First evidence of Gymnodimine D in Alexandrium ostenfeldii strain K-1354

This study presents a comprehensive analysis of gymnodimine-series toxins produced by Alexandrium ostenfeldii (K- 1354) using liquid chromatography tandem mass spectrometry (LC-MS/MS). Three peaks with identical precursor ions but different retention times were observed, suggesting the presence of isomers identified as gymnodimines B, C, and D. Employing an integrated approach combining LC-MS/MS with electron transfer dissociation, the study revealed the characteristic fragment ions of gymnodimine D. Notably, this study demonstrated the potential for isolating and purifying gymnodimine D from culturable A. ostenfeldii, addressing the current lack of commercially available standards for this isomer. This study contributes remarkably to marine biotoxin monitoring and the understanding of these structurally complex compounds.