Acute effects of three Geitlerinema spp. (Cyanobacteria) extracts administrated in mice: symptoms and histopathological aspects

Cyanobacteria are commonly found in drinking water supplies, and are responsible by numerous cases of humans’ intoxications. Geitlerinema is a genus described as unable to form blooms, however, it is very frequent in Sao Paulo’s reservoirs, the most densely populated area in Brazil. During the search for bioactive substances from strains maintained in the Cyanobacteria Culture Collection of the Institute of Botany, Sao Paulo, Brazil, three strains of Geitlerinema spp. (CCIBt920, CCIBt1044—G. amphibium; CCIBt939—G. splendidum) showed toxicity in mouse bioassay (i.p.). The symptoms observed in this bioassay were very distinct from those presented by animals poisoned with the already known cyanotoxins. In such cases, histological analysis of vital organs is very important to determine the cause of deaths and intoxication. Histological analyses were performed in mice administrated with CCIBt920 and CCIBt1044 methanol extract (ME), and CCIBt939 0.1 M acetic acid extract (AE). All extracts caused very similar histopathological features: hemorrhagic focuses, edema, alveolar collapse and hyperplasia in the lungs, due to an increase in the number of immune system cells (macrophages); disorganization of the hepatic parenchyma, necrosis, loss of vein endothelium, presence of polymorphonuclear cells in the liver; alterations in the convoluted tubules and necrotic areas in the kidneys of mice intoxicated with CCIBt939 AE, while the other G. amphibium extracts had no major effects in this organ. The histopathological findings indicate the occurrence of inflammatory processes in the mice treated with these cyanobacteria extracts. Taken together, our results suggest the presence of new cyanotoxins(s), different from the known cyanotoxins. The isolation and characterization of this toxin(s) are in progress in our laboratories.