Evaluation of green tea polyphenols as novel corona virus (SARS CoV-2) main protease (Mpro) inhibitors - an in silico docking and molecular dynamics simulation study

Exemplifying the next generation of antibiotic susceptibility intensifiers of phytochemicals by LasR-mediated quorum sensing inhibition

There persists a constant threat from multidrug resistance being acquired by all human pathogens that challenges the well-being of humans. This phenomenon is predominantly led by Pseudomonas aeruginosa which is already resistant to the current generations of antibiotic by altering its metabolic pathways to survive. Specifically for this microbe the phenomenon of quorum sensing (QS) plays a crucial role in acquiring virulence and pathogenicity. QS is simply the cross talk between the bacterial community driven by signals that bind to receptors, enabling the entire bacterial microcosm to function as a single unit which has led to control P. aeruginosa cumbersome even in presence of antibiotics. Inhibition of QS can, therefore, be of a significant importance to curb such virulent and pathogenic strains of P. aeruginosa. Natural compounds are well known for their antimicrobial properties, of which, information on their mode of action is scarce. There can be many antimicrobial phytochemicals that act by hindering QS-pathways. The rationale of the current study is to identify such natural compounds that can inhibit QS in P. aeruginosa driven by LasR, PhzR, and RhlR dependent pathways. To achieve this rationale, in silico studies were first performed to identify such natural compounds which were then validated by in vitro experiments. Gingerol and Curcumin were identified as QS-antagonists (QSA) which could further suppress the production of biofilm, EPS, pyocyanin, and rhamnolipid along with improving the susceptibility to antibiotics.

Nanotechnology Applications of Flavonoids for Viral Diseases

Recent years have witnessed the emergence of several viral diseases, including various zoonotic diseases such as the current pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Other viruses, which possess pandemic-causing potential include avian flu, Ebola, dengue, Zika, and Nipah virus, as well as the re-emergence of SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome) coronaviruses. Notably, effective drugs or vaccines against these viruses are still to be discovered. All the newly approved vaccines against the SARS-CoV-2-induced disease COVID-19 possess real-time possibility of becoming obsolete because of the development of ‘variants of concern’. Flavonoids are being increasingly recognized as prophylactic and therapeutic agents against emerging and old viral diseases. Around 10,000 natural flavonoid compounds have been identified, being phytochemicals, all plant-based. Flavonoids have been reported to have lesser side effects than conventional anti-viral agents and are effective against more viral diseases than currently used anti-virals. Despite their abundance in plants, which are a part of human diet, flavonoids have the problem of low bioavailability. Various attempts are in progress to increase the bioavailability of flavonoids, one of the promising fields being nanotechnology. This review is a narrative of some anti-viral dietary flavonoids, their bioavailability, and various means with an emphasis on the nanotechnology system(s) being experimented with to deliver anti-viral flavonoids, whose systems show potential in the efficient delivery of flavonoids, resulting in increased bioavailability.

Characterization of the Trans-Epithelial Transport of Green Tea (C. sinensis) Catechin Extracts with In Vitro Inhibitory Effect against the SARS-CoV-2 Papain-like Protease Activity

This work describes an untargeted analytical approach for the screening, identification, and characterization of the trans-epithelial transport of green tea (Camellia sinensis) catechin extracts with in vitro inhibitory effect against the SARS-CoV-2 papain-like protease (PLpro) activity. After specific catechin extraction, a chromatographic separation obtained six fractions were carried out. The fractions were assessed in vitro against the PLpro target. Fraction 5 showed the highest inhibitory activity against the SARS-CoV-2 PLpro (IC₅₀ of 0.125 μg mL^-1). The untargeted characterization revealed that (-)-epicatechin-3-gallate (ECG) was the most abundant compound in the fraction and the primary molecule absorbed by differentiated Caco-2 cells. Results indicated that fraction 5 was approximately 10 times more active than ECG (IC₅₀ value equal to 11.62 ± 0.47 μg mL^-1) to inhibit the PLpro target. Overall, our findings highlight the synergistic effects of the various components of the crude extract compared to isolated ECG.

Linseed Silesia, Diverse Crops for Diverse Diets. New Solutions to Increase Dietary Lipids in Crop Species

The aim of the work was to compare the new variety of oil flax (Silesia) with already cultivated varieties in terms of plant productivity, oil content, fatty acid composition and significant secondary metabolites. The analyzed linseed varieties are characterized by low (Linola), medium (Silesia) and high (Szafir) content of omega-3 fatty acids. Special attention was paid to the quality of the oil and the characteristics that determine its stability (reduction of susceptibility to oxidation). A number of antioxidant compounds of secondary metabolism (simple phenols, phenolic acids, flavonoids, tannins) were identified in the linseed oils. All of these compounds can affect lipid oxidation by a mechanism that attenuates initiating radicals such as hydroxyl or forms an oxidizing primary product such as peroxides. Chelation of metal ions may also be involved in lipid oxidation. We propose a mechanism that encompasses all these processes and facilitates understanding of the complex relationships between them. The general thesis is that the ratio of polyunsaturated fatty acids is associated with a better metabolic state of flaxseed, and thus with a higher nutritional value. In addition, we find a number of specialized secondary metabolites characteristic of the flax studied, which could be useful for chemotaxonomy.

Rooibos, a supportive role to play during the COVID-19 pandemic?

This article presents the potential health benefits of Rooibos to be considered a support during the COVID-19 pandemic. The recent pandemic of COVID-19 has led to severe morbidity and mortality. The highly infectious SARS-CoV-2 is known to prime a cytokine storm in patients and progression to acute lung injury/acute respiratory distress syndrome. Based on clinical features, the pathology of acute respiratory disorder induced by SARS-CoV-2 suggests that excessive inflammation, oxidative stress, and dysregulation of the renin angiotensin system are likely contributors to the COVID-19 disease. Rooibos, a well-known herbal tea, consumed for centuries, has displayed potent anti-inflammatory, antioxidant, redox modulating, anti-diabetic, anti-cancer, cardiometabolic support and organoprotective potential. This article describes how Rooibos can potentially play a supportive role by modulating the risk of some of the comorbidities associated with COVID-19 in order to promote general health during infections.

The potential of BEN815 as an anti-inflammatory, antiviral and antioxidant agent for the treatment of COVID-19

BACKGROUND

The corona virus disease 2019 (COVID-19) pandemic has highlighted the fact that there are few effective antiviral agents for treating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Although the very recent development of vaccines is an extremely important breakthrough, it remains unclear how long-lived such vaccines will be. The development of new agents therefore remains an important goal.

PURPOSE

Given the multifaceted pathology of COVID-19, a combinatorial formulation may provide an effective treatment. BEN815, a natural nutraceutical composed of extracts from guava leaves (Psidium guajava), green tea leaves (Camellia sinensis), and rose petals (Rosa hybrida), had previously shown to have a therapeutic effect on allergic rhinitis. We investigated whether BEN815 possesses anti-inflammatory, antiviral and antioxidant activities, since the combination of these effects could be useful for the treatment of COVID-19.

STUDY DESIGN

We examined the anti-inflammatory effects of BEN815 and its principal active components quercetin and epigallocatechin gallate (EGCG) in lipopolysaccharide (LPS)-induced RAW264.7 cells and in an LPS-challenged mouse model of endotoxemia. We also assessed the antioxidant activity, and antiviral effect of BEN815, quercetin, and EGCG in SARS-CoV-2-infected Vero cells.

METHODS

The principal active ingredients in BEN815 were determined and quantified using HPLC. Changes in the levels of LPS-induced pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α were measured by ELISA. Changes in the expression levels of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) were analyzed using western blotting. Antioxidant assay was performed using DPPH and ABTS assay. SARS-CoV-2 replication was measured by immunofluorescence staining.

RESULTS

BEN815 significantly suppressed the induction of IL-6 and TNF-α as well as COX-2 and iNOS in LPS-induced RAW264.7 cells. In addition, BEN815 protected against LPS-challenged endotoxic shock in mice. Two major constituents of BEN815, quercetin and EGCG, reduced the induction of IL-6 and TNF-α as well as COX-2 and iNOS synthase in LPS-induced RAW264.7 cells. BEN815, quercetin, and EGCG were also found to have antioxidant effects. Importantly, BEN815 and EGCG could inhibit SARS-CoV-2 replications in Vero cells.

CONCLUSION

BEN815 is an anti-inflammatory, antiviral, and antioxidant natural agent that can be used to prevent and improve inflammation-related diseases, COVID-19.

Mutual Pan-African support paradigm to produce scientific evidence of traditional medical practices for use against COVID-19 and emerging pandemics

Africa is endowed with a profoundly rich and diverse system of plants and other bio-resources out of which, by traditional medicine practice, the people have satisfied their healthcare needs right from antiquity. In contemporary times, it has become necessary to modernize this traditional medical care system via scientific studies. Validation of the efficacy of health-enhancement products and drugs from plants and other bio-resources is predicated on diligent and intensive research accompanied by rigorous and conclusive clinical trials. Africa has eminently qualified human resources but due to the finance-intensive nature of medical research, individual African states on their own cannot fund the level of research desired for dealing with such serious issues as the COVID-19 pandemic. A collaboration among African states guided by a Mutual Pan-African support paradigm (MPASP) is a unique strategy for achieving success in any such a high-impact global project as the use of traditional medicine against COVID-19 and emerging pandemics; and this is hereby advocated.

In silico identification of potential inhibitors against main protease of SARS-CoV-2 6LU7 from Andrographis panniculata via molecular docking, binding energy calculations and molecular dynamics simulation studies

Background

The ongoing global outbreak of new corona virus (SARS-CoV-2) has been recognized as global public health concern since it causes high morbidity and mortality every day. Due to the rapid spreading and re-emerging, we need to find a potent drug against SARS-CoV-2. Synthetic drugs, such as hydroxychloroquine, remdisivir have paid more attention and the effects of these drugs are still under investigation, due to their severe side effects. Therefore, the aim of the present study was performed to identify the potential inhibitor against main protease SARS-CoV-2 6LU7.

Objective

In this study, RO5, ADME properties, molecular dynamic simulations and free binding energy prediction were mainly investigated.

Results

The molecular docking study findings revealed that andrographolide had higher binding affinity among the selected natural diterpenoids compared to co-crystal native ligand inhibitor N3. The persistent inhibition of Ki for diterpenoids was analogous. Furthermore, the simulations of molecular dynamics and free binding energy findings have shown that andrographolide possesses a large amount of dynamic properties such as stability, flexibility and binding energy.

Conclusion

In conclusion, findings of the current study suggest that selected diterpenoids were predicted to be the significant phytonutrient-based inhibitor against SARS-CoV-2 6LU7 (M^pro). However, preclinical and clinical trials are needed for the further scientific validation before use.

Research progress of epigallocatechin-3-gallate (EGCG) on anti-pathogenic microbes and immune regulation activities

At the end of 2019, the COVID-19 virus spread worldwide, infecting millions of people. Infectious diseases induced by pathogenic microorganisms such as the influenza virus, hepatitis virus, and Mycobacterium tuberculosis are also a major threat to public health. The high mortality caused by infectious pathogenic microorganisms is due to their strong virulence, which leads to the excessive counterattack by the host immune system and severe inflammatory damage of the immune system. This paper reviews the efficacy, mechanism and related immune regulation of epigallocatechin-3-gallate (EGCG) as an anti-pathogenic microorganism drug. EGCG mainly shows both direct and indirect anti-infection effects. EGCG directly inhibits early infection by interfering with the adsorption on host cells, inhibiting virus replication and reducing bacterial biofilm formation and toxin release; EGCG indirectly inhibits infection by regulating immune inflammation and antioxidation. At the same time, we reviewed the bioavailability and safety of EGCG in vivo. At present, the bioavailability of EGCG can be improved to some extent using nanostructured drug delivery systems and molecular modification technology in combination with other drugs. This study provides a theoretical basis for the development of EGCG as an adjuvant drug for anti-pathogenic microorganisms.

Fighting coronaviruses with natural polyphenols

Few licensed drugs and vaccines are available concerning COVID-19, a disease caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2). Furthermore, numerous recent SARS-COV-2 variants of have arisen globally, demonstrating the need to develop broadly protective interventions for different coronavirus strains. Polyphenols are the largest class of natural bioactive compounds, categorized as flavonoids (catechins, quercetin and kaempferol) and non-flavonoids (gallic acid and resveratrol), and these compounds have been described as effective antiviral agents. This is because they can inhibit coronavirus enzymes, blocking replication and infection. The present short manuscript aimed to summarize and report the current evidence from well-known powerful flavonoid (catechin, quercetin, and kaempferol) and non-flavonoid (gallic acid and resveratrol) polyphenols obtained from plant extracts that inhibit coronavirus strains in in vitro models or by computer modeling. The knowledge of strategies beyond conventional treatments may be helpful in the development of new coronavirus drugs, treatments/medicines, or formulations.

Recent insights on tea metabolites, their biosynthesis and chemo-preventing effects: A review

Tea manufactured from the cultivated shoots of Camellia sinensis (L.) O. Kuntze is the most commonly consumed nonalcoholic drink around the world. Tea is an agro-based, environmentally sustainable, labor-intensive, job-generating, and export-oriented industry in many countries. Tea includes phenolic compounds, flavonoids, alkaloids, vitamins, enzymes, crude fibers, protein, lipids, and carbohydrates, among other biochemical constituents. This review described the nature of tea metabolites, their biosynthesis and accumulation with response to various factors. The therapeutic application of various metabolites of tea against microbial diseases, cancer, neurological, and other metabolic disorders was also discussed in detail. The seasonal variation, cultivation practices and genetic variability influence tea metabolite synthesis. Tea biochemical constituents, especially polyphenols and its integral part catechin metabolites, are broadly focused on potential applicability for their action against various diseases. In addition to this, tea also contains bioactive flavonoids that possess health-beneficial effects. The catechin fractions, epigallocatechin 3-gallate and epicatechin 3-gallate, are the main components of tea that has strong antioxidant and medicinal properties. The synergistic function of natural tea metabolites with synthetic drugs provides effective protection against various diseases. Furthermore, the application of nanotechnologies enhanced bioavailability, enhancing the therapeutic potential of natural metabolites against numerous diseases and pathogens.

Effect of dihydromyricetin on SARS-CoV-2 viral replication and pulmonary inflammation and fibrosis

BACKGROUND

COVID-19 (Coronavirus Disease-2019) has spread widely around the world and impacted human health for millions. The lack of effective targeted drugs and vaccines forces scientific world to search for new effective antiviral therapeutic drugs. It has reported that flavonoids have potential inhibitory activity on SARS-CoV-2 M^pro and anti-inflammatory properties. Dihydromyricetin, as a flavonol, also has antiviral and anti-inflammatory potential. However, the inhibition of dihydromyricetin on SARS-CoV-2 M^pro and the protective effect of dihydromyricetin on pulmonary inflammation and fibrosis have not been proved and explained.

PURPOSE

The coronavirus main protease (M^pro) is essential for SARS-CoV-2 replication and to be recognized as an attractive drug target, we expect to find the inhibitor of M^pro. Novel coronavirus infection can cause severe inflammation and even sequelae of pulmonary fibrosis in critically ill patients. We hope to find a drug that can not only inhibit virus replication but also alleviate inflammation and pulmonary fibrosis in patients.

METHODS

FRET-based enzymatic assay was used to evaluate the inhibit activity of dihydromyricetin on SARS-CoV-2 M^pro. Molecular docking was used to identify the binding pose of dihydromyricetin with SARS-CoV-2 M^pro. The protective effects of dihydromyricetin against BLM-induced pulmonary inflammation and fibrosis were investigated in C57BL6 mice. BALF and lung tissue were collected for inflammation cells count, ELISA, masson and HE staining, western blotting and immunohistochemistry to analyze the effects of dihydromyricetin on pulmonary inflammation and fibrosis. MTT, western blotting, reverse transcription-polymerase chain reaction (RT-PCR) and wound healing were used to analyze the effects of dihydromyricetin on lung fibrosis mechanisms in Mlg cells.

RESULTS

In this study, we found that dihydromyricetin is a potent inhibitor targeting the SARS-CoV-2 M^pro with a half-maximum inhibitory concentration (IC₅₀) of 1.716 ± 0.419 μM, using molecular docking and the FRET-based enzymatic assay. The binding pose of dihydromyricetin with SARS-CoV-2 M^pro was identified using molecular docking method. In the binding pocket of SARS-CoV-2 M^pro, the dihydrochromone ring of dihydromyricetin interact with the imidazole side chain of His163 through π-π stacking. The 1-oxygen of dihydromyricetin forms a hydrogen bond with the backbone nitrogen of Glu166. The 3-, 7-, 3'- and 4'-hydroxyl of dihydromyricetin interact with Gln189, Leu141, Arg188 and Thr190 through hydrogen bonds. Moreover, our results showed that dihydromyricetin can significantly alleviate BLM-induced pulmonary inflammation by inhibiting the infiltration of inflammation cells and the secretion of inflammation factors in the early process and also ameliorate pulmonary fibrosis by improving pulmonary function and down-regulate the expression of α-SMA and fibronectin in vivo. Our results also showed that dihydromyricetin inhibits the migration and activation of myofibroblasts and extracellular matrix production via transforming growth factor (TGF)-β1/Smad signaling pathways.

CONCLUSION

Dihydromyricetin is an effective inhibitor for SARS-CoV-2 M^pro and it prevents BLM-induced pulmonary inflammation and fibrosis in mice. Dihydromyricetin will be a potential medicine for the treatment of COVID-19 and its sequelae.

Catechins: Therapeutic Perspectives in COVID-19-Associated Acute Kidney Injury

Data obtained from several intensive care units around the world have provided substantial evidence of the strong association between impairment of the renal function and in-hospital deaths of critically ill COVID-19 patients, especially those with comorbidities and requiring renal replacement therapy (RRT). Acute kidney injury (AKI) is a common renal disorder of various etiologies characterized by a sudden and sustained decrease of renal function. Studies have shown that 5-46% of COVID-19 patients develop AKI during hospital stay, and the mortality of those patients may reach up to 100% depending on various factors, such as organ failures and RRT requirement. Catechins are natural products that have multiple pharmacological activities, including anti-coronavirus and reno-protective activities against kidney injury induced by nephrotoxic agents, obstructive nephropathies and AKI accompanying metabolic and cardiovascular disorders. Therefore, in this review, we discuss the anti-SARS-CoV-2 and reno-protective effects of catechins from a mechanistic perspective. We believe that catechins may serve as promising therapeutics in COVID-19-associated AKI due to their well-recognized anti-SARS-CoV-2, and antioxidant and anti-inflammatory properties that mediate their reno-protective activities.

Preventive effects of tea and tea catechins against influenza and acute upper respiratory tract infections: a systematic review and meta-analysis

Purpose

Gargling with tea has protective effects against influenza infection and upper respiratory tract infection (URTI). To evaluate if tea and tea catechin consumption has the same protective effects as gargling with tea, we performed a systematic review and meta-analysis.

Methods

We performed a comprehensive literature search using the PubMed, Cochrane Library, Web of Science, and Ichu-shi Web databases. The search provided six randomized controlled trials (RCTs) and four prospective cohort studies (n = 3748). The quality of each trial or study was evaluated according to the Cochrane risk-of-bias tool or Newcastle–Ottawa Scale. We collected data from publications meeting the search criteria and conducted a meta-analysis of the effect of tea gargling and tea catechin consumption for preventing URTI using a random effects model.

Results

Tea gargling and tea catechin consumption had significant preventive effects against URTI (risk ratio [RR] = 0.74, 95% confidence interval [CI] 0.64–0.87). In sub-analyses, a significant preventive effect was observed by study type (prospective cohort study: RR = 0.67, 95% CI 0.50–0.91; RCT: RR = 0.79, 95% CI 0.66–0.94) and disease type (influenza: RR = 0.69, 95% CI 0.58–0.84; acute URTI: RR = 0.78, 95% CI 0.62–0.98). Both gargling with tea and consuming tea catechins effectively protected against URTI (tea and tea catechins consumption: RR = 0.68, 95% CI 0.52–0.87; tea gargling: RR = 0.83, 95% CI 0.72–0.96).

Conclusion

Our findings suggest that tea gargling and tea catechin consumption may have preventive effects against influenza infection and URTI. The potential effectiveness of these actions as non-pharmaceutical interventions, however, requires further investigation.

Polyphenols as alternative treatments of COVID-19

Although scientists around the world have put lots of effort into the development of new treatments for COVID-19 since the outbreak, no drugs except Veklury (remdesivir) have been approved by FDA. There is an urgent need to discover some alternative antiviral treatment for COVID-19. Because polyphenols have been shown to possess antiviral activities, here we conducted a large-scale virtual screening for more than 400 polyphenols. Several lead compounds such as Petunidin 3-O-(6″-p-coumaroyl-glucoside) were identified to have promising binding affinities and convincing binding mechanisms. Analyzing the docking results and ADME properties sheds light on the potential efficacy of the top-ranked drug candidates and pinpoints the key residues on the target proteins for the future of drug development.

Computational approach towards the design of artemisinin-thymoquinone hybrids against main protease of SARS-COV-2

Background

The sanitary emergency installed in the world, generated by the pandemic of COVID-19, instigates the search for scientific strategies to mitigate the damage caused by the disease to different sectors of society. The disease caused by the coronavirus, SARS-CoV-2, reached 216 countries/territories, where about 199 million people were reported with the infection. Of these, more than 4 million died. In this sense, strategies involving the development of new antiviral molecules are extremely important. The main protease (Mpro) from SARS-CoV-2 is an important target, which has been widely studied for antiviral treatment. This work aims to perform a screening of pharmacodynamics and pharmacokinetics of synthetic hybrids from thymoquinone and artemisin (THY-ART) against COVID-19.

Results

Molecular docking studies indicated that hybrids of artemisinin and thymoquinone showed a relevant interaction with the active fraction of the enzyme Mpro, when compared to the reference drugs. Furthermore, hybrids show an improvement in the interaction of substances with the enzyme, mainly due to the higher frequency of interactions with the Thr199 residue. ADMET studies indicated that hybrids tend to permeate biological membranes, allowing good human intestinal absorption, with low partition to the central nervous system, potentiation for CYP-450 enzyme inhibitors, low risk of toxicity compared to commercially available drugs, considering mainly mutagenicity and cardiotoxicity, low capacity of hybrids to permeate the blood–brain barrier, high absorption and moderate permeability in Caco-2 cells. In addition, T1–T7 tend to have a better distribution of their available fractions to carry out diffusion and transport across cell membranes, as well as increase the energy of interaction with the SARS-CoV-2 target.

Conclusions

Hybrid products of artemisinin and thymoquinone have the potential to inhibit Mpro, with desirable pharmacokinetic and toxicity characteristics compared to commercially available drugs, being indicated for preclinical and subsequent clinical studies against SARS-CoV-2. Emphasizing the possibility of synergistic use with currently used drugs in order to increase half-life and generate a possible synergistic effect. This work represents an important step for the development of specific drugs against COVID-19.

An overview of potential inhibitors targeting non-structural proteins 3 (PLpro and Mac1) and 5 (3CLpro/Mpro) of SARS-CoV-2

There is an urgent need to develop effective treatments for coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The rapid spread of SARS-CoV-2 has resulted in a global pandemic that has not only affected the daily lives of individuals but also had a significant impact on the global economy and public health. Although extensive research has been conducted to identify inhibitors targeting SARS-CoV-2, there are still no effective treatment strategies to combat COVID-19. SARS-CoV-2 comprises two important proteolytic enzymes, namely, the papain-like proteinase, located within non-structural protein 3 (nsp3), and nsp5, both of which cleave large replicase polypeptides into multiple fragments that are required for viral replication. Moreover, a domain within nsp3, known as the macrodomain (Mac1), also plays an important role in viral replication. Inhibition of their functions should be able to significantly interfere with the replication cycle of the virus, and therefore these key proteins may serve as potential therapeutic targets. The functions of the above viral targets and their corresponding inhibitors have been summarized in the current review. This review provides comprehensive updates of nsp3 and nsp5 inhibitor development and would help advance the discovery of novel anti-viral therapeutics against SARS-CoV-2.

Anticoronavirus and Immunomodulatory Phenolic Compounds: Opportunities and Pharmacotherapeutic Perspectives

In 2019, COVID-19 emerged as a severe respiratory disease that is caused by the novel coronavirus, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The disease has been associated with high mortality rate, especially in patients with comorbidities such as diabetes, cardiovascular and kidney diseases. This could be attributed to dysregulated immune responses and severe systemic inflammation in COVID-19 patients. The use of effective antiviral drugs against SARS-CoV-2 and modulation of the immune responses could be a potential therapeutic strategy for COVID-19. Studies have shown that natural phenolic compounds have several pharmacological properties, including anticoronavirus and immunomodulatory activities. Therefore, this review discusses the dual action of these natural products from the perspective of applicability at COVID-19.

From Fighting Critters to Saving Lives: Polyphenols in Plant Defense and Human Health

Polyphenols, such as flavonoids and phenolic acids, are a group of specialized metabolites in plants that largely aid in plant defense by deterring biotic stressors and alleviating abiotic stress. Polyphenols offer a wide range of medical applications, acting as preventative and active treatments for diseases such as cancers and diabetes. Recently, researchers have proposed that polyphenols may contribute to certain applications aimed at tackling challenges related to the COVID-19 pandemic. Understanding the beneficial impacts of phytochemicals, such as polyphenols, could potentially help prepare society for future pandemics. Thus far, most reviews have focused on polyphenols in cancer prevention and treatment. This review aims to provide a comprehensive discussion on the critical roles that polyphenols play in both plant chemical defense and human health based on the most recent studies while highlighting prospective avenues for future research, as well as the implications for phytochemical-based applications in both agricultural and medical fields.

Computational Chemistry to Repurposing Drugs for the Control of COVID-19

Thus far, in 2021, 219 countries with over 175 million people have been infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 is a positive sense, single-stranded RNA virus, and is the causal agent for coronavirus disease (COVID-19). Due to the urgency of the situation, virtual screening as a computational modeling method offers a fast and effective modality of identifying drugs that may be effective against SARS-CoV-2. There has been an overwhelming abundance of molecular docking against SARS-CoV-2 in the last year. Due to the massive volume of computational studies, this systematic review has been created to evaluate and summarize the findings of existing studies. Herein, we report on computational articles of drugs which target, (1) viral protease, (2) Spike protein-ACE 2 interaction, (3) RNA-dependent RNA polymerase, and (4) other proteins and nonstructural proteins of SARS-CoV-2. Based on the studies presented, there are 55 identified natural or drug compounds with potential anti-viral activity. The next step is to show anti-viral activity in vitro and translation to determine effectiveness into human clinical trials.

Immunotherapies and immunomodulatory approaches in clinical trials - a mini review

The coronavirus disease (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created havoc worldwide. Due to the non-availability of any vaccine or drugs against COVID-19, immunotherapies involving convalescent plasma, immunoglobulins, antibodies (monoclonal or polyclonal), and the use of immunomodulatory agents to enhance immunity are valuable alternative options. Cell-based therapies including natural killer cells, T cells, stem cells along with cytokines and toll-like receptors (TLRs) based therapies are also being exploited potentially against COVID-19. Future research need to strengthen the field of developing effective immunotherapeutics and immunomodulators with a thrust of providing appropriate, affordable, convenient, and cost-effective prophylactic and treatment regimens to combat global COVID-19 crisis that has led to a state of medical emergency enforcing entire countries of the world to devote their research infrastructure and manpower in tackling this pandemic.

Antiviral Effects of Green Tea EGCG and Its Potential Application against COVID-19

(–)-Epigallocatechin-3-O-gallate (EGCG), the most abundant component of catechins in tea (Camellia sinensis (L.) O. Kuntze), plays a role against viruses through inhibiting virus invasiveness, restraining gene expression and replication. In this paper, the antiviral effects of EGCG on various viruses, including DNA virus, RNA virus, coronavirus, enterovirus and arbovirus, were reviewed. Meanwhile, the antiviral effects of the EGCG epi-isomer counterpart (+)-gallocatechin-3-O-gallate (GCG) were also discussed.

Myricetin Inhibits SARS-CoV-2 Viral Replication by Targeting Mpro and Ameliorates Pulmonary Inflammation

The coronavirus disease 2019 (COVID-19) has spread widely around the world and has seriously affected the human health of tens of millions of people. In view of lacking anti-virus drugs target to SARS-CoV-2, there is an urgent need to develop effective new drugs. In this study, we reported our discovery of SARS-CoV-2 M^pro inhibitors. We selected 15 natural compounds, including 7 flavonoids, 3 coumarins, 2 terpenoids, one henolic, one aldehyde and one steroid compound for molecular docking and enzymatic screening. Myricetin were identified to have potent inhibit activity with IC₅₀ 3.684 ± 0.076 μM in the enzyme assay. The binding pose of Myricetin with SARS-CoV-2 M^pro was identified using molecular docking method. In the binding pocket of SARS-CoV-2 M^pro, the chromone ring of Myricetin interacts with His41 through π-π stacking, and the 3'-, 4'- and 7-hydroxyl of Myricetin interact with Phe140, Glu166and Asp187 through hydrogen bonds. Significantly, our results showed that Myricetin has potent effect on bleomycin-induced pulmonary inflammation by inhibiting the infiltration of inflammatory cells and the secretion of inflammatory cytokines IL-6, IL-1α, TNF-α and IFN-γ. Overall, Myricetin may be a potential drug for anti-virus and symptomatic treatment of COVID-19.

Potential role of Nigella sativa supplementation with physical activity in prophylaxis and treatment of COVID-19: a contemporary review

The widespread prevalence and mortality of coronavirus diseases-2019 (COVID-19) lead many researchers to study the SARS-CoV-s2 infection to find a treatment for this disease. Discovering the mechanisms of action of COVID-19 and coping at the cellular level with this disease can have better effects. Including the target tissues of this disease are the lungs and the immune system. It is stated that COVID-19 easily infiltrates into alveoli through its receptors and then starts to proliferate. Subsequently, with the weakening of immune cells and increase inflammatory cytokines, it increases the rate of inflammation in the body. Strengthening the immune system and inhibiting COVID-19 receptors can play a preventive or even therapeutic role for this disease. Nigella sativa (N. sativa) is one of the herbal medicines to possess numerous pharmacological effects related to several organs of the body. Among the extraordinary properties of this plant is improving asthma and several lung diseases. The recent studies have shown that N. sativa at the cellular level can inhibit COVID-19 receptors. It was also stated that performing regular exercise training (especially moderate-intensity exercise training) can modulate the immune system and have an anti-inflammatory effect. Since the use of herbal supplements with exercise can have tremendous therapeutic effects at the cellular level, the hypothesis to use the Nigella sativa along with exercise training to prophylaxis and treatment COVID-19 will be highlighted in this paper.

Potential protective mechanisms of green tea polyphenol EGCG against COVID-19

Background

The world is in the midst of the COVID-19 pandemic. In this comprehensive review, we discuss the potential protective effects of (−)-epigallocatechin-3-gallate (EGCG), a major constituent of green tea, against COVID-19.

Scope and approach

Information from literature of clinical symptoms and molecular pathology of COVID-19 as well as relevant publications in which EGCG shows potential protective activities against COVID-19 is integrated and evaluated.

Key findings and conclusions

EGCG, via activating Nrf2, can suppress ACE2 (a cellular receptor for SARS-CoV-2) and TMPRSS2, which mediate cell entry of the virus. Through inhibition of SARS-CoV-2 main protease, EGCG may inhibit viral reproduction. EGCG via its broad antioxidant activity may protect against SARS-CoV-2 evoked mitochondrial ROS (which promote SARS-CoV-2 replication) and against ROS burst inflicted by neutrophil extracellular traps. By suppressing ER-resident GRP78 activity and expression, EGCG can potentially inhibit SARS-CoV-2 life cycle. EGCG also shows protective effects against 1) cytokine storm-associated acute lung injury/acute respiratory distress syndrome, 2) thrombosis via suppressing tissue factors and activating platelets, 3) sepsis by inactivating redox-sensitive HMGB1, and 4) lung fibrosis through augmenting Nrf2 and suppressing NF-κB. These activities remain to be further substantiated in animals and humans. The possible concerted actions of EGCG suggest the importance of further studies on the prevention and treatment of COVID-19 in humans. These results also call for epidemiological studies on potential preventive effects of green tea drinking on COVID-19.

Integrative web-based analysis of omics data for study of drugs against SARS-CoV-2

Research on drugs against SARS-CoV-2 (cause of COVID-19) has been one of the major world concerns at present. There have been abundant research data and findings in this field. The interference of drugs on gene expression in cell lines, drug-target, protein-virus receptor networks, and immune cell infiltration of the host may provide useful information for anti-SARS-CoV-2 drug research. To simplify the complex bioinformatics analysis and facilitate the evaluation of the latest research data, we developed OmiczViz ( http://medcode.link/omicsviz ), a web tool that has integrated drug-cell line interference data, virus-host protein-protein interactions, and drug-target interactions. To demonstrate the usages of OmiczViz, we analyzed the gene expression data from cell lines treated with chloroquine and ruxolitinib, the drug-target protein networks of 48 anti-coronavirus drugs and drugs bound with ACE2, and the profiles of immune cell infiltration between different COVID-19 patient groups. Our research shows that chloroquine had a regulatory role of the immune response in renal cell line but not in lung cell line. The anti-coronavirus drug-target network analysis suggested that antihistamine of promethaziney and dietary supplement of Zinc might be beneficial when used jointly with antiviral drugs. The immune infiltration analysis indicated that both the COVID-19 patients admitted to the ICU and the elderly with infection showed immune exhaustion status, yet with different molecular mechanisms. The interactive graphic interface of OmiczViz also makes it easier to analyze newly discovered and user-uploaded data, leading to an in-depth understanding of existing findings and an expansion of existing knowledge of SARS-CoV-2. Collectively, OmicsViz is web program that promotes the research on medical agents against SARS-CoV-2 and supports the evaluation of the latest research findings.

Scutellaria barbata D. Don Inhibits the Main Proteases (Mpro and TMPRSS2) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

In late 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic emerged to severely impact the global population, creating an unprecedented need for effective treatments. This study aims to investigate the potential of Scutellaria barbata D. Don (SB) as a treatment for SARS-CoV-2 infection through the inhibition of the proteases playing important functions in the infection by SARS-CoV-2. FRET assay was applied to investigate the inhibitory effects of SB on the two proteases involved in SARS-CoV-2 infection, Mpro and TMPRSS2. Additionally, to measure the potential effectiveness of SB treatment on infection inhibition, cellular models based on the Calu3 and VeroE6 cells and their TMPRSS2- expressing derivatives were assessed by viral pseudoparticles (Vpp) infection assays. The experimental approaches were conjugated with LC/MS analyses of the aqueous extracts of SB to identify the major constituent compounds, followed by a literature review to determine the potential active components of the inhibitory effects on protease activities. Our results showed that SB extracts inhibited the enzyme activities of Mpro and TMPRSS2. Furthermore, SB extracts effectively inhibited SARS-CoV-2 Vpp infection through a TMPRSS2-dependent mechanism. The aqueous extract analysis identified six major constituent compounds present in SB. Some of them have been known associated with inhibitory activities of TMPRSS2 or Mpro. Thus, SB may effectively prevent SARS-CoV-2 infection and replication through inhibiting Mpro and TMPRSS2 protease activities.

Efficacy of Phytochemicals Derived from Avicennia officinalis for the Management of COVID-19: A Combined In Silico and Biochemical Study

The recent coronavirus disease 2019 (COVID-19) pandemic is a global threat for healthcare management and the economic system, and effective treatments against the pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus responsible for this disease have not yet progressed beyond the developmental phases. As drug refinement and vaccine progression require enormously broad investments of time, alternative strategies are urgently needed. In this study, we examined phytochemicals extracted from Avicennia officinalis and evaluated their potential effects against the main protease of SARS-CoV-2. The antioxidant activities of A. officinalis leaf and fruit extracts at 150 µg/mL were 95.97% and 92.48%, respectively. Furthermore, both extracts displayed low cytotoxicity levels against Artemia salina. The gas chromatography-mass spectroscopy analysis confirmed the identifies of 75 phytochemicals from both extracts, and four potent compounds, triacontane, hexacosane, methyl linoleate, and methyl palminoleate, had binding free energy values of -6.75, -6.7, -6.3, and -6.3 Kcal/mol, respectively, in complexes with the SARS-CoV-2 main protease. The active residues Cys145, Met165, Glu166, Gln189, and Arg188 in the main protease formed non-bonded interactions with the screened compounds. The root-mean-square difference (RMSD), root-mean-square fluctuations (RMSF), radius of gyration (Rg), solvent-accessible surface area (SASA), and hydrogen bond data from a molecular dynamics simulation study confirmed the docked complexes' binding rigidity in the atomistic simulated environment. However, this study's findings require in vitro and in vivo validation to ensure the possible inhibitory effects and pharmacological efficacy of the identified compounds.

Identification of alkaloids from Justicia adhatoda as potent SARS CoV-2 main protease inhibitors: An in silico perspective

The COVID-19 pandemic, caused by SARS CoV-2, is responsible for millions of death worldwide. No approved/proper therapeutics is currently available which can effectively combat this outbreak. Several attempts have been undertaken in the search of effective drugs to control the spread of SARS CoV-2 infection. The main protease (Mpro), key component for the cleavage of the viral polyprotein, is considered to be one of the important drug targets for treating COVID-19. Various phytochemicals, including polyphenols and alkaloids, have been proposed as potent inhibitors of Mpro. The alkaloids from leaf extracts of Justicia adhatoda have also been reported to possess anti-viral activity. But whether these alkaloids exhibit any inhibitory effect on SARS CoV-2 Mpro is far from clear. To explore this in detail, we have adopted computational approaches. Justicia adhatoda alkaloids possessing proper drug-likeness properties and two anti-HIV drugs (lopinavir and darunavir; having binding affinity -7.3 to -7.4 kcal/mol) were docked against SARS CoV-2 Mpro to study their binding properties. Only one alkaloid (anisotine) had interaction with both the catalytic residues (His41 and Cys145) of Mpro and exhibited good binding affinity (-7.9 kcal/mol). Molecular dynamic simulations (100 ns) revealed that Mpro-anisotine complex is more stable, conformationally less fluctuated; slightly less compact and marginally expanded than Mpro-darunavir/lopinavir complex. Even the number of intermolecular H-bonds and MM-GBSA analysis suggested that anisotine is a more potent Mpro inhibitor than the two previously recommended antiviral drugs (lopinavir and darunavir) and may evolve as a promising anti-COVID-19 drug if proven in animal experiments and on patients.

Chemo-Preventive Effect of Vegetables and Fruits Consumption on the COVID-19 Pandemic

Coronavirus disease 2019 (COVID-19) is a new disease caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is a global pandemic that has claimed the death of 1,536,957 human beings worldwide including 287,842 deaths in the United States as of December 3, 2020. It has become a major threat to the medical community and the entire healthcare system in every part of the world. Recently, the Food and Drug Administration (FDA) has approved the emergency use of Pfizer and Moderna COVID-19 vaccine on December 12, 2020. However, there are concern about the new COVID-19 vaccine safety, efficacy, and immunity after the vaccination. In addition, both coronavirus and COVID-19 vaccine are new at this point and there is no scientific evidence to know whether people who are vaccinated can still carry the COVID 19 pathogens and pass them along to others. Therefore, many people all over the world have an increased interest in consuming more VF for the purpose of maintaining their health and boosting their immune system. Identifying novel antiviral agents for COVID-19 is of critical importance, and VF is an excellent source for drug discovery and therapeutic development. The objective of this study is to test the hypothesis that a high intake of vegetables and/or fruits prevents COVID-19 incidence and reduces the mortality rate. To achieve this objective, we collected the diet data of COVID-19 from Kaggle (https://www.kaggle.com/mariaren/covid19-healthy-diet-dataset), and used a machine-learning algorithm to examine the effects of different food types on COVID-19 incidences and deaths. Specifically, we used the feature selection method to identify the factors (e.g., diet-related factors) that contribute to COVID-19 morbidity and mortality. Data generated from the study demonstrated that VF intake can help to combat the SARS-CoV-2. Taken together, VF may be potential chemopreventive agents for COVID-19 due to their antiviral properties and their ability to boost the human body immune system.

Medicinal Plants, Phytochemicals, and Herbs to Combat Viral Pathogens Including SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2), is the most important health issue, internationally. With no specific and effective antiviral therapy for COVID-19, new or repurposed antiviral are urgently needed. Phytochemicals pose a ray of hope for human health during this pandemic, and a great deal of research is concentrated on it. Phytochemicals have been used as antiviral agents against several viruses since they could inhibit several viruses via different mechanisms of direct inhibition either at the viral entry point or the replication stages and via immunomodulation potentials. Recent evidence also suggests that some plants and its components have shown promising antiviral properties against SARS-CoV-2. This review summarizes certain phytochemical agents along with their mode of actions and potential antiviral activities against important viral pathogens. A special focus has been given on medicinal plants and their extracts as well as herbs which have shown promising results to combat SARS-CoV-2 infection and can be useful in treating patients with COVID-19 as alternatives for treatment under phytotherapy approaches during this devastating pandemic situation.

Mechanisms Modified by (-)-Epicatechin and Taxifolin Relevant for the Treatment of Hypertension and Viral Infection: Knowledge from Preclinical Studies

Various studies have shown that certain flavonoids, flavonoid-containing plant extracts, and foods can improve human health. Experimental studies showed that flavonoids have the capacity to alter physiological processes as well as cellular and molecular mechanisms associated with their antioxidant properties. An important function of flavonoids was determined in the cardiovascular system, namely their capacity to lower blood pressure and to improve endothelial function. (-)-Epicatechin and taxifolin are two flavonoids with notable antihypertensive effects and multiple beneficial actions in the cardiovascular system, but they also possess antiviral effects, which may be of particular importance in the ongoing pandemic situation. Thus, this review is focused on the current knowledge of (-)-epicatechin as well as (+)-taxifolin and/or (-)-taxifolin-modified biological action and underlining molecular mechanisms determined in preclinical studies, which are relevant not only to the treatment of hypertension per se but may provide additional antiviral benefits that could be relevant to the treatment of hypertensive subjects with SARS-CoV-2 infection.

Agri-Food Extracts Effectiveness in Improving Antibacterial and Antiviral Properties of Face Masks: A Proof-of-Concept Study

The European dependencies for raw materials supply from foreign countries have been unquestionably shown by COVID-19 outbreak and have become particular evident from the slow response to the need for high quality personal protective equipment (PPEs). Among all medical devices, surgical face masks have earned themselves a primary role for the containment of the epidemic. In this context, our work aims at improving the barrier effect of surgical mask by depositing on their external surface a mixture of bioactive compounds, mainly polyphenols, extracted from agronomical sources. The main objective is the integration of the biorefining of agri-food solid wastes with the potential virucidal properties of the polyphenolic extracts for the treatment of PPEs.

Therapeutic Potential of EGCG, a Green Tea Polyphenol, for Treatment of Coronavirus Diseases

Epigallocatechin gallate (EGCG) is a major catechin found in green tea, and there is mounting evidence that EGCG is potentially useful for the treatment of coronavirus diseases, including coronavirus disease 2019 (COVID-19). Coronaviruses encode polyproteins that are cleaved by 3CL protease (the main protease) for maturation. Therefore, 3CL protease is regarded as the main target of antivirals against coronaviruses. EGCG is a major constituent of brewed green tea, and several studies have reported that EGCG inhibits the enzymatic activity of the coronavirus 3CL protease. Moreover, EGCG has been reported to regulate other potential targets, such as RNA-dependent RNA polymerase and the viral spike protein. Finally, recent studies have demonstrated that EGCG treatment interferes with the replication of coronavirus. In addition, the bioavailability of EGCG and future research prospects are discussed.

Potential SARS-CoV-2 main protease inhibitors

The coronavirus disease 2019 (COVID-19) pandemic has prompted an urgent need for new treatment strategies. No target-specific drugs are currently available for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but new drug candidates targeting the viral replication cycle are being explored. A prime target of drug-discovery efforts is the SARS-CoV-2 main protease (Mpro). The main proteases of different coronaviruses, including SARS-CoV-2, SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), share a structurally conserved substrate-binding region that can be exploited to design new protease inhibitors. With the recent reporting of the X-ray crystal structure of the SARS-CoV-2 Mpro, studies to discover Mpro inhibitors using both virtual and in vitro screening are progressing rapidly. This review focusses on the recent developments in the search for small-molecule inhibitors targeting the SARS-CoV-2 Mpro.

Inhibition of ACE2 Expression by Ascorbic Acid Alone and its Combinations with Other Natural Compounds

BACKGROUND

Angiotensin-converting enzyme II or ACE2 is an integral membrane protein present on many types of cells, including vascular endothelial cells and lung alveolar epithelial cells. This receptor serves as the entry point for SARS-coronaviruses (SARS-CoVs), including a novel coronavirus 2019-nCoV. Limited availability of these receptors can thwart cellular entry of this virus.

METHODS

We tested the effects of ascorbic acid (vitamin C) on cellular expression of ACE2 at the protein and RNA levels in human small alveolar epithelial cells and microvascular endothelial cells. In addition, we investigated whether combinations of ascorbic acid with other natural compounds can affect ACE2 expression.

RESULTS

The results show that ascorbic acid itself has moderate but consistent lowering effects on ACE2 expression at the cellular, protein, and RNA levels. Some natural compounds were effective in lowering ACE2 cellular expression, with the highest inhibitory effects observed for baicalin (75%) and theaflavin (50%). Significantly, combinations of these and other test compounds with ascorbic acid further decreased ACE2 expression. The highest impact of ascorbate on ACE2 expression was noted when combined with theaflavin (decrease from 50% to 87%), zinc (decrease from 22% to 62%), and with 10-undecenoic acid (from 18% to 53%). Ascorbic acid showed moderate additional benefits in decreasing ACE2 expression when combined with N-acetylcysteine and baicalin.

CONCLUSION

Our study provides valuable experimental confirmation of the efficacy of micronutrients in controlling ACE2 expression-the coronavirus cellular "entry" point. It further validates the importance of nutrient interactions in various aspects of cellular metabolism and in considering potential therapeutic applications of nutrient-based approaches. The study shows that ascorbic acid and its combination with some natural compounds could be included in developing preventive and therapeutic approaches toward the current pandemic.

A molecular docking study of EGCG and theaflavin digallate with the druggable targets of SARS-CoV-2

BACKGROUND

COVID-19 is an infectious disease caused by a novel positive-sense single-stranded RNA coronavirus called as SARS-CoV-2. This viral disease is known to infect the respiratory system, eventually leading to pneumonia. Crystallographic studies of the viral structure reveal its mechanism of infection as well as active binding sites and the druggable targets as scope for treatment of COVID-19.

HYPOTHESIS

The role of tea polyphenols in prophylaxis and treatment of COVID-19 was established in this study.

STUDY DESIGN

Molecular docking interactions of tea polyphenols with some of the possible binding sites of SARS-CoV-2 were performed.

MATERIALS AND METHODS

From various studies on the SARS-CoV-2 reported in the literature, we chose possible drug targets (Chymotrypsin-like protease, RNA dependant RNA polymerase, Papain like protease, Spike RBD and ACE2 receptor with spike RBD) which are vital proteins. These receptors were docked against two tea polyphenols, Epigallocatechin gallate (EGCG) from green tea and Theaflavin digallate (TF3) from black tea. These polyphenols have been previously reviewed for their antiviral activities, especially against single-stranded RNA viruses. Two antiviral drugs, Remdesivir and Favipiravir were studied for comparative docking results.

RESULTS

A comparative study of docking scores and the type of interactions of EGCG, TF3 with the possible targets of COVID-19 showed that the tea polyphenols had good docking scores with significant in-silico activity.

CONCLUSION

These results can provide a lead in exploring both the tea polyphenols in prophylaxis as well as treatment of COVID-19.

In silico docking analysis revealed the potential of phytochemicals present in Phyllanthus amarus and Andrographis paniculata, used in Ayurveda medicine in inhibiting SARS-CoV-2

The Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has resulted in outbreak of global pandemic, fatal pneumonia in human referred as Coronavirus Disease-2019 (Covid-19). Ayurveda, the age old practice of treating human ailments in India, can be considered against SARS-CoV-2. Attempt was made to provide preliminary evidences for interaction of 35 phytochemicals from two plants (Phyllanthus amarus and Andrographis paniculata used in Ayurveda) with SARS-CoV-2 proteins (open & closed state S protein, 3CLpro, PLpro and RdRp) through in silico docking analysis. The nucleotide analogue remdesivir, being used in treatment of SARS-CoV-2, was used as a positive control. The results revealed that 18 phytochemicals from P. amarus and 14 phytochemicals from A. paniculata shown binding energy affinity/dock score < - 6.0 kcal/mol, which is considered as minimum threshold for any compound to be used for drug development. Phytochemicals used for docking studies in the current study from P. amarus and A. paniculata showed binding affinity up to - 9.10 kcal/mol and - 10.60 kcal/mol, respectively. There was no significant difference in the binding affinities of these compounds with closed and open state S protein. Further, flavonoids (astragalin, kaempferol, quercetin, quercetin-3-O-glucoside and quercetin) and tannins (corilagin, furosin and geraniin) present in P. amarus have shown more binding affinity (up to - 10.60 kcal/mol) than remdesivir (up to - 9.50 kcal/mol). The pharmacokinetic predictions suggest that compounds from the two plants species studied in the current study are found to be non-carcinogenic, water soluble and biologically safe. The phytochemicals present in the extracts of P. amarus and A. paniculata might have synergistic effect with action on multiple target sites of SARS-CoV-2. The information generated here might serve as preliminary evidence for anti SARS-CoV-2 activity of phytochemicals present from P. amarus and A. paniculata and the potential of Ayurveda medicine in combating the virus.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-020-02578-7.

Targeting Neurological Manifestations of Coronaviruses by Candidate Phytochemicals: A Mechanistic Approach

The novel coronavirus 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made a wide range of manifestations. In this regard, growing evidence is focusing on COVID-19 neurological associations; however, there is a lack of established pathophysiological mechanisms and related treatments. Accordingly, a comprehensive review was conducted, using electronic databases, including PubMed, Scopus, Web of Science, and Cochrane, along with the author's expertize in COVID-19 associated neuronal signaling pathways. Besides, potential phytochemicals have been provided against neurological signs of COVID-19. Considering a high homology among SARS-CoV, Middle East Respiratory Syndrome and SARS-CoV-2, revealing their precise pathophysiological mechanisms seems to pave the road for the treatment of COVID-19 neural manifestations. There is a complex pathophysiological mechanism behind central manifestations of COVID-19, including pain, hypo/anosmia, delirium, impaired consciousness, pyramidal signs, and ischemic stroke. Among those dysregulated neuronal mechanisms, neuroinflammation, angiotensin-converting enzyme 2 (ACE2)/spike proteins, RNA-dependent RNA polymerase and protease are of special attention. So, employing multi-target therapeutic agents with considerable safety and efficacy seems to show a bright future in fighting COVID-19 neurological manifestations. Nowadays, natural secondary metabolites are highlighted as potential multi-target phytochemicals in combating several complications of COVID-19. In this review, central pathophysiological mechanisms and therapeutic targets of SARS-CoV-2 has been provided. Besides, in terms of pharmacological mechanisms, phytochemicals have been introduced as potential multi-target agents in combating COVID-19 central nervous system complications.

Health Benefits and Chemical Composition of Matcha Green Tea: A Review

Japanese matcha is a type of powdered green tea, grown in a traditional way. Shading of the plants during the growth period enhances the processes of synthesis and accumulation of biologically active compounds, including theanine, caffeine, chlorophyll and various types of catechins. Green tea contains four main catechins, i.e., (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), of which the latter is the most active and abundant and matcha is their best condensed source. Due to its unique chemical composition and prized flavour, which sets it apart from other tea beverages, it is considered the highest quality tea. Its health-promoting properties are attributed to the high content of antioxidant and anti-inflammatory substances. Studies confirming the high antioxidant potential of tea beverages claim that it originates from the considerable content of catechins, a type of phenolic compound with beneficial effects on human health. Due to its potential for preventing many diseases and supporting cognitive function, regular consumption of matcha may have a positive effect on both physical and mental health. The aim of this review was to compile the health benefits of matcha tea. It is the first such review to be undertaken, and presents its main bioactive compounds in a systematic manner.

Identification of Small Molecule Inhibitors of the Deubiquitinating Activity of the SARS-CoV-2 Papain-Like Protease: in silico Molecular Docking Studies and in vitro Enzymatic Activity Assay

COVID-19 is an ongoing pandemic caused by the SARS-CoV-2 virus with important political, socio-economic, and public health consequences. Inhibiting replication represents an important antiviral approach, and in this context two viral proteases, the SARS-CoV-2 main and papain-like proteases (PLpro), which cleave pp1a and pp1ab polypeptides, are critical. Along with protease activity, the PLpro possesses deubiquitinating activity, which is important in immune regulation. Naphthalene-based inhibitors, such as the well-investigated GRL-0617 compound, have been shown to possess dual effects, inhibiting both protease and deubiquitinating activity of the PLpro. Rather than binding to the canonical catalytic triad, these type of non-covalent inhibitors target an adjacent pocket, the naphthalene-inhibitor binding site. Using a high-throughput screen, we have previously identified the dietary hypericin, rutin, and cyanidin-3-O-glucoside compounds as potential protease inhibitors targeting the naphthalene-inhibitor binding site. Here, our aim was to investigate the binding characteristics of these compounds to the PLpro, and to evaluate deubiquitinating activity, by analyzing seven different PLpro crystal structures. Molecular docking highlighted the relatively high affinity of GRL-0617 and dietary compounds. In contrast binding of the small molecules was abolished in the presence of ubiquitin in the palm subdomain of the PLpro. Further, docking the small molecules in the naphthalene-inhibitor binding site, followed by protein-protein docking revealed displacement of ubiquitin in a conformation inconsistent with functional activity. Finally, the deubiquitinating activity was validated in vitro using an enzymatic activity assay. The findings indicated that the dietary compounds inhibited deubiquitinase activity in the micromolar range with an order of activity of GRL-0167, hypericin >> rutin, cyanidin-3-O-glucoside > epigallocatechin gallate, epicatechin gallate, and cefotaxime. Our findings are in accordance with mechanisms and potential antiviral effects of the naphthalene-based, GRL-0617 inhibitor, which is currently progressing in preclinical trials. Further, our findings indicate that in particular hypericin, rutin, and cyanidin-3-O-glucoside, represent suitable candidates for subsequent evaluation as PLpro inhibitors.

Docking Characterization and in vitro Inhibitory Activity of Flavan-3-ols and Dimeric Proanthocyanidins Against the Main Protease Activity of SARS-Cov-2

We report to use the main protease (M^pro) of SARS-Cov-2 to screen plant flavan-3-ols and proanthocyanidins. Twelve compounds, (-)-afzelechin (AF), (-)-epiafzelechin (EAF), (+)-catechin (CA), (-)-epicatechin (EC), (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (+)-catechin-3-O-gallate (CAG), (-)-epicatechin-3-O-gallate (ECG), (-)-gallocatechin-3-O-gallate (GCG), (-)-epigallocatechin-3-O-gallate (EGCG), procyanidin A2 (PA2), and procyanidin B2 (PB2), were selected for docking simulation. The resulting data predicted that all 12 metabolites could bind to M^pro. The affinity scores of PA2 and PB2 were predicted to be -9.2, followed by ECG, GCG, EGCG, and CAG, -8.3 to -8.7, and then six flavan-3-ol aglycones, -7.0 to -7.7. Docking characterization predicted that these compounds bound to three or four subsites (S1, S1', S2, and S4) in the binding pocket of M^pro via different spatial ways and various formation of one to four hydrogen bonds. In vitro analysis with 10 available compounds showed that CAG, ECG, GCG, EGCG, and PB2 inhibited the M^pro activity with an IC₅₀ value, 2.98 ± 0.21, 5.21 ± 0.5, 6.38 ± 0.5, 7.51 ± 0.21, and 75.3 ± 1.29 μM, respectively, while CA, EC, EGC, GC, and PA2 did not have inhibitory activities. To further substantiate the inhibitory activities, extracts prepared from green tea (GT), two muscadine grapes (MG), cacao, and dark chocolate (DC), which are rich in CAG, ECG, GAG, EGCG, or/and PB2, were used for inhibitory assay. The resulting data showed that GT, two MG, cacao, and DC extracts inhibited the M^pro activity with an IC₅₀ value, 2.84 ± 0.25, 29.54 ± 0.41, 29.93 ± 0.83, 153.3 ± 47.3, and 256.39 ± 66.3 μg/ml, respectively. These findings indicate that on the one hand, the structural features of flavan-3-ols are closely associated with the affinity scores; on the other hand, the galloylation and oligomeric types of flavan-3-ols are critical in creating the inhibitory activity against the M^pro activity.

Epitope-Based Potential Vaccine Candidate for Humoral and Cell-Mediated Immunity to Combat Severe Acute Respiratory Syndrome Coronavirus 2 Pandemic

The emergence of severe acute respiratory syndrome from novel Coronavirus (SARS-CoV-2) has put an immense pressure worldwide where vaccination is believed to be an efficient way for developing hard immunity. Herein, we employ immunoinformatic tools to identify B-cell, T-cell epitopes associated with the spike protein of SARS-CoV-2, which is important for genome release. The results showed that the highly immunogenic epitopes located at the stalk part are mostly conserved compared to the receptor binding domain (RDB). Further, two vaccine candidates were computationally modeled from the linear B-cell, T-cell epitopes. Molecular docking reveals the crucial interactions of the vaccines with immune-receptors, and their stability is assessed by MD simulation studies. The chimeric vaccines showed remarkable binding affinity toward the immune cell receptors computed by the MM/PBSA method. van der Waals and electrostatic interactions are found to be the dominant factors for the stability of the complexes. The molecular-level interaction obtained from this study may provide deeper insight into the process of vaccine development against the pandemic of COVID-19.

In Search of Herbal Anti-SARS-Cov2 Compounds

On March 11, 2020, the World Health Organization (WHO) announced that the spread of the new coronavirus had reached the stage of a pandemic. To date (23.10.2020), there are more than 40 million confirmed cases of the disease in the world, at the same time there is still no effective treatment for the disease. For management and treatment of SARS-Cov2, the development of an antiviral drug is needed. Since the representatives of all human cultures have used medicinal plants to treat viral diseases throughout their history, plants can be considered as sources of new antiviral drug compounds against emerging viruses. The huge metabolic potential of plants allows us to expect discovery of plant compounds for the prevention and treatment of coronavirus infection. This idea is supported by number of papers on the anti-SARS-Cov2 activity of plant extracts and specific compounds in the experiments in silico, in vitro, and in vivo. Here, we summarize information on methods and approaches aimed to search for anti-SARS-Cov2 compounds including cheminformatics, bioinformatics, genetic engineering of viral targets, interacting with drugs, biochemical approaches etc. Our mini-review may be useful for better planning future experiments (including rapid methods for screening compounds for antiviral activity, the initial assessment of the antiviral potential of various plant species in relation to certain pathogens, etc.) and giving a hand to those who are making first steps in this field.

Role of heterocyclic compounds in SARS and SARS CoV-2 pandemic

Coronaviruses have led to severe emergencies in the world since the outbreak of SARS CoV in 2002, followed by MERS CoV in 2012. SARS CoV-2, the novel pandemic caused by coronaviruses that began in December 2019 in China has led to a total of 24,066,076 confirmed cases and a death toll of 823,572 as reported by World Health Organisation on 26 August 2020, spreading to 213 countries and territories. However, there are still no vaccines or medications available till date against SARS coronaviruses which is an urgent requirement to control the current pandemic like situations. Since many decades, heterocyclic scaffolds have been explored exhaustively for their anticancer, antimalarial, anti-inflammatory, antitubercular, antimicrobial, antidiabetic, antiviral and many more treatment capabilities. Therefore, through this review, we have tried to emphasize on the anticipated role of heterocyclic scaffolds in the design and discovery of the much-awaited anti-SARS CoV-2 therapy, by exploring the research articles depicting different heterocyclic moieties as targeting SARS, MERS and SARS CoV-2 coronaviruses. The heterocyclic motifs mentioned in the review can serve as crucial resources for the development of SARS coronaviruses treatment strategies.

Tea Bioactive Modulate Innate Immunity: In Perception to COVID-19 Pandemic

Innate immunity impairment led to disruption in cascade of signaling pathways upregulating pro-inflammatory cytokines, diminish interferons, depleted natural killer cells and activate reactive oxygen species production. These conditions severely affected body's ability to fight against infectious diseases and also plays a pivotal role in disease progression. Here, in emphasis is on nutritional immunity for regulating effective innate immune response for combating against infectious diseases like novel coronavirus disease (COVID 19). Drawing from discoveries on in-vitro experiments, animal models and human trials, tea polyphenols, micronutrients, and vitamins has the potential to modulate and enhance innate immune response. This article provides a comprehensive review on tea (Camellia sinensis L) infusion (a hot water extract of dried processed tea leaves prepared from young shoots of tea plant) as an innate immunity modulator. Tea infusion is rich in polyphenols; epigallocatechin gallate (EGCG) and theaflavin (TF), major green and black tea polyphenols, respectively. Studies showed their immunomodulatory competence. Tea infusions are also rich in alkaloids; caffeine and its intermediates, theophylline and theobromine, which have anti-inflammatory properties. Tea plant being an acidophilic perennial crop can accumulate different micronutrients, viz., copper (Cu), iron (Fe), manganese (Mn), selenium (Se), and zinc (Zn) from growing medium, i.e., from soil, which led to their considerable presence in tea infusion. Micronutrients are integral part of innate immune response. Overall, this review presents tea infusion as an important source of nutritional immunity which can enhance innate immune response in order to mitigate the unprecedented COVID-19 pandemic.

Protease Inhibitory Effect of Natural Polyphenolic Compounds on SARS-CoV-2: An In Silico Study

The current pandemic, caused by SARS-CoV-2 virus, is a severe challenge for human health and the world economy. There is an urgent need for development of drugs that can manage this pandemic, as it has already infected 19 million people and led to the death of around 711,277 people worldwide. At this time, in-silico studies are providing lots of preliminary data about potential drugs, which can be a great help in further in-vitro and in-vivo studies. Here, we have selected three polyphenolic compounds, mangiferin, glucogallin, and phlorizin. These compounds are isolated from different natural sources but share structural similarities and have been reported for their antiviral activity. The objective of this study is to analyze and predict the anti-protease activity of these compounds on SARS-CoV-2main protease (Mpro) and TMPRSS2 protein. Both the viral protein and the host protein play an important role in the viral life cycle, such as post-translational modification and viral spike protein priming. This study has been performed by molecular docking of the compounds using PyRx with AutoDock Vina on the two aforementioned targets chosen for this study, i.e., SARS-CoV-2 Mpro and TMPRSS2. The compounds showed good binding affinity and are further analyzed by (Molecular dynamic) MD and Molecular Mechanics Poisson-Boltzmann Surface Area MM-PBSA study. The MD-simulation study has predicted that these natural compounds will have a great impact on the stabilization of the binding cavity of the Mpro of SARS-CoV-2. The predicted pharmacokinetic parameters also show that these compounds are expected to have good solubility and absorption properties. Further predictions for these compounds also showed no involvement in drug-drug interaction and no toxicity.

Prevention and Management of Type 2 Diabetes and Metabolic Syndrome in the Time of COVID-19: Should We Add a Cup of Coffee?

Recent evidence shows that COVID-19 patients with existing metabolic disorders, such as diabetes and metabolic syndrome, are exposed to a high risk of morbidity and mortality. At the same time, in order to manage the pandemic, the health authorities around the world are advising people to stay at home. This results in decreased physical activity and an increased consumption of an unhealthy diet, which often leads to an increase in body weight, risk for diabetes, insulin resistance, and metabolic syndrome, and thus, paradoxically, to a high risk of morbidity and mortality due to COVID-19 complications. Here we summarize the evidence demonstrating that the promotion of a healthy life style, including physical activity and a dietary intake of natural polyphenols present in coffee and tea, has the potential to improve the prevention and management of insulin resistance and diabetes in the time of COVID-19 pandemic. Particularly, it would be pertinent to evaluate further the potential positive effects of coffee beverages, rich in natural polyphenols, as an adjuvant therapy for COVID-19, which appear not to be studied sufficiently.

The Pathophysiology, Diagnosis and Treatment of Corona Virus Disease 2019 (COVID-19)

Since the beginning of this century, beta coronaviruses (CoV) have caused three zoonotic outbreaks. However, little is currently known about the biology of the newly emerged SARS-CoV-2 in late 2019. There is a spectrum of clinical features from mild to severe life threatening disease with major complications like severe pneumonia, acute respiratory distress syndrome, acute cardiac injury and septic shock. The genome of SARS-CoV-2 encodes polyproteins, four structural proteins and six accessory proteins. SARS-CoV-2 tends to utilize Angiotensin-converting enzyme 2 (ACE2) of various mammals. The imbalance between ACE/Ang II/AT1R pathway and ACE2/Ang(1-7)/Mas receptor pathway in the renin-angiotensin system leads to multi-system inflammation. The early symptoms of COVID-19 pneumonia are low to midgrade fever, dry cough and fatigue. Vigilant screening is important. The diagnosis of COVID-19 should be based on imaging findings along with epidemiological history and nucleic acid detection. Isolation and quarantine of suspected cases is recommended. Management is primarily supportive, with newer antiviral drugs/vaccines under investigation.