Cyanobacteria are microorganisms found in different parts of the world. Some genera are cyanotoxins producers a sodium channel blockingneurotoxin (saxitoxins). Some homeopathic preparations have been identified as remedial action on toxicity models in Artemia salina. This study aimed to observe whether homeopathic products influence the toxicity ofR.raciborskiiextract onA.salinaby inducing cyst hatching arrest, anembryo bioresiliencemodel previously developed in our laboratory (Pinto et al., 2021; Mohammad et al., 2022). Thus, previous toxicity testswere carried out on cysts in 96-well plates, using different concentrations of the extract obtained from regular cultivation of R. raciborskii in HCl 0.05M, whose strain, named T3, is kept in the laboratory of Cyanobacteria at FURGS, Brazil.The standardization of toxin concentration was based on an established scale developed at FURGS, in which the number of T3 filaments is associated withspecific saxitoxin concentrationsdefined by chromatography. The concentration of 2.6 μg/L was chosen since it reducedthe cysthatching rate by 30%, the ideal level to observe embryo bioresilience. Then, a screeningstudy with 22 homeopathic preparations was tested blind in three experimental series, in duplicate,against threecontrols (unchallenged, water,and succussed water)for possible toxicity attenuationon Artemia salinacysts hatching rate. Homeopathic medicines were prepared in pure,sterile water from a stock homeopathic solution, one potency below the working potency.

After the 1:

100 dilution, 100 succussions were made using a robotic arm (Denise, Autic). The medicines were inserted into the seawater on a 10% basis. Due to the high sensitivity of A. salinato the circalunar variations, all experiments were performed during the first quarter moon. Statistical analysis was performed by two-way ANOVA followed by Tukey, with α=0.05. The most significant results indicative of bioresilience improvement were seen after the treatment with Nitric acidum6 cH, Plumbum metallicum6 cH, isotherapic 200 cH, and hydrochloric acid 1 cH being the last one used as a vehicle of the extracts. Thus, these preparations were chosen to be used in further experiments. In conclusion, the Artemia salinamodel has also beenuseful to study bioresilienceimprovement by homeopathic medicines after intoxication with saxitoxin.