Surface enhanced Raman spectroscopy based analysis of SARS-CoV-2 spike protein binding to ACE2 receptor

The SARS-CoV-2 virus is still a challenge because of its diversity and mutations. The binding interactions of the angiotensin converting enzyme 2 (ACE2) receptor and the spike protein are relevant for the SARS-CoV-2 virus to enter the cell. Consequently, it is important and helpful to analyze binding activities and the changes in the structure of the ACE2 receptor and the spike protein. Surface enhanced Raman spectroscopy is able to analyze small concentrations of the proteins without contact, non-invasively and label-free. In this work, we present a SERS based approach in the visible wavelength range to analyze and study the binding interactions of the ACE2 receptor and the spike protein. SERS measurements of the ACE2 receptor, the spike protein and the ACE2-spike complex were performed. Additionally, an inhibitor was used to prevent the spike protein from binding to ACE2 and to compare the results. The analysis of the measured SERS spectra reveals structural differences and changes due to binding activities. Thus, we show that the performed SERS based approach can help for rapid and non-invasive analysis of binding interactions of the ACE2-spike complex and also of protein binding in general. © 2023 SPIE.

CHARACTERIZING A "N-CoV-2-IgG PS" DIAGNOSTIC KIT TO QUANTIFY SARS-CoV-2 NUCLEOCAPSID PROTEIN-SPECIFIC HUMAN IgG ANTIBODIES

Confirming detected SARS-CoV-2-specific antibodies is necessary to reveal immune response in COVID-19 convalescent subjects as well as to conduct population studies by screening for specific antibodies to assess rate of COVID-19 prevalence. With this purpose St. Petersburg Pasteur Institute was the first in Russia to develop the ELISA kit for the quantitative determination of human IgG to the SARS-CoV-2 nucleocapsid (N-CoV-2-IgG PS). Arbitrary units (AU/ml) were used to assess the level of antibodies. The data shown in AU/ml were recalculated later to the international units (BAU/ml) in accordance with established the First WHO International Standard for anti-SARS-CoV-2 human Immunoglobulin. Comparing the data of the N-CoV-2-IgG PS calibration curve with those of the First WHO International Standard for anti-SARS- CoV-2 human Immunoglobulin revealed a complete inter-assay association (r = 0.999, R-2 = 0.997) allowing to find that 1BAU/ml = 5.97 AU/ml. The aim of the study was to characterize the "SARS-CoV-2 protein N Human IgG Quantitative ELISA Kit" (N-CoV-2-IgG PS), compare quantitative and qualitative data of ELISA kits, assess a correlation between the binding antibodies to SARS-CoV-2 N proteins and the neutralizing antibodies against SARS-CoV-2. The data of correlation analysis of the 83 COVID-19 convalescent blood plasma samples a significant relationship between the antibodies quantitative values and titers SARS-CoV-2-specific antibody (r = 0.8436, R-2 = 0.7802) as well as a moderate relationship between antibody concentration and positivity index (r = 0.6648, R-2 = 0.3307), assessed by Chaddock scale. Comparing concentration of N-protein binding antibodies with neutralizing antibody titers level uncovered data consistency obtained by quantitative and virus microneutralization assays (r = 0.7310, R-2 = 0.6527) used in parallel to analyze 80 blood plasma samples obtained from COVID-19 patients and convalescents. AUC under the ROC curve comprised 0.701 (P < 0.0001) evidencing about a satisfactory informative value for "N-CoV-2-IgG PS" compared with microneutralization assay. In addition, the efficacy of the "N-CoV-2-IgG PS" was 95%, while the positive and negative prognostic value was 97% and 87%, respectively. The data obtained confirmed a correlation between N-protein binding antibody level and neutralizing antibody titer. Checking inter-assay agreement evidenced about acceptance for informativeness and efficacy of using "N-CoV-2-IgG PS", thereby confirming an opportunity to apply the Kit to screen for SARS-CoV-2 N protein-specific IgG antibody level and assess seroprevalence in diverse population cohorts.

Human variation in the protein receptor ACE2 affects its binding affinity to SARS-CoV-2 in a variant-dependent manner.

SARS-CoV-2 infection depend on the binding of the viral Spike glycoprotein (S) to the human receptor Angiotensin Converting Enzyme 2 (ACE2) to induce virus-cell membrane fusion. S protein evolved diverse amino acid changes that are possibly linked to more efficient binding to human ACE2, which might explain part of the increase in frequency of SARS-CoV-2 Variants Of Concern (VOCs). In this work, we investigated the role of ACE2 protein variations that are naturally found in human populations and its binding affinity with S protein from SARS-CoV-2 representative genotypes, based on a series of in silico approaches involving molecular modelling, docking and molecular dynamics simulations. Our results indicate that SARS-CoV-2 VOCs bind more efficiently to the human receptor ACE2 than the ancestral Wuhan genotype. Additionally, variations in the ACE2 protein can affect SARS-CoV-2 binding and protein-protein stability, mostly making the interaction weaker and unstable in some cases. We show that some VOCs, such as B.1.1.7 and P.1 are much less sensitive to ACE2 variants, while others like B.1.351 appear to be specifically optimized to bind to the widespread wild-type ACE2 protein.Communicated by Ramaswamy H. Sarma.

Rna-Dependent Rna Polymerase (Rdrp) Inhibitor Drugs against Sars-Cov-2: A Molecular Docking Study

Objective: SARS-CoV-2 associated viral pandemic was first reported in Wuhan, China, in December 2019. Due to the rapid increase in its pathogenicity, SARS-CoV-2 was declared a global pandemic by WHO on March 11, 2020. For that reason, determining the most attractive viral protein targets became a must. One of the most important target proteins is SARS-COV-2 RNA-dependent RNA polymerase (RdRp) on which COVID-19 depends in its replication process. This study aimed to examine the possible interactions between RdRp and the most promising RdRp nucleoside inhibitors especially Purine nucleoside analogs, to detect the most important residues that commonly interact with RdRp's inhibitors and to investigate whether if there any mutations have been observed so far in these residues or not. Material(s) and Method(s): Molecular docking studies were carried out using AutoDock Vina between SARS-CoV-2 RdRp and drugs approved against different viral RdRps (Galidesivir, Remdesivir, Ribavirin, Sofosbuvir, and Favipiravir) as well as physiological nucleotides (ATP and GTP). Based on the obtained results, a detailed surface-interaction analysis was also performed using Pymol and Discovery Studio Visualizer software for the models that exhibited the most suitable location and configuration in space. Result and Discussion: All the tested molecules were able to bind to SARS-CoV-2 RdRp successfully. Also, they all commonly interact with 9 different amino acids (Arg553, Arg555, Asp618, Asp623, Ser682, Asn691, Ser759, Asp760, and Asp761), and 3 different Template-primer RNA nucleotides (U10, A11, and U20) causing inhibition of viral RdRp via non obligate RNA chain termination.Copyright © 2022 University of Ankara. All rights reserved.

Computational Docking Study of the Phytochemical Constituent, Silybin (Silybum marianum) against SARS-CoV-2 Omicron Variant Spike Glycoprotein: An In-silico Approach

SARS-CoV-2 is continually evolving with the emergence of new variants with increased viral pathogenicity. The emergence of heavily mutated Omicron (B.1.1.529) with spike protein mutations are known to mediate its higher transmissibility and immune escape that has brought newer challenges for global public health to contain SARS-CoV-2 infection. One has to come up with a therapeutic strategy against the virus so as to effectively contain the infection and spread. Natural phytochemicals are being considered a significant source of bioactive compounds possessing an antiviral therapeutic potential. Being a promising anticancer and chemo-preventive agent, Silybin holds a significant potential to be used as a therapeutic. In the present study, molecular docking of Silybin with Omicron spike protein (7QNW) was carried out. Molecular docking results showed greater stability of Silybin in the active site of the Omicron spike protein with suitable binding mode of interactions. The study reveals that Silybin has the potential to block the host ACE2 receptor-viral spike protein binding;thereby inhibiting the viral entry to human cells. Therefore, Silybin may be further developed as a medication with the ability to effectively combat SARS-CoV-2 Omicron.Copyright © The Author(s) 2023.

Pharmacokinetics and pharmacodynamics of imatinib in COVID-19 patients

Introduction: In the randomised double-blind placebo-controlled CounterCovid study, imatinib reduced mortality in COVID-19 patients. High levels of alpha-1 acid glycoprotein (AAG) were associated with increased total imatinib concentrations in COVID-19 patients. Aim(s): We aimed to explore possible relationships between pharmacokinetic(PK) profiles of oral imatinib in COVID19 patients and pharmacodynamic (PD) outcomes. We hypothesize that high total imatinib concentrations may be associated with improved clinical outcomes in COVID-19 patients, when adjusted for AAG. Method(s): PK profiles were expressed as trough concentration at steady state(Css). PD responses were the ratio between partial oxygen pressure and fraction of inspired oxygen(P/F), WHO ordinal scale for clinical improvement(WHO-score) and oxygen supplementation liberation(O2lib). Linear regression, linear mixed effects models and time-to-event analysis were performed and adjusted for possible confounders. Result(s): Individual Css could be determined from 168 patients. Css did associate significantly with P/F (beta=-199,42;p-value=0.013) and O2lib (HR 0.75;p-value= 0.021), adjusted for sex, age, neutrophil-lymphocyte ratio, dexamethasone usage, AAG and baseline P/F-and WHO-score. Css did not significantly associate with WHO-score. Concusion: Higher total exposure following oral imatinib in COVID-19 patients did not associate with improved clinical outcomes. Total Css showed an inverse association with PD-outcomes. This association may be biased by disease-course and variability in metabolic rate and protein binding. Therefore, additional PKPD analyses into unbound imatinib and its main metabolite at Css may better explain exposure-response associations.

Molecular Docking Strategy for Multi-Target Inhibitor Discovery of Selected Plant Constituents in Bauhinia Acuminata

Objective: Traditional medicine is often considered to be a kind of complementary or alternative medicine (CAM) nowadays. Therefore, documenting and identifying the herbs that are effective in treating various diseases is vital for future disease control programs. This study aims to perform a molecular docking analysis of the thirteen plant components in Bauhinia acuminata against the target proteins in lung cancer (PDB IDs: 2ITY), breast cancer (1A52), diabetes (3L4U), obesity (IT02), inflammation (5COX) and corona viral infections (6VYO). Material(s) and Method(s): All the plant components used for the present study were retrieved from the plant Bauhinia acuminata and were evaluated for their biological activity results using molinspiration. Further in-silico docking analysis was performed using AutoDock Vina software and the binding interactions were visualized using Discovery studio program. Result and Discussion: The docking scores and analysis of the interactions of the plant components with targets suggest that all the selected plant components showed excellent binding to the chosen targets when compared to that of the standard drugs. As a result of the docking process on 6 different targets, the selected plant components like Quercetin, Beta-sitosterol, and Rheagenine were observed to show good binding energy values against all the 5 targets except 6VYO as shown in (Table 9). These results can further pave the way for getting better insights in identifying and designing potential lead candidates.Copyright © 2022 University of Ankara. All rights reserved.

Species differences in plasma protein binding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease inhibitor nirmatrelvir.

Plasma protein binding (PPB) studies on the SARS-CoV-2 main protease inhibitor nirmatrelvir revealed considerable species differences primarily in dog and rabbit, which prompted further investigations into the biochemical basis for these differences.The unbound fraction (fu) of nirmatrelvir in dog and rabbit plasma was concentration (2-200 µM)-dependent (dog fu,p 0.024-0.69, rabbit fu,p 0.010-0.82). Concentration (0.1-100 µM)-dependent binding in serum albumin (SA) (fu,SA 0.040-0.82) and alpha-1-acid glycoprotein (AAG) (fu,AAG 0.050-0.64) was observed in dogs. Nirmatrelvir showed minimal binding to rabbit SA (1-100 µM: fu,SA 0.70-0.79), while binding to rabbit AAG was concentration-dependent (0.1-100 µM: fu,AAG 0.024-0.66). In contrast, nirmatrelvir (2 µM) revealed minimal binding (fu,AAG 0.79-0.88) to AAG from rat and monkeys. Nirmatrelvir showed minimal-to-moderate binding to SA (1-100 µM; fu,SA 0.70-1.0) and AAG (0.1-100 µM; fu,AAG 0.48-0.58) from humans across tested concentrations.Nirmatrelvir molecular docking studies using published crystal structures and homology models of human and preclinical species SA and AAG were used to rationalise the species differences to plasma proteins. This suggested that species differences in PPB are primarily driven by molecular differences in albumin and AAG resulting in differences in binding affinity.

A Computational Framework for Determining the Breadth of Antibodies Against Highly Mutable Pathogens

Highly mutable pathogens pose daunting challenges for antibody design. The usual criteria of high potency and specificity are often insufficient to design antibodies that provide long-lasting protection. This is due, in part, to the ability of the pathogen to rapidly acquire mutations that permit them to evade the designed antibodies. To overcome these limitations, design of antibodies with a larger neutralizing breadth can be pursued. Such broadly neutralizing antibodies (bnAbs) should remain targeted to a specific epitope, yet show robustness against pathogen mutability, thereby neutralizing a higher number of antigens. This is particularly important for highly mutable pathogens, like the influenza virus and the human immunodeficiency virus (HIV). The protocol describes a method for computing the "breadth” of a given antibody, an essential aspect of antibody design. © 2023, Springer Science+Business Media, LLC, part of Springer Nature.

Surface-Functionalized Metal-Organic Frameworks for Binding Coronavirus Proteins.

Since the outbreak of SARS-CoV-2, a multitude of strategies have been explored for the means of protection and shielding against virus particles: filtration equipment (PPE) has been widely used in daily life. In this work, we explore another approach in the form of deactivating coronavirus particles through selective binding onto the surface of metal-organic frameworks (MOFs) to further the fight against the transmission of respiratory viruses. MOFs are attractive materials in this regard, as their rich pore and surface chemistry can easily be modified on demand. The surfaces of three MOFs, UiO-66(Zr), UiO-66-NH2(Zr), and UiO-66-NO2(Zr), have been functionalized with repurposed antiviral agents, namely, folic acid, nystatin, and tenofovir, to enable specific interactions with the external spike protein of the SARS virus. Protein binding studies revealed that this surface modification significantly improved the binding affinity toward glycosylated and non-glycosylated proteins for all three MOFs. Additionally, the pores for the surface-functionalized MOFs can adsorb water, making them suitable for locally dehydrating microbial aerosols. Our findings highlight the immense potential of MOFs in deactivating respiratory coronaviruses to be better equipped to fight future pandemics.

Virology, clinical features and diagnosis of covid 19: Review analysis

COVID-19 requires unprecedented mobilization of the health systems to prevent the rapid spread of this unique virus, which spreads via respiratory droplet and causes respiratory disease. There is an urgent need for an accurate and rapid test method to quickly identify many infected patients and asymptomatic carriers to prevent virus transmission and assure timely treatment of the patients. This article aims as an outcome of review of the evidence on viral load and its virulence of SARS-CoV2,so that it will help in further understanding the fact useful for investigating and managing the COVID-19 cases. A search of available evidence was conducted in pub-med "COVID-19 viral load and virulence" and its associated characters world-wide and Google Scholar to capture the most recently published articles. The WHO and Centre for Disease Control and Prevention (CDC) database of publications on novel coronavirus were also screened for relevant publications. s of 55 articles were screened by two authors and 15 were included in this study based on the inclusion criteria. SARS-coV2, the causative agent of COVID-19 falls under the coronavirus family but it has higher infectivity compared to SARS and MERS with higher reproduction numbers(Ro). Virulence has been found to be different throughout the world,however lower compared to SARS and MERS,till date. The most common clinical features have been found to be cough and fever. RT - PCR remains the most sensitive and specific method for the diagnosis of COVID-19 although it is time consuming, costly and requires highly skilled human resources. Hence, newer modalities like RT-LAMP can be alternative for point of care diagnosis as this is both cost effective and requires less skilled human resources. Despite recent advances in disease diagnosis and treatment outcomes using latest technological advances in molecular biology, the global pandemic COVID-19 remains a major headache for governments across the world due to limited testing capacity and lack of appropriate treatment and vaccine. Copyright © 2020, Kathmandu University. All rights reserved.

Computational tools for aptamer identification and optimization

Aptamers are single-stranded DNA or RNA oligonucleotides that can selectively bind to a specific target. They are generally obtained by SELEX, but the procedure is challenging and time-consuming. Moreover, the identified aptamers tend to be insufficient in stability, specificity, and affinity. Thus, only a handful of aptamers have entered the practical use stage. Recently, computational approaches have demonstrated a significant capacity to assist in the discovery of high-performance aptamers. This review discusses the advances achieved in several aspects of computational tools in this field, as well as the new progress in machine learning and deep learning, which are used in aptamer identification and optimization. To illustrate these computationally aided processes, aptamer selections against SARS-CoV-2 are discussed in detail as a case study. We hope that this review will aid and motivate researchers to develop and utilize more computational techniques to discover ideal aptamers effectively. Copyright © 2022 Elsevier B.V.

How to advise women on the safe use of medicines while breastfeeding

Medicines use plays an important role in women's decisions to start or continue breastfeeding. Some may stop breastfeeding or the medicine to avoid combining the two, as they feel very strongly about tainting their milk when breastfeeding[10]. Women deserve to be involved in discussions on compatibility, using evidence-based resources presented in a manner in which they can understand. There is a presumption by some healthcare professionals, mothers, families and wider society that formula has benefits over breast milk with a trace of medication in, or that adverse events are likely and serious if this breast milk is consumed. In addition, there is a reticence from healthcare professionals to use professional judgement and go outside the licence application for medicines. This leaves the mother with a dilemma: to interrupt or stop breastfeeding to take the medication, or to delay medication - with chronic diseases, the latter is rarely an acceptable option. In January 2021, the MHRA launched the Safer Medicines Consortium, owing to the "need for reliable and consistent information about medicines used before or during pregnancy and breastfeeding for women and the healthcare professionals who advise them". The vision of the consortium is that "all women will have access to accurate and accessible information to make informed decisions with their healthcare professional about taking medicines before or during pregnancy or breastfeeding"[44]. As experts in medicines, pharmacists should share evidence-based information with the mother and support her in making a decision that is right for her and her baby, as outlined above. Copyright © 2021 Pharmaceutical Press. All rights reserved.

Weighted gene co-expression network-based identification of genetic effect of mRNA vaccination and previous infection on SARS-CoV-2 infection.

To investigate the effect conferred by vaccination and previous infection against SARS-CoV-2 infection in molecular level, weighted gene co-expression network analysis was applied to screen vaccination, prior infection and Omicron infection-related gene modules in 46 Omicron outpatients and 8 controls, and CIBERSORT algorithm was used to infer the proportions of 22 subsets of immune cells. 15 modules were identified, where the brown module showed positive correlations with Omicron infection (r = 0.35, P = 0.01) and vaccination (r = 0.62, P = 1 × 10-6). Enrichment analysis revealed that LILRB2 was the unique gene shared by both phosphatase binding and MHC class I protein binding. Pathways including "B cell receptor signaling pathway" and "FcγR-mediated phagocytosis" were enriched in the vaccinated samples of the highly correlated LILRB2. LILRB2 was also identified as the second hub gene through PPI network, after LCP2. In conclusion, attenuated LILRB2 transcription in PBMC might highlight a novel target in overcoming immune evasion and improving vaccination strategies.

Evaluation of In Vitro Distribution and Plasma Protein Binding of Selected Antiviral Drugs (Favipiravir, Molnupiravir and Imatinib) against SARS-CoV-2.

There are a number of uncertainties regarding plasma protein binding and blood distribution of the active drugs favipiravir (FAVI), molnupiravir (MOLNU) and imatinib (IMA), which were recently proposed as therapeutics for the treatment of COVID-19 disease. Therefore, proton dissociation processes, solubility, lipophilicity, and serum protein binding of these three substances were investigated in detail. The drugs display various degrees of lipophilicity at gastric (pH 2.0) and blood pH (pH 7.4). The determined pKa values explain well the changes in lipophilic character of the respective compounds. The serum protein binding was studied by membrane ultrafiltration, frontal analysis capillary electrophoresis, steady-state fluorometry, and fluorescence anisotropy techniques. The studies revealed that the ester bond in MOLNU is hydrolyzed by protein constituents of blood serum. Molnupiravir and its hydrolyzed form do not bind considerably to blood proteins. Likewise, FAVI does not bind to human serum albumin (HSA) and α1-acid glycoprotein (AGP) and shows relatively weak binding to the protein fraction of whole blood serum. Imatinib binds to AGP with high affinity (logK' = 5.8-6.0), while its binding to HSA is much weaker (logK' ≤ 4.0). The computed constants were used to model the distribution of IMA in blood plasma under physiological and 'acute-phase' conditions as well.

Phyllanthus tenellus Roxb. And Kaempferia parviflora Wall. ex Baker compounds as inhibitors of SARS-CoV-2 main protease and RNA-dependent RNA polymerase: A molecular docking study

Context: The outbreak of a novel coronavirus, SARS-CoV-2 has caused an unprecedented COVID-19 pandemic. To put an end to this pandemic, effective antivirals should be identified or developed for COVID-19 treatment. However, specific and effective antivirals or inhibitors against SARS-CoV-2 are still lacking. Aim(s): To evaluate bioactive compounds from Phyllanthus tenellus and Kaempferia parviflora as inhibitors against two essential SARS-CoV-2 proteins, main protease (Mpro) and RNA-dependent RNA polymerase (RdRp), through molecular docking studies and to predict the drug-likeness properties of the compounds. Method(s): The inhibition potential and interaction of P. tenellus and K. parviflora compounds against Mpro and RdRp were assessed through molecular docking. The drug-likeness properties of the compounds were predicted using SwissADME and AdmetSAR tools. Result(s): Rutin and ellagic acid glucoside from P. tenellus and 4-hydroxy-6-methoxyflavone and 5-hydroxy-3,7,4'-trimethoxyflavone from K. parviflora exhibited the highest binding conformations to Mpro by interacting with its substrate binding site that was predicted to halt the Mpro activity. As for RdRp, ellagitannin and rutin from P. tenellus and peonidin and 5,3'-dihydroxy-3,7,4'-trimethoxyflavone from K. parviflora were the best-docked compounds that bound to the RdRp catalytic domain (Asp760 and Asp761) and NTP-entry channel that were anticipated to stop RNA polymerization. However, in the context of drug developability, 4-hydroxy-6-methoxyflavone, 5-hydroxy-3,7,4'-trimethoxyflavone, peonidin and 5,3'-dihydroxy-3,7,4'-trimethoxyflavone from K. parviflora were highly potential to be oral active drugs compared to rutin, ellagic acid glucoside and ellagitannin from P. tenellus. Conclusion(s): P. tenellus and K. parviflora compounds, particularly the aforementioned compounds, were suggested as potential inhibitors of SARS-CoV-2 Mpro and RdRp. Copyright © 2022 Journal of Pharmacy & Pharmacognosy Research.

Highly Efficient Base-Catalyzed Synthesisof Piperidine-4-Imine Lead Molecules for SARS-Cov-2 Mutant Spike Proteasevia in Silico Method

For the discovery of drugs to SARS-CoV-2 pandemics, we have developed a new series of piperidine-4-imines as the central core owing to significant pharmaceuticaldemands on it. The synthesis of piperidine-4-imines involvesatwo-step base-catalyzed reaction, namely (i)condensations followed by cyclization with aromatic aldehyde, aliphatic ketone, and ammonia to yield piperidine-4-ketone core, and (ii) a simple Schiff base/piperidine-4-imines formation between piperidine-4-ketone andvarious aromatic primary amines. All the synthesized intermediate and target piperidine-4-imines molecular structures were well characterized by NMR, FT-IR, and mass spectral studies. Further, the ground state geometry of synthesized molecules was optimized using density function theory (DFT) with basis set of b3lyp 6-31g (d,p) in Gaussian 09 program. Using this molecular geometry, we docked against SARS-CoV-2 mutant spike protease of delta, delta plus, and omicron, which shows an effective binding ability. In addition, Lipinski's rule, pre ADME and toxicity studies also reveal drug-likeness properties. Copyright © 2022 Wolters Kluwer Medknow Publications. All rights reserved.

Chemical Attachment of 5-Nitrosalicylaldimine Motif to Silatrane Resulting in an Organic-Inorganic Structure with High Medicinal Significance.

Two chemical motifs of interest for medicinal chemistry, silatrane as 1-(3-aminopropyl) silatrane (SIL M), and nitro group attached in position 5 to salicylaldehyde, are coupled in a new structure, 1-(3-{[(2-hydroxy-5-nitrophenyl)methylidene]amino}propyl)silatrane (SIL-BS), through an azomethine moiety, also known as a versatile pharmacophore. The high purity isolated compound was structurally characterized by an elemental, spectral, and single crystal X-ray diffraction analysis. Given the structural premises for being a biologically active compound, different specific techniques and protocols have been used to evaluate their in vitro hydrolytic stability in simulated physiological conditions, the cytotoxicity on two cancer cell lines (HepG2 and MCF7), and protein binding ability-with a major role in drug ADME (Absorption, Distribution, Metabolism and Excretion), in parallel with those of the SIL M. While the latter had a good biocompatibility, the nitro-silatrane derivative, SIL-BS, exhibited a higher cytotoxic activity on HepG2 and MCF7 cell lines, performance assigned, among others, to the known capacity of the nitro group to promote a specific cytotoxicity by a "activation by reduction" mechanism. Both compounds exhibited increased bio- and muco-adhesiveness, which can favor an optimized therapeutic effect by increased drug permeation and residence time in tumor location. Additional benefits of these compounds have been demonstrated by their antimicrobial activity on several fungi and bacteria species. Molecular docking computations on Human Serum Albumin (HSA) and MPRO COVID-19 protease demonstrated their potential in the development of new drugs for combined therapy.

Spike protein receptor-binding domains from SARS-CoV-2 variants of interest bind human ACE2 more tightly than the prototype spike protein.

Several SARS-CoV-2 variants of interest (VOI) have emerged since this virus was first identified as the etiologic agent responsible for COVID-19. Some of these variants have demonstrated differences in both virulence and transmissibility, as well as in evasion of immune responses in hosts vaccinated against the original strain of SARS-CoV-2. There remains a lack of definitive evidence that identifies the genetic elements that are responsible for the differences in transmissibility among these variants. One factor affecting transmissibility is the initial binding of the surface spike protein (SP) of SARS-CoV-2 to human angiotensin converting enzyme-2 (hACE2), the widely accepted receptor for SP. This step in the viral replication process is mediated by the receptor binding domain (RBD) of SP that is located on the surface of the virus. This current study was conducted with the aim of assessing potential differences in binding affinity between recombinant hACE2 and the RBDs of emergent SARS-CoV-2 WHO VOIs. Mutations that affect the binding affinity of SP play a dominant initial role in the infectivity of the virus.

Screening of Selected Stingless Bee Honey Varieties for ACE2-Spike Protein-Binding Inhibition Activity: A Potential Preventive Medicine Against SARS-Cov-2 Infection.

The broader objective of this study is to identify natural materials that might inhibit the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We have focused on stingless bee honey, which has a unique taste that is both sweet and sour and sometimes bitter. We screened 12 samples of honey from 11 species of stingless bees using an angiotensin-converting enzyme 2 (ACE2)-spike protein-binding assay and phytochemical analysis. Ten of the samples showed inhibition above 50% in this assay system. Most of the honey contained tannins, alkaloids, flavonoids, triterpenoids, carotenoids and carbohydrates. Our findings in this in vitro study showed that honey from stingless bees may have a potent effect against SARS-CoV-2 infection by inhibiting the ACE2-spike protein-binding.