Evaluation of Cytotoxicity and Cell Death Induced In Vitro by Saxitoxin in Mammalian Cells

Abstract

Since the cyanotoxin saxitoxin (STX) is a neurotoxin and induces ecological changes in aquatic environments, a potential risk to public and environmental health exists. However, data on STX-mediated cytotoxic and genotoxic effects are still scare. In order to gain a better understanding of the effects of this toxin, the cytotoxic and genotoxic potential of STX was examined in two mammalian cell lines. Neuro 2A (N2A), a neuroblastoma mouse cell line, and Vero cell line, derived from Vero green monkey kidney cells, were exposed to several concentrations of STX ranging from 0.5 to 64 nM to determine cell viability, induction of apoptosis (DNA fragmentation assay), and formation of micronuclei (MN) (cytokinesis-block micronucleus assay; CBMN) following 24 h of incubation. The half maximal effective concentration (EC50) values for STX calculated in cell viability tests were 1.01 nM for N2A and 0.82 nM for Vero cells. With increasing STX concentration there was evidence of DNA fragmentation indicating apoptosis induction in Vero cells with a 50% increase in DNA fragmentation compared to control at the highest STX concentration tested (3 nM). The results demonstrated no significant changes in the frequency of micronucleated binucleated cells in N2A and Vero cells exposed to STX, indicating the absence of genotoxicity under these test conditions. There was no apparent cellular necrosis as evidenced by a lack of formation of multinucleated cells. In conclusion, data reported herein demonstrate that STX produced death of both cell types tested through an apoptotic process.

Dereplication of Natural Products with Antimicrobial and Anticancer Activity from Brazilian Cyanobacteria

“…Aeruginosin and anabaenopeptin are protease inhibitors with no reported cytotoxic effects. Lastly, saxitoxin is a neurotoxin that is associated with cytotoxic effects on mammalian cells [66][67][68]. Further analysis using isolated compounds would be necessary to show which are the antileukemic compounds produced by the tested Brazilian cyanobacteria.…”

Integrating In Vitro Data and Physiologically Based Kinetic Modeling to Predict and Compare Acute Neurotoxic Doses of Saxitoxin in Rats, Mice, and Humans

“…In all these studies, electrophysiological signal changes under increasing STX concentrations were recorded using the multielectrode (MEA) assay and patch-clamp technique or monitored with a voltage-sensitive fluorescent probe. Additionally, in vitro toxicity data were also obtained from a binding assay characterizing the competitive binding of STX against tritium-labeled STX for receptor sites on rat brain synaptosomes or from the cytotoxicity assay in mouse Neuro-2a cells in the presence or absence of ouabain and veratridine as a sodium/potassium ATPase pump blocker and a sodium channel activator, respectively …”

Genotoxicity of Natural Water during the Mass Development of Cyanobacteria Evaluated by the Allium Test Method: A Model Experiment with Microcosms

“…However, this depends on different parameters: exposure concentrations, time of exposure, test systems, pure material or in complex mixtures and other conditions. The mutagenic and/or genotoxic effects of cyanotoxins such as MCs, cylindrospermopsins, nodularins and saxitoxins have been shown in several studies [ 16 , 17 , 18 , 19 ].…”

“…However, additional research is needed for the better understanding of cyanotoxin behaviors in different conditions and concentrations, as well as co-interactions in natural mixtures and various ecosystems. In addition, the underlying mechanisms of genotoxicity are not entirely clear [ 16 , 17 , 18 , 19 , 23 , 24 , 25 ].…”