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  • 1
    Electronic Resource
    Electronic Resource
    Latrunculins - novel marine macrolides that disrupt microfilament organization and affect cell growth: I. Comparison with cytochalasin D (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 127-144 
    Details
    ISSN: 0886-1544
    Keywords: latrunculin A ; latrunculin B ; cell shape ; actin organization ; cell growth and division ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The latrunculins are architecturally novel marine compounds isolated from the Red Sea sponge Latrunculia magnifica. In vivo, they alter cell shape, disrupt microfilament organization, and inhibit the microfilament-mediated processes of fertilization and early development. In vitro, latrunculin A was recently found to affect the polymerization of pure actin in a manner consistent with the formation of a 1:1 molar complex with G-actin. These in vitro effects as well as previous indications that the latrunculins are more potent than the cytochalasins suggest differences in the in vivo mode of action of the two clases of drugs. To elucidate these differences we have compared the short- and long-term effects of latrunculins on cell shape and actin organization to those of cytochalasin D. Exposure of hamster fibroblast NIL8 cells for 1-3 hr to latrunculin A, latrunculin B, and cytochalasin D causes concentration-dependent changes in cell shape and actin organization. However, the latrunculin-induced changes were strikingly different from those induced by cytochalasin D. Furthermore, while initial effects were manifest with both latrunculin A and cytochalasin D already at concentrations of about 0.03 μg/ml, latrunculin A caused complete rounding up of all cells at 0.2 μg/ml, whereas with cytochalasin D maximum contraction was reached at concentrations 10-20 times higher. The short-term effects of latrunculin B were similar to those of latrunculin A although latrunculin B was slightly less potent. All three drugs inhibited cytokinesis in synchronized cells, but their long-term effects were markedly different. NIL8 cells treated with latrunculin A maintained their altered state for extended periods. In contrast, the effects of cytochalasin D progressed with time in culture, and the latrunculin B-induced changes were transient in the continued presence of the drug. These transient effects were found to be due to a gradual inactivation of latrunculin B by serum and were used to compare recovery patterns of cell shape and actin organization in two different cell lines. This comparison showed that the transient effects of latrunculin B were fully reversible for the NIL8 cells and not for the mouse neuroblastoma N1E-115 cells.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970130302
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  • 2
    Electronic Resource
    Electronic Resource
    Novel marine alkaloids from the tunicate Eudistoma sp. are potent regulators of cellular growth and differentiation and affect cAMP-mediated processes (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 157 (1993), S. 481-492 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Six novel alkaloids that contain a fused tetracyclic pyrido[2,3,4-kl]acridine ring system were purified recently from the Red Sea purple tunicate Eudistoma sp. Evaluation of the effects of these alkaloids on cultured neuroblastoma and fibroblast cells revealed that they possess potent growth regulatory properties, and affect cell shape and adhesion. In mouse neuroblastoma cells, the Eudistoma alkaloids inhibited cell proliferation and induced a process of differentiation during which the cels flattened onto the surface, increased considerably in size, and extended long neurites. In hamster fibroblasts the alkaloids slowed down cell multiplication, and caused an exceptional cell flattening or elongation. In a virustransformed derivative of the hamster fibroblasts the alkaloids restored many aspects of normal cell growth and morphology. In addition, several of the alkaloids mimicked the effects of cAMP analogs on two well-characterized cAMP-mediated processes involved in hepatic glucose metabolism-inhibition of pyruvate kinase (PK) activity and induction of mRNA for phosphoenolpyruvate carboxykinase (PEPCK). All these effects suggest that the Eudistoma alkaloids may act on the cAMP signaling system. However, a single application of these compounds was sufficient to completely block cell multiplication and to induce and sustain differentiation and “reverse transformation”. Furthermore, these effects were not readily reversible following removal of the drugs. In contrast, a single application of agents that mimic or elevate cAMP induced a transient response that waned with time in culture, and the effects induced by constant elevation of cAMP reverse rapidly following drug removal. We propose that the Eudistoma alkaloids cause growth inhibition, differentiation, and reverse transformation by modifying the activity state of proteins that are involved in the regulation of cell shape and adhesion and serve as a target for the cAMP and/or other second messenger systems. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041570307
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  • 3
    Electronic Resource
    Electronic Resource
    On the Chemistry of Latrunculins A and B (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1171-1188 
    Details
    ISSN: 0170-2041
    Keywords: Actin ; Latrunculins ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die Chemie der Latrunculine A und BDas chemische Verhalten von Latrunculin A (1) und B (2) (Lat A und B) unter verschiedenen Reaktionsbedingungen wird beschrieben. Die Kombination der Makrolid-, THP-Lactol- und 2-Thiazolidinon-Ringsysteme führt zu interessanten unerwarteten chemischen Umwandlungen. Die Strukturen zweier neuer, aus Latrunculia magnifica isolierter Lats, 6,7-Epoxy-Lat A (3) und Lat M (4), werden diskutiert.
    Notes: The chemical behavior of latrunculins A (1) and B (2) (Lat A and B) under a variety of reaction conditions is described. The combination of the macrolide, the THP-lactol, and the 2-thiazolidinone rings was found to result in interesting unpredicted chemical transformations. The structures of two new Lats, 6,7-epoxy-Lat A (3) and Lat M (4) isolated from Latrunculia magnifica are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890289
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  • 4
    Electronic Resource
    Electronic Resource
    Ergosta-5,7,9(11), 22-tetraen-3β-ol and its 24ξ-Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortisPart XIV in the Stanford series ‘Minor and Trace Sterols in Marine Invertebrates’. Part XIII: [1]. (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 2037-2045 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The steroidal components of a Red Sea sponge, Biemna fortis, were fractionated through reversed phase HPLC. and analyzed by a combination of physical methods, including high resolution GC./MS. and 360 MHz 1H-NMR. The sponge contains five conventional Δ5-sterols, 1a-c, 1e, 1g, which comprise about 25% of the mixture and 2,5% of gorgosterol (1h), a sterol never found before in Porifera. Three Δ5,7,22-sterols were also present as major components in the mixture (∼70%): cholesta-5,7,22-trien-3β-ol (2a), ergosta-5,7,22-trien-3β-ol (2c) and (24R)-ethylcholesta-5,7,22-trien-3β-ol (2e) whereas two new tetra-unsaturated sterols were identified in minor amounts (2%): ergosta-5,7,9(11),22-tetraen-3β-ol (3c) and 24ξ-ethylcholesta-5,7,9 (11), 22-tetraen-3β-ol (3e or 3f). NMR. spectroscopy made possible the assignment of a 24R configuration for all the C(24) substituted sterols isolated in sufficient amount from the mixture. The possible symbiotic, dietary or biosynthetic origins of these sterols are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620633
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  • 5
    Electronic Resource
    Electronic Resource
    Swinholide-A, a new marine macrolide. Complete assignment of 1H and 13C spectra by 2D NMR techniques (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 343-349 
    Details
    ISSN: 0749-1581
    Keywords: 2D NMR ; marine sponge ; polyketide ; long range couplings ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H and 13C NMR spectra of the novel marine macrolide swinholide-A, which provide the basis for its structure elucidation, have been completely assigned by parallel use of 1D and homo- and hetero-nuclear 2D NMR techniques. Swinholide-A (1) probably a polyketide, is a 22-membered macrolide embodying a dihydropyran ring and a 10-carbon side-chain ending with a substituted tetrahydropyran ring. The high degree of overlap of eleven CH - O and nine CH2 signals in the 1D proton NMR spectrum of 1 necessitated the structure elucidation of swinholide-A tetraformate (2) by 2D homo- (up to 6J with formyl groups) and hetero-nuclear NMR correlations. Formyl groups can be good structural probes in complex polyalcohols, as shown by the observed 5J and 6J formate couplings in 2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240414
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