Previous studies have shown that COSAN has moderate to low toxicity toward eukaryotic cells. However, the mechanism of this toxicity is still obscure. To assess whether COSAN toxicity depends on interaction with DNA, we conducted in vitro experiments on six cell lines and red blood cells (RBCs) because mature RBCs lack a nucleus (anuclear) and DNA but are packed with hemoglobin. By in vitro hemolysis, we determined COSAN toxicity to RBCs by measuring hemoglobin release due to RBC membrane disruption. COSAN showed moderate hemolytic activity, with a concentration at 50% hemolysis (EC50) of 100.5 µM (Table ). Accordingly, COSAN may have a purely membranolytic activity towards cells without interacting with DNA.