Virtual Combinatorial Library Screening of Quinadoline B Derivatives against SARS-CoV-2 RNA-Dependent RNA Polymerase

The unprecedented global health threat of SARS-CoV-2 has sparked a continued interest in discovering novel anti-COVID-19 agents. To this end, we present here a computer-based protocol for identifying potential compounds targeting RNA-dependent RNA polymerase (RdRp). Starting from our previous study wherein, using a virtual screening campaign, we identified a fumiquinazolinone alkaloid quinadoline B (Q3), an antiviral fungal metabolite with significant activity against SARS-CoV-2 RdRp, we applied in silico combinatorial methodologies for generating and screening a library of anti-SARS-CoV-2 candidates with strong in silico affinity for RdRp. For this study, the quinadoline pharmacophore was subjected to structural iteration, obtaining a Q3-focused library of over 900,000 unique structures. This chemical library was explored to identify binders of RdRp with greater affinity with respect to the starting compound Q3. Coupling this approach with the evaluation of physchem profile, we found 26 compounds with significant affinities for the RdRp binding site. Moreover, top-ranked compounds were submitted to molecular dynamics to evaluate the stability of the systems during a selected time, and to deeply investigate the binding mode of the most promising derivatives. Among the generated structures, five compounds, obtained by inserting nucleotide-like scaffolds (1, 2, and 5), heterocyclic thiazolyl benzamide moiety (compound 3), and a peptide residue (compound 4), exhibited enhanced binding affinity for SARS-CoV-2 RdRp, deserving further investigation as possible antiviral agents. Remarkably, the presented in silico procedure provides a useful computational procedure for hit-to-lead optimization, having implications in anti-SARS-CoV-2 drug discovery and in general in the drug optimization process.

Study of uric acid oxidation reaction products in medium of ammonia or primary amines

This work is considered in more detail the most important stage of obtaining one of the promising heteroatomic polycyclic compounds 3,7,10-trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane (THAP). THAP is a potential compound for creating high-energy substances due to the presence of six nitrogen atoms in the structure and tight packing. Uric acid is the starting compound in the THAP synthesis chain. When it is oxidized by sodium persulfate or potassium ferrocyanide, 1,5-diaminoglycoluril is formed, from which the propellane structure is formed by the tricyclization reaction. This work expanded the range of oxidants for the conversion of uric acid to 1,5-diaminoglycoluril. It was found that 1,5-diaminoglycoluril was formed with a yield of 29 % when using equimolar proportions of uric acid and KMnO4. When using MnO2 in a ten times more excess, the yield of 1,5-diaminoglycoluril was 38 %. The article also presents the results of a study of the interaction of uric acid with some amines. The reaction of interaction of uric acid with benzylamine was studied in more detail, the reaction products of which were 4-benzylimino-5-benzylaminoallantoin, 4- benzylimino-1-benzylamino-allantoin and 4-benzyliminoallantoin. Based on the synthesis of 4- benzyliminoallantoin, a number of promising derivatives of 4-iminoallantoin were obtained, namely 4- ethyliminoallantoin, 4-propyliminoallantoin, 4-i-propyliminoallantoin, 4-n-butyliminoallantoin, 4-i- butyliminoallantoin, 4-tert-butyliminoallantoin.

EPSP Synthase-Depleted Cells Are Aromatic Amino Acid Auxotrophs in Mycobacterium smegmatis

We found that cells from Mycobacterium smegmatis , a model organism safer and easier to study than the disease-causing mycobacterial species, when depleted of an enzyme from the shikimate pathway, are auxotrophic for the three aromatic amino acids (AroAAs) that serve as building blocks of cellular proteins: l- tryptophan, l -phenylalanine, and l -tyrosine. That supplementation with only AroAAs is sufficient to rescue viable cells with the shikimate pathway inactivated was unexpected, since this pathway produces an end product, chorismate, that is the starting compound of essential pathways other than the ones that produce AroAAs.

Combinatorial library screening of quinadoline B derivatives against SARS-CoV-2 RNA-dependent RNA polymerase

The unprecedented global health threat of SARS-CoV-2 has sparked a continued interest to discover novel anti-COVID-19 agents. To this end, we present here a computer-based protocol for identifying potential compounds targeting RNA-dependent RNA polymerase (RdRp). Starting from our previous study in which, by a virtual screening campaign, we identified a fumiquinazolinone alkaloid quinadoline B (Q3), an antiviral fungal metabolite with significant activity against SARS-CoV-2 RdRp, we applied an in silico combinatorial methodologies for generating and screening a library of anti-SARS-CoV-2 candidates with strong in silico affinity for RdRp. For this study, the quinadoline pharmacophore was subjected to structural iteration obtaining a Q3-focused library of over 900,000 unique structures. This chemical library was explored to identify binders of RdRp with greater affinity with respect to the starting compound Q3. Coupling this approach with the evaluation of physchem profile, we found 26 compounds with significant affinities for the RdRp binding site. Moreover, top-ranked compounds were submitted to molecular dynamics to evaluate the stability of the systems during a selected time, and for deeply investigating the binding mode of the most promising derivatives. Among the generated structures, five compounds, obtained by inserting nucleotide-like scaffolds (1, 2, and 5), heterocyclic thiazolyl benzamide moiety (compound 3), and a peptide residue (compound 4), exhibited enhanced binding affinity for SARS-CoV-2 RdRp, deserving further investigation as possible antiviral agents. Remarkably, the presented in silico procedure provides a useful computational procedure for hit-to-lead optimization, having implications in anti-SARS-CoV-2 drug discovery and in general in the drug optimization process.

TEST RESULTS OF STARTING COMPOUND FEEDS FOR INDUSTRIAL CULTIVATION OF SALMONIDS (CHUM SALMON)

The analysis of data on the conduct of fish-biological tests for the period 2016-2020 is presented at fish breeding plants of Primorsky and Khabarovsk territories on juveniles of chum salmon experimental granulated and extruded starter feeds, both with the use (compound feed V1M) and without the use of fermentolysate (compound feed V1M-BF). The highest average daily gains, as well as the average final weight of juveniles, were noted when dry fermentolysate was used as part of the starting compound feed. This is consistent with the data available in the literature on the positive effect of the products of partial protein fermentolysis at the initial stages of salmon development. When carrying out biological experiments, there is a high survival rate of fry from 97.5 to 99.9%, a low feed ratio for granulated feed with dry fermentolysate (0,64-0,80) and a protein utilization ratio (0,25-0,35).

Safety and quality of feed for piglets

The results of research on the safety and quality of compound feed of domestic producers for piglets have been presented in the article. The materials for the investigation were 4 samples of the starting complete feed for piglets of main domestic producers. Organoleptic characteristics of compound feed for piglets met the requirements of Federal standard 34109-2017. The assessment of the total bacterial contamination showed that sample No. 3 (the feed plant “VEGA”) has the maximum level of contamination, and the lowest level in sample No. 1 - new feeding technologies plant. The content of toxic elements in compound feed did not exceed their maximum permissible level and met the requirements of Federal standard 34141-2017. The level of radionuclides in compound feed did not exceed their maximum permissible level and corresponded to the standards provided for in the instructions on radiological quality control of feed of the Ministry of Justice No. 831 on 14.04.1995. Thus, the analysis of samples of the starting compound feed of domestic producers for piglets on organoleptic, physic and chemical, bacteriological and sanitary-mycological indicators, for the presence of toxic elements and radionuclides showed that all samples meet the requirements of safety and quality.

Cross Pharmacological, Biochemical and Computational Studies of a Human Kv3.1b Inhibitor from Androctonus australis Venom

The voltage-gated K+ channels Kv3.1 display fast activation and deactivation kinetics and are known to have a crucial contribution to the fast-spiking phenotype of certain neurons. AahG50, as a natural product extracted from Androctonus australis hector venom, inhibits selectively Kv3.1 channels. In the present study, we focused on the biochemical and pharmacological characterization of the component in AahG50 scorpion venom that potently and selectively blocks the Kv3.1 channels. We used a combined optimization through advanced biochemical purification and patch-clamp screening steps to characterize the peptide in AahG50 active on Kv3.1 channels. We described the inhibitory effect of a toxin on Kv3.1 unitary current in black lipid bilayers. In silico, docking experiments are used to study the molecular details of the binding. We identified the first scorpion venom peptide inhibiting Kv3.1 current at 170 nM. This toxin is the alpha-KTx 15.1, which occludes the Kv3.1 channel pore by means of the lysine 27 lateral chain. This study highlights, for the first time, the modulation of the Kv3.1 by alpha-KTx 15.1, which could be an interesting starting compound for developing therapeutic biomolecules against Kv3.1-associated diseases.

Potassium Complexes of Quercetin-5′-Sulfonic Acid and Neutral O-Donor Ligands: Synthesis, Crystal Structure, Thermal Analysis, Spectroscopic Characterization and Physicochemical Properties

The coordination ability of QSA− ligand towards potassium cations was investigated. Potassium complex of quercetin-5’-sulfonate of the general formula [KQSA(H2O)2]n was obtained. The [KQSA(H2O)2] (1) was a starting compound for solvothermal syntheses of acetone (2) and dimethylsulfoxide (3) complexes. For the crystalline complexes 1–3, crystals morphology was analyzed, IR and Raman spectra were registered, as well as thermal analysis for 1 was performed. Moreover, for 1 and 3, molecular structures were established. The potassium cations are coordinated by eight oxygen atoms (KO8) of a different chemical nature; coordinating groups are sulfonic, hydroxyl, and carbonyl of the QSA− anion, and neutral molecules—water (1) or DMSO (3). The detailed thermal studies of 1 confirmed that water molecules were strongly bonded in the complex structure. Moreover, it was stated that decomposition processes depended on the atmosphere used above 260 °C. The TG–FTIR–MS technique allowed the identification of gaseous products evolving during oxidative decomposition and pyrolysis of the analyzed compound: water vapor, carbon dioxide, sulfur dioxide, carbonyl sulfide, and carbon monoxide. The solubility studies showed that 1 is less soluble in ethanol than quercetin dihydrate in ethanol, acetone, and DMSO. The exception was aqueous solution, in which the complex exhibited significantly enhanced solubility compared to quercetin. Moreover, the great solubility of 1 in DMSO explained the ease of ligand exchange (water for DMSO) in [KQSA(H2O)2].

Compound feed from different producers for piglets and their comparative assessment

The quality of raw materials and goods of animal origin depends first of all on the safety of feed, their balance in terms of the main nutrients and digestibility by the body. As a rule, the lower the quality and safety of feed, the lower the productivity of all types of animals and poultry. The quality of feed is influenced by all stages of their production: growing conditions, harvesting and storage, processing technologies, canning and preparation for feeding. Where high-quality feed is used in diets, maximum productivity and high realization of the genetic potential of animals are obtained. During the storage and processing of plant and animal raw materials its physic and mechanical, biochemical, sanitary and microbiological properties change. This can be avoided only by observing the sanitary and hygienic requirements for bagging, harvesting, and storing feed. The quality of feed is confirmed by its physical, chemical, organoleptic, microbiological and other indicators, which determines the variety of feed control methods at all stages of their turnover. In this connection, the development and strengthening of control over the quality and safety of feed and feed additives is one of the important tasks of modern animal feeding science. The purpose of the work was to carried out a comparative assessment of four samples of the starting compound feed SK-3 for piglets of different producers. The experimental part of the work has been carried out in the laboratory of veterinary expertise at the compound feed plant LLC “Athens-Volga”. For the study of compound feed an average sample was taken from each sample, separating from the combined sample using a hand scoop according to Federal standard 13496.0-2016. Methods of sampling. Quality and safety control was carried out according to organoleptic, physic and chemical, microbiological indicators and the content of mycotoxins in compound feed. Monitoring of compound feed of the compared samples of the starting compound feed for piglets SK-3 according to the studied indicators has shown that all samples meet the sanitary and hygienic requirements of Federal standard of our country.

Synthesis, characterization and antioxidant activity of 2-(4-Phenyl-6-p-Tolylpyrimidin-2-ylthio)-N-(4-substituted Phenyl)acetamides

A series of 2-(4-phenyl-6-p-tolylpyrimidin-2-ylthio)-N- (4-substituted phenyl)acetamide(4a-o) has been synthesized. Compounds have been characterized and tested for their antioxidant activity. The titled compounds (4a-o) have been synthesized by the reaction between 4-phenyl-6-p-tolylpyrimidine-2-thiol (2) with 2-chloro-N-substituted phenylacetamide (3ao) refluxed in acetone using catalytic amount of K2CO3. Compound (2) has been synthesized from (E)-1-phenyl- 3-p-tolylprop-2-en-1-one (1) with equimolar amount thiourea refluxed in alcoholic KOH to get compound (2). Starting compound chalcone was synthesized by Claisen-Schmidt condensation. All synthesized compounds have been characterized using spectroscopic techniques such as FT-IR, 1H NMR, 13C NMR, Mass Spectrometry and elemental analysis. Antioxidant assay has been performed by using DPPH radical scavenging method. Compounds 4-h and 4-o have shown good antioxidant activity.