Plant Products as Inhibitors of Coronavirus 3CL Protease

Role of dietary supplements in the continuous battle against COVID-19

A sudden outbreak of the COVID-19 pandemic was a big blow to the world community on every level. Created by a novel coronavirus, SARS-CoV-2, which was previously unknown to the human immune system. The expert opinion almost immediately united on the fact that the most effective way of fighting the pandemic would be by building immunity artificially via a mass immunization program. However, it took about a year for the approval of the first vaccine against COVID-19. In the meantime, a big part of the general population started adapting nutritious diet plans and dietary supplements to boost natural immunity as a potential prophylactic strategy against SARS-CoV-2 infection. Whether they originate from mainstream medicine, such as synthetic supplements, or traditional herbal remedies in the form of single or poly-herbs, these supplements may comprise various components that exhibit immunomodulatory, anti-inflammatory, antioxidant, and antimicrobial characteristics. There is a substantial body of predictions and expert opinions suggesting that enhancing one's diet with dietary supplements containing additional nutrients and bioactive compounds like vitamins, minerals, amino acids, fatty acids, phytochemicals, and probiotics can enhance the immune system's ability to develop resistance against COVID-19, although none of them have any conclusive evidence nor officially recommended by World Health Organization (WHO). The current review critically acclaims the gap between public perception-based preference and real evidence-based study to weigh the actual benefit of dietary supplements in relation to COVID-19 prevention and management.

The influence of propolis plus Hyoscyamus niger L. against COVID-19: A phase II, multicenter, placebo-controlled, randomized trial

The incubation period of COVID-19 symptoms, along with the proliferation and high transmission rate of the SARS-CoV-2 virus, is the cause of an uncontrolled epidemic worldwide. Vaccination is the front line of prevention, and antiinflammatory and antiviral drugs are the treatment of this disease. In addition, some herbal therapy approaches can be a good way to deal with this disease. The aim of this study was to evaluate the effect of propolis syrup with Hyoscyamus niger L. extract in hospitalized patients with COVID-19 with acute disease conditions in a double-blinded approach. The study was performed on 140 patients with COVID-19 in a double-blind, randomized, and multicentral approach. The main inclusion criterion was the presence of a severe type of COVID-19 disease. The duration of treatment with syrup was 6 days and 30 CC per day in the form of three meals. On Days 0, 2, 4, and 6, arterial blood oxygen levels, C-reactive protein (CRP), erythrocyte sedimentation rate, and white blood cell, as well as the patient's clinical symptoms such as fever and chills, cough and shortness of breath, chest pain, and other symptoms, were recorded and analyzed. Propolis syrup with H. niger L. significantly reduces cough from the second day, relieving shortness of breath on the fourth day, and significantly reduces CRP, weakness, and lethargy, as well as significantly increased arterial blood oxygen pressure on the sixth day compared to the placebo group (p < 0.05). The results in patients are such that in the most severe conditions of the disease 80% < SpO2 (oxygen saturation), the healing process of the syrup on reducing CRP and increasing arterial blood oxygen pressure from the fourth day is significantly different compared with the placebo group (p < 0.05). The use of syrup is associated with a reduction of 3.6 days in the hospitalization period compared with the placebo group. Propolis syrup with H. niger L. has effectiveness in the viral and inflammatory phases on clinical symptoms and blood parameters and arterial blood oxygen levels of patients with COVID-19. Also, it reduces referrals to the intensive care unit and mortality in hospitalized patients with COVID-19. So, this syrup promises to be an effective treatment in the great challenge of COVID-19.

Antiviral Effects of Pyrroloquinoline Quinone through Redox Catalysis To Prevent Coronavirus Infection

The global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronavirus disease (COVID-19) is ongoing. Therefore, effective prevention of virus infection is required. Pyrroloquinoline quinone (PQQ), a natural compound found in various foods and human breast milk, plays a role in various physiological processes and is associated with health benefits. In this study, we aimed to determine the effects of PQQ on preventing coronavirus infections using a proxy Feline Infectious Peritonitis Virus (FIPV; belongs to the coronavirus family). In plaque reduction assays, we showed that pre- and post-PQQ-treated viruses were less infectious. IC50 was 87.9 and 5.1 μM for pre- and post-PQQ-treated viral infections, respectively. These results suggest that PQQ decreased the virion stability and viral replication. RT-qPCR confirmed these results. TEM findings showed that PQQ damaged viral capsids and aggregated viral particles, leading to inhibited virus attachment and entry into the host cells. PQQ was optimized by the addition of ascorbic acid and glutamic acid, which increased the number of redox cycles of PQQ and increased reactive oxygen species production by 14 times. In vitro, PQQ inhibited 3 CLpro/Mpro enzymes (an enzyme critical for viral replication) activity of SARS-CoV-2. Our results demonstrate the antiviral effect of PQQ on coronavirus, mainly by disrupting virion stability and loss of infectivity (occurring outside the host cell), due to increased redox activity. Furthermore, PQQ may hinder viral replication (inside the host cell) by 3 CLpro/Mpro enzyme inhibition. In summary, this study demonstrates the antiviral effect of PQQ and its potential application in coronavirus diseases.

In silico guided screening of active components of C. lanceolata as 3-chymotrypsin-like protease inhibitors of novel coronavirus

Despite the intense worldwide efforts towards the identification of potential anti-CoV therapeutics, no antiviral drugs have yet been discovered. Numerous vaccines are now approved for use, but they all serve as preventative measures. To effectively treat viral infections, it is crucial to find new antiviral drugs that are derived from natural sources. Various compounds with potential activity against 3 chymotrypsin-like protease (3CLpro) were reported and some are validated by bioassay studies. Therefore, we performed the computational screening of phytoconstituents of Codonopsis lanceolata to search for potential antiviral hit candidates. The curated compounds of the plant C. lanceolata were collected and downloaded from the literature. The binding affinity of the curated datasets was predicted for the target 3CLpro. Stigmasterol exhibits the highest docking score for the 3CLpro target. In addition, molecular dynamics (MD) simulations were conducted for the validation of docking results using root mean square deviation and root mean square fluctuation plots. The MD results indicated that the docked complex was stable and retained hydrogen bonding and non-bonding interactions. Furthermore, the calculation of pharmacokinetic parameters and Lipinski's rule of five suggest that C. lanceolata has the potential for drug-likeness. In order to develop new medicines for this debilitating disease, we will focus on the primary virus-based and host-based targets that can direct medicinal chemists to identify novel treatments to produce new drugs for it.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03745-2.

Medicinal plant molecules against hepatitis C virus: Current status and future prospect

Hepatitis C virus (HCV), a global malady, causes acute and chronic hepatitis leading to permanent liver damage, hepatocellular carcinoma, and death. Modern anti-HCV therapies are efficient, but mostly inaccessible for residents of underdeveloped regions. To innovate more effective treatments at affordable cost, medicinal plant-based products need to be explored. The aim of this article is to review plant constituents in the light of putative anti-HCV mechanisms of action, and discuss existing problems, challenges, and future directions for their potential application in therapeutic settings. One hundred sixty literatures were collected by using appropriate search strings via scientific search engines: Google Scholar, PubMed, ScienceDirect, and Scopus. Bibliography was prepared using Mendeley desktop software. We found a substantial number of plants that were reported to inhibit different stages of HCV life cycle. Traditional medicinal plants such as Phyllanthus amarus Schumach. and Thonn., Eclipta alba (L.) Hassk., and Acacia nilotica (L.) Delile exhibited strong anti-HCV activities. Again, several phytochemicals such as epigallocatechin-3-gallate, honokilol, punicalagin, and quercetin have shown broad-spectrum anti-HCV effect. We have presented promising phytochemicals like silymarin, curcumin, glycyrrhizin, and camptothecin for nanoparticle-based hepatocyte-targeted drug delivery. Nevertheless, only a few animal studies have been performed to validate the anti-HCV effect of these plant products. Again, insufficient clinical evaluation of the safety and effectiveness of herbal medications remain a problem. Selected plants products could be developed as novel therapeutics for HCV patients only after scrupulous evaluation of their safety and efficacy in a clinical set-up.

Oridonin inhibits SARS-CoV-2 replication by targeting viral proteinase and polymerase

COVID-19 has become a global public health crisis since its outbreak in China in December 2019. Currently there are few clinically effective drugs to combat SARS-CoV-2 infection. The main protein (M^pro), papain-like protease (PLpro) and RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 are involved in the viral replication, and might be prospective targets for anti-coronavirus drug development. Here, we investigated the antiviral activity of oridonin, a natural small-molecule compound, against SARS-CoV-2 infection in vitro. The time-of-addition analysis showed that oridonin efficiently inhibited SARS-CoV-2 infection by interfering with the genome replication at the post-entry stage. Mechanistically, the inhibition of viral replication by oridonin depends on the oxidation activity of α, β-unsaturated carbonyl. Further experiments showed that oridonin not only effectively inhibited SARS-CoV-2 M^pro activity, but also had some inhibitory effects on PLpro-mediated deubiquinating and viral polymerase-catalyzed RNA elongation activities at high concentrations. In particular, oridonin could inhibit the bat SARS-like CoV and the newly emerged SARS-CoV-2 omicron variants (BA.1 and BA.2), which highlights its potential as a pan-coronavirus antiviral agent. Overall, our data provide strong evidence that oridonin is an efficient antiviral agent against SARS-CoV-2 infection.

Application of molecular dynamics simulation for exploring the roles of plant biomolecules in promoting environmental health

Understanding the dynamic changes of plant biomolecules is vital for exploring their mechanisms in the environment. Molecular dynamics (MD) simulation has been widely used to study structural evolution and corresponding properties of plant biomolecules at the microscopic scale. Here, this review (i) outlines structural properties of plant biomolecules, and the crucial role of MD simulation in advancing studies of the biomolecules; (ii) describes the development of MD simulation in plant biomolecules, determinants of simulation, and analysis parameters; (iii) introduces the applications of MD simulation in plant biomolecules, including the response of the biomolecules to multiple stresses, their roles in corrosive environments, and their contributions in improving environmental health; (iv) reviews techniques integrated with MD simulation, such as molecular biology, quantum mechanics, molecular docking, and machine learning modeling, which bridge gaps in MD simulation. Finally, we make suggestions on determination of force field types, investigation of plant biomolecule mechanisms, and use of MD simulation in combination with other techniques. This review provides comprehensive summaries of the mechanisms of plant biomolecules in the environment revealed by MD simulation and validates it as an applicable tool for bridging gaps between macroscopic and microscopic behavior, providing insights into the wide application of MD simulation in plant biomolecules.

An Attention towards the Prophylactic and Therapeutic Options of Phytochemicals for SARS-CoV-2: A Molecular Insight

The novel pathogenic virus was discovered in Wuhan, China (December 2019), and quickly spread throughout the world. Further analysis revealed that the pathogenic strain of virus was corona but it was distinct from other coronavirus strains, and thus it was renamed 2019-nCoV or SARS-CoV-2. This coronavirus shares many characteristics with other coronaviruses, including SARS-CoV and MERS-CoV. The clinical manifestations raised in the form of a cytokine storm trigger a complicated spectrum of pathophysiological changes that include cardiovascular, kidney, and liver problems. The lack of an effective treatment strategy has imposed a health and socio-economic burden. Even though the mortality rate of patients with this disease is lower, since it is judged to be the most contagious, it is considered more lethal. Globally, the researchers are continuously engaged to develop and identify possible preventive and therapeutic regimens for the management of disease. Notably, to combat SARS-CoV-2, various vaccine types have been developed and are currently being tested in clinical trials; these have also been used as a health emergency during a pandemic. Despite this, many old antiviral and other drugs (such as chloroquine/hydroxychloroquine, corticosteroids, and so on) are still used in various countries as emergency medicine. Plant-based products have been reported to be safe as alternative options for several infectious and non-infectious diseases, as many of them showed chemopreventive and chemotherapeutic effects in the case of tuberculosis, cancer, malaria, diabetes, cardiac problems, and others. Therefore, plant-derived products may play crucial roles in improving health for a variety of ailments by providing a variety of effective cures. Due to current therapeutic repurposing efforts against this newly discovered virus, we attempted to outline many plant-based compounds in this review to aid in the fight against SARS-CoV-2.

Masitinib analogues with the N-methylpiperazine group replaced - A new hope for the development of anti-COVID-19 drugs

Masitinib is an orally acceptable tyrosine kinase inhibitor that is currently investigated under clinical trials against cancer, asthma, Alzheimer's disease, multiple sclerosis and amyotrophic lateral sclerosis. A recent study confirmed the anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activity of masitinib through inhibition of the main protease (M^pro) enzyme, an important pharmacological drug target to block the replication of the coronavirus. However, due to the adverse effects and lower potency of the drug, there are opportunities to design better analogues of masitinib. Herein, we substituted the N-methylpiperazine group of Masitinib with different chemical moieties and evaluated their drug-likeness and toxicities. The filtered analogues were subjected to molecular docking studies which revealed that the analogues with substituents methylamine in M10 (CID10409602), morpholine in M23 (CID59789397) and 4-methylmorpholine in M32 (CID143003625) have a stronger affinity to the drug receptor compared to masitinib. The molecular dynamics (MD) simulation analysis reveals that the identified analogues alter the mobility, structural compactness, accessibility to solvent molecules, and the number of hydrogen bonds in the native target enzyme. These structural alterations can help explain the inhibitory mechanisms of these analogues against the target enzyme. Thus, our studies provide avenues for the design of new masitinib analogues as the SARS-CoV-2 M^pro inhibitors.

Phytonutrient Inhibitors of SARS-CoV-2/NSP5-Encoded Main Protease (Mpro) Autocleavage Enzyme Critical for COVID-19 Pathogenesis

The genomic reshuffling, mutagenicity, and high transmission rate of the SARS-CoV-2 pathogen highlights an urgent need for effective antiviral interventions for COVID-19 control. Targeting the highly conserved viral genes and/or gene-encoded viral proteins such as main proteinase (M^pro), RNA-dependent RNA polymerase (RdRp) and helicases are plausible antiviral approaches to prevent replication and propagation of the SARS-CoV-2 infection. Coronaviruses (CoVs) are prone to extensive mutagenesis; however, any genetic alteration to its highly conserved M^pro enzyme is often detrimental to the viral pathogen. Therefore, inhibitors that target the M^pro enzyme could reduce the risk of mutation-mediated drug resistance and provide effective antiviral protection. Several existing antiviral drugs and dietary bioactives are currently repurposed to treat COVID-19. Dietary bioactives from three ayurvedic medicinal herbs, 18 β-glycyrrhetinic acid (ΔG = 8.86 kcal/mol), Solanocapsine (ΔG = 8.59 kcal/mol), and Vasicoline (ΔG = 7.34 kcal/mol), showed high-affinity binding to M^pro enzyme than the native N3 inhibitor (ΔG = 5.41 kcal/mol). Flavonoids strongly inhibited SARS-CoV-2 M^pro with comparable or higher potency than the antiviral drug, remdesivir. Several tannin hydrolysates avidly bound to the receptor-binding domain and catalytic dyad (His₄₁ and Cys₁₄₅) of SARS-CoV-2 M^pro through H-bonding forces. Quercetin binding to M^pro altered the thermostability of the viral protein through redox-based mechanism and inhibited the viral enzymatic activity. Interaction of quercetin-derivatives with the M^pro seem to be influenced by the 7-OH group and the acetoxylation of sugar moiety on the ligand molecule. Based on pharmacokinetic and ADMET profiles, several phytonutrients could serve as a promising redox nutraceutical for COVID-19 management.

Exploring the Targets of Novel Corona Virus and Docking-based Screening of Potential Natural Inhibitors to Combat COVID-19

There is a need to explore natural compounds against COVID-19 due to their multitargeted actions against various targets of nCoV. They act on multiple sites rather than single targets against several diseases. Thus, there is a possibility that natural resources can be repurposed to combat COVID-19. However, the biochemical mechanisms of these inhibitors were not known. To reveal the mode of anti-nCoV action, structure-based docking plays a major role. The present study is an attempt to explore various potential targets of SARS-CoV-2 and the structure-based screening of various potential natural inhibitors to combat the novel coronavirus.

Review on Plant-Based Management in Combating Antimicrobial Resistance - Mechanistic Perspective

Antimicrobial resistance (AMR) occurs when microbes no longer respond to any pharmacological agents, rendering the conventional antimicrobial agents ineffective. AMR has been classified as one of the top 10 life-threatening global health problems needed multilevel attention and global cooperation to attain the Sustainable Development Goals (SDGs) according to the World Health Organization (WHO), making the discovery of a new and effective antimicrobial agent a priority. The recommended treatments for drug-resistant microbes are available but limited. Furthermore, the transformation of microbes over time increases the risk of developing drug resistance. Hence, plant metabolites such as terpenes, phenolic compounds and alkaloids are widely studied due to their antibacterial, antiviral, antifungal and antiparasitic effects. Plant-derived antimicrobials are preferred due to their desirable efficacy and safety profile. Plant metabolites work by targeting microbial cell membranes, interfering with the synthesis of microbial DNA/RNA/enzymes and disrupting quorum sensing and efflux pump expression. They also work synergistically with conventional antibiotics to enhance antimicrobial effects. Accordingly, this review aims to identify currently available pharmacological therapies against microbes and AMR, as well as to discuss the importance of plant and secondary metabolites as a possible solution for AMR together with their mechanisms of action. All the information was obtained from government databases, WHO websites, PubMed, Springer, Google Scholar and Science Direct. Based on the information obtained, AMR is regarded as a significant warning to global healthcare. Plant derivatives such as secondary metabolites may be considered as potential therapeutic targets to mitigate the non-ending AMR.

The current status of old traditional medicine introduced from Persia to China

Traditional Chinese medicine (TCM) includes over ten thousand herbal medicines, some of which were introduced from outside countries and territories. The Silk Road enabled the exchange of merchandise such as teas, silks, carpets, and medicines between the East and West of the Eurasia continent. During this time, the ‘Compendium of Materia Medica’ (CMM) was composed by a traditional medicine practitioner, Shizhen Li (1,518–1,593) of the Ming Dynasty. This epoch-making masterpiece collected knowledge of traditional medical materials and treatments in China from the 16th century and before in utmost detail, including the origin where a material was obtained. Of 1892 medical materials from the CMM, 46 came from Persia (now Iran). In this study, the basic information of these 46 materials, including the time of introduction, the medicinal value in TCM theory, together with the current status of these medicines in China and Iran, are summarized. It is found that 20 herbs and four stones out of the 46 materials are registered as medicinal materials in the latest China Pharmacopoeia. Now most of these herbs and stones are distributed in China or replacements are available but saffron, ferula, myrrh, and olibanum are still highly dependent on imports. This study may contribute to the further development, exchange, and internationalization of traditional medicine of various backgrounds in the world, given the barriers of transportation and language are largely eased in nowadays.

The SARS-CoV-2 main protease (Mpro): Structure, function, and emerging therapies for COVID-19

The main proteases (M^pro), also termed 3‐chymotrypsin‐like proteases (3CL^pro), are a class of highly conserved cysteine hydrolases in β‐coronaviruses. Increasing evidence has demonstrated that 3CL^pros play an indispensable role in viral replication and have been recognized as key targets for preventing and treating coronavirus‐caused infectious diseases, including COVID‐19. This review is focused on the structural features and biological function of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) main protease M^pro (also known as 3CL^pro), as well as recent advances in discovering and developing SARS‐CoV‐2 3CL^pro inhibitors. To better understand the characteristics of SARS‐CoV‐2 3CL^pro inhibitors, the inhibition activities, inhibitory mechanisms, and key structural features of various 3CL^pro inhibitors (including marketed drugs, peptidomimetic, and non‐peptidomimetic synthetic compounds, as well as natural compounds and their derivatives) are summarized comprehensively. Meanwhile, the challenges in this field are highlighted, while future directions for designing and developing efficacious 3CL^pro inhibitors as novel anti‐coronavirus therapies are also proposed. Collectively, all information and knowledge presented here are very helpful for understanding the structural features and inhibitory mechanisms of SARS‐CoV‐2 3CL^pro inhibitors, which offers new insights or inspiration to medicinal chemists for designing and developing more efficacious 3CL^pro inhibitors as novel anti‐coronavirus agents.

The Main Protease of SARS-CoV-2 as a Target for Phytochemicals against Coronavirus

In late December 2019, the first cases of COVID-19 emerged as an outbreak in Wuhan, China that later spread vastly around the world, evolving into a pandemic and one of the worst global health crises in modern history. The causative agent was identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although several vaccines were authorized for emergency use, constantly emerging new viral mutants and limited treatment options for COVID-19 drastically highlighted the need for developing an efficient treatment for this disease. One of the most important viral components to target for this purpose is the main protease of the coronavirus (Mpro). This enzyme is an excellent target for a potential drug, as it is essential for viral replication and has no closely related homologues in humans, making its inhibitors unlikely to be toxic. Our review describes a variety of approaches that could be applied in search of potential inhibitors among plant-derived compounds, including virtual in silico screening (a data-driven approach), which could be structure-based or fragment-guided, the classical approach of high-throughput screening, and antiviral activity cell-based assays. We will focus on several classes of compounds reported to be potential inhibitors of Mpro, including phenols and polyphenols, alkaloids, and terpenoids.

A Systemic Review for Ethnopharmacological Studies on Isatis indigotica Fortune: Bioactive Compounds and their Therapeutic Insights

Isatis indigotica Fortune is a biennial Chinese woad of the Cruciferae family. It is primarily cultivated in China, where it was a staple in indigo dye manufacture till the end of the 17th century. Today, I. indigotica is used primarily as a therapeutic herb in traditional Chinese medicine (TCM). The medicinal use of the plant is separated into its leaves (Da-Qing-Ye) and roots (Ban-Lan-Gen), whereas its aerial components can be processed into a dried bluish-spruce powder (Qing-Dai), following dehydration for long-term preservation. Over the past several decades, I. indigotica has been generally utilized for its heat-clearing effects and bodily detoxification in TCM, attributed to the presence of several classes of bioactive compounds, including organic acids, alkaloids, terpenoids, and flavonoids, as well as lignans, anthraquinones, glucosides, glucosinolates, sphingolipids, tetrapyrroles, and polysaccharides. This paper aims to delineate I. indigotica from its closely-related species (Isatis tinctoria and Isatis glauca) while highlighting the ethnomedicinal uses of I. indigotica from the perspectives of modern and traditional medicine. A systematic search of PubMed, Embase, PMC, Web of Science, and Google Scholar databases was done for articles on all aspects of the plant, emphasizing those analyzing the bioactivity of constituents of the plant. The various key bioactive compounds of I. indigotica that have been found to exhibit anti-inflammatory, antimicrobial, anticancer, and anti-allergic properties, along with the protective effects against neuronal injury and bone fracture, will be discussed. Collectively, the review hopes to draw attention to the therapeutic potential of I. indigotica not only as a TCM, but also as a potential source of bioactive compounds for disease management and treatment.

Antiviral drug discovery by targeting the SARS-CoV-2 polyprotein processing by inhibition of the main protease

The spread of SARS-CoV-2, the causative agent for COVID-19, has led to a global and deadly pandemic. To date, few drugs have been approved for treating SARS-CoV-2 infections. In this study, a structure-based approach was adopted using the SARS-CoV-2 main protease (M^pro) and a carefully selected dataset of 37,060 compounds comprising M^pro and antiviral protein-specific libraries. The compounds passed two-step docking filtration, starting with standard precision (SP) followed by extra precision (XP) runs. Fourteen compounds with the highest XP docking scores were examined by 20 ns molecular dynamics simulations (MDs). Based on backbone route mean square deviations (RMSD) and molecular mechanics/generalized Born surface area (MM/GBSA) binding energy, four drugs were selected for comprehensive MDs analysis at 100 ns. Results indicated that birinapant, atazanavir, and ritonavir potently bound and stabilized SARS-CoV-2 M^pro structure. Binding energies higher than -102 kcal/mol, RMSD values <0.22 nm, formation of several hydrogen bonds with M^pro, favourable electrostatic contributions, and low radii of gyration were among the estimated factors contributing to the strength of the binding of these three compounds with M^pro. The top two compounds, atazanavir and birinapant, were tested for their ability to prevent SARS-CoV-2 plaque formation. At 10 µM of birinapant concentration, antiviral tests against SARS-CoV-2 demonstrated a 37% reduction of virus multiplication. Antiviral assays demonstrated that birinapant has high anti-SARS-CoV-2 activity in the low micromolar range, with an IC50 value of 18 ± 3.6 µM. Therefore, birinapant is a candidate for further investigation to determine whether it is a feasible therapy option.

Naringenin as a Possible Candidate Against SARS-CoV-2 Infection and in the Pathogenesis of COVID-19

Naringenin, widely distributed in fruits and vegetables, is endowed with antiviral and other health beneficial activities, such as immune-stimulating and anti-inflammatory actions that could play a role in contributing, to some extent, to either preventing or alleviating coronavirus infection. Several computational studies have identified naringenin as one of the prominent flavonoids that can possibly inhibit internalization of the virus, virus-host interactions that trigger the cytokine storm, and replication of the virus. This review highlights the antiviral potential of naringenin in COVID-19 associated risk factors and its predicted therapeutic targets against SARS-CoV-2 infection.

Herbal medicine use for the management of COVID-19: A review article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause pandemic of coronavirus disease 2019 (COVID-19). For many thousands of years, herbal products and dietary plants have been prescribed for various diseases by traditional healers. Thus, the aim of this review is to present main herbal products, their source, characteristics, and potential antiviral actions concerning COVID-19. Publications on herbal products related to antiviral effects were searched from different databases, such as Web of Science, Google Scholar, Medline, Scopus, and PubMed, until August 2021, using English key terms. According to different studies, there are so many important medicinal plants with antiviral activity, which can be used for viral infections or can be prescribed as supportive treatment. lack of information on the safety profile and amount of dose for different diseases is some of the limitations of medicinal plants. herbal medicine can interfere with COVID-19 pathogenesis by inhibiting SARS-CoV-2 replication and entry to host cells. Some of the antiviral medicinal plant species are citrus Spp., orange (C. Sinensis), Allium sativum, Allium cepa, Mentha piperita, and nigella sativa are the most desirable herbal drink or fruit that can introduce effective adjuvant components in COVID-19 management.

Ayurveda Rasayana as antivirals and immunomodulators: potential applications in COVID-19

Coronavirus disease (COVID-19) has been declared as a pandemic by the World Health Organization with rapid spread across 216 countries. COVID-19 pandemic has left its imprints on various health systems globally and caused immense social and economic disruptions. The scientific community across the globe is in a quest for digging the effective treatment for COVID-19 and exploring potential leads from traditional systems of healthcare across the world too. Ayurveda (Indian traditional system of medicine) has a comprehensive aspect of immunity through Rasayana which is a rejuvenation therapy. Here we attempt to generate the potential leads based on the classical text from Ayurveda in general and Rasayana in particular to develop effective antiviral and/or immunomodulator for potential or adjunct therapy in SARS-CoV-2. The Rasayana acts not only by resisting body to restrain or withstand the strength, severity or progression of a disease but also by promoting power of the body to prevent the manifestation of a disease. These Rasayana herbs are common in practice as immunomodulator, antiviral and protectives. The studies on Rasayana can provide an insight into the future course of research for the plausible development of effective management of COVID-19 by the utilization and development of various traditional systems of healthcare. Keeping in view the current pandemic situation, there is an urgent need of developing potential medicines. This study proposes certain prominent medicinal plants which may be further studied for drug development process and also in clinical setup under repurposing of these herbs.

Drugs repurposing against SARS-CoV2 and the new variant B.1.1.7 (alpha strain) targeting the spike protein: molecular docking and simulation studies

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) is responsible for the global COVID-19 pandemic and millions of deaths worldwide. In December 2020, a new alpha strain of SARS-CoV2 was identified in the United Kingdom. It was referred to as VUI 202012/01 (Alpha strain modelled under investigation, 2020, month 12, number 01). The interaction between spike protein and ACE2 receptor is a prerequisite for entering virion into the host cell. The present study is focussed on the spike protein of the SARS-COV 2, involving the comparison of binding affinity of new alpha strain modelled spike with previous strain spike (PDB ID:7DDN) using in silico molecular docking, dynamics and simulation studies. The molecular docking studies of the alpha strain modelled spike protein confirmed its higher affinity for the ACE2 receptor than the spike protein of the dominant strain. Similar computational approaches have also been used to investigate the potency of FDA approved drugs from the ZINC Database against the spike protein of new alpha strain modelled and old ones. The drug molecules which showed strong affinity for both the spike proteins are then subjected to ADME analysis. The overall binding energy of Conivaptan (-107.503 kJ/mol) and Trosec (-94.029 kJ/mol) is indicative of their strong binding affinities, well supported by interactions with critical residues.

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We investigated the potential FDA drugs for repurposing against the spike protein of alpha strain modelled of SARS-CoV-2.

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Spike protein of alpha strain modelled of SARS-CoV-2 has more affinity for the ACE2 receptor of host cell than previous strains and, therefore, is more contagious.

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Conivaptan, Ecamsule and Trosec are common drugs that bind strongly with spike protein of both the strains .

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Molecular Docking and simulation studies show that Conivaptan and Trosec emerged as potential inhibitors of the alpha strain modelled spike protein.