Gymnodimine C, an Isomer of Gymnodimine B, from Karenia selliformis

Abstract
Gymnodimine C (1), an oxidized analogue of the spiro-imine algal toxin gymnodimine (3), was isolated from extracts of the cells of Karenia selliformis. The structure of gymnodimine C, determined by one- and two-dimensional 1H NMR spectroscopy and mass spectrometry, was found to be isomeric with gymnodimine B (2) at C-18. Keywords: Gymnodimine; Gymnodinium selliforme; Karenia selliformis; shellfish toxin; spiro-imine