Anti-influenza virus activity of Ginkgo biloba leaf extracts

Unraveling antiviral efficacy of multifunctional immunomodulatory triterpenoids against SARS-COV-2 targeting main protease and papain-like protease

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be over, but its variants continue to emerge, and patients with mild symptoms having long COVID is still under investigation. SARS-CoV-2 infection leading to elevated cytokine levels and suppressed immune responses set off cytokine storm, fatal systemic inflammation, tissue damage, and multi-organ failure. Thus, drug molecules targeting the SARS-CoV-2 virus-specific proteins or capable of suppressing the host inflammatory responses to viral infection would provide an effective antiviral therapy against emerging variants of concern. Evolutionarily conserved papain-like protease (PLpro) and main protease (Mpro) play an indispensable role in the virus life cycle and immune evasion. Direct-acting antivirals targeting both these viral proteases represent an attractive antiviral strategy that is also expected to reduce viral inflammation. The present study has evaluated the antiviral and anti-inflammatory potential of natural triterpenoids: azadirachtin, withanolide_A, and isoginkgetin. These molecules inhibit the Mpro and PLpro proteolytic activities with half-maximal inhibitory concentrations (IC50) values ranging from 1.42 to 32.7 μM. Isothermal titration calorimetry (ITC) analysis validated the binding of these compounds to Mpro and PLpro. As expected, the two compounds, withanolide_A and azadirachtin, exhibit potent anti-SARS-CoV-2 activity in cell-based assays, with half-maximum effective concentration (EC50) values of 21.73 and 31.19 μM, respectively. The anti-inflammatory roles of azadirachtin and withanolide_A when assessed using HEK293T cells, were found to significantly reduce the levels of CXCL10, TNFα, IL6, and IL8 cytokines, which are elevated in severe cases of COVID-19. Interestingly, azadirachtin and withanolide_A were also found to rescue the decreased type-I interferon response (IFN-α1). The results of this study clearly highlight the role of triterpenoids as effective antiviral molecules that target SARS-CoV-2-specific enzymes and also host immune pathways involved in virus-mediated inflammation.

Treating COVID-19 with Medicinal Plants: Is It Even Conceivable? A Comprehensive Review

In 2020, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) challenged the world with a global outbreak that led to millions of deaths worldwide. Coronavirus disease 2019 (COVID-19) is the symptomatic manifestation of this virus, which can range from flu-like symptoms to utter clinical complications and even death. Since there was no clear medicine that could tackle this infection or lower its complications with minimal adverse effects on the patients' health, the world health organization (WHO) developed awareness programs to lower the infection rate and limit the fast spread of this virus. Although vaccines have been developed as preventative tools, people still prefer going back to traditional herbal medicine, which provides remarkable health benefits that can either prevent the viral infection or limit the progression of severe symptoms through different mechanistic pathways with relatively insignificant side effects. This comprehensive review provides scientific evidence elucidating the effect of 10 different plants against SARS-CoV-2, paving the way for further studies to reconsider plant-based extracts, rich in bioactive compounds, into more advanced clinical assessments in order to identify their impact on patients suffering from COVID-19.

Fighting the flu: a brief review on anti-influenza agents

The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.

Exploring the Protective Effect of Food Drugs against Viral Diseases: Interaction of Functional Food Ingredients and SARS-CoV-2, Influenza Virus, and HSV

A complex network of processes inside the human immune system provides resistance against a wide range of pathologies. These defenses form an innate and adaptive immunity, in which certain immune components work together to counteract infections. In addition to inherited variables, the susceptibility to diseases may be influenced by factors such as lifestyle choices and aging, as well as environmental determinants. It has been shown that certain dietary chemical components regulate signal transduction and cell morphologies which, in turn, have consequences on pathophysiology. The consumption of some functional foods may increase immune cell activity, defending us against a number of diseases, including those caused by viruses. Here, we investigate a range of functional foods, often marketed as immune system boosters, in an attempt to find indications of their potential protective role against diseases caused by viruses, such as the influenza viruses (A and B), herpes simplex virus (HSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in some cases mediated by gut microbiota. We also discuss the molecular mechanisms that govern the protective effects of some functional foods and their molecular constituents. The main message of this review is that discovering foods that are able to strengthen the immune system can be a winning weapon against viral diseases. In addition, understanding how the dietary components function can aid in the development of novel strategies for maintaining human bodily health and keeping our immune systems strong.

MD simulation and MM/PBSA identifies phytochemicals as bifunctional inhibitors of SARS-CoV-2

The global spread of SARS-CoV-2 has resulted in millions of fatalities worldwide, making it crucial to identify potent antiviral therapeutics to combat this virus. We employed structure-assisted virtual screening to identify phytochemicals that can target the two proteases which are essential for SARS-CoV-2 replication and transcription, the main protease and papain-like protease. Using virtual screening and molecular dynamics, we discovered new phytochemicals with inhibitory activity against the two proteases. Isoginkgetin, kaempferol-3-robinobioside, methyl amentoflavone, bianthraquinone, podocarpusflavone A, and albanin F were shown to have the best affinity and inhibitory potential among the compounds, and can be explored clinically for use as inhibitors of novel coronavirus SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Evaluation of the antimicrobial function of Ginkgo biloba exocarp extract against clinical bacteria and its effect on Staphylococcus haemolyticus by disrupting biofilms

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Ginkgo biloba L. (Ginkgo nuts) has been used for a long time as a critical Chinese medicine material to treat cough and asthma, as well as a disinfectant. Similar records were written in the Compendium of Materia Medica (Ben Cao Gang Mu, pinyin in Chinese) and Sheng Nong's herbal classic (Shen Nong Ben Cao Jing, pinyin in Chinese). Recent research has shown that Ginkgo biloba exocarp extract (GBEE) has the functions of unblocking blood vessels and improving brain function, as well as antitumour activity and antibacterial activity. GBEE was shown to inhibit methicillin-resistant Staphylococcus aureus (MRSA) biofilm formation as a traditional Chinese herb in our previous report in this journal. AIM OF THE STUD: yThe antibiotic resistance of clinical bacteria has recently become increasingly serious. Thus, this study aimed to investigate the Ginkgo biloba exocarp extract (GBEE) antibacterial lineage, as well as its effect and mechanism on S. haemolyticus biofilms. This study will provide a new perspective on clinical multidrug resistant (MDR) treatment with ethnopharmacology herbs.

METHODS

The microbroth dilution assay was carried out to measure the antibacterial effect of GBEE on 13 types of clinical bacteria. Bacterial growth curves with or without GBEE treatment were drawn at different time points. The potential targets of GBEE against S. haemolyticus were screened by transcriptome sequencing. The effects of GBEE on bacterial biofilm formation and mature biofilm disruption were determined by crystal violet staining and scanning electron microscopy. The metabolic activity of bacteria inside the biofilm was assessed by colony-forming unit (CFU) counting and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2HY-tetrazolium bromide (MTT) assay. Quantitative polymerase chain reaction (qPCR) was used to measure the gene expression profile of GBEE on S. haemolyticus biofilm-related factors.

RESULTS

The results showed that GBEE has bacteriostatic effects on 3 g-positive (G⁺) and 2 g-negative (G^-) bacteria among 13 species of clinical bacteria. The antibacterial effect of GBEE supernatant liquid was stronger than the antibacterial effect of GBEE supernviaould-like liquid. GBEE supernatant liquid inhibited the growth of S. epidermidis, S. haemolyticus, and E. faecium at shallow concentrations with minimum inhibitory concentrations (MICs) of 2 μg/ml, 4 μg/ml and 8 μg/ml, respectively. Genes involved in quorum sensing, two-component systems, folate biosynthesis, and ATP-binding cassette (ABC) transporters were differentially expressed in GBEE-treated groups compared with controls. Crystal violet, scanning electron microscopy (SEM) and MTT assays showed that GBEE suppressed S. haemolyticus biofilm formation in a dose-dependent manner. Moreover, GBEE supernatant liquid downregulated cidA, cidB and atl, which are involved in cell lysis and extracellular DNA (eDNA) release, as well as downregulated the cbp, ebp and fbp participation in encoding cell-surface binding proteins.

CONCLUSIONS

GBEE has an excellent antibacterial effect on gram-positive bacteria and also inhibits the growth of gram-negative bacteria, such as A. baumannii (carbapenem-resistant Acinetobacter baumannii) CRABA and S. maltophilia. GBEE inhibits the biofilm formation of S. haemolyticus by altering the regulation and biofilm material-related genes, including the release of eDNA and cell-surface binding proteins.

Antiviral Effect of Isoquercitrin against Influenza A Viral Infection via Modulating Hemagglutinin and Neuraminidase

Isoquercitrin (IQC) is a component abundantly present in many plants and is known to have an anti-viral effect against various viruses. In this study, we demonstrate that IQC exhibits strong anti-influenza A virus infection, and its effect is closely related to the suppression of hemagglutinin (HA) and neuraminidase (NA) activities. We used green fluorescent protein-tagged Influenza A/PR/8/34 (H1N1), A/PR/8/34 (H1N1), and HBPV-VR-32 (H3N2) to evaluate the anti-IAV effect of IQC. The fluorescence microscopy and fluorescence-activated cell sorting analysis showed that IQC significantly decreases the levels of GFP expressed by IAV infection, dose-dependently. Consistent with that, IQC inhibited cytopathic effects by H1N1 or H3N2 IAV infection. Immunofluorescence analysis confirmed that IQC represses the IAV protein expression. Time-of-addition assay showed that IQC inhibits viral attachment and entry and exerts a strong virucidal effect during IAV infection. Hemagglutination assay confirmed that IQC affects IAV HA. Further, IQC potently reduced the NA activities of H1N1 and H3N2 IAV. Collectively, IQC prevents IAV infection at multi-stages via virucidal effects, inhibiting attachment, entry and viral release. Our results indicate that IQC could be developed as a potent antiviral drug to protect against influenza viral infection.

Ginkgo biloba in the management of the COVID-19 severity

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is linked with inflammatory disorders and the development of oxidative stress in extreme cases. Therefore, anti-inflammatory and antioxidant drugs may alleviate these complications. Ginkgo biloba L. folium extract (EGb) is a herbal medicine containing various active constituents. This review aims to provide a critical discussion on the potential role of EGb in the management of coronavirus disease 2019 (COVID-19). The antiviral effect of EGb is mediated by different mechanisms, including blocking SARS-CoV-2 3-chymotrypsin-like protease that provides trans-variant effectiveness. Moreover, EGb impedes the development of pulmonary inflammatory disorders through the diminution of neutrophil elastase activity, the release of proinflammatory cytokines, platelet aggregation, and thrombosis. Thus, EGb can attenuate the acute lung injury and acute respiratory distress syndrome in COVID-19. In conclusion, EGb offers the potential of being used as adjuvant antiviral and symptomatic therapy. Nanosystems enabling targeted delivery, personalization, and booster of effects provide the opportunity for the use of EGb in modern phytotherapy.

Broccoli Leaves Attenuate Influenza A Virus Infection by Interfering With Hemagglutinin and Inhibiting Viral Attachment

Broccoli (Brassica oleracea L. var. Italica) leaves are a byproduct of broccoli and could be used as a food source. The study aimed to evaluate the effect of broccoli leaves on influenza A virus (IAV) infection. We investigated the effect of ethanol extract of Broccoli leaves (EBL) on IAV infection using green fluorescent protein (GFP)–tagged Influenza A/PR/8/34 virus (PR8-GFP IAV). When EBL and PR8-GFP IAV were cotreated to RAW 264.7 cells, the fluorescence microscopy and fluorescence-activated cell sorting (FACS) analysis showed that EBL significantly reduced the levels of GFP expression by influenza viral infection dose-dependently. Immunofluorescence (IF) analysis confirmed that EBL decreased the expression of IAV proteins. EBL exhibited a strong inhibitory effect of IAV binding on the cells and moderate virucidal impact. Consistently, EBL potently suppressed the hemagglutination by IAV infection. These results indicate that EBL prevents IAV attachment via the inhibition of HA upon viral infection. Finally, EBL as an HA inhibitor of IAV could be used as the natural antiviral source to protect against influenza viral infection.

Biflavonoids: Important Contributions to the Health Benefits of Ginkgo (Ginkgo biloba L.)

Ginkgo (Ginkgo biloba L.) is one of the most distinctive plants, characterized by excellent resistance to various environmental conditions. It is used as an ornamental plant and is recognized as a medicinal plant in both traditional and Western medicine. Its bioactive potential is associated with the presence of flavonoids and terpene trilactones, but many other compounds may also have synergistic effects. Flavonoid dimers-biflavonoids-are important constituents of ginkgophytopharmaceuticals. Currently, the presence of 13 biflavonoids has been reported in ginkgo, of which amentoflavone, bilobetin, sciadopitysin, ginkgetin and isoginkgetin are the most common. Their role in plants remains unknown, but their bioactivity and potential role in the management of human health are better investigated. In this review, we have provided an overview of the chemistry, diversity and biological factors that influence the presence of biflavonoids in ginkgo, as well as their bioactive and health-related properties. We have focused on their antioxidant, anticancer, antiviral, antibacterial, antifungal and anti-inflammatory activities as well as their potential role in the treatment of cardiovascular, metabolic and neurodegenerative diseases. We also highlighted their potential toxicity and pointed out further research directions.

Isatis indigotica: from (ethno) botany, biochemistry to synthetic biology

Isatis indigotica Fort. (Chinese woad) is a species with an ancient and well-documented history as an indigo dye and medicinal plant. It is often confused with Isatis tinctoria L. (European woad), a medicinal plant in Europe. Here, the differences between I. indigotica and I. tinctoria are systematically described. The usage development history, clinical applications and pharmacological activities, and chemical components of I. indigotica are also summarized. Lignans, indole alkaloids, and their corresponding derivatives have been identified as the major active ingredients of I. indigotica and are associated with anti-viral, anti-inflammatory, anti-cancer, and other health-promoting activities. Notable progress has been made in understanding the biosynthetic pathway and regulation mechanism of lignans and indole alkaloids in I. indigotica, the results from which should facilitate the process of targeted metabolic engineering or synthetic biology. Moreover, multiple biotechnology methods such as polyploid breeding and genetic engineering have been used with I. indigotica to result in, for example, greater yields, higher levels of bioactive component accumulation, and enhanced stress tolerance to salt, drought, and insects. Some issues require additional analyses, and suggestions for future research on I. indigotica are also discussed.

Evaluation of botanicals as potential COVID-19 symptoms terminator

Information about the coronavirus disease 2019 (COVID-19) pandemic is still evolving since its appearance in December 2019 and has affected the whole world. Particularly, a search for an effective and safe treatment for COVID-19 continues. Botanical mixtures contain secondary metabolites (such as flavonoids, phenolics, alkaloids, essential oils etc.) with many therapeutic effects. In this study, the use of herbal treatments against COVID-19 was evaluated. Medical synthetic drugs focus mainly on respiratory symptoms, however herbal therapy with plant extracts may be useful to relieve overall symptoms of COVID-19 due to the variety of bioactive ingredients. Since COVID-19 is a virus that affects the respiratory tract, the antiviral effects of botanicals/plants against respiratory viruses have been examined through clinical studies. Data about COVID-19 patients revealed that the virus not only affects the respiratory system but different organs including the gastrointestinal (GI) system. As GI symptoms seriously affect quality of life, herbal options that might eliminate these problems were also evaluated. Finally, computer modeling studies of plants and their active compounds on COVID-19 were included. In summary, herbal therapies were identified as potential options for both antiviral effects and control of COVID-19 symptoms. Further data will be needed to enlighten all aspects of COVID-19 pathogenesis, before determining the effects of plants on severe acute respiratory syndrome coronavirus 2.

Development of an HPLC-MS method for the determination of four terpene trilactones in Ginkgo biloba leaf extract via quality by design

Previously reported HPLC-evaporative light scattering detection methods for terpene trilactone determination in Ginkgo biloba leaf extract (EGBL) have complicated sample preparation steps and are time-consuming. Thus, in this work, an HPLC-MS method for the determination of terpene trilactones in EGBL was developed with a novel analytical quality by design approach to provide robust and simple measurements. For this purpose, analytical target profiles and systematic risk analyses were performed to identify potential critical method attributes and critical method parameters. After screening experiments, a Box-Behnken design approach was utilized to investigate the relationships between critical method attributes and critical method parameters. A hypercube design space obtained by a Monte Carlo method was used for choosing the analytical control strategy. Then, verification experiments were performed within the design space, and the models were found to be accurate. After that, the optimized method was verified and successfully used for quality control analysis of EGBL from different manufacturers, and the results were almost the same as those determined by HPLC-evaporative light scattering detection. To our knowledge, this is the first study to establish a robust HPLC-MS method for determination of terpene trilactones in EGBL based on a novel analytical quality by design concept, which can improve the quality control of commercial EGBL.

Ginkgo biloba exocarp extracts inhibit S. aureus and MRSA by disrupting biofilms and affecting gene expression

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgo biloba L. fruit, also known as Bai Guo, Ya Jiao Zi (in pinyin Chinese), and ginkgo nut (in English), has been used for many years as an important material in Chinese traditional medicine to treat coughs and asthma and as a disinfectant, as described in the Compendium of Materia Medica (Ben Cao Gang Mu, pinyin in Chinese), an old herbal book. Ginkgo nuts are used to treat phlegm-associated asthma, astringent gasp, frequent urination, gonorrhoea and turgidity; consumed raw to reduce phlegm and treat hangovers; and used as a disinfectant and insecticide. A similar record was also found in Sheng Nong's herbal classic (Shen Nong Ben Cao Jing, pinyin in Chinese). Recent research has shown that Ginkgo biloba L. exocarp extract (GBEE) can unblock blood vessels and improve brain function and exhibits antitumour and antibacterial activities.

AIM OF STUDY

To investigate the inhibitory effect of Ginkgo biloba L. exocarp extract (GBEE) on methicillin-resistant S. aureus (MRSA) biofilms and assess its associated molecular mechanism.

MATERIALS AND METHODS

The antibacterial effects of GBEE on S. aureus and MRSA were determined using the broth microdilution method. The growth curves of bacteria treated with or without GBEE were generated by measuring the CFU (colony forming unit) of cultures at different time points. The effects of GBEE on bacterial biofilm formation and mature biofilm disruption were determined by crystal violet staining. Quantitative polymerase chain reaction (qPCR) was used to measure the effects of GBEE on the gene expression profiles of MRSA biofilm-related factors at 6, 8, 12, 16 and 24 h.

RESULTS

The minimum inhibitory concentration (MIC) of GBEE on S. aureus and MRSA was 4 μg/mL, and the minimum bactericidal concentration (MBC) was 8 μg/ml. Moreover, GBEE (4-12 μg/mL) inhibited S. aureus and MRSA biofilm formation in a dose-dependent manner. Interestingly, GBEE also destroyed mature biofilms of S. aureus and MRSA at 12 μg/ml. The expression of the MRSA biofilm-associated factor icaA and sarA were downregulated after 6 h of treatment with GBEE, while sigB was downregulated after 12 h. MeanwhileMeanwhile, icaR was upregulated at 12 h. In addition, GBEE also downregulated the virulence gene hld and inhibited the synthesis of staphyloxanthin.

CONCLUSIONS

GBEE has excellent antibacterial effects against S. aureus and MRSA and inhibits their biofilm-forming ability by altering related gene expression.

Evidence that Ginkgo Biloba could use in the influenza and coronavirus COVID-19 infections

Coronavirus COVID-19 pandemic invades the world. Public health evaluates the incidence of infections and death, which should be reduced and need desperately quarantines for infected individuals. This article review refers to the roles of Ginkgo Biloba to reduce the risk of infection in the respiratory tract, the details on the epidemiology of corona COVID-19 and influenza, and it highlights how the Ginko Biloba could have been used as a novel treatment.Ginkgo Biloba can reduce the risk of infection by several mechanisms; these mechanisms involve Ginkgo Biloba contains quercetin and other constituents, which have anti-inflammatory and immune modulator effects by reducing pro-inflammatory cytokines concentrations. Cytokines cause inflammation which have been induced the injuries in lung lining.Some observational studies confirmed that Ginkgo Biloba reduced the risk of asthma, sepsis and another respiratory disease as well as it reduced the risk of cigarette smoking on respiratory symptoms. While other evidences suggested the characters of Ginkgo Biloba as an antivirus agent through several mechanisms. Ginkgolic acid (GA) can inhibit the fusion and synthesis of viral proteins, thus, it inhibit the Herpes Simplex Virus type1 (HSV-1), genome replication in Human Cytomegalovirus (HCMV) and the infections of the Zika Virus (ZIKV). Also, it inhibits the wide spectrum of fusion by inhibiting the three types of proteins that have been induced fusion as (Influenza A Virus [IAV], Epstein Barr Virus [EBV], HIV and Ebola Virus [EBOV]).The secondary mechanism of GA targeting inhibition of the DNA and protein synthesis in virus, greatly have been related to its strong effects, even afterward the beginning of the infection, therefore, it potentially treats the acute viral contaminations like (Measles and Coronavirus COVID-19). Additionally, it has been used topically as an effective agent on vigorous lesions including (varicella-zoster virus [VZV], HSV-1 and HSV-2). Ginkgo Biloba may be useful for treating the infected people with coronavirus COVID-19 through its beneficial effect. To assess those recommendations should be conducted with random control trials and extensive population studies.

COVID-19, microthromboses, inflammation, and platelet activating factor

Recent articles report elevated markers of coagulation, endothelial injury, and microthromboses in lungs from deceased COVID-19 patients. However, there has been no discussion of what may induce intravascular coagulation. Platelets are critical in the formation of thrombi and their most potent trigger is platelet activating factor (PAF), first characterized by Demopoulos and colleagues in 1979. PAF is produced by cells involved in host defense and its biological actions bear similarities with COVID-19 disease manifestations. PAF can also stimulate perivascular mast cell activation, leading to inflammation implicated in severe acute respiratory syndrome (SARS). Mast cells are plentiful in the lungs and are a rich source of PAF and of inflammatory cytokines, such as IL-1β and IL-6, which may contribute to COVID-19 and especially SARS. The histamine-1 receptor antagonist rupatadine was developed to have anti-PAF activity, and also inhibits activation of human mast cells in response to PAF. Rupatadine could be repurposed for COVID-19 prophylaxis alone or together with other PAF-inhibitors of natural origin such as the flavonoids quercetin and luteolin, which have antiviral, anti-inflammatory, and anti-PAF actions.

The Chinese herbal prescription JZ-1 induces autophagy to protect against herpes simplex Virus-2 in human vaginal epithelial cells by inhibiting the PI3K/Akt/mTOR pathway

ETHNOPHAMACOLOGICAL RELEVANCE

The Chinese herbal prescription JieZe-1 (JZ-1) is based on the modification of Yihuang Tang, which was first described in Fu Qingzhu Nvke by the famous Qing Dynasty doctor Shan Fu as a treatment for leukorrheal diseases. As an in-hospital preparation, JZ-1 has been used in Tongji Hospital for many years to treat various infectious diseases of the lower female genital tract, including cervicitis, vaginitis, genital herpes and condyloma acuminatum. Our previous studies have shown that JZ-1 has curative effects on Candida albicans, Trichomonas vaginalis and Ureaplasma urealyticum infections.

AIM OF THE STUDY

Genital herpes is among the most common sexually transmitted diseases (STDs) worldwide and is mainly caused by herpes simplex virus type-2 (HSV-2). Current therapies can relieve symptoms in patients but do not cure or prevent the spread of the virus. This study was designed to investigate the effect of JZ-1 on HSV-2 infection and its mechanism, which is based on autophagy induction, to provide new ideas and a basis for the study of antiviral drugs.

MATERIALS AND METHODS

Evaluation of the antiviral activity of JZ-1 was conducted by MTT assay and western blotting. Then, Western blot and immunofluorescence analyses, observations through transmission electron microscopy and experiments with the recombinant lentivirus vector mRFP-GFP-LC3B were used to monitor autophagic flux in VK2/E6E7 cells. To explore the mechanism by which JZ-1 regulates autophagy, western blotting and real-time quantitative PCR (qRT-PCR) were used to determine the expression of phosphoinositide 3-kinase (PI3K)/Akt/mTOR pathway proteins and to detect changes in critical molecules in the pathway after the application of a PI3K inhibitor. Additionally, the mRNA expression levels of inflammatory cytokines, namely, IL-6, IFN-α, IFN-β and TNF-α, were measured with qRT-PCR.

RESULTS

HSV-2 infection inhibited autophagy in the VK2/E6E7 cells. Further study revealed that the activation of the PI3K/Akt/mTOR pathway induced by HSV-2 infection may result in the blocked autophagic flux and inhibited autophagosome and autolysosome formation. JZ-1 exhibited significant antiviral activity in the VK2/E6E7 cells, which showed increased cell vitality and reduced viral protein expression, namely, earliest virus-specific infected cell polypeptides 5 (ICP5) and glycoprotein D (gD). We found that JZ-1 treatment inhibited the upregulation of the PI3K/Akt/mTOR pathway proteins and promoted autophagy to combat HSV-2 infection, while PI3K inhibitor pretreatment prevented the enhanced autophagy induced by JZ-1. Moreover, JZ-1 attenuated the increase in inflammatory cytokines that had been induced HSV-2 infection.

CONCLUSION

Our results showed that JZ-1 protects against HSV-2 infection, and this beneficial effect may be mediated by inducing autophagy via inhibition of the PI3K/Akt/mTOR signaling axis.

Hampering Herpesviruses HHV-1 and HHV-2 Infection by Extract of Ginkgo biloba (EGb) and Its Phytochemical Constituents

Despite the availability of several anti-herpesviral agents, it should be emphasized that the need for new inhibitors is highly encouraged due to the increasing resistant viral strains as well as complications linked with periods of recurring viral replication and reactivation of latent herpes infection. Extract of Ginkgo biloba (EGb) is a common phytotherapeutics around the world with health benefits. Limited studies, however, have addressed the potential antiviral activities of EGb, including herpesviruses such as Human alphaherpesvirus 1 (HHV-1) and Human alphaherpesvirus 2 (HHV-2). We evaluated the antiviral activity of EGb and its phytochemical constituents: flavonoids and terpenes against HHV-1 and HHV-2. Pretreatment of the herpesviruses with EGb prior to infection of cells produced a remarkable anti-HHV-1 and anti-HHV-2 activity. The extract affected the viruses before adsorption to cell surface at non-cytotoxic concentrations. In this work, through a comprehensive anti-HHV-1 and anti-HHV-2 activity study, it was revealed that flavonoids, especially isorhamnetin, are responsible for the antiviral activity of EGb. Such activity was absent in quercetin and kaempferol. However, EGb showed the most potent antiviral potency compared to isorhamnetin. EGb could augment current therapies for herpes labialis and genital herpes. Moreover, the potential use of EGb in multidrug therapy with synthetic anti-herpes compounds might be considered.

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.

Herbal Medicines with Antiviral Activity Against the Influenza Virus, a Systematic Review

The rapidly changing influenza virus has remained a consistent threat to the well-being of a variety of species on the planet. Influenza virus' high mutation rate has allowed the virus to rapidly and continuously evolve, as well as generate new strains that are resistant to the current commercially available antivirals. Thus, the increased resistance has compelled the scientific community to explore alternative compounds that have antiviral effects against influenza virus. In this paper, the authors systematically review numerous herbal extracts that were shown to have antiviral effects against the virus. Specifically, the herbal antiviral targets mainly include hemagglutinin, neuraminidase and matrix 2 proteins. In some instances, herbal extracts inhibited the replication of oseltamivir-resistant strains and certain pentacyclic triterpenes exhibited higher antiviral activity than oseltamivir. This paper also explores the possibility of targeting various host-cell signaling pathways that are utilized by the virus during its replication process. Infected cell pathways are hijacked by intracellular signaling cascades such as NF-kB signaling, PI3K/Akt pathway, MAPK pathway and PKC/PKR signaling cascades. Herbal antivirals have been shown to target these pathways by suppressing nuclear export of influenza vRNP and thus inhibiting the phosphorylation signaling cascade. In conclusion, copious amounts of herbal antivirals have been shown to inhibit influenza virus, however further studies are needed for these new compounds to be up to modern pharmacological standards.

A Novel Natural Influenza A H1N1 Virus Neuraminidase Inhibitory Peptide Derived from Cod Skin Hydrolysates and Its Antiviral Mechanism

In this paper, a novel natural influenza A H1N1 virus neuraminidase (NA) inhibitory peptide derived from cod skin hydrolysates was purified and its antiviral mechanism was explored. From the hydrolysates, novel efficient NA-inhibitory peptides were purified by a sequential approach utilizing an ultrafiltration membrane (5000 Da), sephadex G-15 gel column and reverse-phase high-performance liquid chromatography (RP-HPLC). The amino acid sequence of the pure peptide was determined by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was PGEKGPSGEAGTAGPPGTPGPQGL, with a molecular weight of 2163 Da. The analysis of the Lineweacer–Burk model indicated that the peptide was a competitive NA inhibitor with Ki of 0.29 mM and could directly bind free enzymes. In addition, docking studies suggested that hydrogen binding might be the driving force for the binding affinity of PGEKGPSGEAGTAGPPGTPGPQGL to NA. The cytopathic effect reduction assay showed that the peptide PGEKGPSGEAGTAGPPGTPGPQGL protected Madin–Darby canine kidney (MDCK) cells from viral infection and reduced the viral production in a dose-dependent manner. The EC₅₀ value was 471 ± 12 μg/mL against H1N1. Time-course analysis showed that PGEKGPSGEAGTAGPPGTPGPQGL inhibited influenza virus in the early stage of the infectious cycle. The virus titers assay indicated that the NA-inhibitory peptide PGEKGPSGEAGTAGPPGTPGPQGL could directly affect the virus toxicity and adsorption by host cells, further proving that the peptide had an anti-viral effect with multiple target sites. The activity of NA-inhibitory peptide was almost inactivated during the simulated in vitro gastrointestinal digestion, suggesting that oral administration is not recommended. The peptide PGEKGPSGEAGTAGPPGTPGPQGL acts as a neuraminidase blocker to inhibit influenza A virus in MDCK cells. Thus, the peptide PGEKGPSGEAGTAGPPGTPGPQGL has potential utility in the treatment of the influenza virus infection.

Ginkgetin induces autophagic cell death through p62/SQSTM1-mediated autolysosome formation and redox setting in non-small cell lung cancer

Promoting cell death by autophagy could be a novel treatment for cancer. The major player in autophagy, p62, serves as a good therapeutic target. Ginkgetin, a biflavonoid from Ginkgo biloba leaves, exhibited promising anticancer activity in non-small cell lung cancer cell lines, with an IC50 lower than that of cisplatin. This anticancer effect of ginkgetin was illustrated in a xenograft nude mouse model. Ginkgetin induced autophagic cell death in A549 cells, and this effect was markedly reversed by chemical and genetic approaches. Ginkgetin showed potential binding affinity to p62. Upregulation of p62 through chemical and genetic means decreased cell death, lysosome acidification, and autophagosome formation, which consequently disrupted autolysosome formation. In addition, the decreased autophagy induced by p62 overexpression increased Nrf2/ARE activity and the oxygen consumption rate and decreased on formation of reactive oxygen species. These phenomena were exhibited in a reciprocal manner when p62 was knocked down. Thus, p62 may be a potential target in ginkgetin-induced autophagic cell death, and ginkgetin could be developed as a novel anticancer drug.

Identification of small molecule inhibitors for influenza a virus using in silico and in vitro approaches

Influenza viruses have acquired resistance to approved neuraminidase-targeting drugs, increasing the need for new drug targets for the development of novel anti-influenza drugs. Nucleoprotein (NP) is an attractive target since it has an indispensable role in virus replication and its amino acid sequence is well conserved. In this study, we aimed to identify new inhibitors of the NP using a structure-based drug discovery algorithm, named Nagasaki University Docking Engine (NUDE), which has been established especially for the Destination for GPU Intensive Machine (DEGIMA) supercomputer. The hit compounds that showed high binding scores during in silico screening were subsequently evaluated for anti-influenza virus effects using a cell-based assay. A 4-hydroxyquinolinone compound, designated as NUD-1, was found to inhibit the replication of influenza virus in cultured cells. Analysis of binding between NUD-1 and NP using surface plasmon resonance assay and fragment molecular orbital calculations confirmed that NUD-1 binds to NP and could interfere with NP-NP interactions essential for virus replication. Time-of-addition experiments showed that the compound inhibited the mid-stage of infection, corresponding to assembly of the NP and other viral proteins. Moreover, NUD-1 was also effective against various types of influenza A viruses including a clinical isolate of A(H1N1)pdm09 influenza with a 50% inhibitory concentration range of 1.8-2.1 μM. Our data demonstrate that the combined use of NUDE system followed by the cell-based assay is useful to obtain lead compounds for the development of novel anti-influenza drugs.

Inhibition of Murine Norovirus and Feline Calicivirus by Edible Herbal Extracts

Human noroviruses (HuNoVs) cause foodborne and waterborne viral gastroenteritis worldwide. Because HuNoV culture systems have not been developed thus far, no available medicines or vaccines preventing infection with HuNoVs exist. Some herbal extracts were considered as phytomedicines because of their bioactive components. In this study, the inhibitory effects of 29 edible herbal extracts against the norovirus surrogates murine norovirus (MNV) and feline calicivirus (FCV) were examined. FCV was significantly inhibited to 86.89 ± 2.01 and 48.71 ± 7.38% by 100 μg/mL of Camellia sinensis and Ficus carica, respectively. Similarly, ribavirin at a concentration of 100 μM significantly reduced the titer of FCV by 77.69 ± 10.40%. Pleuropterus multiflorus (20 μg/mL) showed antiviral activity of 53.33 ± 5.77, and 50.00 ± 16.67% inhibition was observed after treatment with 20 μg/mL of Alnus japonica. MNV was inhibited with ribavirin by 59.22 ± 16.28% at a concentration of 100 μM. Interestingly, MNV was significantly inhibited with 150 µg/mL Inonotus obliquus and 50 μg/mL Crataegus pinnatifida by 91.67 ± 5.05 and 57.66 ± 3.36%, respectively. Treatment with 20 µg/mL Coriandrum sativum slightly reduced MNV by 45.24 ± 4.12%. The seven herbal extracts of C. sinensis, F. carica, P. multiflorus, A. japonica, I. obliquus, C. pinnatifida, and C. sativum may have the potential to control noroviruses without cytotoxicity.

In vitro Anti-viral Activity of Psoraleae Semen Water Extract against Influenza A Viruses

Influenza causes respiratory infections and poses health risks to humans and animals; its effects are complicated by increasing resistance to existing anti-influenza viral agents. Therefore, novel therapeutic approaches against influenza virus infection are required. Psoraleae semen has been widely used in traditional medicine in Korea, Taiwan, China, and Japan for treating and preventing various diseases. In this study, we examined the anti-viral activities and mechanism of action of the water extract of Psoraleae semen (WPS) using RAW 264.7 and MDCK cells. We found that pre- and post-treatment with 100 μg/mL WPS markedly inhibited influenza A virus replication as assessed using a green fluorescent protein reporter virus, reduced viral protein expression (NS-1, PA, HA, PB-1, M1, and M2), and inhibited NA and HA activities. Mechanism studies revealed that WPS induced type I interferon cytokine secretion and subsequent stimulation of an anti-viral state in RAW 264.7 cells. Further, WPS exerted inhibitory effects on neuraminidase in influenza virus strains H1N1 and H3N2. Meanwhile, WPS exhibited inhibitory effects on hemagglutination in H3N2 but not in H1N1. Based on these results, WPS serves as an immunomodulator and inhibitor of influenza hemagglutinin and neuraminidase. Our results suggest that WPS is a promising source of novel anti-influenza drug candidates.

Antiviral Effects of Novel Herbal Medicine KIOM-C, on Diverse Viruses

In order to identify new potential antiviral agents, recent studies have advocated thorough testing of herbal medicines or natural substances that are traditionally used to prevent viral infections. Antiviral activities and the mechanism of action of the total aqueous extract preparation of KIOM-C, a novel herbal medicine, against diverse types of viruses were investigated. In vitro antiviral activity against A/Puerto Rico/8/34 (H1N1) (PR8), vesicular stomatitis virus (VSV), and Newcastle disease virus (NDV) through the induction of type-I interferon related protein phosphorylation and up-regulation of pro-inflammatory cytokines in murine macrophage cells (RAW264.7) were determined. In vivo, KIOM-C-treated BALB/c mice showed higher survivability and lower lung viral titers when challenged with A/Aquatic bird/Korea/W81/2005 (H5N2), A/PR/8/34(H1N1), A/Aquatic bird/Korea/W44/2005(H7N3) or A/Chicken/Korea/116 /2004(H9N2) influenza subtypes in contrast with the non-treated group. The present study revealed that total aqueous extract preparation of KIOM-C stimulates an antiviral state in murine macrophage cells and in mice leading to inhibition of viral infection and protection against lethal challenges.

Epimedium koreanum Nakai displays broad spectrum of antiviral activity in vitro and in vivo by inducing cellular antiviral state

Epimedium koreanum Nakai has been extensively used in traditional Korean and Chinese medicine to treat a variety of diseases. Despite the plant's known immune modulatory potential and chemical make-up, scientific information on its antiviral properties and mode of action have not been completely investigated. In this study, the broad antiviral spectrum and mode of action of an aqueous extract from Epimedium koreanum Nakai was evaluated in vitro, and moreover, the protective effect against divergent influenza A subtypes was determined in BALB/c mice. An effective dose of Epimedium koreanum Nakai markedly reduced the replication of Influenza A Virus (PR8), Vesicular Stomatitis Virus (VSV), Herpes Simplex Virus (HSV) and Newcastle Disease Virus (NDV) in RAW264.7 and HEK293T cells. Mechanically, we found that an aqueous extract from Epimedium koreanum Nakai induced the secretion of type I IFN and pro-inflammatory cytokines and the subsequent stimulation of the antiviral state in cells. Among various components present in the extract, quercetin was confirmed to have striking antiviral properties. The oral administration of Epimedium koreanum Nakai exhibited preventive effects on BALB/c mice against lethal doses of highly pathogenic influenza A subtypes (H1N1, H5N2, H7N3 and H9N2). Therefore, an extract of Epimedium koreanum Nakai and its components play roles as immunomodulators in the innate immune response, and may be potential candidates for prophylactic or therapeutic treatments against diverse viruses in animal and humans.

In vitro evaluation of synergistic inhibitory effects of neuraminidase inhibitors and methylglyoxal against influenza virus infection

BACKGROUND AND AIMS

Influenza virus infections are serious public health concerns worldwide that cause considerable mortality and morbidity. Moreover, the emergence of resistance to anti-influenza viral agents underscores the need to develop new anti-influenza viral agents and novel treatment strategies. Recently, we identified anti-influenza viral activity of manuka honey. Therefore, we hypothesized that methylglyoxal (MGO), a key component of manuka honey, may impart anti-influenza viral activity. The aim of this study was to evaluate the anti-influenza viral activity of MGO and its potential in combination treatments with neuraminidase (NA) inhibitors.

METHODS

MDCK cells were used to evaluate anti-influenza viral activity. To evaluate the mechanism of MGO, plaque inhibition assays were performed. The synergistic effects of MGO and viral NA inhibitors were tested.

RESULTS

MGO inhibited influenza virus A/WSN/33 replication 50% inhibitory concentration = 240 ± 190 μM; 50% cytotoxic concentration = 1.4 ± 0.4 mM; selective index (SI) = 5.8, which is related to its virucidal effects. Moreover, we found that MGO showed promising activity against various influenza strains. A synergistic effect was observed by a marked increase in SI of NA inhibitors at ∼1/100(th) of their single usage. A synergistic effect of MGO and oseltamivir was also observed against oseltamivir-resistant virus.

CONCLUSIONS

Our results showed that MGO has potent inhibitory activity against influenza viruses and also enhanced the effect of NA inhibitors. Thus, the co-administration of MGO and NA inhibitors should be considered for treatment of influenza virus infections.

Anti-influenza viral effects of honey in vitro: potent high activity of manuka honey

BACKGROUND AND AIMS

Influenza viruses are a serious threat to human health and cause thousands of deaths annually. Thus, there is an urgent requirement for the development of novel anti-influenza virus drugs. Therefore, the aim of this study was to evaluate the anti-influenza viral activity of honey from various sources.

METHODS

Antiviral activities of honey samples were evaluated using MDCK cells. To elucidate the possible mechanism of action of honey, plaque inhibition assays were used. Synergistic effects of honey with known anti-influenza virus drugs such as zanamivir or oseltamivir were tested.

RESULTS

Manuka honey efficiently inhibited influenza virus replication (IC50 = 3.6 ± 1.2 mg/mL; CC50 = 82.3 ± 2.2 mg/mL; selective index = 22.9), which is related to its virucidal effects. In the presence of 3.13 mg/mL manuka honey, the IC50 of zanamivir or oseltamivir was reduced to nearly 1/1000th of their single use.

CONCLUSIONS

Our results showed that honey, in general, and particularly manuka honey, has potent inhibitory activity against the influenza virus, demonstrating a potential medicinal value.

Prevention and Control of Influenza Viruses

The 2003–2004 outbreaks of highly pathogenic avian influenza (HPAI) have proven to be disastrous to the regional poultry industry in Asia, and have raised serious worldwide public health apprehension regarding the steps that should be taken to urgently control HPAI. Control measures must be taken based on the principles of biosecurity and disease management and at the same time making public aware of the precautionary measures at the verge of outbreak. Creation of protection and surveillance zones, various vaccination strategies viz. routine, preventive, emergency, mass and targeted vaccination programmes using live, inactivated and recombinant vaccines are the common strategies adopted in different parts of the globe. The new generation vaccines include recombinant vaccines and recombinant fusion vaccine. The pro-poor disease control programmes, giving compensation and subsidies to the farmers along with effective and efficient Veterinary Services forms integral part of control of HPAI. Following biosecurity principles and vaccination forms integral part of control programme against swine and equine influenza as well. Use of neuraminidase (NA) inhibitors (Zanamivir and Oseltamivir) for the treatment of human influenza has been widely accepted worldwide. The threat of increasing resistance of the flu viruses to these antivirals has evoked interest in the development of novel antiviral drugs for influenza virus such as inhibitors of cellular factors and host signalling cascades, cellular miRNAs, siRNA and innate immune peptides (defensins and cathelicidins). Commercial licensed inactivated vaccines for humans against influenza A and B viruses are available consisting of three influenza viruses: influenza type A subtype H3N2, influenza type A subtype H1N1 (seasonal) virus strain and influenza type B virus strain. As per WHO, use of tetravaccine consisting of antigens of influenza virus serotypes H3N2, H1N1, B and H5 is the most promising method to control influenza pandemic. All healthy children in many countries are required to be vaccinated between 6 and 59 months of age. The seasonal vaccines currently used in humans induce strain-specific humoral immunity as the antibodies. Universal influenza virus vaccines containing the relatively conserved ectodomain of M2 (M2e), M1, HA fusion peptide and stalk domains, NA, NP alone or in combination have been developed which have been shown to induce cross-protection. The T cell-based vaccines are another recent experimental approach that has been shown to elicit broad-spectrum heterosubtypic immunity in the host. As far as HPAI is concerned, various pandemic preparedness strategies have been documented.