Characterization of the Preferred Stereochemistry for the Neuropharmacologic Actions of Antillatoxin

W. I. Li, B. L. Marquez, T. Okino, F. Yokokawa, T. Shioiri, W. H. Gerwick, T. F. Murray

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24 Scopus citations


Antillatoxin is a potent ichthyotoxin and cytotoxin previously discovered from the marine cyanobacterium Lyngbya majuscula. Ensuing studies of its mechanism of action showed it to activate the mammalian voltage-gated sodium channel at a pharmacological site that is distinct from any previously described. The structure of antillatoxin, initially formulated from spectroscopic information, was subsequently corrected at one stereocenter (C-4) as a result of synthesis of four different antillatoxin stereoisomers (all possible C-4 and C-5 diastereomers). In the current study these four stereoisomers, (4R,5R)-, (4S,5R)-, (4S,5S)-, and (4R,5S)-antillatoxin, were characterized in five different biological assay systems: ichthyotoxicity to goldfish, microphysiometry using cerebellar granule cells (CGCs), lactose dehydrogenase efflux from CGCs, monitoring of intracellular Ca2+ concentrations in CGCs, and cytotoxicity to Neuro 2a cells. Across these various biological measures there was great consistency in that the natural antillatoxin (the 4R,5R-isomer) was greater than 25-fold more potent than any of the other stereoisomers. Detailed NMR studies provided a number of torsion and distance constraints that were modeled using the MM2* force field to yield predicted solution structures of the four antillatoxin stereoisomers. The macrocycle and side chain of natural (4R,5R)-antillatoxin present an overall "L-shaped" topology with an accumulation of polar substituents on the external surface of the macrocycle and a hydrogen bond between N(H)-7′ and the C(O)-1 carbonyl. The decreased potency of the three non-naturally occurring antillatoxin stereoisomers is certainly a result of their dramatically altered overall molecular topologies.

Original languageEnglish (US)
Pages (from-to)559-568
Number of pages10
JournalJournal of Natural Products
Issue number4
StatePublished - Apr 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Drug Discovery
  • Complementary and alternative medicine
  • Organic Chemistry


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