Synthesis and antiviral evaluation of 7-O-arylmethylquercetin derivatives against SARS-associated coronavirus (SCV) and hepatitis C virus (HCV)

NASAFYTOL® supplementation in adults hospitalized with COVID-19 infection: results from an exploratory open-label randomized controlled trial

Objectives

The effect and safety of Nasafytol^®, a food supplement combining curcumin, quercetin, and Vitamin D, on hospitalized COVID-19-positive patients as support to standard of care were to be assessed.

Methods

This exploratory, open-label, randomized, controlled trial was carried out among hospitalized adults with COVID-19 infection. Participants were randomly assigned to receive Nasafytol^® or Fultium^® control. The improvement of the clinical condition and occurrence of (serious) adverse events were evaluated. The study was registered on clincaltrials.gov with the identifier NCT04844658.

Results

Twenty-five patients received Nasafytol^®, and 24 received Fultium^®. Demographic characteristics were well balanced between the groups. On day 14 (or at hospital leave if < 14 days), no difference was observed between groups regarding their clinical condition, fever, or the need of oxygen therapy. At day 7, however, 19 participants had been discharged from the hospital in the Nasafytol^® arm compared to 10 participants in the Fultium^® arm. No participants were transferred to the ICU or died in the Nasafytol^® arm, vs. 4 transfers and 1 death in the Fultium^® arm. The clinical condition of participants in the Nasafytol^® arm had improved, as evidenced by a decrease in the COVID-19 WHO score. Interestingly, five SAEs occurred with Fultium^®, while no SAE was observed with Nasafytol^®.

Conclusion

Supplementation with Nasafytol^®, in addition to standard-of-care treatment, led to a faster discharge from the hospital, improved clinical conditions of participants, and a reduced risk of serious outcomes, including transfer to the intensive care unit or death, in patients hospitalized with COVID-19.

Drug target of natural products and COVID-19: how far has science progressed?

The new coronavirus [severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] that caused a viral disease with a high risk of mortality (coronavirus disease 2019) was found toward the end of 2019. This was a significant acute respiratory syndrome. In a brief period, this virus spread throughout the entire planet, causing tremendous loss of life and economic damage. The process of developing new treatments takes time, and there are presently no recognized specific treatments to treat this infection. The most promising participants, who subsequently developed into prospective leads, were dropped from the clinical research in their latter phases. Medication that has previously acquired permission may only be repurposed for use for various medical reasons following a thorough investigation for safety and effectiveness. Because there are now no effective treatments available, natural products are being used haphazardly as antiviral medications and immunity boosters. The fundamental statement that most natural compounds have powerful antiviral action does not apply to SARS-CoV-2. Middle East respiratory syndrome coronavirus and severe acute respiratory syndrome coronavirus infections are inhibited by natural treatments. According to an in silico study, the virus' nonstructural proteins, including PLpro, Mpro, and RdRp, as well as structural proteins like the spike (S) protein, have been shown to have a strong affinity for several natural products and to be inhibited by them. The virus also suggests that it is a valid candidate for therapeutic research since it utilizes the intracellular angiotensin-converting enzyme 2 receptor of the host cell. In this study, interesting targets for SARS-CoV-2 medication development are explored, as well as the antiviral properties of some well-known natural compounds.

COVID-19 signalome: Potential therapeutic interventions

The COVID-19 pandemic has triggered intensive research and development of drugs and vaccines against SARS-CoV-2 during the last two years. The major success was especially observed with development of vaccines based on viral vectors, nucleic acids and whole viral particles, which have received emergent authorization leading to global mass vaccinations. Although the vaccine programs have made a big impact on COVID-19 spread and severity, emerging novel variants have raised serious concerns about vaccine efficacy. Due to the urgent demand, drug development had originally to rely on repurposing of antiviral drugs developed against other infectious diseases. For both drug and vaccine development the focus has been mainly on SARS-CoV-2 surface proteins and host cell receptors involved in viral attachment and entry. In this review, we expand the spectrum of SARS-CoV-2 targets by investigating the COVID-19 signalome. In addition to the SARS-CoV-2 Spike protein, the envelope, membrane, and nucleoprotein targets have been subjected to research. Moreover, viral proteases have presented the possibility to develop different strategies for the inhibition of SARS-CoV-2 replication and spread. Several signaling pathways involving the renin-angiotensin system, angiotensin-converting enzymes, immune pathways, hypoxia, and calcium signaling have provided attractive alternative targets for more efficient drug development.

Pathophysiology of SARS-CoV2 Mediated Depression, Therapeutics, and Consequences: A Comprehensive Narrative

The Coronavirus Disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2), belongs to emerging and reemerging diseases, which was first identified and reported in Wuhan, China, in December 2019. The genetic sequence of SARS-CoV-2 was similar to the SARS virus, a β-coronavirus. The epidemiological studies suggest that the transmission of SARS-CoV-2 mainly occurs from an infected person to others through close contact with the respiratory droplets or by having contact with SARS-CoV-2 adhering to objects and surfaces. The incubation period ranges from 5 to14 days. The symptoms include fever, dry cough, tiredness, aches, chest pain, conjunctivitis, diarrhea, headache, difficulty in breathing or short breath, loss of taste, smell, rashes on the skin, and sore throat. Some reports indicated that males exhibited lower scores than females, the younger populations displayed increased symptoms, Chinese/Taiwanese people registered only scarce symptoms, and Canadians experienced more symptoms. The results of several studies suggested that while COVID-19 had a significant effect on depression, job instability affected anxiety and depression. The diagnostics to detect the presence of coronavirus involve ELISA and RT-PCR. There is no specific treatment available to eradicate COVID-19. The therapeutics used to treat COVID 19 exhibited severe side effects. Recently, some Indian traditional medicinal plants have shown promise in reducing the risk of viral infection and also boosting the immunity of an individual. This paper presents an overview of the current status of depression in the SARS CoV2 infected people and the measures required to overcome COVID-19 induced depression in patients even after recovery.

In vitro testing and computational analysis of specific phytochemicals with antiviral activities considering their possible applications against COVID-19

The purpose of this study was to investigate the reservoir of natural products against the SARS-CoV-2 virus and to identify suitable candidates in order to recommend appropriate phytotherapy. Adequately prepared 65 molecules from traditional Chinese medicine with proven antiviral properties were subjected to docking analysis using AutoDock Vina 4 software with the aim to investigate binding affinity and interactions of compounds with Mpro from the SARS-CoV-2 virus. Biflavonoids and tannins show best docking scores with -9,80 kcal/mol for biflavonoids and -9,00 kcal/mol for tannins. Biflavonoids: amentoflavone, agathistaflavone, robustaflavone, hinokiflavone and rhusflavanone were tested for their radical scavenging activity. Partition coefficients were examined by RP-HPLC. Evaluation of drug-likeness properties of investigated biflavonoids suggested rhusflavanone as a molecule with the best ADMET characteristics. Anti-inflammatory activity of rhusflavanone was investigated in LPS stimulated RAW264.7 macrophages. Tested biflavonoids exibit beneficial effects against inflammation by scavenging free radicals and by suppressing the production of proinflammatory mediators by macrophages. Both predictions of affinity spectra for substances (PASS) and in vitro testing showed promising biological activity of investigated biflavonoids. A Quantum chemical study was performed in order to calculate the thermodynamic, molecular orbital, and electrostatic potential of selected molecules and to compare their biological and chemical features. Our results highlighted antioxidant, anti-inflammatory and antiviral properties of investigated compounds, emphasizing the significance of biflavonoid moiety to selected characteristics, which encourage further investigational strategies against COVID-19.

Pharmacological Potential of Flavonoids against Neurotropic Viruses

Flavonoids are a group of natural compounds that have been described in the literature as having anti-inflammatory, antioxidant, and neuroprotective compounds. Although they are considered versatile molecules, little has been discussed about their antiviral activities for neurotropic viruses. Hence, the present study aimed to investigate the pharmacological potential of flavonoids in the face of viruses that can affect the central nervous system (CNS). We carried out research from 2011 to 2021 using the Pubmed platform. The following were excluded: articles not in the English language, letters to editors, review articles and papers that did not include any experimental or clinical tests, and papers that showed antiviral activities against viruses that do not infect human beings. The inclusion criteria were in silico predictions and preclinical pharmacological studies, in vitro, in vivo and ex vivo, and clinical studies with flavonoids, flavonoid fractions and extracts that were active against neurotropic viruses. The search resulted in 205 articles that were sorted per virus type and discussed, considering the most cited antiviral activities. Our investigation shows the latest relevant data about flavonoids that have presented a wide range of actions against viruses that affect the CNS, mainly influenza, hepatitis C and others, such as the coronavirus, enterovirus, and arbovirus. Considering that these molecules present well-known anti-inflammatory and neuroprotective activities, using flavonoids that have demonstrated both neuroprotective and antiviral effects could be viewed as an alternative for therapy in the course of CNS infections.

Polyphenols as Potential Inhibitors of SARS-CoV-2 RNA Dependent RNA Polymerase (RdRp)

An increasing number of studies have demonstrated the antiviral nature of polyphenols, and many polyphenols have been proposed to inhibit SARS-CoV or SARS-CoV-2. Our previous study revealed the inhibitory mechanisms of polyphenols against DNA polymerase α and HIV reverse transcriptase to show that polyphenols can block DNA elongation by competing with the incoming NTPs. Here we applied computational approaches to examine if some polyphenols can also inhibit RNA polymerase (RdRp) in SARS-CoV-2, and we identified some better candidates than remdesivir, the FDA-approved drug against RdRp, in terms of estimated binding affinities. The proposed compounds will be further examined to develop new treatments for COVID-19.

Natural Products for the Prevention and Control of the COVID-19 Pandemic: Sustainable Bioresources

Background: The world has been unprecedentedly hit by a global pandemic which broke the record of deadly pandemics that faced humanity ever since its existence. Even kids are well-versed in the terminologies and basics of the SARS-CoV-2 virus and COVID-19 now. The vaccination program has been successfully launched in various countries, given that the huge global population of concern is still far behind to be vaccinated. Furthermore, the scarcity of any potential drug against the COVID-19-causing virus forces scientists and clinicians to search for alternative and complementary medicines on a war-footing basis. Aims and Objectives: The present review aims to cover and analyze the etiology and epidemiology of COVID-19, the role of intestinal microbiota and pro-inflammatory markers, and most importantly, the natural products to combat this deadly SARS-CoV-2 virus. Methods: A primary literature search was conducted through PubMed and Google Scholar using relevant keywords. Natural products were searched from January 2020 to November 2020. No timeline limit has been imposed on the search for the biological sources of those phytochemicals. Interactive mapping has been done to analyze the multi-modal and multi-target sources. Results and Discussion: The intestinal microbiota and the pro-inflammatory markers that can serve the prognosis, diagnosis, and treatment of COVID-19 were discussed. The literature search resulted in yielding 70 phytochemicals and ten polyherbal formulations which were scientifically analyzed against the SARS-CoV-2 virus and its targets and found significant. Retrospective analyses led to provide information about 165 biological sources that can also be screened if not done earlier. Conclusion: The interactive analysis mapping of biological sources with phytochemicals and targets as well as that of phytochemical class with phytochemicals and COVID-19 targets yielded insights into the multitarget and multimodal evidence-based complementary medicines.

Flavonoids as Molecules With Anti-Zika virus Activity

Zika virus (ZIKV) is an arthropod-born virus that is mainly transmitted to humans by mosquitoes of the genus Aedes spp. Since its first isolation in 1947, only a few human cases had been described until large outbreaks occurred on Yap Island (2007), French Polynesia (2013), and Brazil (2015). Most ZIKV-infected individuals are asymptomatic or present with a self-limiting disease and nonspecific symptoms such as fever, myalgia, and headache. However, in French Polynesia and Brazil, ZIKV outbreaks led to the diagnosis of congenital malformations and microcephaly in newborns and Guillain-Barré syndrome (GBS) in adults. These new clinical presentations raised concern from public health authorities and highlighted the need for anti-Zika treatments and vaccines to control the neurological damage caused by the virus. Despite many efforts in the search for an effective treatment, neither vaccines nor antiviral drugs have become available to control ZIKV infection and/or replication. Flavonoids, a class of natural compounds that are well-known for possessing several biological properties, have shown activity against different viruses. Additionally, the use of flavonoids in some countries as food supplements indicates that these molecules are nontoxic to humans. Thus, here, we summarize knowledge on the use of flavonoids as a source of anti-ZIKV molecules and discuss the gaps and challenges in this area before these compounds can be considered for further preclinical and clinical trials.

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.

Natural Bioactive Molecules as Potential Agents Against SARS-CoV-2

In the past two decades, pandemics of several fatal coronaviruses have posed enormous challenges for public health, including SARS-CoV (2003), MERS-CoV (2012), and SARS-CoV-2 (2019). Among these, SARS-CoV-2 continues to ravage the world today and has lead to millions of deaths and incalculable economic damage. Till now, there is no clinically proven antiviral drug available for SARS-CoV-2. However, the bioactive molecules of natural origin, especially medicinal plants, have been proven to be potential resources in the treatment of SARS-CoV-2, acting at different stages of the viral life cycle and targeting different viral or host proteins, such as PLpro, 3CLpro, RdRp, helicase, spike, ACE2, and TMPRSS2. They provide a viable strategy to develop therapeutic agents. This review presents fundamental biological information on SARS-CoV-2, including the viral biological characteristics and invasion mechanisms. It also summarizes the reported natural bioactive molecules with anti-coronavirus properties, arranged by their different targets in the life cycle of viral infection of human cells, and discusses the prospects of these bioactive molecules for the treatment of COVID-19.

Structure-based virtual screening of bioactive compounds from Indonesian medical plants against severe acute respiratory syndrome coronavirus-2

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a virus that causes the infectious disease coronavirus disease-2019. Currently, there is no effective drug for the prevention and treatment of this virus. This study aimed to identify secondary metabolites that potentially inhibit the key proteins of SARS-CoV-2. This was an in silico molecular docking study of several secondary metabolites of Indonesian herbal plant compounds and other metabolites with antiviral testing history. Virtual screening using AutoDock Vina of 216 Lipinski rule-compliant plant metabolites was performed on 3C-like protease (3CL^pro), RNA-dependent RNA polymerase (RdRp), and spike glycoprotein. Ligand preparation was performed using JChem and Schrödinger's software, and virtual protein elucidation was performed using AutoDockTools version 1.5.6. Virtual screening identified several RdRp, spike, and 3CL^pro inhibitors. Justicidin D had binding affinities of −8.7, −8.1, and −7.6 kcal mol⁻¹ on RdRp, 3CL^pro, and spike, respectively. 10-methoxycamptothecin had binding affinities of −8.5 and −8.2 kcal mol⁻¹ on RdRp and spike, respectively. Inoxanthone had binding affinities of −8.3 and −8.1 kcal mol⁻¹ on RdRp and spike, respectively, while binding affinities of caribine were −9.0 and −7.5 mol⁻¹ on 3CL^pro and spike, respectively. Secondary metabolites of compounds from several plants were identified as potential agents for SARS-CoV-2 therapy.

Theoretical Study of the Molecular Mechanism of Maxingyigan Decoction Against COVID-19: Network Pharmacology-based Strategy

AIM AND OBJECTIVE

Maxingyigan (MXYG) decoction is a traditional Chinese medicine (TCM) prescription. However, how MXYG acts against coronavirus disease 2019 (COVID-19) is not known. We investigated the active ingredients and the therapeutic targets of MXYG decoction against COVID-19.

METHODS

A network pharmacology strategy involving drug-likeness evaluation, prediction of oral bioavailability, network analyses, and virtual molecular docking was used to predict the mechanism of action of MXYG against COVID-19.

RESULTS

Thirty-three core COVID-19-related targets were identified from 1023 gene targets through analyses of protein-protein interactions. Eighty-six active ingredients of MXYG decoction hit by 19 therapeutic targets were screened out by analyses of a compound-compound target network. Via network topology, three "hub" gene targets (interleukin (IL-6), caspase-3, IL-4) and three key components (quercetin, formononetin, luteolin) were recognized and verified by molecular docking. Compared with control compounds (ribavirin, arbidol), the docking score of quercetin to the IL-6 receptor was highest, with a score of 5. Furthermore, the scores of three key components to SARS-CoV-2 are large as 4, 5, and 5, respectively, which are even better than those of ribavirin at 3. Bioinformatics analyses revealed that MXYG could prevent and treat COVID-19 through anti-inflammatory and immunity-based actions involving activation of T cells, lymphocytes, and leukocytes, as well as cytokine-cytokine-receptor interaction, and chemokine signaling pathways.

CONCLUSION

The hub genes of COVID-19 helped to reveal the underlying pathogenesis and therapeutic targets of COVID-19. This study represents the first report on the molecular mechanism of MXYG decoction against COVID-19.

Polyphenols as promising biologically active substances for preventing SARS-CoV-2: A review with research evidence and underlying mechanisms

Currently, antiviral drugs and/or vaccines are not yet available to treat or prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this review, we narrated the available data, from credible publishers, regarding the possible role of polyphenols and natural extracts-containing polyphenols in the prevention of coronavirus disease 2019 (COVID-19), and their immune-boosting properties. It was revealed that polyphenols could be considered as promising biologically active substances for the prevention of COVID-19. The underlying potential mechanism behind this action is mostly due to the antiviral activities and the immune-regulation functions of polyphenols against COVID-19-infections. Antivirus polyphenolic-based medications can mitigate SARS-CoV-2-enzymes, which are vital for virus duplication and infection. It was also found that triterpenoid, anthraquinone, flavonoids, and tannins are possible keys to scheming antiviral therapies for inhibiting SARS-CoV-2-proteases. The identified pharmacophore structures of polyphenols could be utilized in the explanation of novel anti-COVID-19 designs. The advantage of using mixtures containing polyphenols is related to the high-safety profile without having major side-effects, but further randomized controlled trials are required in the upcoming studies.

Mechanistic Aspects and Therapeutic Potential of Quercetin against COVID-19-Associated Acute Kidney Injury

The inflammatory mediator and oxidant agent storm caused by the SARS-CoV-2 infection has been strongly associated with the failure of vital organs observed in critically ill patients with coronavirus disease 2019 (COVID-19) and the death of thousands of infected people around the world. Acute kidney injury (AKI) is a common renal disorder characterized by a sudden and sustained decrease in renal function with a critical influence on poor prognosis and lethal clinical outcomes of various etiologies, including some viral infection diseases. It is known that oxidative stress and inflammation play key roles in the pathogenesis and development of AKI. Quercetin is a natural substance that has multiple pharmacological properties, such as anti-inflammatory action, and is used as a dietary supplement. There is evidence of the anti-coronavirus activities of this compound, including against the target SARS-CoV-2 3CLpro. The ability to inhibit coronavirus and its inflammatory processes is strongly desired in a new drug for the treatment of COVID-19. Therefore, in this review, the dual effect of quercetin is discussed from a mechanistic perspective in relation to AKI kidney injury and its nephroprotective potential to SARS-CoV-2 patients.

The Inhibitory Activities and Antiviral Mechanism of Medicinal Plant Ingredient Quercetin Against Grouper Iridovirus Infection

Singapore grouper iridovirus (SGIV) causes high mortality rates in mariculture, and effective treatments against SGIV infection are urgently required. Illicium verum Hook. f. (I. verum) is a well-known medicinal plant with a variety of biological activities. The natural ingredient quercetin isolated from I. verum could effectively inhibit SGIV infection in a dose-dependent manner. The possible antiviral mechanism of quercetin was further analyzed in this study. It showed that quercetin did obvious damages to SGIV particles. Furthermore, quercetin could interfere with SGIV binding to targets on host cells (by 76.14%), disturb SGIV invading into host cells (by 56.03%), and effect SGIV replication in host cells (by 52.73%), respectively. Quercetin had the best antiviral effects during the SGIV life cycle of binding to the receptors on host cells' membranes. Overall, the results suggest that quercetin has direct and host-mediated antiviral effects against SGIV and holds great potential for developing effective drugs to control SGIV infection in aquaculture.

A role for quercetin in coronavirus disease 2019 (COVID-19)

Several months ago, an outbreak of pneumonia of unknown aetiology was detected in Wuhan City (China) and the aetiological agent of the atypical pneumonia was isolated by the Chinese authorities as novel coronavirus (2019‐nCoV or SARS‐CoV‐2). The WHO announced this new disease was to be known as “COVID‐19.” When looking for new antiviral compounds, knowledge of the main viral proteins is fundamental. The major druggable targets of SARS‐CoV‐2 include 3‐chymotrypsin‐like protease (3CLpro), papain‐like protease (PLpro), RNA‐dependent RNA polymerase, and spike (S) protein. Quercetin inhibits 3CLpro and PLpro with a docking binding energy corresponding to −6.25 and −4.62 kcal/mol, respectively. Quercetin has a theoretical, but significant, capability to interfere with SARS‐CoV‐2 replication, with the results showing this to be the fifth best compound out of 18 candidates. On the basis of the clinical COVID‐19 manifestations, the multifaceted aspect of quercetin as both antiinflammatory and thrombin‐inhibitory actions, should be taken into consideration.

Phytochemicals containing biologically active polyphenols as an effective agent against Covid-19-inducing coronavirus

The outbreak of Covid-19 disease caused by SARS-CoV-19, along with the lack of targeted medicaments and vaccines, forced the scientific world to search for new antiviral formulations. In this review, we describe the current knowledge about plant extracts containing polyphenols that inhibit Covid-19. Many plant-derived natural compounds (polyphenols) might provide a starting point for the research on the use of plant extracts in coronavirus treatment and prevention. Antivirus polyphenolic drugs can inhibit coronavirus enzymes, which are essential for virus replication and infection. This group of natural substances (betulinic acid, indigo, aloeemodine, luteolin, and quinomethyl triterpenoids, quercitin or gallates) is a potential key to designing antiviral therapies for inhibiting viral proteases. The known pharmacophore structures of bioactive substances can be useful in the elaboration of new anti-Covid-19 formulations. The benefit of using preparations containing phytochemicals is their high safety for patients and no side effects.

Flavonoids: A complementary approach to conventional therapy of COVID-19?

COVID-19, the highly contagious novel disease caused by SARS-CoV-2, has become a major international concern as it has spread quickly all over the globe. However, scientific knowledge and therapeutic treatment options for this new coronavirus remain limited. Although previous outbreaks of human coronaviruses (CoVs) such as SARS and MERS stimulated research, there are, to date, no antiviral therapeutics available that specifically target these kinds of viruses. Natural compounds with a great diversity of chemical structures may provide an alternative approach for the discovery of new antivirals. In fact, numerous flavonoids were found to have antiviral effects against SARS-and MERS-CoV by mainly inhibiting the enzymes 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro). In this review, we specifically focused on the search for flavonoids, polyphenolic compounds, which are proven to be effective against human CoVs. We therefore summarized and analyzed the latest progress in research to identify flavonoids for antiviral therapy and proposed strategies for future work on medicinal plants against coronaviruses such as SARS-CoV-2. We discovered quercetin, herbacetin, and isobavachalcone as the most promising flavonoids with anti-CoV potential.

Synergistic antiviral effects against SARS-CoV-2 by plant-based molecules

The exponential spread of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emphasizes the immediate need for effective antiviral drugs and vaccines that could control and prevent the spread of this pandemic. Several new and repurposed drugs are being tested for their effectiveness in the treatment regime, and the development of vaccines is underway. The availability of genome sequence information of the virus and the identification of potential targets to neutralize and eradicate the infection have enabled the search for novel as well as existing molecules to perform the desired function. However, the application of plants in the development of potential biomolecules, such as antibiotics and vaccines, is limited. Traditional medicines involving plant-based formulations have proven successful in boosting immunity and providing tolerance to virus infections. Still, in-depth studies are not available to explore the bioactive compounds of plant origin and their mechanism of action. Given this, the current opinion article conveys our thoughts and perspectives on the promising usage of plant-based biomolecules in circumventing SARS-CoV-2, and how these molecules can work synergistically with other potential drugs for treating SARS-CoV-2.

Roles of flavonoids against coronavirus infection

In terms of public health, the 21st century has been characterized by coronavirus pandemics: in 2002-03 the virus SARS-CoV caused SARS; in 2012 MERS-CoV emerged and in 2019 a new human betacoronavirus strain, called SARS-CoV-2, caused the unprecedented COVID-19 outbreak. During the course of the current epidemic, medical challenges to save lives and scientific research aimed to reveal the genetic evolution and the biochemistry of the vital cycle of the new pathogen could lead to new preventive and therapeutic strategies against SARS-CoV-2. Up to now, there is no cure for COVID-19 and waiting for an efficacious vaccine, the development of "savage" protocols, based on "old" anti-inflammatory and anti-viral drugs represents a valid and alternative therapeutic approach. As an alternative or additional therapeutic/preventive option, different in silico and in vitro studies demonstrated that small natural molecules, belonging to polyphenol family, can interfere with various stages of coronavirus entry and replication cycle. Here, we reviewed the capacity of well-known (e.g. quercetin, baicalin, luteolin, hesperetin, gallocatechin gallate, epigallocatechin gallate) and uncommon (e.g. scutellarein, amentoflavone, papyriflavonol A) flavonoids, secondary metabolites widely present in plant tissues with antioxidant and anti-microbial functions, to inhibit key proteins involved in coronavirus infective cycle, such as PL^pro, 3CL^pro, NTPase/helicase. Due to their pleiotropic activities and lack of systemic toxicity, flavonoids and their derivative may represent target compounds to be tested in future clinical trials to enrich the drug arsenal against coronavirus infections.

Micronutrients as immunomodulatory tools for COVID-19 management

COVID-19 rapidly turned to a global pandemic posing lethal threats to overwhelming health care capabilities, despite its relatively low mortality rate. The clinical respiratory symptoms include dry cough, fever, anosmia, breathing difficulties, and subsequent respiratory failure. No known cure is available for COVID-19. Apart from the anti-viral strategy, the supports of immune effectors and modulation of immunosuppressive mechanisms is the rationale immunomodulation approach in COVID-19 management. Diet and nutrition are essential for healthy immunity. However, a group of micronutrients plays a dominant role in immunomodulation. The deficiency of most nutrients increases the individual susceptibility to virus infection with a tendency for severe clinical presentation. Despite a shred of evidence, the supplementation of a single nutrient is not promising in the general population. Individuals at high-risk for specific nutrient deficiencies likely benefit from supplementation. The individual dietary and nutritional status assessments are critical for determining the comprehensive actions in COVID-19.

SARS, MERS and SARS-CoV-2 (COVID-19) treatment: a patent review

INTRODUCTION

Coronavirus has been responsible for several virus outbreaks since 2003, caused by SARS-CoV-1, MERS-CoV, and currently SARS-CoV-2 (COVID-19), the causative agent of coronavirus disease in 2019. COVID-19 has become a global public health emergency because of its high virulence and mortality capacity. This patent review aims to provide an overview of the patents that present possible treatments for SARS-CoV-1, SARS-CoV-2 and MERS-CoV.

AREAS COVERED

To treat SARS, MERS and SARS-CoV-2, researchers have filed patents for a number of therapeutic agents. Most of the treatments found were protease inhibitors aimed at proteases such as PLpro, 3 CLpro, RNA helicase, and Spike protein, or used monoclonal antibodies and interferons. In addition, the use of Chinese folk medicine and its multitude of medicinal plants with strong antiviral properties was reinforced. Thus, these therapies used in previous epidemics can serve as an aid in the new pandemic by SARS-CoV-2 and be a starting point for new treatments.

EXPERT OPINION

The various antiviral alternatives presented in this review offer therapeutic options to fight coronavirus infections. If shown to be effective, these drugs may be extremely important in the current pandemic.

Synthesis and In vitro Leishmanicidal Activities of Six Quercetin Derivatives

Background:

Today, leishmaniasis is a widespread, infectious parasitic disease caused by Leishmania spp. Natural-derived compounds are likely to provide a valuable source of new pharmaceuticals, and among them, quercetin derivatives may have antileishmanial effects. The antileishmanial activity of 3,5,7,3’,4’-pentahydroxyflavonol (quercetin) derivatives is partly attributed to the position and pKa of phenolic or catechol hydroxyl groups. Therefore, to optimize their leishmanicidal effect, the structural features of quercetin and its derivatives were improved by acylation or alkylation of hydroxyl groups and changing their pKa and consequently their activities.

Materials and Methods:

In this study, during a regioselective method, quercetin derivatives were synthesized. The structures of synthesized compounds were confirmed by mass, IR, ¹H-, and ¹³C-NMR spectral data. The antileishmanial activities of compounds 1–6 were compared with glucantime as the standard drug against promastigotes of Leishmania major using standard cell-based leishmanicidal assay.

Results:

In this study, during a regioselective method, two 7-O-quercetin derivatives (5 and 6), and three quercetin acetate derivatives (2, 3, and 4) were synthesized. In detail, the IC₅₀ values found against L. major were (1) 2.5 ± 0.92; (2) 2.85 ± 0.99; (3) 15.5 ± 1.95; (4) 13.5 ± 3.5; (5) 2.6 ± 0.57; and (6) 1.3 ± 0.35 μM while IC₅₀ value of glucantime as the standard drug was 88.5 ± 9.47 μM.

Conclusions:

The present study showed an effective antileishmanial activity of quercetin semisynthetic compounds (1–6) against in vitro promastigotes of L. major. Among them, quercetin analogs with more lipophilic and iron-chelating activity showed more antiparasite activity.

Herbal products: benefits, limits, and applications in chronic liver disease

Complementary and alternative medicine soughts and encompasses a wide range of approaches; its use begun in ancient China at the time of Xia dynasty and in India during the Vedic period, but thanks to its long-lasting curative effect, easy availability, natural way of healing, and poor side-effects it is gaining importance throughout the world in clinical practice. We conducted a review describing the effects and the limits of using herbal products in chronic liver disease, focusing our attention on those most known, such as quercetin or curcumin. We tried to describe their pharmacokinetics, biological properties, and their beneficial effects (as antioxidant role) in metabolic, alcoholic, and viral hepatitis (considering that oxidative stress is the common pathway of chronic liver diseases of different etiology). The main limit of applicability of CAM comes from the lacking of randomized, placebo-controlled clinical trials giving a real proof of efficacy of those products, so that anecdotal success and personal experience are frequently the driving force for acceptance of CAM in the population.