Evaluation of the toxic effects of some antiviral drugs on Xenopus laevis embryo

Starting in late 2019, humanity faced one of the largest pandemics in its history at a time when its population increased more than ever before, and both vaccines and antiviral drugs were used extensively in the fight against the pandemic. Favipiravir and oseltamivir, which were also used extensively in our country during this period, are antiviral drugs that have been used extensively for many years in the fight against common viral infections. Oseltamivir is an antiviral agent used extensively against the H5N1 virus, while favipiravir has been used extensively in the COVID-19 pandemic. The intensive use of these chemicals in disease control causes them to reach high concentrations in environmental waters and to enter the aquatic ecosystem and interact with non-target organisms. Therefore, in this study, the lethality level, malformation status, developmental levels and biochemical marker levels of Xenopus laevis embryos exposed to different concentrations of commercial antiviral drugs were measured to evaluate toxic and teratogenic effects. According to the results, the 96-hour median lethal concentrations (LC50) and teratogenic index (TI) values of commercial and pure favipiravir for X. laevis embryos exposed to antiviral drugs were 137.9 mg/L and 4.67, 156.9 mg/L and 6.28, respectively. The 96-hour LC50 values for commercial and pure oseltamivir were 32.3 and 58.8 mg/L, respectively. According to these results, among the antiviral drugs tested, favipiravir both limits embryo development and is teratogenic. According to biochemical marker results, the responses of stage 8-11 embryos were different from those of stage 46 tadpoles. Both antiviral drugs caused inhibition of GR, CaE and AChE in embryos, albeit with different severity. In conclusion, these two antiviral drugs, which are likely to enter the aquatic environment, may cause growth retardation and teratogenicity at high concentrations and biochemical changes at low concentrations in the organisms they interact with.