RECENT DEVELOPMENTS IN THE MOLECULAR STRUCTURE OF CIGUATOXIN

¹ Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822

Crystalline ciguatoxin isolated from moray eel (Lycodontis Gymnothorax javanicus) viscera has an LD₅₀ of 0.45 g/kg (i.p., mice). It has a molecular weight of 1111.7 ± 0.2 daltons. ¹H NMR studies have shown that it is a polar and highly oxygenated molecule belonging to the class of polyethers. On basic alumina ciguatoxin is reversibly converted to a chromatographically distinct less polar form, which is equally toxic and elicits typical ciguatoxin symptoms in mice.

From parrotfish (Scarus sordidus), which originated on a ciguateric reef on Tarawa atoll (Kiribati), we have isolated two toxins that evoke ciguatera symptoms in mice at approximately equal levels. Chromatographic evidence suggests that the two toxins are identical with the two ciguatoxins of different polarity and that the less polar form is the previously described scaritoxin.