Identification of teratogenic polymethoxy-1-alkenes from Cylindrospermopsis raciborskii,and taxonomically diverse freshwater cyanobacteria and green algae

Cylindrospermopsis raciborskii is among the most commonly recognized toxigenic cyanobacteria associated with harmful algal blooms (HAB) in freshwater systems, and specifically associated with multiple water-soluble toxins. Lipophilic metabolites from C. raciborskii, however, were previously shown to exert teratogenicity (i.e. inhibition of vertebrate development) in the zebrafish (Danio rerio) embryo model, specifically suggesting the presence of additional bioactive compounds unrelated to the currently known toxins. In the present study, a series of known teratogenic polymethoxy-1-alkenes (PMA) were identified, purified and chemically characterized from an otherwise well-characterized strain of toxigenic C. raciborskii. Although PMA have been previously identified in other cyanobacteria, this is the first time they have been identified from this recognized HAB species. Following their identification from C. raciborskii, the taxonomic distribution of the PMA was additionally investigated by chemical screening of a freshwater algal (i.e. cyanobacteria, green algal) culture collection. Screening suggests that these compounds are distributed among phylogenetically diverse taxa. Furthermore, parallel screening of the algal culture collection, using the zebrafish embryo model of teratogenicity, the presence of PMA was found to closely correlate with developmental toxicity of these diverse algal isolates. Taken together, the data suggest PMA contribute to the toxicity of C. raciborskii, as well as apparently several other taxonomically disparate cyanobacterial and green algal genera, and may, accordingly, contribute to the toxicity of diverse freshwater HAB.