Today, the development of drugs against influenza viruses remains an urgent problem. Hydrated fullerenes have high stability and relatively low toxicity, which undoubtedly makes them attractive candidates for the role of antiviral agents.

Therefore, the aim of this work was to study the cytotoxicity and antiviral activity of the drug K050 (manufactured in Ukraine) - an aqueous colloidal solution of a polyhydrated mixture of fullerenes HyFn5 and HyFn6 - against influenza A virus H1N1. Cell culture MDCK was used in the experiments. Cytotoxicity was determined using the MTT assay. De novo infectivity of influenza virus was determined by Median Tissue Culture Infectious Dose assay, TCID50 titers were calculated by the Reed-Muench method.

The cytotoxicity of HyFn5 and HyFn6 was 11.79 mg/ml and 16.03 mg/ml, respectively. Oseltamivir at a concentration of 0.15 mg/ml was used as a reference drug and showed 22.33% of inhibition of viral activity (or AVA). Hydrated fullerenes showed a high dose-dependent effect, with the highest rates of AVA by 96.48% for HyFn5 and 96.54% for HyFn6. A study of de novo virus infectivity showed a decrease in titer, compared with the virus control with the largest reduction by 4 orders of magnitude for both HyFn5 and HyFn6.

Therefore, the obtained results show that polyhydrated fullerenes show not only high activity in inhibiting the reproduction of influenza virus type H1N1, but also a decrease in its infectious titer. This gives a good start for further research and determination of the mechanisms of action of these fullerenes.