Integrative assessment of the genotoxic effects of the neurotoxin saxitoxin produced by the freshwater cyanobacterium <i>Raphidiopsis raciborskii</i>

Saxitoxin (STX), a potent neurotoxin produced by cyanobacteria, has not been comprehensively investigated with respect to genotoxic potential, especially in freshwater environments. This study aimed to characterize the genotoxic potential of STX obtained from <i>Raphidiopsis</i>. <i>raciborskii</i> cultures using <i>in vitro</i> and <i>in silico</i> approaches. Mutagenic potential was determined through the Ames test with <i>Salmonella typhimurium</i> strains TA98, TA100, and TA102. DNA damage and chromosomal instability were assessed in human glioblastoma U87-MG cells using the comet and cytokinesis-block micronucleus cytome (CBMN-Cyt) assay, respectively. In addition, systems biology tools were applied to explore STX interactions with genes involved in DNA damage response pathways. Data demonstrated no marked mutagenic activity in the Ames test across tested concentrations (0.625-10 µg/L). However, significant DNA damage and increased micronucleus (MN) formation were observed at 2.5, 5, or 10 µg/L in U87-MG cells, without accompanying cytotoxicity. <i>In silico</i> analysis identified interactions between STX and key proteins, including P53, CDK5, and GSK3B, indicating pathways related to DNA damage, cell cycle regulation, and neurogenesis. These findings suggest that STX from freshwater cyanobacteria might induce genotoxic effects at environmentally relevant concentrations. The integration of <i>in vitro</i> and computational data supports the need for regulatory monitoring of STX in drinking water and emphasizes the relevance of neural cell-based models in assessing cyanotoxin-related adverse risks.