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  • 1
    Electronic Resource
    Electronic Resource
    Full stereochemical understanding in a new (2R,3R,4R)-4-hydroxyisoleucine synthesis (2001)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 1415-1417 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: We present the crystal and molecular structures of 2,3,6,7,8,8a-hexahydro-6,8-methano-7,7,8a-trimethyl-3-(1-methyl-2-oxopropylidene)-5H-1,4-benzoxazin-2-one, C16H21NO3, (III), and 2,3,6,7,8,8a-hexahydro-3-(2-hydroxy-1-methylpropyl)-6,8-methano-7,7,8a-trimethyl-5H-1,4-benzoxazin-2-one, C16H25NO3, (V). These compounds are two of the four key intermediates in our synthetic route to (2R,3R,4R)-4-hydroxyisoleucine. The two structures provide a full understanding of the stereochemistry in successive steps. This synthesis was based on a new optically pure chiral oxazinone auxiliary derived from (1R,2R,5R)-2-hydroxypinan-3-one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270101014597
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  • 2
    Electronic Resource
    Electronic Resource
    Two key chiral intermediates in a new 4-hydroxyisoleucine synthesis (2000)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 1037-1039 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: We present the crystal and molecular structure of two key compounds of a new synthesis strategy for isomers of natural (2S,3R,4S)-4-hydroxyisoleucines, 2,3,5,6,7,8-hexahydro-3-(1-hydroxy-1-methyl-2-oxopropyl)-6,8-methano-7,7,8a-trimethyl-5H-1,4-benzoxazin-2-one, C16H23NO4, and 2,3,5,6,7,8-hexahydro-3-(1-methyl-2-oxopropyl)-6,8-methano-7,7,8a-trimethyl-5H-1,4-benzoxazin-2-one, C16H23NO3. A new optically pure chiral oxazinone auxiliary derived from (1R,2R,5R)-2-hydroxypinan-3-one was used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010827010000740X
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  • 3
    Electronic Resource
    Electronic Resource
    Nouveaux dérivés de N-phtalimido-2-arylepropanoate de pantolactonyle (2000)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 445-447 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: We present the crystal and molecular structures of two new N-phthalyl-3-amino-2-arylpropionic acid pantolactonyl ester derivatives with 4-fluorophenyl and 3,4-dimethoxyphenyl as the aryl group, 2,3,4,5-tetrahydro-4,4-dimethyl-2-oxofuran-3-yl 3-phthalimido-2-(4-fluorophenyl)propanoate, C23H20FNO6, and 2,3,4,5-tetrahydro-4,4-dimethyl-2-oxofuran-3-yl 3-phthalimido-2-(3,4-dimethoxyphenyl)propanoate ethyl acetate hemisolvate, C25H25NO8·0.5C4H8O2. This structural study confirms the S configuration of the C2 and validates the stereospecificity of our synthesis strategy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270199015292
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  • 4
    Electronic Resource
    Electronic Resource
    Diméthyl 3-benzyl-2-(4-méthyl-2,5-dioxoimidazolidin-1-yl)butanedioate (2001)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 62-63 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: There are two symmetry-independent formula units of the title compound, dimethyl 3-benzyl-2-(4-methyl-2,5-dioxoimidazolidin-1-yl)butanedioate, C17H20N2O6, per cell. The two symmetry-independent molecules differ in their configuration and are diastereomers. This structural study confirms a new side reaction during the synthesis of seven-membered cyclopeptides. The stereochemistry of both diastereomers has been established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270100010830
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  • 5
    Electronic Resource
    Electronic Resource
    N-acetyl oxyntomodulin30–37: pharmacokinetics and activity on gastric acid secretion (1992)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 345 (1992), S. 57-63 
    Details
    ISSN: 1432-1912
    Keywords: Oxyntomodulin ; Oxyntomodulin30–37 ; Acetylation ; Gastric acid secretion ; Conscious rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oxyntomodulin, an intestinal hormone which inhibits gastric acid secretion, is composed of glucagon and a C-terminal octapeptide. This octapeptide mimics the biological activity of the hormone. We have studied the activity of the N-acetyl octapeptide, partially protected against enzymatic degradation, on pentagastrin-, histamine- and milk meal-stimulated secretion in conscious rats and compared it to that of oxyntomodulin and its derivatives. The N-acetylated octapeptide had a 3-fold higher potency than the octapeptide on pentagastrin-stimulated secretion. On histamine-stimulated secretion, the differences between the acetylated and the free octapeptides were that the former displayed a dose-response curve parallel to that of oxyntomodulin and a 4-fold higher potency. The increase in potency appears to be related in part to a decrease in the metabolic clearance rate in vivo (6-fold) and, in vitro, to an increase in half-life (3-fold) when incubated with rat liver plasma membranes. Similarly to the free octapeptide, the acetylated form decreased acid secretion stimulated by a milk meal, when infused before the meal. Acetylation of the Lysine side chains resulted in a totally inactive molecule. The results indicate that acetylating the N-terminus of the octapeptide of oxyntomodulin increases the similarities with the natural hormone. The still large difference in potency (≈ 40-fold) between the 37-amino acid peptide and its acetylated 8-amino acid derivative is explained by the higher (≈ 40-fold) metabolic clearance rate (MCR) of the latter, indicating that further decreasing this parameter, in particular by protecting the short peptide from the enzymatic degradation, should result in a potent and efficient molecule, usable for pharmacological research and therapeutics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175470
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  • 6
    Electronic Resource
    Electronic Resource
    Total structure and biological properties of laxaphycins A and B, cyclic lipopeptides from the marine cyanobacterium Lyngbya majuscula (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 289-292 
    Details
    ISSN: 1573-3904
    Keywords: Antifungal ; Cytotoxic ; Synergism ; Marfey's reagent ; E-didehydroaminobutyric acid ; β-Aminodeca(octa)noic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The tropical marine cyanobacterium Lyngbyamajuscula produces a series of cytotoxic andantimicrobial cyclic peptides. The totalstructure of the two major components,laxaphycins A and B, was determined byinterpretation of physical data, principallyhigh field NMR, FAB MS and MS/MS, in combinationwith chemical derivatization and degradationschemes. Absolute stereochemistries of thenatural and ‘exotic’ amino acids weredetermined. The two cyclic peptides exhibited anunusual biological synergism when tested forantifungal or cytotoxic effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008884402484
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  • 7
    Electronic Resource
    Electronic Resource
    Total structure and biological properties of laxaphycins A and B, cyclic lipopeptides from the marine cyanobacteriumLyngbya majuscula (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 289-292 
    Details
    ISSN: 1573-3904
    Keywords: Antifungal ; Cytotoxic ; Synergism ; Marfey's reagent ; E-didehydroaminobutyric acid ; β-Aminodeca(octa)noic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The tropical marine cyanobacteriumLyngbya majuscula produces a series of cytotoxic and antimicrobial cyclic peptides. The total structure of the two major components, laxaphycins A and B, was determined by interpretation of physical data, principally high field NMR, FAB MS and MS/MS, in combination with chemical derivatization and degradation schemes. Absolute stereochemistries of the natural and ‘exotic’ amino acids were determined. The two cyclic peptides exhibited an unusual biological synergism when tested for antifungal or cytotoxic effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442891
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