. The coupling constants observed by 1H NMR and the NOEs show that the predominant conformation of roxithromycin in CDCl3 solution is very similar to that in the crystalline state. However, variable-temperature and variable-solvent NMR experiments show that the major conformation of roxithromycin presents a conformational flexibility in the C-2-C-8 region and, particularly, in the C-4-C-5 bond of the molecule. The NOE data indicate that the 9-[O-(2,5-dioxahexyl)oxime] chain is directed towards the 6-OH, certainly involving an intramolecular hydrogen bond. This results in a globular structure for roxithromycin with less freedom for the macrolactone ring and the sugar units.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260281003
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of long-range 13C, 1H coupling constants of macrolide antibiotics by 2D J - δ selective INEPT experiments (1994)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 32 (1994), S. 1-7 
    Details
    ISSN: 0749-1581
    Keywords: 2D J - δ heteronuclear ; NMR spectroscopy ; Selective excitation ; Long-range carbon-proton coupling constants ; Macrolide antibiotics ; Molecular dynamics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2D J - δ selective INEPT experiments were used to measure long-range 13C,1H coupling constants for the macrolide antibiotics roxithromycin, erythromycin and their metabolites, RU 39001 and erythralosamine, respectively. The 2D J - δ selective INEPT experiment was performed using selective excitation by a DANTE pulse train. In some cases, to avoid truncation problems in the t1 domain, treatment of the data using a linear prediction method was adopted. Dihedral angles for the glycosidic bonds and the erythronolid unit were deduced from a Karplus-type equation for conformational study. The apparent equilibrium between different conformers is discussed by comparison of experimental results and theoretical calculations by molecular dynamics.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260320102
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  • 4
    Electronic Resource
    Electronic Resource
    Ecdysone metabolism in Pieris brassicae during the feeding last larval instar (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 4 (1987), S. 139-149 
    Details
    ISSN: 0739-4462
    Keywords: ecdysteroids ; development ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ecdysone metabolism in Pieris brassicae during the feeding last larval stage was investigated by using 3H-labeled ecdysteroid injections followed by high-performance liquid chromatographic (HPLCAbbreviations: 3DE = 3-dehydroecdysone; 3D20E = 3-dehydro-20-hydroxyecdysone; 2026E = 20,26-dihydroxyecdysone; E = ecdysone; Eoic = ecdysonoic acid; 2026E′ = 3-epi-20,26-dihydroxyecdysone; E′ = 3-epiecdysone; E′oic = 3-epiecdysonoic acid; E′8P = 3-epiecdysone 3-phosphate; 20E′ = 3-epi-20-hydroxyecdysone; 20E′3P = 3-epi-20-hydroxyecdysone 3-phosphate; FT = Fourier transform; HPLC = high-performance liquid chromatography; 20E = 20-hydroxyecdysone; 20Eoic = 20-hydroxyecdysonoic acid; NMR = nuclear magnetic resonance; NP-HPLC = normal phase HPLC; RP-HPLC = reverse phase HPLC; TFA = trifluoroacetic acid; Tris = tris(hydroxymethyl)-aminomethane.) analysis of metabolites. Metabolites were generally identified by comigration with available references in different HPLC systems. Analysis of compounds for which no reference was available required a large-scale preparation and purification for their identification by 1H nuclear magnetic resonance spectrometry.The metabolic reactions affect the ecdysone molecule at C-3, C-20, and C-26, leading to molecules which are modified at one, two, or three of these positions. At C-20, hydroxylation leads to 20-hydroxyecdysteroids. At C-26, hydroxylation leads to 26-hydroxyecdysteroids which can be further converted into 26-oic derivatives (ecdysonoic acids) by oxidation. At C-3, there are several possibilities: there may be oxidation into 3-dehydroecdysteroids, or epimerization possibly followed by phosphate conjugation.Thus, injected 20-hydroxyecdysone was converted principally into 20-hydroxyecdysonoic acid, 3-dehydro-20-hydroxyecdysone, and 3-epi-20-hydroxyecdysone 3-phosphate. Labelled ecdysone mainly gave the same metabolites doubled by a homologous series lacking the 20-hydroxyl group.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940040207
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  • 5
    Electronic Resource
    Electronic Resource
    24-Epi-makisterone a (not makisterone A) is the major ecdysteroid in the leaf-cutting ant Acromyrmex octospinosus (reich) (hymenoptera, formicidae: Attini) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 23 (1993), S. 29-35 
    Details
    ISSN: 0739-4462
    Keywords: 1H-NMR ; 24β-configuration ; symbiosis ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The chemical nature of the major ecdysteroid from pupae of the leaf-cutting ant Acromyrmex octospinosus has been reinvestigated. On the basis of reversed phase high performance liquid chromatography and mass spectrometry, this compound was previously identified as makisterone A [Maurer et al., Arch Insect Biochem Physiol 16, 1 (1991)] but a more careful examination has led to the conclusion that it is in fact 24-epi-makisterone A. This finding stresses the limits of criteria used for the identification of ecdysteroids and the possible need for reexamination of makisterone A identification in some other species feeding on a 24β-methyl sterol source. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940230105
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and nuclear magnetic resonance study of 3-dehydroecdysteroids (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 10 (1989), S. 199-213 
    Details
    ISSN: 0739-4462
    Keywords: ecdysteroids ; proton NMR ; carbon NMR ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Several 3-dehydro- (or 3-oxo-) ecdysteroids have been prepared by enzymatic and/or chemical means. Methods for their purification using various high-performance liquid chromatography systems are described. Proton and carbon nuclear magnetic resonance analyses show that 3-dehydroecdysteroids when dissolved in water or methanol (but not in chloroform) present a temperature-dependent equilibrium between two forms. The possible structure of these two forms is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940100304
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