Research on the antiviral activity of water-soluble melanin from the pharmaceutical chaga mushroom (Inonotus obliquus) against influenza А virus subtypes H5N1, H3N2 and H1N1pdm09 in experiments in vitro

Introduction. Influenza A virus is the cause of epidemics and pandemics that severely affect the health and socioeconomic status of the world's population. The need to develop new methods of etiotropic therapy, and the increasing ability of viruses to counteract the antiviral drugs makes extremely relevant the search for new pharmacologically active substances and the subsequent study of their medicinal properties. The aim of the study is to conduct research into the antiviral properties of melanin obtained from the pharmaceutical chaga mushroom in relation to different subtypes of the influenza A virus. Materials and methods. A sample of water-soluble melanin from Inonotus obliquus obtained by alkaline hydrolysis and dried at 40C was tested for toxicity and antiviral activity. The commercial anti-influenza drug Tamiflu was used as a reference drug. Statistical processing of the obtained data was carried out according to the Spearman-Kerber method. Results. Inonotus obliquus melanin (sample 20-24) toxicity markers, such as a maximum tolerable concentration (MTC) of 237.0 g/mL, and a 50% cytotoxic concentration (CC50) of 153,45 g/mL were established for MDCK cell culture. The assessment of antiviral activity of test sample against three subtypes of the influenza A virus (H5N1, H3N2 and H1N1pdm09) demonstrated a decrease in the infectivity of the influenza virus by 2.53.5 lg with 50% virus-inhibiting concentrations (IC50) of 1.559.52 g/mL. Based on the obtained values of CC50 and IC50, the selectivity indices (SI) of the sample were calculated, characterizing its prospects for further research. Conclusions. Melanin obtained from the pharmaceutical chaga mushroom showed the highest activity against the strain of the human pandemic influenza virus A/California/04/2009 (H1N1)pdm09, caused a decrease in its infectivity by 3.5 lg and had an IC50 of 1.6 g/ml. The obtained results indicate the prospects for creating an antiviral drug based on Inonotus obliquus melanins against the influenza virus.