Abstract
Three new imidazole alkaloids, leucettamines A [1] and B [2] and leucettamidine [3], have been isolated from the Palauan sponge Leucetta microraphis. Their structures were established on the basis of extensive spectral analyses. Leucettamine A showed potent leukotriene B4 receptor binding activity (K(i) = 1.3 microM), while leucettamine B was essentially inactive (K(i) = 100 microM) and leucettamidine showed significant activity (K(i) = 5.3 microM). With leucettamine A identified as a pure LTB4 receptor antagonist, a new structure lead is presented to inflammation therapy.
MeSH terms
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Alkaloids / pharmacology*
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Animals
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Cells, Cultured
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Dioxoles / isolation & purification*
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Dioxoles / pharmacology
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Gas Chromatography-Mass Spectrometry
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Imidazoles / isolation & purification*
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Imidazoles / pharmacology*
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Magnetic Resonance Spectroscopy
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Porifera / chemistry*
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Receptors, Immunologic / antagonists & inhibitors*
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Receptors, Immunologic / metabolism
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Receptors, Leukotriene B4
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Spectrometry, Mass, Fast Atom Bombardment
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Structure-Activity Relationship
Substances
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Alkaloids
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Dioxoles
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Imidazoles
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Receptors, Immunologic
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Receptors, Leukotriene B4
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leucettamine B
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leucettamine A