A Review of Human Coronaviruses’ Receptors: The Host-Cell Targets for the Crown Bearing Viruses

A novel human coronavirus prompted considerable worry at the end of the year 2019. Now, it represents a significant global health and economic burden. The newly emerged coronavirus disease caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the primary reason for the COVID-19 global pandemic. According to recent global figures, COVID-19 has caused approximately 243.3 million illnesses and 4.9 million deaths. Several human cell receptors are involved in the virus identification of the host cells and entering them. Hence, understanding how the virus binds to host-cell receptors is crucial for developing antiviral treatments and vaccines. The current work aimed to determine the multiple host-cell receptors that bind with SARS-CoV-2 and other human coronaviruses for the purpose of cell entry. Extensive research is needed using neutralizing antibodies, natural chemicals, and therapeutic peptides to target those host-cell receptors in extremely susceptible individuals. More research is needed to map SARS-CoV-2 cell entry pathways in order to identify potential viral inhibitors.     

The Biodiversity of the Genus Dictyota: Phytochemical and Pharmacological Natural Products Prospectives

Although a broad variety of classes of bioactive compounds have already been isolated from seaweeds of the genus Dictyota, most different species are still chemically and biologically unexplored. Dictyota species are well-known brown seaweeds belonging to the Dictyotaceae (Phaeophyta). The phytochemical composition within the genus Dictyota has recently received considerable interest, and a vast array of components, including diterpenes, sesquiterepenes, sterols, amino acids, as well as saturated and polyunsaturated fatty acids, have been characterized. The contribution of these valued metabolites to the biological potential, which includes anti-proliferative, anti-microbial, antiviral, antioxidant, anti-inflammatory, and anti-hyperpigmentation activities, of the genus Dictyota has also been explored. Therefore, this is the most comprehensive review, focusing on the published literature relevant to the chemically and pharmacologically diverse biopharmaceuticals isolated from different species of the genus Dictyota during the period from 1976 to now.     

Particle Size of X-ray Pumped UVC-Emitting Nanoparticles Defines Intracellular Localization and Biological Activity Against Cancer Cells

Effectiveness of radiation treatment for cancer is limited in hypoxic tumors. Previous data shows that UVC-emitting nanoparticles enhance cytotoxicity of X-ray irradiation in hypoxic tumor cells. This study examines the impact on cell killing, particle size, uptake into cells, incubation time, and UV emission intensity of LuPO₄:Pr³⁺,Nd³⁺. A549 cells are treated with LuPO₄:Pr³⁺,Nd³⁺ and X-rays. The surviving fraction is evaluated using the colony formation assay after treatment of cells with different particle sizes (D₅₀ = 0.16 and 5.05 µm) and after different incubation times before X-ray irradiation. Nanoparticle uptake into cells is verified by transmission electron microscopy and quantified by inductively coupled plasma mass spectrometry. The microparticles exhibit a five times higher emission intensity compared to nanoparticles. Both particle sizes show an increased cytotoxic effect after X-ray excitation with prolonged incubation times. Surprisingly, the smaller nanoparticles show a significantly higher biological effect compared to the larger particles, despite their significantly lower UVC emission. Nanoparticles accumulate more quickly and closer to the nucleus than the microparticles, resulting in higher localized UVC emission and greater lethality. The results suggest that the number of intracellular particles and their proximity to the cell DNA is more important than the emission intensity of the particles.     

A Glossary for Chemical Approaches towards Unlocking the Trove of Metabolic Treasures in Actinomycetes

Actinobacterial natural products showed a critical basis for the discovery of new antibiotics as well as other lead secondary metabolites. Varied environmental and physiological signals touch the antibiotic machinery that faced a serious decline in the last decades. The reason was exposed by genomic sequencing data, which revealed that Actinomycetes harbor a large portion of silent biosynthetic gene clusters in their genomes that encrypt for secondary metabolites. These gene clusters are linked with a great reservoir of yet unknown molecules, and arranging them is considered a major challenge for biotechnology approaches. In the present paper, we discuss the recent strategies that have been taken to augment the yield of secondary metabolites via awakening these cryptic genes in Actinomycetes with emphasis on chemical signaling molecules used to induce the antibiotics biosynthesis. The rationale, types, applications and mechanisms are discussed in detail, to reveal the productive path for the unearthing of new metabolites, covering the literature until the end of 2020.     

Fruit Bromelain-Derived Peptide Potentially Restrains the Attachment of SARS-CoV-2 Variants to hACE2: A Pharmacoinformatics Approach

Before entering the cell, the SARS-CoV-2 spike glycoprotein receptor-binding domain (RBD) binds to the human angiotensin-converting enzyme 2 (hACE2) receptor. Hence, this RBD is a critical target for the development of antiviral agents. Recent studies have discovered that SARS-CoV-2 variants with mutations in the RBD have spread globally. The purpose of this in silico study was to determine the potential of a fruit bromelain-derived peptide. DYGAVNEVK. to inhibit the entry of various SARS-CoV-2 variants into human cells by targeting the hACE binding site within the RBD. Molecular docking analysis revealed that DYGAVNEVK interacts with several critical RBD binding residues responsible for the adhesion of the RBD to hACE2. Moreover, 100 ns MD simulations revealed stable interactions between DYGAVNEVK and RBD variants derived from the trajectory of root-mean-square deviation (RMSD), radius of gyration (Rg), and root-mean-square fluctuation (RMSF) analysis, as well as free binding energy calculations. Overall, our computational results indicate that DYGAVNEVK warrants further investigation as a candidate for preventing SARS-CoV-2 due to its interaction with the RBD of SARS-CoV-2 variants.     

A Convenient and Efficient Conversion of 4‐Aminobenzophenone into Some New 1,2,3‐Triazole and Benzothiazole Derivatives

Several heterocyclic systems such as 1,2,3‐triazoles ( 5–9 ), pyrimidotriazoles ( 10–13 ), benzothiazole ( 16 ), thiazolo ( 17 ), and pyrimidinone derivative ( 18 ) was obtained from 4‐aminobenzophenone ( 1 ) and the appropriate reagents.     

Kinetics and mechanism of the oxidation of diaqua(nitrilotri- acetato)chromium(III) complex by N-bromosuccinimide

The kinetics of oxidation of the diaqua(nitrilotriacetato)chromium(III) complex [CrIIInta(H2O)2], by N-bromosuccinimide (NBS) to chromium(VI) in aqueous solution obeys the equation: where k1 is the rate constant for the electron-transfer process, K1 the equilibrium constant for the dissociation of [CrIIInta(H2O)2] to [CrIIInta(H2O)(OH)]−, and K2 is the pre-equilibrium formation constant for the precursor complex [CrIIInta(OH)(NBS)]−. The thermodynamic activation parameters were calculated and it is proposed that electron transfer proceeds via an inner-sphere mechanism. This revised version was published online in June 2006 with corrections to the Cover Date.     

On-line elimination of spectral interference of iron matrix in the flame atomic absorption determination of zinc by anion-exchange separation

A flow injection analysis (FIA) system has been developed for the flame atomic absorption spectroscopic (FAAS) determination of zinc in iron matrix. The spectral line interference of iron at 213.859 nm was eliminated by on-line separation using a micro-column of strong anion-exchange resin (Dowex 1-X8). The zinc chloro complexes were retained from 2 M HCl solution while most of the iron chloro complexes were passed to waste. For a 2% iron solution, matrix removal efficiency was 98.2% which means that positive spectral line interference of iron at the Zn line was reduced from 0.42 to 0.008 μg ml⁻¹ Zn. The optimized flow injection system can handle up to 48 samples with good precision (less than 3.5% relative standard deviation (R.S.D.)) in the working range of 0.075-2.2 μg ml⁻¹ Zn. Comparative analysis of a certified reference material and synthetic sample solutions containing traces of Zn in 2% Fe by the proposed method and by graphite furnace atomic absorption spectroscopy (GFAAS) showed no evidence of analytical bias at the 95% confidence level.