In May 2020 the Russian Ministry of Health granted fast-track marketing authorization to RNA polymerase inhibitor AVIFAVIR (favipiravir) for the treatment of COVID-19 patients. In the pilot stage of Phase II/III clinical trial, AVIFAVIR enabled SARS-CoV-2 viral clearance in 62.5% of patients within 4 days, and was safe and well-tolerated.

Animal cells counteract oxidative stress and electrophilic attack through coordinated expression of a set of detoxifying and antioxidant enzyme genes mediated by transcription factor Nrf2. In unstressed cells, Nrf2 appears to be sequestered in the cytoplasm via association with an inhibitor protein, Keap1. Here, by using the yeast two-hybrid screen, human Keap1 has been identified as a partner of the nuclear protein prothymosin ␣. The in vivo and in vitro data indicated that the prothymosin ␣-Keap1 interaction is direct, highly specific, and functionally relevant. Furthermore, we showed that Keap1 is a nuclear-cytoplasmic shuttling protein equipped with a nuclear export signal that is important for its inhibitory action. Prothymosin ␣ was able to liberate Nrf2 from the Nrf2-Keap1 inhibitory complex in vitro through competition with Nrf2 for binding to the same domain of Keap1. In vivo, the level of Nrf2-dependent transcription was correlated with the intracellular level of prothymosin ␣ by using prothymosin ␣ overproduction and mRNA interference approaches. Our data attribute to prothymosin ␣ the role of intranuclear dissociator of the Nrf2-Keap1 complex, thus revealing a novel function for prothymosin ␣ and adding a new dimension to the molecular mechanisms underlying expression of oxidative stress-protecting genes.

In May 2020 the Russian Ministry of Health granted fast-track marketing authorization to RNA polymerase inhibitor AVIFAVIR (favipiravir) for the treatment of COVID-19 patients. In the pilot stage of Phase II/III clinical trial, AVIFAVIR enabled SARS-CoV-2 viral clearance in 62.5% of patients within 4 days, and was safe and well-tolerated.

Identification of molecular targets and mechanism of action is always a challenge, in particular – for natural compounds due to inherent chemical complexity. BP-Cx-1 is a water-soluble modification of hydrolyzed lignin used as the platform for a portfolio of innovative pharmacological products aimed for therapy and supportive care of oncological patients. The present study describes a new approach, which combines in vitro screening of potential molecular targets for BP-Cx-1 using Diversity Profile - P9 panel by Eurofins Cerep (France) with a search of possible active components in silico in ChEMBL - manually curated chemical database of bioactive molecules with drug-like properties. The results of diversity assay demonstrate that BP-Cx-1 has multiple biological effects on neurotransmitters receptors, ligand-gated ion channels and transporters. Of particular importance is that the major part of identified molecular targets are involved in modulation of inflammation and immune response and might be related to tumorigenesis. Characterization of molecular composition of BP-Cx-1 with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and subsequent identification of possible active components by searching for molecular matches in silico in ChEMBL indicated polyphenolic components, nominally, flavonoids, sapogenins, phenanthrenes, as the major carriers of biological activity of BP-Cx-1. In vitro and in silico target screening yielded overlapping lists of proteins: adenosine receptors, dopamine receptor DRD4, glucocorticoid receptor, serotonin receptor 5-HT1, prostaglandin receptors, muscarinic cholinergic receptor, GABAA receptor. The pleiotropic molecular activities of polyphenolic components are beneficial in treatment of multifactorial disorders such as diseases associated with chronic inflammation and cancer.

The divalent cation binding properties of human prothymosin a, an abundant nuclear protein involved in cell proliferation, were evaluated. By using prothymosin a retardation on a weak cation chelating resin charged with various divalent cations, specific binding of Zn 21 ions by prothymosin a was observed. This finding was further confirmed by the equilibrium dialysis analysis which demonstrated that, within the micromolar range of Zn 21 concentrations, prothymosin a could bind up to three zinc ions in the presence of 100 mm NaCl and up to 13 zinc ions in the absence of NaCl. Equilibrium dialysis analysis also revealed that prothymosin a could bind Ca 21 , although the parameters of Ca 21 binding by prothymosin a were less pronounced than those of Zn 21 binding in terms of the number of metal ions bound, the K D values, and the resistance of the bound metal ions to 100 mm NaCl. The effects of Zn 21 and Ca 21 on the interaction of prothymosin a with its putative partners, Rev of HIV type 1 and histone H1, were examined. We demonstrated that Rev binds prothymosin a, and that prothymosin a binding to Rev but not to histone H1 was significantly enhanced in the presence of zinc and calcium ions. Our data suggest that the modes of prothymosin a interaction with Rev and histone H1 are distinct and that the observed zinc and calcium-binding properties of prothymosin a might be functionally relevant.

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A new chemical series was identified via high-throughput screening as having antiproliferative activity on DU-145 human prostate carcinoma cell line (hit compound potency - 2.9 microM). Medicinal chemistry optimization of two peripheral diversity vectors of the hit molecule, independently, led to SAR generalizations and identification of the 'best' moieties. The latter were merged in a single compound that exhibited an over 100-fold better potency than the hit compound. For the most potent compounds it was confirmed that the observed antiproliferative potency was not associated with the compounds' non-specific cytotoxicity.

4-Substituted 2,4-dioxobutanoic acids inhibit influenza virus cap-dependent endonuclease (CEN) activity. Baloxavir marboxil, 4, is approved for treating influenza virus infections. We describe here the synthesis and biological evaluation of active compounds, 5a–5g, and their precursors (6a, 6b, 6d, and 6e) with flexible bulky hydrophobic groups instead of the rigid polyheterocyclic moieties. In silico docking confirmed the ability of 5a–5g to bind to the active site of influenza A CEN (PDB code: 6FS6) like baloxavir acid, 3. These novel compounds inhibited polymerase complex activity, inhibited virus replication in cells, prevented death in a lethal influenza A virus mouse challenge model, and dramatically lowered viral lung titers. 5a and 5e potently inhibited different influenza genera in vitro. Precursors 6a and 6d demonstrated impressive mouse oral bioavailability with 6a, providing effective in vivo protection. Thus, these novel compounds are potent CEN inhibitors with in vitro and in vivo activity comparable to baloxavir.