Avaliação da ecotoxicidade e genotoxicidade de losartana potássica após fotólise UVC e processo UV/H2O2

Abstract

Losartan potassium is a drug belonging to the hypertensive AT1 receptor inhibitor of angiotensin II class, which evokes vasoconstriction and elevation of blood pressure. It is widely used in the arterial hypertension and heart failure treatment, being the most commonly used antihypertensive in Brazil. The inefficiency of conventional methods in wastewater treatment for removal of emerging contaminants contributes to the drugs insertion in water bodies, such as losartan potassium and its active carboxylic acid metabolite, losartan potassium concentrations from 0.295 ng L-1 to 2.5 mg L-1 were found in the environment, so it is necessary the study and application of complementary techniques for this xenobiotic removal. In this sense, the objective was to evaluate the degradation, ecotoxicity and genotoxicity of the drug losartan potassium (2.5 mg L-1) after treatment by photolysis (UVC radiation) and UV/H2O2 process. For reaching this goal, acute tests were performed by using Daphnia magna (NBR 12713:2016) and chronic tests with Desmodesmus subspicatus (NBR 12648:2018). To evaluate the genotoxicity, the comet assay was performed with D. magna cells by applying the alkaline gel electrophoresis technique. The untreated drug was more toxic for D. magna compared to the treated samples, with the toxicity factor (TF) value equal to 4 before treatment and ≤ 2 after treatments by photolysis and UV/H2O2. For D. subspicatus, no previously treated and post-treatment toxicity was found. The exception for both bioindicators was the treatment of 240 minutes by UV/H2O2 process, which was highly toxic for D. magna and D. subspicatus, with FT > 2. A genotoxic effect of losartan potassium was observed in its unchanged structure and after UV/H2O2 degradation, however, for the treatment by photolysis the attenuation of this harmful effect was observed. By means of high performance liquid chromatography (HPLC), the drug’s complete degradation was verified from 30- minute-degradation for both treatments. However, degradation subproducts came up. It is observed that, despite the low FT values for the acute and chronic assay, the drug is genotoxic to D. magna. Even though it is a drug easily degraded by UVC radiation treatment by photolysis, it can be an alternative for removal of this contaminant without potentiating acute, chronical and genotoxic toxicity effects, which does not apply to UV/H2O2 treatment.