Many species of cyanobacteria (blue-green algae) produce secondary metabolites with potent biotoxic or cytotoxic properties. These metabolites differ from the intermediates and cofactor compounds that are essential for cell structural synthesis and energy transduction. The mass growth of cyanobacteria which develop in fresh, brackish and, marine waters commonly contain potent toxins.
Cyanobacterial toxins or
cyanotoxins are responsible for or implicated in animal
poisoning, human
gastroenteritis, dermal contact irritations and primary
liver cancer in humans. These toxins (
microcystins, nodularins, saxitoxins,
anatoxin-a,
anatoxin-a(s),
cylindrospermopsin) are structurally diverse and their effects range from liver damage, including
liver cancer to neurotoxicity. Several incidents of human illness and more recently, the death of 60 haemodialysis patients in Caruaru, Brazil, have been linked to the presence of
microcystins in water. In response to the growing concern about the non-lethal acute and chronic effects of
microcystins, World Health Organization has recently set a new provisional guideline value for
microcystin-LR of 1.0 microg/L in
drinking water. Cyanobacteria including
microcystin-producing strains produce a large number of
peptide compounds, e.g. micropeptins, cyanopeptolins, microviridin, circinamide, aeruginosin, with varying bioactivities and potential pharmacological application. This article discusses briefly
cyanobacterial toxins and their implications on human health.