14-Deoxy-11,12-dehydroandrographolide exerts anti-influenza A virus activity and inhibits replication of H5N1 virus by restraining nuclear export of viral ribonucleoprotein complexes

Targeting chemokine-receptor mediated molecular signaling by ethnopharmacological approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Infection and inflammation are critical to global human health status and the goal of current pharmacological interventions intends formulating medications/preventives as a measure to deal with this situation. Chemokines and their cognate receptors are major regulatory molecules in many of these ailments. Natural products have been a keen source to the drug development industry, every year contributing significantly to the growing list of FDA approved drugs. A multiverse of natural resource is employed as a part of curative regimen in folk/traditional/ethnomedicine which can be employed to discover, repurpose, and design potent medications for the diseases of clinical concern.

AIM OF THE STUDY

This review aims to systematically document the ethnopharmacologically active agents targeting the infectious-inflammatory diseases through the chemokine-receptor nexus.

MATERIALS AND METHODS

Articles related to chemokine/receptor modulating ethnopharmacological anti-inflammatory, anti-infectious natural sources, bioactive compounds, and formulations have been examined with special emphasis on women related diseases. The available literature has been thoroughly scrutinized for the application of traditional medicines in chemokine associated experimental methods, their regulatory outcomes, and pertinence to women's health wherever applicable. Moreover, the potential traditional regimens under clinical trials have been critically assessed.

RESULTS

A systematic and comprehensive review on the chemokine-receptor targeting ethnopharmaceutics from the available literature has been provided. The article discusses the implication of traditional medicine in the chemokine system dynamics in diverse infectious-inflammatory disorders such as cardiovascular diseases, allergic diseases, inflammatory diseases, neuroinflammation, and cancer. On this note, critical evaluation of the available data surfaced multiple diseases prevalent in women such as osteoporosis, rheumatoid arthritis, breast cancer, cervical cancer and urinary tract infection. Currently there is no available literature highlighting chemokine-receptor targeting using traditional medicinal approach from women's health perspective. Moreover, despite being potent in vitro and in vivo setups there remains a gap in clinical translation of these formulations, which needs to be strategically and scientifically addressed to pave the way for their successful industrial translation.

CONCLUSIONS

The review provides an optimistic global perspective towards the applicability of ethnopharmacology in chemokine-receptor regulated infectious and inflammatory diseases with special emphasis on ailments prevalent in women, consecutively addressing their current status of clinical translation and future directions.

Anti-inflammatory effect and pharmacokinetics of dehydroandrographolide, an active component of Andrographis paniculata, on Poly(I:C)-induced acute lung injury

Acute lung injury (ALI) is a common and critical respiratory disorder caused by various factors, with viral infection being the leading contributor. Dehydroandrographolide (DAP), a constituent of the Chinese herbal plant Andrographis paniculata, exhibits a range of activities including anti-inflammatory, in vitro antiviral and immune-enhancing effects. This study evaluated the anti-inflammatory effects and pharmacokinetics (PK) profile of DAP in ALI mice induced by intratracheal instillation of Poly(I:C) (PIC). The results showed that oral administration of DAP (10-40 mg/kg) effectively suppressed the increase in lung wet-dry weight ratio, total cells, total protein content, accumulation of immune cells, inflammatory cytokines and neutrophil elastase levels in bronchoalveolar lavage fluid of PIC-treated mice. DAP concentrations, determined by an LC-MS/MS method, in plasma after receiving DAP (20 mg/kg) were unchanged compared to those in normal mice. However, DAP concentrations and relative PK parameters in the lungs were significantly altered in PIC-treated mice, exhibiting a relatively higher maximum concentration, larger AUC, and longer elimination half-life than those in the lungs of normal mice. These results demonstrated that DAP could improve lung edema and inflammation in ALI mice, and suggested that lung injury might influence the PK properties of DAP, leading to increased lung distribution and residence. Our study provides evidence that DAP displays significant anti-inflammatory activity against viral lung injury and is more likely to distribute to damaged lung tissue.

Antihyperglycemic activity of 14-deoxy, 11, 12-didehydro andrographolide on streptozotocin-nicotinamide induced type 2 diabetic rats

BACKGROUND

Diabetic Mellitus is characterized by a lack or failure of insulin to bind to its target receptor or failure of the pancreas to yield insulin. This study evaluated the antihyperglycemic activity of 14-deoxy, 11, 12-didehydro andrographolide on streptozotocin-nicotinamide-induced type 2 diabetic rats. Diabetic conditions were induced by administering streptozotocin at a dosage of 45 mg/kg body weight and nicotinamide at a dosage of 110 mg/kg body weight through intraperitoneal injection.

MATERIALS AND METHODS

Diabetic-induced rats were treated with 14-deoxy, 11, 12-didehydro andrographolide concentrations between 10 and 500 mg/kg body weight. The blood glucose level and body weight of the rats were periodically examined. The pancreas was isolated and the histopathological staining was performed after making fine sections of the pancreas using a microtome. The influence of 14-deoxy, 11, 12-didehydro andrographolide on the expression level of various insulin signaling cascades was determined with q-PCR and western blotting.

RESULTS

The blood glucose level of the diabetic-induced rats was significantly (p < 0.05) higher when compared with the control group and resulted in a drop in the blood glucose level of the diabetic rats. Oral glucose level was also reduced in the treatment group and no significant reduction was noted in the untreated. The lipid profiling revealed that the atherogenic index and cholesterol ratio was increased in the diabetic group over the control group. Upregulation of the insulin cascades like IRTK and GLUT4 was observed by the q-PCR and upregulation of GLUT4 and IR-β was observed by the western blot analysis.

CONCLUSION

Overall, the finding indicates that 14-deoxy, 11, 12-didehydro andrographolide exhibited antihyperglycemic activity by modulating the expression of insulin cascades.

The role and mechanism of TCM in the prevention and treatment of infectious diseases

The constant presence of infectious diseases poses an everlasting threat to the entire world. In recent years, there has been an increased attention toward the application of traditional Chinese medicine (TCM) in the treatment of emerging infectious diseases, as it has played a significant role. The aim of this article is to provide a concise overview of the roles and mechanisms of TCM in treating infectious diseases. TCM possesses the ability to modulate relevant factors, impede signaling pathways, and inhibit microbial growth, thereby exhibiting potent antiviral, antibacterial, and anti-inflammatory effects that demonstrate remarkable efficacy against viral and bacterial infections. This article concludes that the comprehensive regulatory features of Chinese herbal medicines, with their various components, targets, and pathways, result in synergistic effects. The significance of Chinese herbal medicines in the context of infectious diseases should not be underestimated; however, it is crucial to also acknowledge their underutilization. This paper presents constructive suggestions regarding the challenges and opportunities faced by Chinese medicines. Particularly, it emphasizes the effectiveness and characteristics of Chinese medicines in the treatment of infectious diseases, specifying how these medicines' active substances can be utilized to target infectious diseases. This perspective is advantageous in facilitating researchers' pharmacological studies on Chinese medicines, focusing on the specific points of action. The mechanism of action of Chinese herbal medicines in the treatment of infectious diseases is comprehensively elucidated in this paper, providing compelling evidence for the superior treatment of infectious diseases through Chinese medicine. This information is favorable for advancing the development of TCM and its potential applications in the field of infectious diseases.

Inhibitory efficiency of Andrographis paniculata extract on viral multiplication and nitric oxide production

Andrographis paniculata (Burm. F.) Nees is a medicinal plant previously reported with broad-spectrum antivirals but the mode of inhibition remains elusive. The objective of this study was to identify the most active fraction from A. paniculata ethanol extract (APE, APE-2A, APE-2B and APE-2C) and dry powder extract (APSP) against influenza A (H3N2), representing RNA viruses, and herpes simplex virus-1 (HSV-1), representing DNA viruses. The results showed that the fractions APSP, APE, APE-2B, and APE-2C directly neutralized the HSV-1 and influenza A (H3N2) when incubated at room temperature for 60 min before infecting the cells. The results also showed that the additional APE-2A fraction also directly neutralized the influenza A (H3N2), but not the HSV-1. The APE, APE-2B and APE-2C inhibited the HSV-1 by more than 0.5 log when the fractions were introduced after infection. Similarly, the APSP and APE inhibited the influenza A (H3N2) more than 0.5 log after infection. Only 50 μg/mL APE-2C inhibited the viruses greater than 0.5 log. In addition, A. paniculata extracts were also evaluated for their interfering capacities against nitric oxide (NO) production in LPS-activated RAW 264.7 macrophages. As well, APE-2C potently inhibited NO production at the IC50 of 6.08 μg/mL. HPLC and LC-MS analysis indicated that the most actively antiviral fractions did not contain any andrographolide derivatives, whereas the andrographolide-rich fractions showed moderate activity.

Artesunate inhibits PDE4 leading to intracellular cAMP accumulation, reduced ERK/MAPK signaling, and blockade of influenza A virus vRNP nuclear export

Influenza A viruses (IAV) have been a major cause of mortality. Given the potential for future deadly pandemics, effective drugs are needed for the treatment of severe influenzas, such as those caused by H5N1 IAV. The anti-malaria drugs artemisinin and its derivates, including artesunate (AS), have been reported to have broad antiviral activities. Here, we showed AS's antiviral activity against H5N1, H1N1, H3N2 and oseltamivir-resistant influenza A(H1N1)virus in vitro. Moreover, we showed that AS treatment significantly protected mice from lethal challenges with H1N1 and H5N1 IAV. Strikingly, the combination of AS and peramivir treatment significantly improved survival outcomes compared to their monotherapy with either AS or peramivir. Furthermore, we demonstrated mechanistically that AS affected the later stages of IAV replication and limited nuclear export of viral ribonucleoprotein (vRNP) complexes. In A549 cells, we demonstrated for the first time that AS treatment induced cAMP accumulation via inhibiting PDE4, and consequently reduced ERK phosphorylation and blocked IAV vRNP export, and thus suppressed IAV replication. These AS's effects were reversed by the pre-treatment with a cAMP inhibitor SQ22536. Our findings suggest that AS could serve as a novel IAV inhibitor by interfering vRNP nuclear export to prevent and treat IAV infection.

Specialized metabolites from plants as a source of new multi-target antiviral drugs: a systematic review

Viral infections have always been the main global health challenge, as several potentially lethal viruses, including the hepatitis virus, herpes virus, and influenza virus, have affected human health for decades. Unfortunately, most licensed antiviral drugs are characterized by many adverse reactions and, in the long-term therapy, also develop viral resistance; for these reasons, researchers have focused their attention on investigating potential antiviral molecules from plants. Natural resources indeed offer a variety of specialized therapeutic metabolites that have been demonstrated to inhibit viral entry into the host cells and replication through the regulation of viral absorption, cell receptor binding, and competition for the activation of intracellular signaling pathways. Many active phytochemicals, including flavonoids, lignans, terpenoids, coumarins, saponins, alkaloids, etc., have been identified as potential candidates for preventing and treating viral infections. Using a systematic approach, this review summarises the knowledge obtained to date on the in vivo antiviral activity of specialized metabolites extracted from plant matrices by focusing on their mechanism of action.

A systemic review on medicinal plants and their bioactive constituents against avian influenza and further confirmation through in-silico analysis

Background

Avian influenza or more commonly known as bird flu is a widespread infectious disease in poultry. This review aims to accumulate information of different natural plant sources that can aid in combating this disease. Influenza virus (IV) is known for its ability to mutate and infect different species (including humans) and cause fatal consequences.

Methods

Total 33 plants and 4 natural compounds were identified and documented. Molecular docking was performed against the target viral protein neuraminidase (NA), with some plant based natural compounds and compared their results with standard drugs Oseltamivir and Zanamivir to obtain novel drug targets for influenza in chickens.

Results

It was seen that most extracts exhibit their action by interacting with viral hemagglutinin or neuraminidase and inhibit viral entry or release from the host cell. Some plants also interacted with the viral RNA replication or by reducing proinflammatory cytokines. Ethanol was mostly used for extraction. Among all the plants Theobroma cacao, Capparis Sinaica Veil, Androgarphis paniculate, Thallasodendron cillatum, Sinularia candidula, Larcifomes officinalis, Lenzites betulina, Datronia molis, Trametes gibbose exhibited their activity with least concentration (below 10 μg/ml). The dockings results showed that some natural compounds (5,7- dimethoxyflavone, Aloe emodin, Anthocyanins, Quercetin, Hemanthamine, Lyocrine, Terpenoid EA showed satisfactory binding affinity and binding specificity with viral neuraminidase compared to the synthetic drugs.

Conclusion

This review clusters up to date information of effective herbal plants to bolster future influenza treatment research in chickens. The in-silico analysis also suggests some potential targets for future drug development but these require more clinical analysis.

Anti-hepatitis B virus activity of lithospermic acid, a polyphenol from Salvia miltiorrhiza, in vitro and in vivo by autophagy regulation

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia miltiorrhiza (the roots of S. miltiorrhiza Bunge, Danshen in Chinese), a traditional Chinese medicine, has been clinically used to prevent and treat various diseases, such as cardiovascular and cerebrovascular diseases, diabetes, and hepatitis B, in China and some other Asian countries. Lithospermic acid (LA), a polyphenol derived from S. miltiorrhiza, has been reported to exhibit multiple pharmacological properties, such as anti-inflammatory, anti-HIV, and anti-carbon tetrachloride-induced liver injury activities. However, little is known about the anti-hepatitis B virus (HBV) activity of LA.

AIM OF THE STUDY

The study was projected to investigate the anti-HBV activity of LA in vitro (HepG2.2.15 and pHBV1.3-transfected HepG2 cells) and in vivo (pAAV-HBV1.2 hydrodynamic injection [HBV-HDI] mice) and explore the potential mechanism as well.

MATERIALS AND METHODS

Hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) contents were detected by ELISA kits. HBV DNA and hepatitis B core antigen (HBcAg) levels were evaluated by quantitative real-time polymerase chain reaction and immunohistochemistry assay, respectively. The proteins in autophagy process, lysosomal acidic function, and autophagy-related signaling pathways were examined by Western blot. Transmission electron microscopy was used to observe the number of autophagosomes and autolysosomes. Confocal microscopy was applied to analyze the autophagic flux and lysosomal acidification, using mCherry-enhanced green fluorescent protein (EGFP)-microtubule-associated protein light chain (LC)3 and lysosomal probes, respectively.

RESULTS

LA exhibited anti-HBV activity by inhibiting HBV DNA replication in HepG2.2.15 and pHBV-transfected HepG2 cells in dose- and time-dependent manners and hampering HBsAg and HBeAg levels in HepG2.2.15 cells to a certain extent. LA reduced HBV DNA, HBsAg/HBeAg, and HBcAg levels in the serum/liver tissues of HBV-HDI C57BL/6 mice during the 3-week treatment and suppressed the withdrawal rebound of HBV DNA and HBsAg in the mice serum. LA increased LC3-II protein expression and the number of autolysosomes/autophagosomes and promoted the degradation of sequestosome 1(p62) protein in vitro and in vivo. LA enhanced the co-localization of LC3 protein with autolysosomes, further confirming the ability of LA to induce a complete autophagy. Knockdown of autophagy-related gene (Atg) 7 or 5 in vitro and administration of 3-methyladenine (an autophagic inhibitor) in vivo disabled the inhibitory efficacy of LA on HBV DNA replication, suggesting that the anti-HBV efficacy of LA depended on its ability of inducing autophagy. LA could enhance lysosomal acidification and improve the function of lysosomes by promoting the protein expression of lysosomal-associated membrane protein (LAMP)-1, LAMP-2, and mature cathepsin D, which may contribute to the autophagic induction of LA. LA inhibited the activation of AKT and mammalian target of rapamycin (mTOR) induced by HBV, which was reversed by IGF-1 (an agonist of the PI3K/AKT/mTOR signaling pathway), indicating that LA elicited autophagy through hampering the PI3K/AKT/mTOR signaling pathway.

CONCLUSION

We revealed the anti-HBV activity and mechanism of LA in vitro and in vivo. This study facilitates a new understanding of the anti-HBV potent components of S. miltiorrhiza and sheds light on LA for further development as an active constituent or candidate used in the therapy against HBV infection.

Discovery and molecular elucidation of the anti-influenza material basis of Banlangen granules based on biological activities and ultra-high performance liquid chromatography coupled with quadrupole-orbitrap mass spectrometry

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has a wide range of applications, including human healthcare-associated treatments and bioactive compound discovery. However, complex chemical systems present a significant challenge for chemical-material-based research and quality control. For instance, Banlangen (BLG) granules is a well-acknowledged TCM preparation widely used in clinical treatment of virus infection. However, its chemical basis of anti-influenza efficacy remains unclear.

AIM OF THE STUDY

In the present study, a systematic discovery strategy for identifying anti-influenza molecules based on biological activities and chemical analysis was established to contribute to the molecular elucidation of the anti-influenza material basis of Banlangen granules.

MATERIALS AND METHODS

Hemagglutinase inhibition (HAI) and neuraminidase inhibition (NAI) assays were used to compare the anti-influenza activities of different fractions of BLG granules against H1N1, H5N1 and H7N9 viruses. A comparative qualitative analysis of the chemical constituents in BLG granules and their fractions was performed using ultra-high-performance liquid chromatography coupled with quadrupole orbitrap mass spectrometry (UHPLC-Q-Exactive Orbitrap MS), in which a multiple mass spectrometry database platform and three compound identification strategies were used. The association between anti-influenza activities and chemical constituent characteristics was analyzed using multiple stoichiometries and data comparison strategies.

RESULTS

The results showed that the chromatography fractions F3 and F4 of the BLG granules had the highest anti-influenza activity. A total of 88 compounds were identified in the BLG granules, including 31 alkaloids, 16 organic acids, 10 nucleosides, 8 phenylpropanoids, 6 sulfur-containing compounds, 5 amino acids, 4 aromatic compounds, 3 aldehydes and ketones, 2 flavonoids, 1 alcohol, 1 carbohydrate, and 1 aliphatic compound. Out of these, 31 characteristic compounds were identified in fractions F3-F4 as candidate compounds with anti-influenza activity. Additionally, 6-methoxyquinoline and 4-guanidinobutanal were identified in BLG granules and its raw material (Isatidis Radix) for the first time.

CONCLUSION

In this study, we proposed a systematic discovery strategy to thoroughly investigate the anti-influenza activity, chemical identification, and constituents-activity relationship of BLG granules. These data not only provided a deeper understanding of the molecular mechanism of the activity of BLG granules, but also presented a basis for the discovery of potential novel drug candidates and quality evaluation and control of BLG granules.

A Comprehensive Review of Andrographis paniculata (Burm. f.) Nees and Its Constituents as Potential Lead Compounds for COVID-19 Drug Discovery

The COVID-19 pandemic has intensively disrupted global health, economics, and well-being. Andrographis paniculata (Burm. f.) Nees has been used as a complementary treatment for COVID-19 in several Asian countries. This review aimed to summarize the information available regarding A. paniculata and its constituents, to provide critical points relating to its pharmacological properties, safety, and efficacy, revealing its potential to serve as a source of lead compounds for COVID-19 drug discovery. A. paniculata and its active compounds possess favorable antiviral, anti-inflammatory, immunomodulatory, and antipyretic activities that could be beneficial for COVID-19 treatment. Interestingly, recent in silico and in vitro studies have revealed that the active ingredients in A. paniculata showed promising activities against 3CLpro and its virus-specific target protein, human hACE2 protein; they also inhibit infectious virion production. Moreover, existing publications regarding randomized controlled trials demonstrated that the use of A. paniculata alone or in combination was superior to the placebo in reducing the severity of upper respiratory tract infection (URTI) manifestations, especially as part of early treatment, without serious side effects. Taken together, its chemical and biological properties, especially its antiviral activities against SARS-CoV-2, clinical trials on URTI, and the safety of A. paniculata, as discussed in this review, support the argument that A. paniculata is a promising natural source for drug discovery regarding COVID-19 post-infectious treatment, rather than prophylaxis.

Plant-Based Support of Respiratory Health during Viral Outbreaks

Respiratory viruses are linked to major epidemic events that have plagued humans through recorded history and possibly much earlier, ranging from common colds, influenza, and coronavirus infections to measles. However, difficulty in developing effective pharmaceutical solutions to treat infected individuals has hindered efforts to manage and minimize respiratory viral outbreaks and the associated mortality. Here we highlight a series of botanical interventions with different and often overlapping putative mechanisms of action to support the respiratory system, for which the bioactive pharmacophore was suggested and the initial structure-activity relationships have been explored (Bupleurum spp., Glycyrrhiza spp., Andrographis spp.), have been proposed with uncertainty (Echinacea spp., Zingiber spp., Verbascum spp., Marrubium spp.), or remained to be elucidated (Sambucus spp., Urtica spp.). Investigating these metabolites and their botanical sources holds potential to uncover new mediators of the respiratory health outcomes as well as molecular targets for future break-through therapeutic interventions targeting respiratory viral outbreaks.

Antiviral Activities of Andrographolide and Its Derivatives: Mechanism of Action and Delivery System

Andrographispaniculata (Burm.f.) Nees has been used as a traditional medicine in Asian countries, especially China, India, Vietnam, Malaysia, and Indonesia. This herbaceous plant extract contains active compounds with multiple biological activities against various diseases, including the flu, colds, fever, diabetes, hypertension, and cancer. Several isolated compounds from A. paniculata, such as andrographolide and its analogs, have attracted much interest for their potential treatment against several virus infections, including SARS-CoV-2. The mechanisms of action in inhibiting viral infections can be categorized into several types, including regulating the viral entry stage, gene replication, and the formation of mature functional proteins. The efficacy of andrographolide as an antiviral candidate was further investigated since the phytoconstituents of A. paniculata exhibit various physicochemical characteristics, including low solubility and low bioavailability. A discussion on the delivery systems of these active compounds could accelerate their development for commercial applications as antiviral drugs. This study critically reviewed the current antiviral development based on andrographolide and its derivative compounds, especially on their mechanism of action as antiviral drugs and drug delivery systems.

Tracking the deprotonation site of dehydroandrographolide with electrospray ionization mass spectrometry by deuteration

RATIONALE

Dehydroandrographolide (DA) is a diterpene compound of biological interest that contains one α,β-unsaturated lactone group and two hydroxy groups. In the ESI (electrospray ionization) negative ion mode mass spectral analysis of 15-dideuterodehydroandrographolide (15-D₂ -DA), the deuterium nucleus at the γ position of the α,β-unsaturated lactone was more easily dedeuterated than deprotonation of the protons from the hydroxy groups. Exploring the rationality of deuteration as a tool for deprotonation position tracking is significant for gas-phase acidity.

METHODS

The mass spectra of DA and 15-D₂ -DA in positive and negative ion mode were acquired by liquid chromatography/ion trap time-of-flight mass spectrometry (LC/IT-TOF) systems. The deprotonation and dedeuteration energies at specific sites were calculated by the B3LYP and M06-2X density functional theory (DFT) methods with the program Gaussian 16.

RESULTS

The [M + H]⁺ ion of 15-D₂ -DA was 2 amu larger than that of DA due to the substitution of two hydrogens with two deuteriums; however, the anion base peak of 15-D₂ -DA was only 1 amu larger than that of the [M - H]^- ion of DA. Dedeuteration at the C15 site was proposed according to the mass spectral data. The deprotonation (dedeuteration) energies calculated by the B3LYP/6-311++G(3df,3pd)//B3LYP/6-31 + G(d) and M06-2X-D3/ma-TZVP methods showed that the C-H and C-D bonds at the C15 site have lower deprotonation (dedeuteration) energies than the energies of the hydroxy groups of DA, making their deprotonation (dedeuteration) more thermodynamically favourable.

CONCLUSIONS

Deuteration of DA provided direct evidence of the deprotonation site of DA in the ESI source of the mass spectrometer, and the DFT method well predicted the gas-phase deprotonation site of DA.

Which East Asian herbal medicines can decrease viral infections?

Whilst Western research for the COVID-19 crisis focuses on vaccination, in East Asia traditional herbal prescriptions are studied for SARS-CoV2 therapy. In Japan, Maoto (Ephedrae herba 4 g, Armeniacae semen 4 g, Cinnamomi cortex 3 g, and Glycyrrhizae radix 2 g, JPXVII) is used based on clinical evidence for its effect on early phase influenza (also caused by RNA viruses) comparable to that of oseltamivir. The Health Ministry of Thailand has approved Andrographis paniculata (Jap. Senshinren) extracts for treatment of COVID-19. Its combination (4 g) with Maoto, Maoto-ka-senshinren, seems most promising for the treatment of viral pandemics. In China, the official guideline for COVID-19 treatment contains TCM medications with antiviral, as well as immunmodulatory and anti-inflammatory effects such as: Qing-Fei-Pai-Du-Tang (Jap. Seihai-haidokuto) contains 21 drugs; Shufeng Jiedu Jiaonang (Bupleuri radix 8 g, Forsythiae fructus 8 g, Glycyrrhizae radix 4 g, Isatidis radix 8 g, Patriniae herba 8 g, Phragmitis rhizoma 6 g, Polygoni cuspidati rhizoma 10 g, Verbenae herba 8 g); Fufang Yuxingcao Heiji (Forsythiae fructus 0.6 g, Houttuyniae herba 6 g, Isatidis radix 1.5 g, Lonicerae flos 0.6 g, Scutellariae radix 1.5 g) first gained prominence during the 2002 SARS epidemic. With no Western medicine available, the following overview discusses efficacy and mechanisms in view of viral entry and replication of different East Asian herbal remedies for COVID-19 treatment.

3-Indoleacetonitrile Is Highly Effective in Treating Influenza A Virus Infection In Vitro and In Vivo

Influenza A viruses are serious zoonotic pathogens that continuously cause pandemics in several animal hosts, including birds, pigs, and humans. Indole derivatives containing an indole core framework have been extensively studied and developed to prevent and/or treat viral infection. This study evaluated the anti-influenza activity of several indole derivatives, including 3-indoleacetonitrile, indole-3-carboxaldehyde, 3-carboxyindole, and gramine, in A549 and MDCK cells. Among these compounds, 3-indoleacetonitrile exerts profound antiviral activity against a broad spectrum of influenza A viruses, as tested in A549 cells. Importantly, in a mouse model, 3-indoleacetonitrile with a non-toxic concentration of 20 mg/kg effectively reduced the mortality and weight loss, diminished lung virus titers, and alleviated lung lesions of mice lethally challenged with A/duck/Hubei/WH18/2015 H5N6 and A/Puerto Rico/8/1934 H1N1 influenza A viruses. The antiviral properties enable the potential use of 3-indoleacetonitrile for the treatment of IAV infection.

Immunoprotective potential of Ayurvedic herb Kalmegh (Andrographis paniculata) against respiratory viral infections - LC-MS/MS and network pharmacology analysis

INTRODUCTION

Immunity boosting has emerged as a global strategy to fight the SARS-CoV-2 pandemic situation. In India, AYUSH systems of medicine have been promoted as an immune-protection strategy. Andrographis paniculata (Burm. F) Nees (AP) mentioned in Ayurveda has been widely used for treating sore throat, flu, and upper respiratory tract infections which may provide possible novel therapeutic approaches, exclusively targeting SARS-CoV-2 and its pathways.

OBJECTIVES

The present work uses liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics and combination synergy analysis based on network pharmacology to mine multimode evidence to understand the possible mechanism of action, diseases association, protein-protein interaction and major pathways involved therein.

MATERIAL AND METHODS

Metabolite profiling was performed by Agilent QTOF LC-MS/MS system. Network pharmacology analysis was performed by using functional annotation analysis based on databases like Binding DB, STRING, DAVID and KEGG for further data mining. Further combination synergy was evaluated using "neighbourhood approach" and networks were constructed through Cytoscape 3.2.1.

RESULTS

The molecules from kalmegh provides immune-protection and anti-viral response via involving different pathways, like toll-like receptor pathway, PI3/AKT pathway and MAP kinase pathways against COVID-19 infection. The KEGG analysis showed that in a vast majority of the most enriched pathways, AP were associated with viral infections and upper respiratory tract infections.

CONCLUSIONS

The results suggest a synergy between andrographolide and other molecules identified as safe and efficacious anti-inflammatory agent having effects on upper respiratory tract infections and can significantly decrease the production of cytokines and pro-inflammatory factors in viral infections.

Substantial effect of phytochemical constituents against the pandemic disease influenza-a review

Background

Influenza is an acute respiratory tract infection caused by the influenza virus. Vaccination and antiviral drugs are the two methods opted to control the disease. Besides their efficiency, they also cause adverse side effects. Hence, scientists turned their attention to powerful herbal medicines. This review put focus on various proven, scientifically validated anti-influenza compounds produced by the plants suggested for the production of newer drugs for the better treatment of influenza and its related antiviral diseases too.

Main body

In this review, fifty medicinal herb phytochemical constituents and their anti-influenza activities have been documented. Specifically, this review brings out the accurate and substantiates mechanisms of action of these constituents. This study categorizes the phytochemical constituents into primary and secondary metabolites which provide a source for synthesizing and developing new drugs.

Conclusion

This article provides a summary of the actions of the herbal constituents. Since the mechanisms of action of the components are elucidated, the pandemic situation arising due to influenza and similar antiviral diseases can be handled promisingly with greater efficiency. However, clinical trials are in great demand. The formulation of usage may be a single drug compound or multi-herbal combination. These, in turn, open up a new arena for the pharmaceutical industries to develop innovative drugs.

Andrographis paniculata (Burm.f.) Nees and its major constituent andrographolide as potential antiviral agents

ETHNOPHARMACOLOGICAL RELEVANCE

Andrographis paniculata (Burm.f.) Nees is widely used all over the world, especially in subtropical regions such as India, Thailand, Vietnam, and China. As a traditional folk Chinese medicine, A. paniculata has been extensively utilized for the treatment of cold, fever, sore throat, cough, carbuncle, and sores, and it is commonly employed for 'clearing heat and resolving toxicity'. Typical symptoms of 'heat and toxicity' include swollen, painful gums, associated with virus-related diseases to a great extent. In vivo and in vitro experiments have demonstrated the potential antiviral properties of A. paniculata and identified its major active constituents against various viruses.

AIM OF THE STUDY

This review focuses on connecting the traditional 'clearing heat and resolving toxicity' effect to compelling recent research advances on the antiviral effects of A. paniculata, explaining its major antiviral mechanisms, and assessing the shortcomings of existing work. Besides, ethnobotany, ethnopharmacological uses, phytochemicals, and toxicology of A. paniculata have been researched.

MATERIALS AND METHODS

The information about A. paniculata was collected from various sources including classic books about Chinese herbal medicine, and scientific databases including WEB OF SCIENCE, PubMed, ScienceDirect, Springer, ACS, SCOPUS, CNKI, CSTJ, and WANFANG.

RESULTS

In this review, the underlying mechanisms of antiviral effect mainly involve the regulation of virus entry, gene replication, and synthesis of functionally mature proteins. Also, A. paniculata is a safe agent without obvious toxicity. Ethnobotany, ethnopharmacological uses, and chemical constituents have been summarized.

CONCLUSION

Andrographis paniculata (Burm.f.) Nees could be used as an imperative complementary medicine for the treatment of diverse virus infection, efforts should be made to gain insights into its antiviral properties.

Combination of system biology to probe the anti-viral activity of andrographolide and its derivative against COVID-19

The present study aimed to investigate the binding affinity of andrographolide and its derivative i.e., 14-deoxy-11,12-didehydroandrographolide with targets related to COVID-19 and their probable role in regulating multiple pathways in COVID-19 infection. SMILES of both compounds were retrieved from the PubChem database and predicted for probably regulated proteins. The predicted proteins were queried in STRING to evaluate the protein-protein interaction, and modulated pathways were identified concerning the KEGG database. Drug-likeness and ADMET profile of each compound was evaluated using MolSoft and admetSAR 2.0, respectively. Molecular docking was carried using Autodock 4.0. Andrographolide and its derivative were predicted to have a high binding affinity with papain-like protease, coronavirus main proteinase, and spike protein. Molecular dynamics simulation studies were performed for each complex which suggested the strong binding affinities of both compounds with targets. Network pharmacology analysis revealed that both compounds modulated the immune system by regulating chemokine signaling, Rap1 signaling, cytokine-cytokine receptor interaction, MAPK signaling, NF-kappa B signaling, RAS signaling, p53 signaling, HIF-1 signaling, and natural killer cell-mediated cytotoxicity. The study suggests strong interaction of andrographolide and 14-deoxy-11,12-didehydroandrographolide against COVID-19 associated target proteins and exhibited different immunoregulatory pathways.

COVID-19: Drug Targets and Potential Treatments

Currently, humans are immersed in a pandemic caused by the emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which threatens public health worldwide. To date, no drug or vaccine has been approved to treat the severe disease caused by this coronavirus, COVID-19. In this paper, we will focus on the main virus-based and host-based targets that can guide efforts in medicinal chemistry to discover new drugs for this devastating disease. In principle, all CoV enzymes and proteins involved in viral replication and the control of host cellular machineries are potentially druggable targets in the search for therapeutic options for SARS-CoV-2. This Perspective provides an overview of the main targets from a structural point of view, together with reported therapeutic compounds with activity against SARS-CoV-2 and/or other CoVs. Also, the role of innate immune response to coronavirus infection and the related therapeutic options will be presented.

Herbal medicine, a reliable support in COVID therapy

At present, specific therapies for COVID-19 are not well established, being certain only that the immune system plays a decisive role in the initiation and progression of the disease. Plants have given and continue to give compounds with great efficiency and low toxicity, some of them being a starting point for extremely effective synthetic substances. Although herbal remedies are used mainly for preventive purposes, there are also guidelines issued by some countries that indicate the use of traditional remedies for different stages of COVID-19 disease.Europe has a long and strong tradition of using medicinal plants for therapeutic purposes, but clinical trials for this type of approach are scarce, compared to Asia. In this regard, a bridge between tradition and science, would have a strong impact on the capacity for prevention and treatment of COVID-19. The paper reviews compounds of plant origin that have previously proven effective in counteracting some coronaviruses but also some of their major effects - direct action on virus replicative apparatus (viral entry or replication, action on the viral enzymatic system), collateral action of natural compounds on the immune system and also the contribution of herbal medicine as vaccine adjuvants are tackled.

Inhibitory Activity of Honeysuckle Extracts against Influenza A Virus In Vitro and In Vivo

Honeysuckle has been used in the treatment of influenza virus infection for thousands of years in China. However, its main active components and the functional mechanisms remain to be elucidated. Here, four honeysuckle extracts, including acids extract, flavonoids extract, total extract and acids-flavonoids mixture, were prepared to clarify the main active antiviral components. The cytopathic effect reduction assay showed that all the four extracts inhibited the replication of influenza viruses H1N1, H3N2 and the oseltamivir-resistant mutant strain H1N1-H275Y. The acids-flavonoids mixture had the strongest inhibitory effects in vitro with EC₅₀ values of 3.8, 4.1, and > 20 μg/mL against H1N1, H3N2 and H1N1-H275Y, respectively, showing competitive antiviral activity with oseltamivir and ribavirin. Honeysuckle acids extract also showed the most significant antiviral activity in vivo. Oral administration of the acids extract at a dosage of 600 mg/kg/d effectively alleviated viral pneumonia, maintained body weight and improved the survival rate to 30% of the mice infected with a lethal dose of H1N1. The results of time-of-drug addition experiment and neuraminidase (NA) inhibition assay showed that honeysuckle extracts had a broad-spectrum inhibitory effect against influenza virus NAs. The flavonoid extract showed the strongest inhibitory effect on the NA of influenza virus H7N9 with an IC₅₀ of 24.7 μg/mL. These results suggested that these extracts might exert their antiviral activity by suppressing the release of influenza viruses. Briefly, our findings demonstrate that acids and flavonoids extracts of honeysuckle are the major antiviral active components, and the acids extract has the potential to be developed into an antiviral agent against influenza virus, especially for oseltamivir-resistant viruses.

In Silico Drug Repurposing for SARS-CoV-2 Main Proteinase and Spike Proteins

The pandemic caused by SARS-CoV-2 is currently representing a major health and economic threat to humanity. So far, no specific treatment to this viral infection has been developed and the emergency still requires an efficient intervention. In this work, we used virtual screening to facilitate drug repurposing against SARS-CoV-2, targeting viral main proteinase and spike protein with 3000 existing drugs. We used a protocol based on a docking step followed by a short molecular dynamic simulation and rescoring by the Nwat-MMGBSA approach. Our results provide suggestions for prioritizing in vitro and/or in vivo tests of already available compounds.

14-Deoxy-11,12-didehydroandrographolide inhibits apoptosis in influenza A(H5N1) virus-infected human lung epithelial cells via the caspase-9-dependent intrinsic apoptotic pathway which contributes to its antiviral activity

Influenza A virus (IAV) infection represents a global health challenge. Excavating antiviral active components from traditional Chinese medicine (TCM) is a promising anti-IAV strategy. Our previous studies have demonstrated that 14-deoxy-11,12-didehydroandrographolide (DAP), a major ingredient of a TCM herb called Andrographis paniculata, shows anti-IAV activity that is mainly effective against A/chicken/Hubei/327/2004 (H5N1), A/duck/Hubei/XN/2007 (H5N1), and A/PR/8/34 (H1N1) in vitro and in vivo. However, the underlying anti-IAV molecular mechanism of DAP needs further investigation. In the present work, we found that DAP can significantly inhibit the apoptosis of human lung epithelial (A549) cells infected with A/chicken/Hubei/327/2004 (H5N1). After DAP treatment, the protein expression levels of cleaved PARP, cleaved caspase-3, and cleaved caspase-9, and the activities of caspase-3 and caspase-9 in H5N1-infected A549 cells were all obviously downregulated. However, DAP had no inhibitory effect on caspase-8 activity and cleaved caspase-8 production. Meanwhile, the efficacy of DAP in reducing the apoptotic cells was lost after using the inhibitor of caspase-3 or caspase-9 but remained intact after the caspase-8 inhibitor treatment. Moreover, DAP efficiently attenuated the dissipation of mitochondrial membrane potential, suppressed cytochrome c release from the mitochondria to the cytosol, and decreased the protein expression ratio of Bax/Bcl-2 in the mitochondrial fraction. Furthermore, the silencing of caspase-9 reduced the yield of nucleoprotein (NP) and disabled the inhibitory ability of DAP in NP production in A549 cells. Overall results suggest that DAP exerts its antiviral effects by inhibiting H5N1-induced apoptosis on the caspase-9-dependent intrinsic/mitochondrial pathway, which may be one of the anti-H5N1 mechanisms of DAP.

Anti-influenza virus phytochemicals from Radix Paeoniae Alba and characterization of their neuraminidase inhibitory activities

ETHNOPHARMACOLOGICAL RELEVANCE

Bai Shao (Radix Paeoniae Alba, BS), the root of Paeonia lactiflora Pall., in ancient China was used for Wen Bing (Warm Disease) treatment. Wen Bing has the symptoms of influenza. Ethanol extract of the root has recently been shown to possess anti-influenza activity. However, the active compounds have not yet been identified.

AIM

We showed that BS aqueous extract was potent in inhibiting influenza A virus in infected cells. We aimed to isolate the bioactive compounds and characterize the anti-influenza mechanism.

MATERIALS AND METHODS

Plaque reduction assay was performed for fractions isolated from BS. Hemagglutination inhibition assay and neuraminidase inhibition assay were performed to find the target protein. Molecular docking and reverse genetics were used to confirm the action site of gallic acid on the neuraminidase protein.

RESULTS

We identified three tannin compounds gallic acid (GA), methyl gallate (MG) and pentagalloylglucose (PGG) in BS aqueous extract that could inhibit the replication of influenza A virus in MDCK cells. While only PGG was found to inhibit the influenza virus-induced hemagglutination of chicken erythrocytes, all three compounds significantly reduced the activity of the neuraminidase. The results from molecular docking and reverse genetics showed that GA interacted with Arg152 of neuraminidase protein.

CONCLUSION

Three compounds GA, MG and PGG isolated from BS were found to inhibit influenza A virus in MDCK cells. GA interacts with amino acid Arg152 of the viral neuraminidase. Our study identified anti-influenza compounds of BS and demonstrated their antiviral mechanism, thus providing scientific evidence for using this herb for clinical treatment.

A Diterpenoid, 14-Deoxy-11, 12-Didehydroandrographolide, in Andrographis paniculata Reduces Steatohepatitis and Liver Injury in Mice Fed a High-Fat and High-Cholesterol Diet

14-Deoxy-11,12-didehydroandrographolide (deAND), a diterpenoid in Andrographis paniculata (Burm. f.) Nees, acts as a bioactive phytonutrient that can treat many diseases. To investigate the protective effects of deAND on reducing fatty liver disease, male mice were fed a high-fat and high-cholesterol (HFHC) diet without or with 0.05% and 0.1% deAND supplementation. Cholesterol accumulation, antioxidant, and anti-inflammatory activities in liver and liver injury were evaluated after deAND treatment. The results show that deAND treatment for seven weeks reduced plasma alanine aminotransferase activity and lowered hepatic cholesterol accumulation, tumor nuclear factor-α, and histological lesions. The 0.1% deAND treatment reduced HFHC diet-induced apoptosis by lowering the caspase 3/pro-caspase 3 ratio. After 11 weeks of deAND treatment, increased NOD-like receptor protein 3 (NLRP3), capase-1, and interleukin-1β protein levels in liver were suppressed by deAND treatment. In addition, nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA expression, heme oxygenase-1 protein expression, and the activities of glutathione peroxidase and glutathione reductase were increased in mice fed the HFHC diet. However, those activities of antioxidant enzymes or proteins were also upregulated by 0.1% deAND treatment. Furthermore, deAND treatment tended to lower hepatic lipid peroxides. Finally, deAND treatment reversed the depletion of hepatic glutamate level induced by the HFHC diet. These results indicate that deAND may ameliorate HFHC diet-induced steatohepatitis and liver injury by increasing antioxidant and anti-inflammatory activities.

An Oleanolic Acid Derivative Inhibits Hemagglutinin-Mediated Entry of Influenza A Virus

Influenza A viruses (IAV) have been a major public health threat worldwide, and options for antiviral therapy become increasingly limited with the emergence of drug-resisting virus strains. New and effective anti-IAV drugs, especially for highly pathogenic influenza, with different modes of action, are urgently needed. The influenza virus glycoprotein hemagglutinin (HA) plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a potential target for the development of anti-influenza drugs. In this study, we show that OA-10, a newly synthesized triterpene out of 11 oleanane-type derivatives, exhibited significant antiviral activity against four different subtypes of IAV (H1N1, H5N1, H9N2 and H3N2) replications in A549 cell cultures with EC₅₀ ranging from 6.7 to 19.6 μM and a negligible cytotoxicity (CC₅₀ > 640 μM). It inhibited acid-induced hemolysis in a dose-dependent manner, with an IC₅₀ of 26 µM, and had a weak inhibition on the adsorption of H5 HA to chicken erythrocytes at higher concentrations (≥40 µM). Surface plasmon resonance (SPR) analysis showed that OA-10 interacted with HA in a dose-dependent manner with the equilibrium dissociation constants (KD) of the interaction of 2.98 × 10^-12 M. Computer-aided molecular docking analysis suggested that OA-10 might bind to the cavity in HA stem region which is known to undergo significant rearrangement during membrane fusion. Our results demonstrate that OA-10 inhibits H5N1 IAV replication mainly by blocking the conformational changes of HA2 subunit required for virus fusion with endosomal membrane. These findings suggest that OA-10 could serve as a lead for further development of novel virus entry inhibitors to prevent and treat IAV infections.

Successful treatment of plantar warts using topical Zijinding, a traditional Chinese medicine preparation: A case series

Introduction

Plantar warts are associated with high transmissibility and morbidity. Among the available therapeutic options, none is uniformly effective or virucidal. Salicylic acid is the first‐line therapy but approximately one‐third of lesions could not resolve and become recalcitrant despite repeated treatment. Cryotherapy is widely accessible with low cost but may be complicated by pain, blister formation, hemorrhage, infection, excessive granulation tissue formation, and hyper‐/hypo‐pigmentation. Hence, alternative treatment modalities are essential.

Methods

Three patients with debilitating plantar warts refractory or intolerant to cryotherapy were treated with a course of Zijinding (a traditional Chinese medicine preparation) paste prepared with white vinegar.

Results

All three patients showed excellent clinical response with Zijinding application with evolution of lesions to scabs and subsequently healthy skin within 1.5 to 5 months of treatment. Treatment was well tolerated and had no significant side effects with excellent compliance recorded for all three patients. There was no relapse for at least 10 months after stopping the treatment.

Conclusion

Topical Zijinding could be a promising alternative modality for the treatment of plantar warts. Further clinical trials on the comparison of Zijinding and other treatment modalities of plantar warts are warranted. Further studies are required to investigate the mechanism of action of Zijinding and to isolate the active ingredient.

Bioavailability of the diterpenoid 14-deoxy-11,12-didehydroandrographolide in rats and up-regulation of hepatic drug-metabolizing enzyme and drug transporter expression

BACKGROUND

14-Deoxy-11,12-didehydroandrographolide (deAND) is the second most abundant diterpenoid in Andrographis paniculata (Burm. f.) Nees, a traditional medicine used in Asia. To date, the biological activity of deAND has not been clearly investigated.

PURPOSE

In this study, we intended to examine the modulatory effect of deAND on hepatic drug metabolism as well as its bioavailability.

STUDY DESIGN

deAND prepared from A. paniculata was orally given to Sprague-Dawley rats and changes in plasma deNAD were determined by HPLC-MS. Modulation of deAND on drug-metabolizing enzyme and drug transporter expression as well as the possible mechanism involved was examined in primary rat hepatocytes.

RESULTS

After a single oral administration of 50 mg/kg deAND to rats, the maximum plasma concentration (C_max), time to reach the C_max, area under the curve (AUC_0-24h), mean retention time, and half-life (t_1/2) of deAND were 2.65 ± 0.68 μg/ml, 0.29 ± 0.15 h, 6.30 ± 1.66 μg/ml•h, 5.55 ± 2.52 h, and 3.56 ± 1.05 h, respectively. The oral bioavailability was 3.42%. In primary rat hepatocytes treated with up to 10 μM deAND, a dose-dependent increase was noted in the expression of cytochrome P450 (CYP) 1A1/2, CYP2C6, and CYP3A1/2; UDP-glucuronosyltransferase (UGT) 1A1, NAD(P)H:quinone oxidoreductase (NQO1), π form of GSH S-transferase (GSTP), multidrug resistance-associated protein 2, p-glycoprotein, and organic anion transporter protein 2B1. Immunoblotting assay and EMSA revealed that deAND increases the nuclear translocation and DNA binding activity of aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), and nuclear factor erythroid-derived 2-related factor 2 (Nrf2). Knockdown of AhR and Nrf2 expression abolished deAND induction of CYP isozymes and UGT1A1, NQO1, and GSTP expression, respectively.

CONCLUSION

These results indicate that deAND quickly passes through enterocytes in rats and effectively up-regulates hepatic drug-metabolizing enzyme and drug transporter expression in an AhR-, PXR-, and Nrf2-dependent manner.

Repurposing host-based therapeutics to control coronavirus and influenza virus

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Drug repositioning is a cost- and time-efficient approach for new indications.

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Targeting host machineries, used by viruses, could develop broad-spectrum antivirals.

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Repurposing existing drugs could efficiently identify antiviral agents.

The development of highly effective antiviral agents has been a major objective in virology and pharmaceutics. Drug repositioning has emerged as a cost-effective and time-efficient alternative approach to traditional drug discovery and development. This new shift focuses on the repurposing of clinically approved drugs and promising preclinical drug candidates for the therapeutic development of host-based antiviral agents to control diseases caused by coronavirus and influenza virus. Host-based antiviral agents target host cellular machineries essential for viral infections or innate immune responses to interfere with viral pathogenesis. This review discusses current knowledge, prospective applications and challenges in the repurposing of clinically approved and preclinically studied drugs for newly indicated antiviral therapeutics.

Antiviral activity of a synthesized shikonin ester against influenza A (H1N1) virus and insights into its mechanism

This study aimed to examine the antiviral effects of shikonin ester ((R)-1-(5, 8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-en-1-yl3-(1H- indol-3-yl) propanoate (PMM-034) against influenza A (H1N1) virus. We investigated PMM-034 anti-H1N1 activity and its effect on caspase 3 gene expression during cellular apoptosis after influenza virus infection in vitro. Neuraminidase (NA) inhibition was assessed in comparison with oseltamivir in the influenza virus standard strains A/PR/8/34 to understand the viral mechanism. MDCK and A549 cells were used to investigate influenza viral infection and the structure-activity relationship between PMM-034 and NA was evaluated by pharmacophore-based docking modeling. The production of viral protein was tested by western blot. A/PR/8/34 induced cell inhibition but this was reduced by PMM-034 to 16μg/mL and this showed a selective index of 10mM. PMM-034 inhibited NA in a dose dependent manner, similar to oseltamivir inhibition. A sharp decrease in viral nucleocapsid protein mRNA was observed in infected cells after treatment with PMM-034. Apoptosis of infected A459 cells was inhibited by PMM-034 with decreased caspase 3 levels. ARG 118, ARG 152, ARG 371 and GLU 227 in the binding pocket of NA bound to PMM-034 in the docking model. Taken together, these results suggest PMM-034 shikonin ester blocked H1N1 infection and might be a potential anti-H1N1 drug.

Inhibition of CRM1-mediated nuclear export of influenza A nucleoprotein and nuclear export protein as a novel target for antiviral drug development

An anti-influenza compound, DP2392-E10 based on inhibition of the nuclear export function of the viral nucleoprotein-nuclear export signal 3 (NP-NES3) domain was successfully identified by our previous high-throughput screening system. Here, we demonstrated that DP2392-E10 exerts its antiviral effect by inhibiting replication of a broad range of influenza A subtypes. In regard to the molecular mechanism, we revealed that DP2392-E10 inhibits nuclear export of both viral NP and nuclear export protein (NEP). More specifically, in vitro pull-down assays revealed that DP2392-E10 directly binds cellular CRM1, which mediates nuclear export of NP and NEP. In silico docking suggested that DP2392-E10 binds at a region close to the HEAT9 and HEAT10 domains of CRM1. Together, these results indicate that the CRM1-mediated nuclear export function of influenza virus represents a new potential target for antiviral drug development, and also provide a core structure for a novel class of inhibitors that target this function.

Anti-influenza A Virus Activity of Dendrobine and Its Mechanism of Action

Dendrobine, a major component of Dendrobium nobile, increasingly draws attention for its wide applications in health care. Here we explore potential effects of dendrobine against influenza A virus and elucidate the underlying mechanism. Our results indicated that dendrobine possessed antiviral activity against influenza A viruses, including A/FM-1/1/47 (H1N1), A/Puerto Rico/8/34 H274Y (H1N1), and A/Aichi/2/68 (H3N2) with IC₅₀ values of 3.39 ± 0.32, 2.16 ± 0.91, 5.32 ± 1.68 μg/mL, respectively. Mechanism studies revealed that dendrobine inhibited early steps in the viral replication cycle. Notably, dendrobine could bind to the highly conserved region of viral nucleoprotein (NP), subsequently restraining nuclear export of viral NP and its oligomerization. In conclusion, dendrobine shows potential to be developed as a promising agent to treat influenza virus infection. More importantly, the results provide invaluable information for the full application of the Traditional Chinese Medicine named "Shi Hu".