Gambieroxides, a diverse metabolite class produced by the dinoflagellate genera Gambierdiscus and Fukuyoa

Ciguatera poisoning (CP) is the most prevalent marine toxin illness globally and disproportionately affects people from circumtropical regions due to the occurrence of the causative microalgae, Gambierdiscus. Increased reports of CP cases globally are linked to changing ocean temperatures, localized outbreaks in new regions and importation of ciguatoxin-contaminated fish into non-endemic regions. Gambierdiscus spp. produce several classes of bioactive polyether metabolites in addition to ciguatoxins, including gambierones, maitotoxins, gambieroxide, gambierol and gambieric acids. The role of these additional metabolites in CP remains unclear. In this study, non-targeted analysis using LC-HRMS was used to examine gambieroxide profiles in Gambierdiscus and Fukuyoa species. Initially purified gambieroxide was compared with a tentatively assigned gambieroxide analogue detected in G. pacificus and G. lewisii. The method was then used to characterize gambieroxide-like analogue profiles in the extracts of thirteen Gambierdiscus and two Fukuyoa species, with over thirty different analogues detected based on characteristic mass spectral fragmentation patterns in both positive and negative ionization modes. With few prior reports of these compounds, their detection across various species and strains provides valuable insight into the diversity of polyether compounds produced by Gambierdiscus and Fukuyoa. Future work will focus on understanding the significance of these gambieroxide-like analogues in CP.