Potential endocrine disrupting activity of cyanobacteria: Possible roles for microcystins

Abstract

This thesis investigated the connection between two major global concerns: the infamous cyanobacteria (“blue-green algae”), and the endocrine disruptors, compounds able to interfere with the hormonal system. Do cyanobacteria exert endocrine disrupting activity? Are the cyanobacterial toxins “microcystins” involved? Cyanobacterial extracts, complex combinations of known and unknown compounds including microcystins, were screened using specific in vitro assays to assess their potential endocrine activity. Pure microcystins were also tested. Results showed that cyanobacterial compounds (microcystins, but also other metabolites) could have an endocrine disrupting activity, especially interfering with hormone production and metabolism. Furthermore, a combination of chemical analysis and reactions were used to deepen structural knowledge of microcystins (they are a family including hundreds of congeners!). Seven new microcystin congeners were identified in this work. Resulting data on the endocrine activity of cyanobacteria as well as the discovery of new microcystins highlighted the complexity and the many “unknowns” that remain behind these two global concerns and their interconnection.