Toona sinensis Roem tender leaf extract inhibits SARS coronavirus replication

Anti-SARS-CoV Natural Products With the Potential to Inhibit SARS-CoV-2 (COVID-19)

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), known to cause the disease COVID-19, was declared a pandemic in early 2020. The objective of this review was to collate information regarding the potential of plants and natural products to inhibit coronavirus and targets associated with infection in humans and to highlight known drugs, which may have potential activity against SARS-CoV-2. Due to the similarity in the RNA genome, main proteases, and primary host receptor between SARS-CoV and SARS-CoV-2, a review was conducted on plants and secondary metabolites, which have shown activity against SARS-CoV. Numerous scientific reports on the potential of plants and secondary metabolites against SARS-CoV infection were found, providing important information on their possible activity against SARS-CoV-2. Based on current literature, 83 compounds have been identified with the potential to inhibit COVID-19. The most prominent selectivity was found for the alkaloid, lycorine, the lignan, savinin, and the abietane terpenoid, 8-beta-hydroxyabieta-9(11),13-dien-12-one with selectivity index values greater than 945, 667, and 510, respectively. Plants and their secondary metabolites, with activity against targets associated with the SARS-CoV infection, could provide valuable leads for the development into drugs for the novel SARS-CoV-2. The prospects of using computational methods to screen secondary metabolites against SARS-CoV targets are briefly discussed, and the drawbacks have been highlighted. Finally, we discuss plants traditionally used in Southern Africa for symptoms associated with respiratory viral infections and influenza, such as coughs, fever, and colds. However, only a few of these plants have been screened against SARS-CoV. Natural products hold a prominent role in discovering novel therapeutics to mitigate the current COVID-19 pandemic; however, further investigations regarding in vitro, in vivo, pre-clinical, and clinical phases are still required.

Current approaches for target-specific drug discovery using natural compounds against SARS-CoV-2 infection

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The pandemic of COVID-19 remains to affect the whole world.

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Current remedies for COVID-19 is not satisfactory/available.

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The therapeutic efficacy of Natural Compounds is well explored in various viral infections.

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Natural Compounds could be explored as target specific therapeutic agents against COVID-19 infection.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) recently caused a pandemic outbreak called coronavirus disease 2019 (COVID-19). This disease has initially been reported in China and also now it is expeditiously spreading around the globe directly among individuals through coughing and sneezing. Since it is a newly emerging viral disease and obviously there is a lack of anti-SARS-CoV-2 therapeutic agents, it is urgently required to develop an effective anti-SARS-CoV-2-agent.Through recent advancements in computational biology and biological assays, several natural compounds and their derivatives have been reported to confirm their target specific antiviral potential against Middle East respiratory syndrome coronavirus (MERS-CoV) or Severe Acute Respiratory Syndrome(SARS-CoV).These targets including an important host cell receptor, i.e., angiotensin-converting enzyme ACE2 and several viral proteins e.g. spike glycoprotein (S) containing S1 and S2 domains, SARS CoV Chymotrypsin-like cysteine protease (3CL^pro), papain-like cysteine protease (PL^pro), helicases and RNA-dependent RNA polymerase (RdRp). Due to physical, chemical, and some genetic similarities of SARS CoV-2 with SARS−COV and MERS−COV, repurposing various anti-SARS−COV or anti-MERS−COV natural therapeutic agents could be helpful for the development of anti−COVID-19 herbal medicine. Here we have summarized various drug targets in SARS−COV and MERS−COV using several natural products and their derivatives, which could guide researchers to design and develop a safe and cost-effective anti-SARS−COV-2 drugs.

Strategies for Targeting SARS CoV-2: Small Molecule Inhibitors-The Current Status

Severe Acute Respiratory Syndrome-Corona Virus-2 (SARS-CoV-2) induced Coronavirus Disease - 19 (COVID-19) cases have been increasing at an alarming rate (7.4 million positive cases as on June 11 2020), causing high mortality (4,17,956 deaths as on June 11 2020) and economic loss (a 3.2% shrink in global economy in 2020) across 212 countries globally. The clinical manifestations of this disease are pneumonia, lung injury, inflammation, and severe acute respiratory syndrome (SARS). Currently, there is no vaccine or effective pharmacological agents available for the prevention/treatment of SARS-CoV2 infections. Moreover, development of a suitable vaccine is a challenging task due to antibody-dependent enhancement (ADE) and Th-2 immunopathology, which aggravates infection with SARS-CoV-2. Furthermore, the emerging SARS-CoV-2 strain exhibits several distinct genomic and structural patterns compared to other coronavirus strains, making the development of a suitable vaccine even more difficult. Therefore, the identification of novel small molecule inhibitors (NSMIs) that can interfere with viral entry or viral propagation is of special interest and is vital in managing already infected cases. SARS-CoV-2 infection is mediated by the binding of viral Spike proteins (S-protein) to human cells through a 2-step process, which involves Angiotensin Converting Enzyme-2 (ACE2) and Transmembrane Serine Protease (TMPRSS)-2. Therefore, the development of novel inhibitors of ACE2/TMPRSS2 is likely to be beneficial in combating SARS-CoV-2 infections. However, the usage of ACE-2 inhibitors to block the SARS-CoV-2 viral entry requires additional studies as there are conflicting findings and severe health complications reported for these inhibitors in patients. Hence, the current interest is shifted toward the development of NSMIs, which includes natural antiviral phytochemicals and Nrf-2 activators to manage a SARS-CoV-2 infection. It is imperative to investigate the efficacy of existing antiviral phytochemicals and Nrf-2 activators to mitigate the SARS-CoV-2-mediated oxidative stress. Therefore, in this review, we have reviewed structural features of SARS-CoV-2 with special emphasis on key molecular targets and their known modulators that can be considered for the development of NSMIs.

Potential bioactive molecules from natural products to combat against coronavirus

Covid-19 is terribly spreading around the globes and there is no stoppage. It is causing mass destruction in mankind allowing them to lock inside home to contain the disease. At present, there are no remedial medicines, drugs, or vaccines available in the market. Researchers are trying their best level to produce drugs to fight againts the disease. Various efforts are being considered by using different directions of scientific knowledge and technologies on treating the disease. The existing antiviral drugs such as lopinavir/ritonavir, pitavastatin, nelfinavir, perampanel, and praziquantel are being administered as remedies of covid-19 patients. Unfortunately, none of these drugs works absolutely against the current pandemic. Therefore, bioactive molecules from plants, animals, and microorganisms could be a better option to treat against the covid-19 and its family. Plants can treat many diseases due to the presence of bioactive molecules and their antiviral properties. Presence of secondary metabolites such as flavonoids, alkaloids, terpenoids, polyphenols, curcumin, kaempferol, catechin, naringenin, quercetin, apigenin-7-glucoside, luteolin-7-glucoside, demethoxycurcumin, oleuropein, and epigallocatechin can fight against the coronavirus including covid-19. The listed plants such as litchi seeds, Houttuynia cordata, Chinese Rhubarb extracts, beta-sistosterol from Isatis indigotica root extract have capacity to obstruct the enzymatic activity of SARS. In this article, we have highlighted the bioactive molecules from different plants, animals, and microorganism and their potential activity against the coronavirus. It is a need of the hour to come together to explore more on such bioactive compounds of plants, animals and other microorganism to fight against the covid-19.

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.

Identification of potential anti-TMPRSS2 natural products through homology modelling, virtual screening and molecular dynamics simulation studies

Recent outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to a pandemic of COVID-19. The absence of a therapeutic drug and vaccine is causing severe loss of life and economy worldwide. SARS-CoV and SARS-CoV-2 employ the host cellular serine protease TMPRSS2 for spike (S) protein priming for viral entry into host cells. A potential way to reduce the initial site of SARS-CoV-2 infection may be to inhibit the activity of TMPRSS2. In the current study, the three-dimensional structure of TMPRSS2 was generated by homology modelling and subsequently validated with a number of parameters. The structure-based virtual screening of Selleckchem database was performed through 'Virtual Work Flow' (VSW) to find out potential lead-like TMPRSS2 inhibitors. Camostat and bromhexine are known TMPRSS2 inhibitor drugs, hence these were used as control molecules throughout the study. Based on better dock score, binding-free energy and binding interactions compared to the control molecules, six molecules (Neohesperidin, Myricitrin, Quercitrin, Naringin, Icariin, and Ambroxol) were found to be promising against the TMPRSS2. Binding interactions analysis revealed a number of significant binding interactions with binding site amino residues of TMPRSS2. The all-atoms molecular dynamics (MD) simulation study indicated that all proposed molecules retain inside the receptor in dynamic states. The binding energy calculated from the MD simulation trajectories also favour the strong affinity of the molecules towards the TMPRSS2. Proposed molecules belong to the bioflavonoid class of phytochemicals and are reported to possess antiviral activity, our study indicates their possible potential for application in COVID-19.Communicated by Ramaswamy H. Sarma.

Natural Products as Potential Leads Against Coronaviruses: Could They be Encouraging Structural Models Against SARS-CoV-2?

New coronavirus referred to SARS-CoV-2 has caused a worldwide pandemic (COVID-19) declared by WHO. Coronavirus disease 2019 (COVID-19) is an infectious disease with severe acute respiratory syndrome caused by coronavirus-2 (SARS-CoV-2). SARS-CoV-2 is akin to SARS-CoV, which was the causative agent of severe acute respiratory syndrome (SARS) in 2002 as well as to that of Middle East respiratory syndrome (MERS) in 2012. SARS-CoV-2 has been revealed to belong to Coronaviridiae family as a member of β-coronaviruses. It has a positive-sense single-stranded RNA with the largest RNA genome. Since its genomic sequence has a notable similarity to that of SARS-CoV, antiviral drugs used to treat SARS and MERS are now being also applied for COVID-19 treatment. In order to combat SARS-CoV-2, many drug and vaccine development studies at experimental and clinical levels are currently conducted worldwide. In this sense, medicinal plants and the pure natural molecules isolated from plants have been reported to exhibit significant inhibitory antiviral activity against SARS-CoV and other types of coronaviruses. In the present review, plant extracts and natural molecules with the mentioned activity are discussed in order to give inspiration to researchers to take these molecules into consideration against SARS-CoV-2.

The Leaf Extracts of Toona sinensis and Fermented Culture Broths of Antrodia camphorata Synergistically Cause Apoptotic Cell Death in Promyelocytic Leukemia Cells

Toona sinensis is a common edible vegetable that is used in certain Chinese dishes and has importance in folk medicine. The leaf extracts of T sinensis possess and exhibit anticancer efficacy against various cancer cell types. In Taiwanese folklore, Antrodia camphorata, also known as “Niu-Cheng-Zi,” is used in traditional medicine to treat various illnesses. Its fruit and mycelium possess various potent antiproliferative properties. Two studies from our group have reported that T sinensis or A camphorata has the ability to cause apoptosis in various cancer cells. Conversely, underlying molecular mechanisms and any beneficial effects remain unknown. This study shows anticancer efficacy for both T sinensis and A camphorata co-treatments that target HL-60 cells. The combination index values indicate that 40 µg/mL of T sinensis and 25 µg/mL of A camphorata as a combined treatment shows a synergetic effect, which reduces HL-60 cell proliferation. Alternately, this treatment exhibited no cytotoxic effects for human umbilical vein endothelial cells. Western blot data showed that T sinensis and A camphorata as a combined treatment result in augmented expression of apoptosis, cytochrome c release, Bcl-2 inhibition, expression of Bax, Fas, and FasL, as well as the cleavage of Bid in HL-60 cells. Moreover, this combined treatment overshadowed monotherapy in its ability to inhibit uPAR, MMP-9, MMP-2, COX-2 expression, and PGE₂ secretions. Our study strongly implies that this combined treatment offers more beneficial effects to suppress and treat leukemia due to apoptosis-mediated cell inhibition. Further in vivo studies related to the combined treatment could establish its future potential.

A Perspective on Emerging Therapeutic Interventions for COVID-19

Coronaviruses are enveloped positive-sense RNA viruses with an unusual large RNA genome and a unique replication mechanism, which are characterized by club-like spikes that protrude from their surface. An outbreak of a novel coronavirus 2019 infection has posed significant threat to the health and economies in the whole world. This article reviewed the viral replication, pathogenicity, prevention and treatment strategies. With a lack of approved treatment options for this virus, alternative approaches to control the spread of disease is in urgent need. This article also covers some management strategies which may be applied to this virus outbreak. Ongoing clinical studies related to possible treatments for COVID-19, potential vaccines, and alternative medication such as natural compounds are also discussed.

Dietary therapy and herbal medicine for COVID-19 prevention: A review and perspective

A novel coronavirus disease (COVID-19), transmitted from humans to humans, has rapidly become the pandemic responsible for the current global health crisis. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is said to be of zoonotic origin. This review describes the etiology and signs and symptoms as well as the current allopathic therapy for COVID-19. Additionally, findings of previous studies on the immunomodulatory effects and antiviral activities of particular foods and herbs on influenza virus and coronaviruses have been collated, with the aim of promoting the use of dietary therapy and herbal medicine as COVID-19 preventive therapies, while specific drugs and vaccines are yet to be discovered or are still under development. The volume of existing reports is irrefutable evidence that foods and herbs possess a potential antiviral ability against SARS-CoV-2 and can prevent COVID-19. Foods and herbs could be used as dietary or complementary therapy to prevent infection and strengthen immunity, as antiviral agents for masks, as disinfectants to curb aerosol transmission, or as sanitizing agents to disinfect surfaces. However, these hypotheses need to be experimentally verified for SARS-CoV-2 and COVID-19 patients.

Coronavirus Treatments: What Drugs Might Work Against COVID-19?

The World Health Organization declared the severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 virus outbreak as a pandemic on May 27, 2020. Since then, more than 5 488 825 cases across the world have been recorded at the time of revising this article. Governments around the world have imposed serious containment measures, meanwhile, the healthcare system is overburdened due to large increases in COVID-19 cases. However, no specific anti-SARS-CoV-2 virus drugs or vaccines have yet been shown to be effective to fight this causative virus of acute infectious pneumonia. The current review was conducted to look for potential natural and synthesized drugs for the treatment of COVID-19 patients. Previously published data in journals, textbooks, periodicals, websites, and sources, including data about the treatment of human coronavirus with natural and synthesized drugs, were taken from the online bibliographical databases. The results showed that syndic drugs approved for other human diseases have been used to improve the symptoms of patients infected with SARS-CoV-2. Several clinical trials across the world evidenced beneficial effects of natural and synthesized drugs in the treatment of SARS-CoV-2 infections. On the other hand, many studies have provided a deep understanding of the therapeutic effects of conventional and traditional medicine in identifying naturally occurring drugs effective against the SARS-CoV-2 virus. Both natural and synthesized drugs should come together to fight the SARS-CoV-2 virus and other potential emerging dangerous viral diseases since they have shown promising findings in clinical trials conducted with COVID-19 patients.

Potentials of plant-based substance to inhabit and probable cure for the COVID-19

COVID-19 has been the most devastating pandemic in human history. Despite the highest scientific efforts and investments, a reliable and certified medication has yet to be developed regarding to immune or cure this virus. However, while synthetic medications are gaining the focus of attentions, it appears from a significant number of recent studies that plant-based substances could also be potential candidates for developing effective and secure remedies against this novel disease. Citing such recent works, this review primarily demonstrates the antiviral potentials of medicinal plants for inhibiting human coronaviruses. It also shows the importance of antiviral plants substances, particularly in the development of a broad spectrum medication for coronaviruses including SARS-CoV-2 responsible for COVID-19.

Geranium and Lemon Essential Oils and Their Active Compounds Downregulate Angiotensin-Converting Enzyme 2 (ACE2), a SARS-CoV-2 Spike Receptor-Binding Domain, in Epithelial Cells

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as coronavirus disease-2019 (COVID-19), is a pandemic disease that has been declared as modern history’s gravest health emergency worldwide. Until now, no precise treatment modality has been developed. The angiotensin-converting enzyme 2 (ACE2) receptor, a host cell receptor, has been found to play a crucial role in virus cell entry; therefore, ACE2 blockers can be a potential target for anti-viral intervention. In this study, we evaluated the ACE2 inhibitory effects of 10 essential oils. Among them, geranium and lemon oils displayed significant ACE2 inhibitory effects in epithelial cells. In addition, immunoblotting and qPCR analysis also confirmed that geranium and lemon oils possess potent ACE2 inhibitory effects. Furthermore, the gas chromatography-mass spectrometry (GC–MS) analysis displayed 22 compounds in geranium oil and 9 compounds in lemon oil. Citronellol, geraniol, and neryl acetate were the major compounds of geranium oil and limonene that represented major compound of lemon oil. Next, we found that treatment with citronellol and limonene significantly downregulated ACE2 expression in epithelial cells. The results suggest that geranium and lemon essential oils and their derivative compounds are valuable natural anti-viral agents that may contribute to the prevention of the invasion of SARS-CoV-2/COVID-19 into the human body.

The antiviral and coronavirus-host protein pathways inhibiting properties of herbs and natural compounds - Additional weapons in the fight against the COVID-19 pandemic?

Introduction

As of March 11th, 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. Articles published after the SARS-CoV-1 (2002) epidemic suggest that the use of an herbal-drug integrative medical approach could have contributed to a lower fatality rate and a more rapid response in controlling the outbreak.

Methods

Pubmed was searched for articles that investigated the antiviral properties and mechanisms of action of herbs or natural compounds against the SARS-coronavirus (CoV).

Results

Forty-three (43) relevant papers were located. A general count rendered 450+ herbs and natural compounds with antiviral properties against the SARS-CoV and related viruses. From the 43 articles, thirty-one (31) uncovered the mechanisms of action of the natural substances able to oppose the coronavirus.

Discussion

A series of herbs and natural compounds demonstrated moderate to strong antiviral activity. Research on many herbs-natural compounds also showed potent and significant inhibition of CoV-host protein pathways responsible for different phases of viral replication specifically targeting 3CL^PRO, PL^PRO, RdRp, helicase protein, S protein, N protein, 3a protein, Cathepsin L, Nsp1, Nsp3c, and ORF7a, and the S protein/ACE-2 interaction.

Conclusion

The herbs-natural compounds with antiviral activity and that caused inhibition/blockade of the CoV-host protein pathways are potential therapeutic candidates. The homology between the SARS-CoV-1 and SARS-CoV-2 is around 80%. Thus, effective herbs-compounds for the former would likely be beneficial for the latter also depending on target protein similarities between the viruses. Here we provide the mechanistic bases supporting an integrative approach that includes natural compounds to fight coronavirus infections.

COVID-19 Evolution and Alternative Medicine- A Review

The current global health emergency, COVID-19, is not the first time that coronaviruses have posed a threat to human world shrinking our numbers by thousands. Before this SARS-CoV in 2003 and MERS-CoV in 2013 have caused epidemics. Four months in existence, and it has already affected 1,995,983 people and taken over 131,037 lives worldwide, yet we do not have any specific treatment available with us and the management is purely empirical. Looking at the similarities between SARS-CoV and SARS-CoV-2 in origin, genomics, pathogenesis and epidemiology, we can bring the researches done for SARS-CoV in use which can be our guide in finding an effective management strategy against SARS-CoV-2. There are various researches and studies reporting the use and effect of various phytochemical compounds in SARS-CoV treatment. Already, the thought has been put into action and in-silico screening for various natural plant compounds have been done to find a potential candidate compound. One such example is of curcumin, a secondary metabolite of turmeric, which is found to be effective against COVID-19 protease by molecular docking analysis.

Natural product-derived phytochemicals as potential agents against coronaviruses: A review

Coronaviruses are responsible for a growing economic, social and mortality burden, as the causative agent of diseases such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), avian infectious bronchitis virus (IBV) and COVID-19. However, there is a lack of effective antiviral agents for many coronavirus strains. Naturally existing compounds provide a wealth of chemical diversity, including antiviral activity, and thus may have utility as therapeutic agents against coronaviral infections. The PubMed database was searched for papers including the keywords coronavirus, SARS or MERS, as well as traditional medicine, herbal, remedy or plants, with 55 primary research articles identified. The overwhelming majority of publications focussed on polar compounds. Compounds that show promise for the inhibition of coronavirus in humans include scutellarein, silvestrol, tryptanthrin, saikosaponin B₂, quercetin, myricetin, caffeic acid, psoralidin, isobavachalcone, and lectins such as griffithsin. Other compounds such as lycorine may be suitable if a therapeutic level of antiviral activity can be achieved without exceeding toxic plasma concentrations. It was noted that the most promising small molecules identified as coronavirus inhibitors contained a conjugated fused ring structure with the majority being classified as being polyphenols.

Potential of DNA Intercalating Alkaloids and Other Plant Secondary Metabolites against SARS-CoV-2 Causing COVID-19

Many plants produce secondary metabolites (PSMs) with antiviral activities. Among the antiviral PSMs, lipophilic terpenoids in essential oils can disturb the lipid envelope of viruses. Phenols and polyphenols (flavonoids, rosmarinic acid and tannins) attack viral proteins present in the viral membrane or inside the virus particle. Both phenolics and essential oils are active against free viral particles but not—or to a lesser degree—after a virus has entered a host cell. Another group of PSMs is directed against DNA or RNA. These are DNA intercalators such as sanguinarine, berberine, emetine and other isoquinoline alkaloids, ß-carboline, and quinoline alkaloids such as quinine, cinchonine, dictamine and skimmianine. The DNA intercalators stabilize double-stranded nucleic acids and inhibit the replication, transcription, and translation of genetic material. These alkaloids can inhibit viral development and viral replication in cells, as shown for SARS-CoV-1 and other viruses. Since chloroquine (which is also a DNA intercalator and a chemical derivative of the alkaloid quinine) is apparently clinically helpful against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, it is assumed that intercalating alkaloids, or the medicinal plants producing them, may be interesting candidates for the development of new antiviral drugs for the treatment of coronavirus disease 2019 (COVID-19).

Becoming a Faithful Defender: Traditional Chinese Medicine against Coronavirus Disease 2019 (COVID-19)

The outbreak caused by COVID-19 is causing a major challenge to clinical management and a worldwide threat to public health. So far, there is no specific anti-coronavirus therapy approved for the treatment of COVID-19. Recently, as the efficacy and safety of traditional Chinese medicine (TCM) is widely acknowledged, it has been brought to a crucial status by the public, governments, and World Health Organization (WHO). For a better popularization of TCM, governments have made several advances in regulations and policies for treatment and measures of novel coronavirus pneumonia (NCP). Therefore, on the basis of epidemiology and virology information, we reviewed relevant meta-analysis and clinical studies of anti-coronavirus therapeutics by TCM, in the aspect of mortality, symptom improvement, duration and dosage of corticosteroid, incidence of complications and the like. In addition, we also summarized preclinical rationale for anti-coronavirus activity by TCM in terms of virion assembly and release, as well as viral entry and replication, which could be a useful contribution for figuring out effective Chinese herbal medicine (CHM) for coronavirus, including ingredients from single monomeric compounds, Chinese herbs, Chinese herb extracts and Chinese herb formulas, or potential targets for medicine. We would like to see these relevant studies, ranging from basic researches to clinical application, could provide some idea on effects of CHM to combat COVID-19 or other coronaviruses, and also offer new thinking for the exploration of therapeutic strategies under the guidance of TCM.

Natural products and their derivatives against coronavirus: A review of the non-clinical and pre-clinical data

Several corona viral infections have created serious threats in the last couple of decades claiming the death of thousands of human beings. Recently, corona viral epidemic raised the issue of developing effective antiviral agents at the earliest to prevent further losses. Natural products have always played a crucial role in drug development process against various diseases, which resulted in screening of such agents to combat emergent mutants of corona virus. This review focuses on those natural compounds that showed promising results against corona viruses. Although inhibition of viral replication is often considered as a general mechanism for antiviral activity of most of the natural products, studies have shown that some natural products can interact with key viral proteins that are associated with virulence. In this context, some of the natural products have antiviral activity in the nanomolar concentration (e.g., lycorine, homoharringtonine, silvestrol, ouabain, tylophorine, and 7-methoxycryptopleurine) and could be leads for further drug development on their own or as a template for drug design. In addition, a good number of natural products with anti-corona virus activity are the major constituents of some common dietary supplements, which can be exploited to improve the immunity of the general population in certain epidemics.

Traditional Chinese Medicine in the Treatment of Patients Infected with 2019-New Coronavirus (SARS-CoV-2): A Review and Perspective

Currently, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, formerly known as 2019-nCoV, the causative pathogen of Coronavirus Disease 2019 (COVID-19)) has rapidly spread across China and around the world, causing an outbreak of acute infectious pneumonia. No specific anti-virus drugs or vaccines are available for the treatment of this sudden and lethal disease. The supportive care and non-specific treatment to ameliorate the symptoms of the patient are the only options currently. At the top of these conventional therapies, greater than 85% of SARS-CoV-2 infected patients in China are receiving Traditional Chinese Medicine (TCM) treatment. In this article, relevant published literatures are thoroughly reviewed and current applications of TCM in the treatment of COVID-19 patients are analyzed. Due to the homology in epidemiology, genomics, and pathogenesis of the SARS-CoV-2 and SARS-CoV, and the widely use of TCM in the treatment of SARS-CoV, the clinical evidence showing the beneficial effect of TCM in the treatment of patients with SARS coronaviral infections are discussed. Current experiment studies that provide an insight into the mechanism underlying the therapeutic effect of TCM, and those studies identified novel naturally occurring compounds with anti-coronaviral activity are also introduced.

Ethnopharmacology, phytochemistry, biological activities, and therapeutic applications of Cedrela serrata Royle: A mini review

ETHNOPHARMACOLOGICAL RELEVANCE

Cedrela serrata Royle (C. serrata) is a medicinal plant not only used for constructions but also an important conventional medicine for the treatment of various diseases such as; diabetes, jaundice, liver diseases, diarrhea, fever, chronic infantile dysentery, intestinal worms, hypertension, skin and blood diseases.

AIMS

This review article documents and critically assesses, for the first time; up to date categorized information about C. serrata including its reported pharmacological activities, cultural uses, active compounds, and botanical description.

MATERIALS AND METHOD

s: All provided information about C. serrata was collected using the electronic databases (e.g. Google Scholar, Web of Science, Scopus, PubMed, Science Direct and Springer Link), books (e.g. Trees of Pakistan and Herbalism, Phytochemistry, and Ethnopharmacology) and thesis.

RESULTS

Qualitative and quantitative phytochemical studies on C. serrata revealed the presence of important chemical constituents such as; flavonoids, phenolic acids, alkaloids, saponins, tannins, and cardiac glycosides. The phytochemicals showed various in vitro activities like antioxidant, anti-infective, antiglycation, cytotoxic activities. Major areas of research conducted on C. serrata are its antioxidant and anti-infective activities. Few historical uses of C. serrata are supported by modern in vitro pharmacological studies such as; antidiarrheal, antidiabetic, and leishmanicidal activity.

CONCLUSION

There were convincing evidence in in vitro studies supporting C. serrata antioxidant, anti-infective, anti-diabetic, anti-glycating, and cytotoxic activities. Nevertheless, all reported pharmacological activities were carried out in vitro and a gap in research i.e. preclinical and clinical investigation still exists. The authors emphasize the need for future in-depth research and clinical trials to investigate C. serrata pharmacological activity, clinical efficacy and safety. The potential chemical compounds with suggestive classes may need to be isolated and pharmacological activities must be established for these compounds. The plant has very limited information about pharmacological activities and the data available for supportive cultural uses needs proper validation.

Polyphenol-Rich Extracts from Toona sinensis Bark and Fruit Ameliorate Free Fatty Acid-Induced Lipogenesis through AMPK and LC3 Pathways

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease found worldwide. The present study aimed to evaluate the mechanisms of inhibiting lipid accumulation in free fatty acid (FFA)-treated HepG2 cells caused by bark and fruit extracts of Toona sinensis (TSB and TSF). FFA induced lipid and triglyceride (TG) accumulation, which was attenuated by TSB and TSF. TSB and/or TSF promoted phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-coA carboxylase and peroxisome proliferator-activated receptor alpha upregulation. Furthermore, TSB and TSF suppressed FFA-induced liver X receptor, sterol regulatory element-binding transcription protein 1, fatty acid synthase, and stearoyl-CoA desaturase 1 protein expression. Moreover, TSB and/or TSF induced phosphorylation of Unc-51 like autophagy-activating kinase and microtubule-associated protein 1A/1B-light chain 3 expressions. Therefore, TSB and TSF relieve lipid accumulation by attenuating lipogenic protein expression, activating the AMPK pathway, and upregulating the autophagic flux to enhance lipid metabolism. Moreover, TSB and TSF reduced TG contents, implying the therapeutic use of TSB and TSF in NAFLD.

Characterization of the Key Aroma Compounds in Two Differently Dried Toona sinensis (A. Juss.) Roem. by Means of the Molecular Sensory Science Concept

A systematic approach for the characterization of the key aroma-active compounds in sun-dried Toona sinensis (SDTS) and vacuum-dried T. sinensis (VDTS) was performed by means of the molecular sensory science concept. A total of 64 aroma-active compounds were identified via gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). Aroma extract dilution analysis (AEDA) and static headspace dilution analysis revealed 39 odorants in SDTS and 32 odorants in VDTS with flavor dilution (FD) factors from 8 to 4096, with the highest for vanillin and eugenol in both samples. Stable isotope dilution analysis (SIDA) and an internal standard method were applied to quantitate 42 odorants, revealing 35 compounds in concentrations above their respective odor thresholds in SDTS and 29 compounds in VDTS, respectively. Calculation of odor activity values (OAVs) indicated 2-isopropyl-3-methoxypyrazine, eugenol, and β-ionone with the highest OAVs in both samples. Recombination experiments of the overall aromas of SDTS and VDTS by mixing the odorants with OAVs ≥1 in their naturally occurring concentrations proved the successful identification and quantitation of the respective key odorants.

Anti-Respiratory Syncytial Virus Activity of Plantago asiatica and Clerodendrum trichotomum Extracts In Vitro and In Vivo

The herbs Plantago asiatica and Clerodendrum trichotomum have been commonly used for centuries in indigenous and folk medicine in tropical and subtropical regions of the world. In this study, we show that extracts from these herbs have antiviral effects against the respiratory syncytial virus (RSV) in vitro cell cultures and an in vivo mouse model. Treatment of HEp2 cells and A549 cells with a non-cytotoxic concentration of Plantago asiatica or Clerodendrum trichotomum extract significantly reduced RSV replication, RSV-induced cell death, RSV gene transcription, RSV protein synthesis, and also blocked syncytia formation. Interestingly, oral inoculation with each herb extract significantly improved viral clearance in the lungs of BALB/c mice. Based on reported information and a high-performance liquid chromatography (HPLC) analysis, the phenolic glycoside acteoside was identified as an active chemical component of both herb extracts. An effective dose of acteoside exhibited similar antiviral effects as each herb extract against RSV in vitro and in vivo. Collectively, these results suggest that extracts of Plantago asiatica and Clerodendrum trichotomum could provide a potent natural source of an antiviral drug candidate against RSV infection.

Toona sinensis: a comprehensive review on its traditional usages, phytochemisty, pharmacology and toxicology

Toona sinensis (Juss.) M.Roem, Meliaceae, a deciduous plant native to eastern and southeastern Asia, is widely used in Traditional Chinese Medicine. This paper was aimed to summarize the current advances in traditional usage, phytochemistry, pharmacology and toxicology of T. sinensis. In this review, various types of data of T. sinensis are discussed in the corresponding parts of this paper, and perspectives for possible future studies of this plant are discussed. The main constituents of T. sinensis are terpenoids, phenylpropanoids and flavonoids, etc., and its pharmacological activities include anti-tumor effects, antioxidant activities, anti-diabetic effects and anti-inflammatory effects. Although a series of phytochemical and pharmacological researches of this plant have been conducted, the active constituents and action mechanism of these activities should be also further explored. Furthermore, the present review also indicates that T. sinensis has potentials to develop into drugs for treating various diseases with high efficacy and low toxicity, particularly in cancer, diabetes and inflammatory disorders. In conclusion, the paper provides a full-scale profile of the traditional usage, phytochemistry, pharmacology and toxicology of T. sinensis, and also provides potential therapeutic uses and drug development prospects of this plant.

Anti-pandemic influenza A (H1N1) virus potential of catechin and gallic acid

BACKGROUND

The pandemic influenza A (H1N1) virus has spread worldwide and infected a large proportion of the human population. Discovery of new and effective drugs for the treatment of influenza is a crucial issue for the global medical community. According to our previous study, TSL-1, a fraction of the aqueous extract from the tender leaf of Toonasinensis, has demonstrated antiviral activities against pandemic influenza A (H1N1) through the down-regulation of adhesion molecules and chemokine to prevent viral attachment.

METHODS

The aim of the present study was to identify the active compounds in TSL-1 which exert anti-influenza A (H1N1) virus effects. XTT assay was used to detect the cell viability. Meanwhile, the inhibitory effect on the pandemic influenza A (H1N1) virus was analyzed by observing plaque formation, qRT-PCR, neuraminidase activity, and immunofluorescence staining of influenza A-specific glycoprotein.

RESULTS

Both catechin and gallic acid were found to be potent inhibitors in terms of influenza virus mRNA replication and MDCK plaque formation. Additionally, both compounds inhibited neuraminidase activities and viral glycoprotein. The 50% effective inhibition concentration (EC₅₀) of catechin and gallic acid for the influenza A (H1N1) virus were 18.4 μg/mL and 2.6 μg/mL, respectively; whereas the 50% cytotoxic concentrations (CC₅₀) of catechin and gallic acid were >100 μg/mL and 22.1 μg/mL, respectively. Thus, the selectivity indexes (SI) of catechin and gallic acid were >5.6 and 22.1, respectively.

CONCLUSION

The present study demonstrates that catechin might be a safe reagent for long-term use to prevent influenza A (H1N1) virus infection; whereas gallic acid might be a sensitive reagent to inhibit influenza virus infection. We conclude that these two phyto-chemicals in TSL-1 are responsible for exerting anti-pandemic influenza A (H1N1) virus effects.

Toona sinensis Inhibits Murine Leukemia WEHI-3 Cells and Promotes Immune Response In Vivo

Toona sinensis (TS) is one of the most popular vegetarian dishes in Taiwan. It has been shown to exhibit antioxidant, antiangiogenic, antiatherosclerotic, and anticancer properties. In this study, we demonstrated the ability of aqueous leaf extracts from TS to promote immune responses in BALB/c mice and to exhibit anti-leukemia activity in murine WEHI-3 cells. BALB/c mice were injected intravenously with WEHI-3 cells and then treated orally with TS (50 mg/kg). In vivo study showed that TS treatment reduced liver and spleen enlargement in WEHI-3 bearing mice compared with the untreated group. Furthermore, TS also decreased white blood cells (WBC), indicating inhibition of differentiation of the precursor of macrophages in WEHI-3 bearing mice. Treatment of WEHI-3 cells with TS (0-75 μg/mL for 24 hours) significantly reduced cell viability. Furthermore, TS treatment-induced late apoptosis was confirmed by Annexin-V/PI staining. Western blot analyses revealed that treatment of WEHI-3 cells with TS statistically increased the protein expression level of cytochrome c in the cytoplasm and activates caspase-3. Notably, TS treatment caused a dramatic reduction in Bcl-2 and increase in Bax protein levels. TS may disturb the Bcl-2 and Bax protein ratio and induce apoptosis. This reports confirms the antitumor activity of this nutritious vegetable potentially against leukemia.

Kampo Medicines for Infectious Diseases

Numerous Kampo medicines and Oriental herbs have been used for the treatment of infectious diseases for several reasons, such as genetic background, economical reasons, fewer adverse effects, and so on. This chapter describes Kampo medicines and related Oriental herbs that are effective or promising in the treatment of infectious diseases at the clinical level and/or in animal models. In addition, effective Kampo medicines tested in vitro in cultured-cell studies are also included in this chapter. Each section is categorized by infectious disease and according to the popularity of the Kampo medicine.

The Fractionated Toona sinensis Leaf Extract Induces Apoptosis of Human Osteosarcoma Cells and Inhibits Tumor Growth in a Murine Xenograft Model

BACKGROUND

Osteosarcoma is a malignant bone tumor prevalent in adolescents with poor prognosis. Toona sinensis showed potent antiproliferation effect on lung, melatonin, ovary, colon, and liver cancers. However, the effects of the species on osteosarcoma cells are rarely investigated.

RESULTS

In this study, we found fraction 1 of Toona sinensis leaf (TSL-1) resulted in inhibition of cell viability in MG-63, Saos-2, and U2OS osteosarcoma cell lines, while it only caused a moderate suppressive effect on normal osteoblasts. In addition, TSL-1 significantly elevated lactate dehydrogenase leakage and induced apoptosis and necrosis in Saos-2 cells. TSL-1 increased mRNA expression of pro-apoptotic factor Bad. Most important, TSL-1 significantly suppressed Saos-2 xenograft tumor growth in nude mice by increasing caspase-3. The IC-50 of TSL-1 for the 3 tested osteosarcoma cells is around 1/9 of that for lung cancer cells.

CONCLUSION

We demonstrated that TSL-1, a fractionated extract from TSL, caused significant cytotoxicity to osteosarcoma cells due to apoptosis. In vivo xenograft study showed that TSL-1 suppressed the growth of osteosarcoma cells at least in part by inducing apoptosis. Our results indicate that TSL-1 has potential to be a promising anti-osteosarcoma adjuvant functional plant extract.

Complex network model of the Treatise on Cold Damage Disorders

Investigating the underlying principles of the Treatise on Cold Damage Disorder is meaningful and interesting. In this study, we investigated the symptoms, herbal formulae, herbal drugs, and their relationships in this treatise based on a multi-subnet composited complex network model (MCCN). Syndrome subnets were constructed for the symptoms and a formula subnet for herbal drugs. By subnet compounding using MCCN, a composited network was obtained that described the treatment relationships between syndromes and formulae. The results obtained by topological analysis suggested some prescription laws that could be validated in clinics. After subnet reduction using the MCCN, six channel (Tai-yang, Yang-ming, Shao-yang, Tai-yin, Shao-yin, and Jue-yin) subnets were obtained. By analyzing the strengths of the relationships among these six channel subnets, we found that the Tai-yang channel and Yang-ming channel were related most strongly with each other, and we found symptoms that implied pathogen movements and transformations among the six channels. This study could help therapists to obtain a deeper understanding of this ancient treatise.

Limonoids isolated from Toona sinensis and their radical scavenging, anti-inflammatory and cytotoxic activities

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Ten new limonoids were obtained from Toona sinensis (A. Juss.) Roem.

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Limonoid 4 display potent ABTS^⋅+ scavenging activity.

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Limonoids 5 and 7–10 possessed the high ABTS^⋅+ and DPPH scavenging activities.

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Limonoids 1–4 and 11 showed the elective inhibition of Cox-1.

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Limonoids 1–4 and 11 exhibited the significant cytotoxicities.

A phytochemical investigation of the ethanol extract of Toona sinensis (A. Juss.) Roem resulted in the isolation of ten new limonoids, toonasinenines A–J (1–10), together with two known compounds, toonafolin (11) and toonacilianin D (12). Their structures were determined by spectroscopic analyses. The isolated components were evaluated in vitro for radical scavenging potential using ABTS^⋅+ and DPPH test, anti-inflammatory activities for Cox-1 and Cox-2, and cytotoxicies against nine tumour cell lines (A549, BGC-823, CHG-5, HCT15, HeLa, HepG2, MDA-MB-231, SHG-44 and SGC-7901 cells). As a result, 4, 5 and 7–10 showed potent radical scavenging activities, while limonoids 1–4 and 11 exhibited significant anti-inflammatory and cytotoxic potential.

Chemical composition, antimicrobial activity against Staphylococcus aureus and a pro-apoptotic effect in SGC-7901 of the essential oil from Toona sinensis (A. Juss.) Roem. leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Leaves of Toona sinensis (A. Juss.) Roem. (TSL), a popular vegetable in China, have anti-inflammatory, antidoting, and worm-killing effects and are used in folk medicine for the treatment of enteritis, dysentery, carbuncles, boils, and especially abdominal tumors. Our aim was to investigate the in vitro antimicrobial activity against Staphylococcus aureus and anticancer property of the essential oil from TSL (TSL-EO), especially the pro-apoptotic effect in SGC-7901.

MATERIALS AND METHODS

TSL-EO obtained by hydrodistillation was analyzed by GC/MS and was tested in vitro against twenty clinically isolated strains of Staphylococcus aureus (SA 1-20), which were either methicillin-sensitive Staphylococcus aureus (MSSA) or methicillin-resistant Staphylococcus aureus (MRSA) and two standard strains viz. ATCC 25923 and ATCC 43300. The anticancer activity of TSL-EO was evaluated in vitro against HepG2, SGC7901, and HT29 through MTT assay. Moreover, the apoptosis-inducing activity of TSL-EO in SGC7901 cells was determined by Hoechst 33324 staining and flow cytometry methods. Also, the apoptosis-related proteins viz. Bax, Bcl-2 and caspase-3 were detected by western-blotting.

RESULTS

GC-MS analysis showed that TSL-EO contained a high amount of sesquiterpenes (84.64%), including copaene (8.27%), β-caryophyllene (10.16%), caryophyllene (13.18%) and β-eudesmene (5.06%). TSL-EO inhibited the growth of both MSSA and MRSA, with the lowest MIC values of 0.125 and 1mg/ml, respectively. Treatment with TSL-EO for 24h could significantly suppress the viability of three different cancer cell lines (P<0.05). Furthermore, the apoptosis-inducing activity of TSL-EO in SGC7901 cells increased in a dose-dependent manner, potentially resulting from the up-regulated expression of Bax, caspase-3 and down-regulated expression of Bcl-2.

CONCLUSIONS

TSL-EO possessed antibacterial activity against Staphylococcus aureus and significant cytotoxicity against cancer cells and particularly prominent pro-apoptotic activity in SGC7901 cells. These bioactivities were probably due to the high content of sesquiterpenes. Our results suggested that TSL-EO possessed potential health benefits and could serve as a promising natural food addictive.

Traditional Chinese medicine herbal extracts of Cibotium barometz, Gentiana scabra, Dioscorea batatas, Cassia tora, and Taxillus chinensis inhibit SARS-CoV replication

Development of anti-severe acute respiratory syndrome associated coronavirus (SARS-CoV) agents is pivotal to prevent the reemergence of the life-threatening disease, SARS. In this study, more than 200 extracts from Chinese medicinal herbs were evaluated for anti-SARS-CoV activities using a cell-based assay that measured SARS-CoV-induced cytopathogenic effect (CPE) in vitro on Vero E6 cells. Six herbal extracts, one each from Gentianae Radix (龍膽 lóng dǎn; the dried rhizome of Gentiana scabra), Dioscoreae Rhizoma (山藥 shān yào; the tuber of Dioscorea batatas), Cassiae Semen (決明子 jué míng zǐ; the dried seed of Cassia tora) and Loranthi Ramus (桑寄生 sāng jì shēng; the dried stem, with leaf of Taxillus chinensis) (designated as GSH, DBM, CTH and TCH, respectively), and two from Rhizoma Cibotii (狗脊 gǒu jǐ; the dried rhizome of Cibotium barometz) (designated as CBE and CBM), were found to be potent inhibitors of SARS-CoV at concentrations between 25 and 200 μg/ml. The concentrations of the six extracts needed to inhibit 50% of Vero E6 cell proliferation (CC₅₀) and 50% of viral replication (EC₅₀) were determined. The resulting selective index values (SI = CC₅₀/EC₅₀) of the most effective extracts CBE, GSH, DBM, CTH and TCH were > 59.4, > 57.5, > 62.1, > 59.4, and > 92.9, respectively. Among these extracts, CBM and DBM also showed significant inhibition of SARS-CoV 3CL protease activity with IC₅₀ values of 39 μg/ml and 44 μg/ml, respectively. Our findings suggest that these six herbal extracts may have potential as candidates for future development of anti-SARS therapeutics.

Toona sinensis leaf aqueous extract displays activity against sepsis in both in vitro and in vivo models

Toona sinensis (TS) leaves are used as a vegetable and in traditional Chinese medicine. However, in vivo experiments regarding the anti-inflammatory function of TS leaves have not previously been conducted. The aim of this study was to investigate the potential role of TS leaf extract (TSL) in the prevention of sepsis-induced lung injury in vivo and on macrophage activation in vitro. The results showed that oral gavage pretreatment with TSL in rats for 30 days improved the survival of cecal ligation and puncture-induced sepsis, potentially by attenuating sepsis-induced histological lung damage rather than inflammatory cell infiltration. Furthermore, we demonstrated that pretreatment with TSL attenuated the lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase, thereby inhibiting nitric oxide production and release in murine macrophage-like RAW 264.7 cells. Interestingly, TSL did not affect the LPS-induced release of other cytokines (e.g., tumor necrosis factor α and interleukin 1β) but increased LPS-induced heme-oxygenase-1 expression. In conclusion, the study provides preliminary data for TSL on cecal ligation and puncture-induced sepsis. The beneficial impact of TSL needs extensive study to get solid evidence.

The aqueous extract from Toona sinensis leaves inhibits microglia-mediated neuroinflammation

The leaves of Toona sinensis, a well‐known traditional oriental medicine, have been prescribed for the treatment of enteritis and infection. Recently, aqueous extracts of Toona sinensis leaves (TSL‐1) have demonstrated many biological effects both in vitro and in vivo. In the central nervous system, microglial activation and their proinflammatory responses are considered an important therapeutic strategy for neuroinflammatory disorders such as cerebral ischemia, Alzheimer's disease, and Parkinson's disease. The present study attempted to validate the effect of TSL‐1 on microglia‐mediated neuroinflammation stimulated by lipopolysaccharide (LPS). As inflammatory parameters, the production of nitric oxide (NO), inducible NO synthase, and tumor necrosis factor‐α were evaluated. Our results demonstrate that TSL‐1 suppresses LPS‐induced NO production, tumor necrosis factor‐α secretion, and inducible NO synthase protein expression in a concentration‐dependent manner, without causing cytotoxicity. In addition, the inhibitory effects of TSL‐1 in LPS‐stimulated BV‐2 microglia were extended to post‐treatment suggesting the therapeutic potential of TSL‐1. Therefore, this work provides the future evaluation of the role of TSL‐1 in the treatment of neurodegenerative diseases by inhibition of inflammatory mediator production in activated microglia.

The Effectiveness and Mechanism of Toona sinensis Extract Inhibit Attachment of Pandemic Influenza A (H1N1) Virus

TSL-1 is a fraction of the aqueous extract from the tender leaf of Toona sinensis Roem, a nutritious vegetable. The pandemic influenza A (H1N1) virus is a recently described, rapidly contagious respiratory pathogen which can cause acute respiratory distress syndrome (ARDS) and poses a major public health threat. In this study, we found that TSL-1 inhibited viral yields on MDCK plaque formation by pandemic influenza A (H1N1) virus on infected A549 cells with high selectivity index. Meanwhile, TSL-1 also suppressed viral genome loads in infected A549 cells, quantified by qRT-PCR. This study further demonstrated that TSL-1 inhibited pandemic influenza A (H1N1) virus activity through preventing attachment of A549 cells but not penetration. TSL-1 inhibited viral attachment through significant downregulation of adhesion molecules and chemokines (VCAM-1, ICAM-1, E-selectin, IL-8, and fractalkine) compared to Amantadine. Our results suggest that TSL-1 may be used as an alternative treatment and prophylaxis against pandemic influenza A (H1N1) virus.

Recent developments in anti-severe acute respiratory syndrome coronavirus chemotherapy

Severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in early 2003 to cause a very severe acute respiratory syndrome, which eventually resulted in a 10% case-fatality rate. Owing to excellent public health measures that isolated focus cases and their contacts, and the use of supportive therapies, the epidemic was suppressed to the point that further cases have not appeared since 2005. However, despite intensive research since then (over 3500 publications), it remains an untreatable disease. The potential for re-emergence of the SARS-CoV or a similar virus with unknown but potentially serious consequences remains high. This is due in part to the extreme genetic variability of RNA viruses such as the coronaviruses, the many animal reservoirs that seem to be able host the SARS-CoV in which reassortment or recombination events could occur and the ability coronaviruses have to transmit relatively rapidly from species to species in a short period of time. Thus, it seems prudent to continue to explore and develop antiviral chemotherapies to treat SARS-CoV infections. To this end, the various efficacious anti-SARS-CoV therapies recently published from 2007 to 2010 are reviewed in this article. In addition, compounds that have been tested in various animal models and were found to reduce virus lung titers and/or were protective against death in lethal models of disease, or otherwise have been shown to ameliorate the effects of viral infection, are also reported.

Stimulation of activity and expression of antioxidant enzymes by solvent fractions and isolated compound from Cedrela sinensis leaves in HepG2 cells

Cedrela sinensis has been widely used in traditional Oriental medicine to treat a variety of diseases. However, little is known about the cellular actions by which this plant mediates its antioxidant effects. In this study, activity-guided fractionations of C. sinensis leaves were performed using column chromatographic techniques as well as biological assays with HepG2 cells. The ethanol (95%) extract of C. sinensis leaves was sequentially extracted with hexane, chloroform, ethyl acetate (EtOAc), butanol, and water, and the fractions were screened for their antioxidant potentials for scavenging radicals as well as inducing antioxidant enzyme activity and expression. The most potent antioxidant EtOAc fraction was further separated using chromatographic techniques including open column and high-performance liquid chromatography. Compound 1 from the EtOAc fraction showed strong radical scavenging activity with a 50% scavenging concentration value close to that of ascorbic acid and induced both the activity and expressions of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase. Inhibitory effects on the phosphorylations of upstream mitogen-activated protein kinases such as c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38 were also observed after treatments with compound 1. Compound 1 was identified as quercitrin by (1)H- and (13)C-nuclear magnetic resonance techniques. Taken together, our findings demonstrated for the first time that C. sinensis leaves appear to be a useful source of a cytoprotective and chemopreventive agent that can stimulate the activity and expression of crucial antioxidant enzymes in cells.

Anti-neoplastic effects of gallic acid, a major component of Toona sinensis leaf extract, on oral squamous carcinoma cells

Extract of Toona sinensis (TS) has been reported to have various effects on cultured cell lines, including anti-proliferative activity in cancer cells. We have studied the effects of TS on various human oral squamous carcinoma cell lines (HOSCC), including UM1, UM2, SCC-4, and SCC-9. These cell lines were treated with TS leaf extract and screened for viability, apoptosis, necrosis, and apoptotic gene expression. Normal human oral keratinocytes (NHOK) served as a control for cytotoxic assays. Viability of TS-treated HOSCC was reduced, whereas that of NHOK was not affected. FACScan analysis revealed that the leaf extract induced apoptosis or a combination of apoptosis and necrosis, depending on cell type. Microarray and semi-quantitative RT-PCR analysis for apoptotic-related gene expression revealed that 3,4,5-trihydroxybenzoic acid (gallic acid, one of the major bioactive compounds purified from TS extract) up-regulated pro-apoptotic genes such TNF-α, TP53BP2, and GADD45A, and down-regulated the anti-apoptotic genes Survivin and cIAP1, resulting in cell death. This study suggests that gallic acid, the major bioactive compound present, is responsible for the anti-neoplastic effect of Toona sinensis leaf extract.

Antiproliferative and antitumorigenic activity of Toona sinensis leaf extracts in lung adenocarcinoma

Toona sinensis is a traditional Chinese herb, and the extracts of T. sinensis leaf possess a variety of biological functions. This study attempted to test the antiproliferative effect of TSL-1 (a bioactive fraction of T. sinensis) in H441 cells (lung adenocarcinoma). The data showed that the antiproliferative effect of TSL-1 on H441 cells is prominent using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. TSL-1-induced apoptosis was confirmed by cell morphology, sub-G(1) peak accumulation, cleavage of poly(ADP)-ribose polymerase, and propidium iodide-annexin V double staining. Furthermore, decreased Bcl-2 accompanied by increased Bax (in western blotting) was found with TSL-1 treatment of H441 cells. TSL-1 treatment-induced G(1) arrest was concurrent with the down-regulation of protein levels of cyclin D1 and cyclin-dependent kinase 4 in H441 cells. Peroral and intraperitoneal administrations of TSL-1 were performed to evaluate the therapeutic efficacy, and peroral administration of TSL-1 was also used to elucidate the therapeutic efficacy in the H441 cell xenograft model in vivo. The data revealed that TSL-1 treatment inhibited H441 tumor growth in both therapeutic and preventive experiments. Taken together, these results demonstrate that TSL-1 possesses the capability of preventing and alleviating lung cancer proliferation in vitro and in vivo with proven nephrological and hepatic safety and has the potential to be developed as an anti-lung cancer drug.