Cylindrospermopsin

• Hepatotoxic
• Protein synthesis inhibitor
• Cited in several environment-related research articles

Cylindrospermopsin is a tricyclic alkaloid hepatotoxin produced by cyanobacteria. Cylindrospermopsin exhibits a completely different mechanism of toxicity than microcystins by targeting/inhibiting the synthesis of glutathione, proteins, and pyrimidine nucleotides. Cylindrospermopsin is considered to be genotoxic. It was shown to break double stranded DNA and reduce cell viability in HepG2 cells.

Cyanobacteria are photosynthetic prokaryotes mostly present in freshwater ecosystems. The increasingly frequent appearance of cyanobacteria blooms in lakes and rivers is linked to climate changes and human activities. Microcystins are a group of cyclic heptapeptide hepatotoxins produced by a number of cyanobacterial genera. The most notable of which, and namesake, is the widespread genus Microcystis. Structurally, all microcystins consist of the generalized structure cyclo(-D-Ala¹-X²-D-MeAsp³-Y⁴-Adda⁵-D-Glu⁶-Mdha⁷-). X and Y are variable L-amino acids, D-MeAsp is D-erythro-β-methylaspartic acid and Mdha is N-methyldehydroalanine. Adda is the cyanobacteria unique C₂₀ β-amino acid 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid. Substitutions of the variable L-amino acids at positions 2 and 4 give rise to at least 21 known primary microcystin analogs and alterations in the other constituent amino acids result in more than 90 reported mycrocystins to date.