Synthesis and biological studies of flexible brevetoxin/ciguatoxin models with marked conformational preference

A comparison of the more active polyether toxins which are selective activators of voltage-sensitive sodium channels (VSSC), indicate that these molecules are mostly flat, with a hinge part around the middle of the molecules and a large curvature at one of the ends. Assuming that the receptor is topographically complementary to the active molecules, from the result reported here we could conclude, that the specific requirements of the receptor region can be achieved by synthetic polyether models based on exclusive participation of oxane/oxepane moieties. A new convergent approach to give oxepene rings via double reduction of methyl diacetals is explored. In searching for biological models to further characterize Na+ channels, our studies show that different voltage-dependent Na+ channels are expressed in the rat uterus and activated by brevetoxin-B. However, selected compound models synthesized in this work, failed to inhibit or activate Na+ channel function. (C) 2002 Elsevier Science Ltd. All rights reserved.