Antiviral effects of Phyllanthus urinaria containing corilagin against human enterovirus 71 and Coxsackievirus A16 in vitro

Corilagin inhibits human cytomegalovirus infection and replication via activating the cGAS-STING signaling pathway in vitro and in vivo

AIM

The existence of human cytomegalovirus (HCMV) is extremely widespread, causing serious diseases in patients with low immune function. The purpose of this study is to explore the efficacy and mechanism of Corilagin in the control of CMV infection, in order to provide scientific basis for the control of CMV infection.

METHODS

Our study employed an animal model in Balb/c mice, infected with MCMV, alongside cellular models in HFF cells and THP-1 cells, stimulated with HCMV. The expression of cGAS-STING signaling pathway molecules was detected in liver tissue, lung tissue, serum, cells and cell supernatant. The liver function and histopathological changes of mice were evaluated.

RESULTS

In vivo and in vitro experiments showed that Corilagin significantly inhibits CMV levels and attenuates pathological damage in liver and lung tissues in vivo, and similarly inhibits viral load in cells in vitro. Corilagin promotes the expression levels of STING and its downstream molecules in vivo and in vitro. Inhibition/down-regulation of STING significantly promotes CMV replication, on the contrary, activation/up-regulation of STING inhibits CMV replication, and Corilagin also promotes the expression levels of molecules related to the cGAS-STING signaling pathway in the above cases.

CONCLUSION

Corilagin could effectively inhibit the infection and replication of CMV in vitro and in vivo, which may be through the activation of cGAS-STING signaling pathway.

Recent Advances in Enterovirus A71 Infection and Antiviral Agents

Enterovirus A71 (EV-A71) is one of the major causative agents of hand, foot, and mouth disease (HFMD) that majorly affects children. Most of the time, HFMD is a mild disease but can progress to severe complications, such as meningitis, brain stem encephalitis, acute flaccid paralysis, and even death. HFMD caused by EV-A71 has emerged as an acutely infectious disease of highly pathogenic potential in the Asia-Pacific region. In this review, we introduced the properties and life cycle of EV-A71, and the pathogenesis and the pathophysiology of EV-A71 infection, including tissue tropism and host range of virus infection, the diseases caused by the virus, as well as the genes and host cell immune mechanisms of major diseases caused by enterovirus 71 (EV-A71) infection, such as encephalitis and neurologic pulmonary edema. At the same time, clinicopathologic characteristics of EV-A71 infection were introduced. There is currently no specific medication for EV-A71 infection, highlighting the urgency and significance of developing suitable anti-EV-A71 agents. This overview also summarizes the targets of existing anti-EV-A71 agents, including virus entry, translation, polyprotein processing, replication, assembly and release; interferons; interleukins; the mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and protein kinase B signaling pathways; the oxidative stress pathway; the ubiquitin-proteasome system; and so on. Furthermore, it overviews the effects of natural products, monoclonal antibodies, and RNA interference against EV-A71. It also discusses issues limiting the research of antiviral drugs. This review is a systematic and comprehensive summary of the mechanism and pathological characteristics of EV-A71 infection, the latest progress of existing anti-EV-A71 agents. It would provide better understanding and guidance for the research and application of EV-A71 infection and antiviral inhibitors.

The antiviral potential of Phyllanthus species: a systematic review

Viral infections and diseases caused by viruses are worldwide problems. According to a WHO report, three to five million people are chronically infected with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) each year globally. Since some viruses mutate very quickly, developing antiviral drugs can be a daunting task. Moreover, currently used synthetic drugs are toxic and associated with side effects. Therefore, there is a need to search for alternative natural remedies that have low toxicity, a new mechanism of action, and no major side effects. Phyllanthus plants have traditionally been used to treat viral hepatitis and liver damage in many tropical and subtropical countries worldwide. In this review, we discuss the therapeutic potential of Phyllanthus spp. against HBV, HCV, HIV, herpes simplex virus, and SARS-CoV-2. The inferences from in vitro and in vivo studies and clinical trials validate the use of Phyllanthus in antiviral remedies.

The Effect and Mechanism of Corilagin from Euryale Ferox Salisb Shell on LPS-Induced Inflammation in Raw264.7 Cells

(1) Background: Euryale ferox Salisb is a large aquatic plant of the water lily family and an edible economic crop with medicinal value. The annual output of Euryale ferox Salisb shell in China is higher than 1000 tons, often as waste or used as fuel, resulting in waste of resources and environmental pollution. We isolated and identified the corilagin monomer from Euryale ferox Salisb shell and discovered its potential anti-inflammatory effects. This study aimed to investigate the anti-inflammatory effect of corilagin isolated from Euryale ferox Salisb shell. (2) Methods: We predict the anti-inflammatory mechanism by pharmacology. LPS was added to 264.7 cell medium to induce an inflammatory state, and the safe action range of corilagin was screened using CCK-8. The Griess method was used to determine NO content. The presence of TNF-α, IL-6, IL-1β, and IL-10 was determined by ELISA to evaluate the effect of corilagin on the secretion of inflammatory factors, while that of reactive oxygen species was detected by flow cytometry. The gene expression levels of TNF-α, IL-6, COX-2, and iNOS were determined using qRT-PCR. qRT-PCR and Western blot were used to detect the mRNA and expression of target genes in the network pharmacologic prediction pathway. (3) Results: Network pharmacology analysis revealed that the anti-inflammatory effect of corilagin may be related to MAPK and TOLL-like receptor signaling pathways. The results demonstrated the presence of an anti-inflammatory effect, as indicated by the reduction in the level of NO, TNF-α, IL-6, IL-1β, IL-10, and ROS in Raw264.7 cells induced by LPS. The results suggest that corilagin reduced the expression of TNF-α, IL-6, COX-2, and iNOS genes in Raw264.7 cells induced by LPS. The downregulation of the phosphorylation of IκB-α protein related to the toll-like receptor signaling pathway and upregulation of the phosphorylation of key proteins in the MAPK signaling pathway, P65 and JNK, resulted in reduced tolerance toward lipopolysaccharide, allowing for the exertion of the immune response. (4) Conclusions: The results demonstrate the significant anti-inflammatory effect of corilagin from Euryale ferox Salisb shell. This compound regulates the tolerance state of macrophages toward lipopolysaccharide through the NF-κB signaling pathway and plays an immunoregulatory role. The compound also regulates the expression of iNOS through the MAPK signaling pathway, thereby alleviating the cell damage caused by excessive NO release.

Interactions of Polyphenolic Gallotannins with Amyloidogenic Polypeptides Associated with Alzheimer's Disease: From Molecular Insights to Physiological Significance

Polyphenols are natural compounds abundantly found in plants. They are known for their numerous benefits to human health, including antioxidant properties and anti-inflammatory activities. Interestingly, many studies have revealed that polyphenols can also modulate the formation of amyloid fibrils associated with disease states and can prevent the formation of cytotoxic oligomer species. In this review, we underline the numerous effects of four hydrolysable gallotannins (HGTs) with high conformational flexibility, low toxicity, and multi-targeticity, e.g., tannic acid, pentagalloyl glucose, corilagin, and 1,3,6-tri-O-galloyl-β-D-glucose, on the aggregation of amyloidogenic proteins associated with the Alzheimer's Disease (AD). These HGTs have demonstrated interesting abilities to reduce, at different levels, the formation of amyloid fibrils involved in AD, including those assembled from the amyloid β-peptide, the tubulin-associated unit, and the islet amyloid polypeptide. HGTs were also shown to disassemble pre-formed fibrils and to diminish cognitive decline in mice. Finally, this manuscript highlights the importance of further investigating these naturally occurring HGTs as promising scaffolds to design molecules that can interfere with the formation of proteotoxic oligomers and aggregates associated with AD pathogenesis.

Recent advances in anti-coxsackievirus A16 viral drug research

Hand, foot and mouth disease, a childhood disorder caused by enteroviruses, is intermittently endemic in the Asia-Pacific region and endangers the lives of many infants and young children. Coxsackievirus A16 (CV-A16) is one of the major pathogens causing hand, foot, and mouth disease on occasion, resulting in catastrophic neurological sequelae and patient death. Currently, no clinical interventions are available that completely block the CV-A16 infection. Therefore, research on anti-CV-A16 treatment continues to be a significant focus of interest. This report provides a detailed background on and an introduction to CV-A16; a description of the viral gene and protein structures and a summary of the current advances in pharmaceutical targets, drug research and other related areas.

Allium sativum@AgNPs and Phyllanthus urinaria@AgNPs: a comparative analysis for antibacterial application

Although medicinal herbs contain many biologically active ingredients that can act as antibiotic agents, most of them are difficult to dissolve in lipids and absorb through biofilms in the gastrointestinal tract. Besides, silver nanoparticles (AgNPs) have been widely used as a potential antibacterial agent, however, to achieve a bactericidal effect, high concentrations are required. In this work, AgNPs were combined into plant-based antibiotic nanoemulsions using biocompatible alginate/carboxyl methylcellulose scaffolds. The silver nanoparticles were prepared by a green method with an aqueous extract of Allium sativum or Phyllanthus urinaria extract. The botanical antibiotic components in the alcoholic extract of these plants were encapsulated with emulsifier poloxamer 407 to reduce the particle size, and make the active ingredients both water-soluble and lipid-soluble. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) analysis showed that the prepared nanosystems were spherical with a size of about 20 nm. Fourier transform infrared spectroscopy (FTIR) confirmed the interaction of the extracts and the alginate/carboxyl methylcellulose carrier. In vitro drug release kinetics of allicin and phyllanthin from the nanosystems exhibited a retarded release under different biological pH conditions. The antimicrobial activity of the synthesized nanoformulations were tested against Escherichia coli. The results showed that the nanosystem based on Allium sativum possesses a significantly higher antimicrobial activity against the tested organisms. Therefore, the combination of AgNPs with active compounds from Allium sativum extract is a good candidate for in vivo infection treatment application.

Antimicrobial Secondary Metabolites from the Mangrove Plants of Asia and the Pacific

Microbes such as the White Spot Syndrome Virus account for severe losses in the shrimp farming industry globally. This review examines the literature on the mangrove plants of Asia and the Pacific with antibacterial, antifungal, or antiviral activities. All of the available data published on this subject were collected from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1968 to 2022. Out of about 286 plant species, 119 exhibited antimicrobial effects, and a total of 114 antimicrobial natural products have been identified including 12 with MIC values below 1 µg/mL. Most of these plants are medicinal. The mangrove plants of Asia and the Pacific yield secondary metabolites with the potential to mitigate infectious diseases in shrimp aquaculture.

Plant-Derived Antiviral Compounds as Potential Entry Inhibitors against Spike Protein of SARS-CoV-2 Wild-Type and Delta Variant: An Integrative in SilicoApproach

The wild-type SARS-CoV-2 has continuously evolved into several variants with increased transmissibility and virulence. The Delta variant which was initially identified in India created a devastating impact throughout the country during the second wave. While the efficacy of the existing vaccines against the latest SARS-CoV-2 variants remains unclear, extensive research is being carried out to develop potential antiviral drugs through approaches like in silico screening and drug-repurposing. This study aimed to conduct the docking-based virtual screening of 50 potential phytochemical compounds against a Spike glycoprotein of the wild-type and the Delta SARS-CoV-2 variant. Subsequently, molecular docking was performed for the five best compounds, such as Lupeol, Betulin, Hypericin, Corilagin, and Geraniin, along with synthetic controls. From the results obtained, it was evident that Lupeol exhibited a remarkable binding affinity towards the wild-type Spike protein (-8.54 kcal/mol), while Betulin showed significant binding interactions with the mutated Spike protein (-8.83 kcal/mol), respectively. The binding energy values of the selected plant compounds were slightly higher than that of the controls. Key hydrogen bonding and hydrophobic interactions of the resulting complexes were visualized, which explained their greater binding affinity against the target proteins-the Delta S protein of SARS-CoV-2, in particular. The lower RMSD, the RMSF values of the complexes and the ligands, Rg, H-bonds, and the binding free energies of the complexes together revealed the stability of the complexes and significant binding affinities of the ligands towards the target proteins. Our study suggests that Lupeol and Betulin could be considered as potential ligands for SARS-CoV-2 spike antagonists. Further experimental validations might provide new insights for the possible antiviral therapeutic interventions of the identified lead compounds and their analogs against COVID-19 infection.

Molecular Interactions of Tannic Acid with Proteins Associated with SARS-CoV-2 Infectivity

The overall impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on our society is unprecedented. The identification of small natural ligands that could prevent the entry and/or replication of the coronavirus remains a pertinent approach to fight the coronavirus disease (COVID-19) pandemic. Previously, we showed that the phenolic compounds corilagin and 1,3,6-tri-O-galloyl-β-D-glucose (TGG) inhibit the interaction between the SARS-CoV-2 spike protein receptor binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 target receptor on the cell membrane of the host organism. Building on these promising results, we now assess the effects of these phenolic ligands on two other crucial targets involved in SARS-CoV-2 cell entry and replication, respectively: transmembrane protease serine 2 (TMPRSS2) and 3-chymotrypsin like protease (3CLpro) inhibitors. Since corilagin, TGG, and tannic acid (TA) share many physicochemical and structural properties, we investigate the binding of TA to these targets. In this work, a combination of experimental methods (biochemical inhibition assays, surface plasmon resonance, and quartz crystal microbalance with dissipation monitoring) confirms the potential role of TA in the prevention of SARS-CoV-2 infectivity through the inhibition of extracellular RBD/ACE2 interactions and TMPRSS2 and 3CLpro activity. Moreover, molecular docking prediction followed by dynamic simulation and molecular mechanics Poisson-Boltzmann surface area (MMPBSA) free energy calculation also shows that TA binds to RBD, TMPRSS2, and 3CLpro with higher affinities than TGG and corilagin. Overall, these results suggest that naturally occurring TA is a promising candidate to prevent and inhibit the infectivity of SARS-CoV-2.

The Separation and Purification of Ellagic Acid from Phyllanthus urinaria L. by a Combined Mechanochemical-Macroporous Resin Adsorption Method

Ellagic acid is a phenolic compound that exhibits both antimutagenic and anticarcinogenic activity in a wide range of assays in vitro and in vivo. It occurs naturally in some foods such as raspberries, strawberries, grapes, and black currants. In this study, a valid and reliable method based on mechanochemical-assisted extraction (MCAE) and macroporous adsorption resin was developed to extract and prepare ellagic acid from Phyllanthus urinaria L. (PUL). The MCAE parameters, acidolysis, and macroporous adsorption resin conditions were investigated. The key MCAE parameters were optimized as follows: the milling time was 5 min, the ball mill speed was 100 rpm, and the ball mill filling rate was 20.9%. Sulfuric acid with a concentration of 0.552 mol/L was applied for the acidolysis with the optimized acidolysis time of 30 min and acidolysis temperature of 40 °C. Additionally, the XDA-8D macroporous resin was chosen for the purification work. Both the static and dynamic adsorption tests were carried out. Under the optimized conditions, the yield of ellagic acid was 10.2 mg/g, and the content was over 97%. This research provided a rapid and efficient method for the preparation of ellagic acid from the cheaply and easily obtained PUL. Meanwhile, it is relatively low-cost work that can provide a technical basis for the comprehensive utilization of PUL.

A Review: Mechanism of Phyllanthus urinaria in Cancers-NF-κB, P13K/AKT, and MAPKs Signaling Activation

Phyllanthus urinaria has been characterized for its several biological and medicinal effects such as antiviral, antibacterial, anti-inflammatory, anticancer, and immunoregulation. In recent years, Phyllanthus urinaria has demonstrated potential to modulate the activation of critical pathways such as NF-κB, P13K/AKT, and ERK/JNK/P38/MAPKs associated with cell growth, proliferation, metastasis, and apoptotic cell death. To date, there is much evidence indicating that modulation of cellular signaling pathways is a promising approach to consider in drug development and discovery. Thus, therapies that can regulate cancer-related pathways are longed-for in anticancer drug discovery. This review's focus is to provide comprehensive knowledge on the anticancer mechanisms of Phyllanthus urinaria through the regulation of NF-κB, P13K/AKT, and ERK/JNK/P38/MAPKs signaling pathways. Thus, the review summarizes both in vitro and in vivo effects of Phyllanthus urinaria extracts or bioactive constituents with emphasis on tumor cell apoptosis. The literature information was obtained from publications on Google Scholar, PubMed, Web of Science, and EBSCOhost. The key words used in the search were "Phyllanthus" or "Phyllanthus urinaria" and cancer. P. urinaria inhibits cancer cell proliferation via inhibition of NF-κB, P13K/AKT, and MAPKs (ERK, JNK, P38) pathways to induce apoptosis and prevents angiogenesis. It is expected that understanding these fundamental mechanisms may help stimulate additional research to exploit Phyllanthus urinaria and other natural products for the development of novel anticancer therapies in the future.

Molecular docking of secondary metabolites from Indonesian marine and terrestrial organisms targeting SARS-CoV-2 ACE-2, M pro, and PL pro receptors

With the uncontrolled spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), development and distribution of antiviral drugs and vaccines have gained tremendous importance. This study focused on two viral proteases namely main protease (Mpro) and papain-like protease (PLpro) and human angiotensin-converting enzyme (ACE-2) to identify which of these are essential for viral replication. We screened 102 secondary metabolites against SARS-CoV-2 isolated from 36 terrestrial plants and 36 marine organisms from Indonesian biodiversity. These organisms are typically presumed to have antiviral effects, and some of them have been used as an immunomodulatory activity in traditional medicine. For the molecular docking procedure to obtain Gibbs free energy value (∆G), toxicity, ADME and Lipinski, AutoDock Vina was used. In this study, five secondary metabolites, namely corilagin, dieckol, phlorofucofuroeckol A, proanthocyanidins, and isovitexin, were found to inhibit ACE-2, Mpro, and PLpro receptors in SARS-CoV-2, with a high affinity to the same sites of ptilidepsin, remdesivir, and chloroquine as the control molecules. This study was delimited to molecular docking without any validation by simulations concerned with molecular dynamics. The interactions with two viral proteases and human ACE-2 may play a key role in developing antiviral drugs for five active compounds. In future, we intend to investigate antiviral drugs and the mechanisms of action by in vitro study.

Corilagin and 1,3,6-Tri-O-galloy-β-D-glucose: potential inhibitors of SARS-CoV-2 variants

The COVID-19 disease caused by the virus SARS-CoV-2, first detected in December 2019, is still emerging through virus mutations. Although almost under control in some countries due to effective vaccines that are mitigating the worldwide pandemic, the urgency to develop additional vaccines and therapeutic treatments is imperative. In this work, the natural polyphenols corilagin and 1,3,6-tri-O-galloy-β-d-glucose (TGG) are investigated to determine the structural basis of inhibitor interactions as potential candidates to inhibit SARS-CoV-2 viral entry into target cells. First, the therapeutic potential of the ligands are assessed on the ACE2/wild-type RBD. We first use molecular docking followed by molecular dynamics, to take into account the conformational flexibility that plays a significant role in ligand binding and that cannot be captured using only docking, and then analyze more precisely the affinity of these ligands using MMPBSA binding free energy. We show that both ligands bind to the ACE2/wild-type RBD interface with good affinities which might prevent the ACE2/RBD association. Second, we confirm the potency of these ligands to block the ACE2/RBD association using a combination of surface plasmon resonance and biochemical inhibition assays. These experiments confirm that TGG and, to a lesser extent, corilagin, inhibit the binding of RBD to ACE2. Both experiments and simulations show that the ligands interact preferentially with RBD, while weak binding is observed with ACE2, hence, avoiding potential physiological side-effects induced by the inhibition of ACE2. In addition to the wild-type RBD, we also study numerically three RBD mutations (E484K, N501Y and E484K/N501Y) found in the main SARS-CoV-2 variants of concerns. We find that corilagin could be as effective for RBD/E484K but less effective for the RBD/N501Y and RBD/E484K-N501Y mutants, while TGG strongly binds at relevant locations to all three mutants, demonstrating the significant interest of these molecules as potential inhibitors for variants of SARS-CoV-2.

LC-ESI-QTOF-MS/MS Analysis, Cytotoxic, Antiviral, Antioxidant, and Enzyme Inhibitory Properties of Four Extracts of Geranium pyrenaicum Burm. f.: A Good Gift from the Natural Treasure

This study focused on the biological evaluation and chemical characterization of Geranium pyrenaicum Burm. f. Different solvent extracts (hexane, ethyl acetate, methanol, and water extracts) were prepared. The phytochemical profile, antioxidant, and enzyme inhibitory activity were investigated. Cytotoxicity was assessed using VERO, FaDu, HeLa and RKO cells. The antiviral activity was carried out against HSV-1 (Herpes simplex virus 1) propagated in VERO cell line. The aqueous extract, possessing high phenolic content (170.50 mg gallic acid equivalent/g extract), showed the highest reducing capacity (613.27 and 364.10 mg Trolox equivalent/g extract, for cupric reducing antioxidant capacity and ferric reducing antioxidant power, respectively), radical scavenging potential (469.82 mg Trolox equivalent/g extract, against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), metal chelating ability (52.39 mg ethylenediaminetetraacetic acid equivalent/g extract) and total antioxidant capacity (3.15 mmol Trolox equivalent/g extract). Liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry (LC-ESI-QTOF-MS/MS) alloved to tentatively identify a total of 56 compounds in the extracts, including ellagitannins, gallic acid and galloyl derivatives amongst others. The ethyl acetate extracts substantially depressed cholinesterase enzymes (4.49 and 12.26 mg galantamine equivalent/g extract against AChE and BChE, respectively) and α-amylase enzyme (1.04 mmol acarbose equivalent/g extract). On the other hand, the methanolic extract inhibited tyrosinase (121.42 mg kojic acid equivalent/g extract) and α-glucosidase (2.39 mmol acarbose equivalent/g extract) activities. The highest selectivity towards all cancer cell lines (SI 4.5-10.8) was observed with aqueous extract with the FaDu cells being the most sensitive (CC50 40.22 µg/mL). It can be concluded that the presence of certain bioactive antiviral molecules may be related to the high anti HSV-1 activity of the methanolic extract. This work has generated vital scientific data on this medicinal plant, which is a prospective candidate for the creation of innovative phyto-pharmaceuticals.

Corilagin prevents SARS-CoV-2 infection by targeting RBD-ACE2 binding

BACKGROUND

The outbreak of coronavirus (SARS-CoV-2) disease caused more than 100,000,000 people get infected and over 2,200,000 people being killed worldwide. However, the current developed vaccines or drugs may be not effective in preventing the pandemic of COVID-19 due to the mutations of coronavirus and the severe side effects of the newly developed vaccines. Chinese herbal medicines and their active components play important antiviral activities. Corilagin exhibited antiviral effect on human immunodeficiency virus (HIV), hepatitis C virus (HCV) and Epstein-Barr virus (EBV). However, whether it blocks the interaction between SARS-CoV-2 RBD and hACE2 has not been elucidated.

PURPOSE

To characterize an active compound, corilagin derived from Phyllanthus urinaria as potential SARS-CoV-2 entry inhibitors for its possible preventive application in daily anti-virus hygienic products.

METHODS

Computational docking coupled with bio-layer interferometry, BLI were adopted to screen more than 1800 natural compounds for the identification of SARS-CoV-2 spike-RBD inhibitors. Corilagin was confirmed to have a strong binding affinity with SARS-CoV-2-RBD or human ACE2 (hACE2) protein by the BLI, ELISA and immunocytochemistry (ICC) assay. Furthermore, the inhibitory effect of viral infection of corilagin was assessed by in vitro pseudovirus system. Finally, the toxicity of corilagin was examined by using MTT assay and maximal tolerated dose (MTD) studies in C57BL/6 mice.

RESULTS

Corilagin preferentially binds to a pocket that contains residues Cys 336 to Phe 374 of spike-RBD with a relatively low binding energy of -9.4 kcal/mol. BLI assay further confirmed that corilagin exhibits a relatively strong binding affinity to SARS-CoV-2-RBD and hACE2 protein. In addition, corilagin dose-dependently blocks SARS-CoV-2-RBD binding and abolishes the infectious property of RBD-pseudotyped lentivirus in hACE2 overexpressing HEK293 cells, which mimicked the entry of SARS-CoV-2 virus in human host cells. Finally, in vivo studies revealed that up to 300 mg/kg/day of corilagin was safe in C57BL/6 mice. Our findings suggest that corilagin could be a safe and potential antiviral agent against the COVID-19 acting through the blockade of the fusion of SARS-CoV-2 spike-RBD to hACE2 receptors.

CONCLUSION

Corilagin could be considered as a safe and environmental friendly anti-SARS-CoV-2 agent for its potential preventive application in daily anti-virus hygienic products.

Corilagin induces apoptosis and autophagy in NRF2‑addicted U251 glioma cell line

Corilagin, extracted from the Euphorbiaceae and Phyllanthus plants, inhibits the growth of a number of types of tumors. Compared with temozolomide, the traditional chemotherapy drug, corilagin has demonstrated stronger antitumor activity. However, the pharmaceutical mechanism of corilagin in glioma remains unclear. Nuclear factor erythroid 2 like 2 (NFE2L2 or NRF2) is positively associated with several types of tumor including glioma. In the present study, NRF2 expression was higher in glioma tissues compared with non-glioma specimens. Therefore, it was hypothesized that corilagin targets NRF2 regulation of U251 cell apoptosis. The present study used Hoechst 33258 staining to demonstrate that corilagin induced glioma cell apoptosis and observed that the expression of the apoptosis-related gene Bcl-2 was reduced. In addition, corilagin induced autophagy and promoted the conversion of light chain 3 (LC3) protein from LC3I to LC3II. NRF2 expression was downregulated by corilagin stimulation. Furthermore, the gene expression pattern following knockdown of NRF2 in U251 cells using siRNA was consistent with corilagin stimulation. Therefore, it was preliminarily concluded that corilagin induces apoptosis and autophagy by reducing NRF2 expression.

Polyphenol-Peptide Interactions in Mitigation of Alzheimer's Disease: Role of Biosurface-Induced Aggregation

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder, responsible for nearly two-thirds of all dementia cases. In this review, we report the potential AD treatment strategies focusing on natural polyphenol molecules (green chemistry) and more specifically on the inhibition of polyphenol-induced amyloid aggregation/disaggregation pathways: in bulk and on biosurfaces. We discuss how these pathways can potentially alter the structure at the early stages of AD, hence delaying the aggregation of amyloid-β (Aβ) and tau. We also discuss multidisciplinary approaches, combining experimental and modelling methods, that can better characterize the biochemical and biophysical interactions between proteins and phenolic ligands. In addition to the surface-induced aggregation, which can occur on surfaces where protein can interact with other proteins and polyphenols, we suggest a new concept referred as "confinement stability". Here, on the contrary, the adsorption of Aβ and tau on biosurfaces other than Aβ- and tau-fibrils, e.g., red blood cells, can lead to confinement stability that minimizes the aggregation of Aβ and tau. Overall, these mechanisms may participate directly or indirectly in mitigating neurodegenerative diseases, by preventing protein self-association, slowing down the aggregation processes, and delaying the progression of AD.

Corilagin suppresses RANKL-induced osteoclastogenesis and inhibits oestrogen deficiency-induced bone loss via the NF-κB and PI3K/AKT signalling pathways

Over‐activated osteoclastogenesis, which is initiated by inflammation, has been implicated in osteoporosis. Corilagin, a natural compound extracted from various medicinal herbaceous plants, such as Cinnamomum cassia, has antioxidant and anti‐inflammatory activities. We found that Corilagin suppressed osteoclast differentiation in a dose‐dependent manner, significantly decreased osteoclast‐related gene expression and impaired bone resorption by osteoclasts. Moreover, phosphorylation of members of the nuclear factor‐kappaB (NF‐κB) and PI3K/AKT signalling pathways was reduced by Corilagin. In a murine model of osteoporosis, Corilagin inhibited osteoclast functions in vivo and restored oestrogen deficiency‐induced bone loss. In conclusion, our findings suggested that Corilagin inhibited osteoclastogenesis by down‐regulating the NF‐κB and PI3K/AKT signalling pathways, thus showing its potential possibility for the treatment of osteoporosis.

High Throughput Virtual Screening to Discover Inhibitors of the Main Protease of the Coronavirus SARS-CoV-2

We use state-of-the-art computer-aided drug design (CADD) techniques to identify prospective inhibitors of the main protease enzyme, 3CLpro of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing COVID-19. From our screening of over one million compounds including approved drugs, investigational drugs, natural products, and organic compounds, and a rescreening protocol incorporating enzyme dynamics via ensemble docking, we have been able to identify a range of prospective 3CLpro inhibitors. Importantly, some of the identified compounds had previously been reported to exhibit inhibitory activities against the 3CLpro enzyme of the closely related SARS-CoV virus. The top-ranking compounds are characterized by the presence of multiple bi- and monocyclic rings, many of them being heterocycles and aromatic, which are flexibly linked allowing the ligands to adapt to the geometry of the 3CLpro substrate site and involve a high amount of functional groups enabling hydrogen bond formation with surrounding amino acid residues, including the catalytic dyad residues H41 and C145. Among the top binding compounds we identified several tyrosine kinase inhibitors, which include a bioflavonoid, the group of natural products that binds best to 3CLpro. Another class of compounds that decently binds to the SARS-CoV-2 main protease are steroid hormones, which thus may be endogenous inhibitors and might provide an explanation for the age-dependent severity of COVID-19. Many of the compounds identified by our work show a considerably stronger binding than found for reference compounds with in vitro demonstrated 3CLpro inhibition and anticoronavirus activity. The compounds determined in this work thus represent a good starting point for the design of inhibitors of SARS-CoV-2 replication.

Preparative purification of corilagin from Phyllanthus by combining ionic liquid extraction, prep-HPLC, and precipitation

In this study, a green extraction and purification process for the rapid preparation of corilagin from Phyllanthus has been designed using an aqueous ionic liquid coupled with preparative high-performance liquid chromatography (prep-HPLC) and precipitation. The results showed that the optimum extraction process for corilagin involved mixing Phyllanthus tenellus Roxb. with 0.4 M [BMIm]Br at a liquid-solid ratio of 10 : 1 and dispersing the mixture by ultrasonication at 50 °C for 15 min. Macroporous resin D101 and prep-HPLC were employed for [BMIm]Br removal and corilagin separation to yield corilagin of 86.49% purity. Subsequently, corilagin was further purified by water precipitation to achieve 99.12% purity. The results indicated the successful development of a new rapid and green process to prepare corilagin on a large scale from plants using [BMIm]Br. This promising process can be applied for the preparative separation and purification of other active compounds from complex plant systems.

Mitigating Alzheimer’s Disease with Natural Polyphenols: A Review

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According to Alzheimer’s Disease International (ADI), nearly 50 million people worldwide were living with dementia in 2017, and this number is expected to triple by 2050. Despite years of research in this field, the root cause and mechanisms responsible for Alzheimer’s disease (AD) have not been fully elucidated yet. Moreover, promising preclinical results have repeatedly failed to translate into patient treatments. Until now, none of the molecules targeting AD has successfully passed the Phase III trial. Although natural molecules have been extensively studied, they normally require high concentrations to be effective; alternately, they are too large to cross the blood-brain barrier (BBB).

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In this review, we report AD treatment strategies, with a virtually exclusive focus on green chemistry (natural phenolic molecules). These include therapeutic strategies for decreasing amyloid-β (Aβ) production, preventing and/or altering Aβ aggregation, and reducing oligomers cytotoxicity such as curcumin, (-)-epigallocatechin-3-gallate (EGCG), morin, resveratrol, tannic acid, and other natural green molecules. We also examine whether consideration should be given to potential candidates used outside of medicine and nutrition, through a discussion of two intermediate-sized green molecules, with very similar molecular structures and key properties, which exhibit potential in mitigating Alzheimer’s disease.

Evaluation of prolyl oligopeptidase and acetylcholinesterase inhibition by Phyllanthus tenellus Roxb. from Brazil

Phyllanthus tenellus Roxb. (Phyllanthaceae) is a plant used in Brazilian folk medicine for the treatment of intestinal infections and diabetes. Despite its use in traditional medicine, it was reported that P. tenellus extract may cause several effects in the central nervous system (CNS) of animals, such as agitation and signs of depression. The aim of this study was to determine the main constituents of P. tenellus methanol extract and to investigate whether the extract is able to inhibit the enzymes prolyl oligopeptidase (POP), acetylcholinesterase (AChE) and dipeptidyl peptidase-IV (DPP-IV). Corilagin (1) was isolated as the main constituent of the P. tenellus extract, along with rutin (2) and vitexin-2″-O-rhamnoside (3). The extract presented the ability to inhibit mainly POP. Dichloromethane and ethyl acetate fractions showed the highest inhibitory potency against POP (IC₅₀ values of 1.7 ± 0.4 and 11.7 ± 2 µg/mL, respectively). All fractions were inactive against AChE. Corilagin displayed selective POP inhibition in a dose-dependent manner, with IC₅₀= 19.7 ± 2.6 µg/mL. Corilagin exhibited moderate capacity to pass through the phospholipid membrane by passive diffusion, presenting effective permeability (Pe) of 1.26 × 10^-7 cm/s.

Permeability of the ellagitannin geraniin and its metabolites in a human colon adenocarcinoma Caco-2 cell culture model

Geraniin and its metabolites, found in many edibles, were classified as per the BCS. This finding can be used to predict its' in vivo oral absorption.

A Review of the Phytochemistry and Pharmacology of Phyllanthus urinaria L

The genus Phyllanthus (L.) is one of the most important groups of plants belonging to the Phyllantaceae family. Phyllanthus urinaria (L.) is an annual perennial herbal species found in tropical Asia, America, China, and the Indian Ocean islands. P. urinaria is used in folk medicine as a cure to treat jaundice, diabetes, malaria, and liver diseases. This review provides traditional knowledge, phytochemistry, and biological activities of P. urinaria. The literature reviewed for this article was obtained from the Web of Science, SciFinder, PubMed, ScienceDirect, and Google Scholar journal papers published prior to December 2017. Phytochemical investigations reveal that the plant is a rich source of lignans, tannins, flavonoids, phenolics, terpenoids, and other secondary metabolites. Pharmacological activities include anticancer, hepatoprotective, antidiabetic, antimicrobial, and cardioprotective effects. Thus, this present review summarizes the phytochemical constituents and their biological activities including biological studies on various crude extracts and fractions both in vitro and in vivo, and on clinical trial information about P. urinaria. This review compiles 93 naturally occurring compounds from P. urinaria along with their structures and pharmacological activities. The review is expected to stimulate further research on P. urinaria, and its pharmacological potential to yield novel therapeutic agents.

Corilagin inhibits breast cancer growth via reactive oxygen species-dependent apoptosis and autophagy

Corilagin is a component of Phyllanthus urinaria extract and has been found of possessing anti‐inflammatory, anti‐oxidative, and anti‐tumour properties in clinic treatments. However, the underlying mechanisms in anti‐cancer particularly of its induction of cell death in human breast cancer remain undefined. Our research found that corilagin‐induced apoptotic and autophagic cell death depending on reactive oxygen species (ROS) in human breast cancer cell, and it occurred in human breast cancer cell (MCF‐7) only comparing with normal cells. The expression of procaspase‐8, procaspase‐3, PARP, Bcl‐2 and procaspase‐9 was down‐regulated while caspase‐8, cleaved PARP, caspase‐9 and Bax were up‐regulated after corilagin treatment, indicating apoptosis mediated by extrinsic and mitochondrial pathways occurred in MCF‐7 cell. Meanwhile, autophagy mediated by suppressing Akt/mTOR/p70S6K pathway was detected with an increase in autophagic vacuoles and LC3‐II conversion. More significantly, inhibition of autophagy by chloroquine diphosphate salt (CQ) remarkably enhanced apoptosis, while the caspase inhibitor z‐VAD‐fmk failed in affecting autophagy, suggesting that corilagin‐induced autophagy functioned as a survival mechanism in MCF‐7 cells. In addition, corilagin induced intracellular reactive oxygen species (ROS) generation, when reduced by ROS scavenger NAC, apoptosis and autophagy were both down‐regulated. Nevertheless, in SK‐BR3 cell which expressed RIP3, necroptosis inhibitor Nec‐1 could not alleviate cell death induced by corilagin, indicating necroptosis was not triggered. Subcutaneous tumour growth in nude mice was attenuated by corilagin, consisting with the results in vitro. These results imply that corilagin inhibits cancer cell proliferation through inducing apoptosis and autophagy which regulated by ROS release.

Hepatoprotective Effects of Corilagin Following Hemorrhagic Shock are Through Akt-Dependent Pathway

Corilagin, a component of Phyllanthus urinaria extract, possesses antioxidant, thrombolytic, antiatherogenic, and hepatoprotective properties, but the mechanism underlying these effects remains unclear. Previous studies showed that the Akt (protein kinase B) signaling pathway exerts anti-inflammatory and organ protective effects. The aim of this study was to investigate the mechanism of action of corilagin and determine whether these effects are mediated through the Akt-dependent pathway in a trauma-hemorrhagic shock-induced liver injury rodent model. Hemorrhagic shock was induced in male Sprague–Dawley rats; mean blood pressure was maintained at 35 mm Hg to 40 mm Hg for 90 min, followed by fluid resuscitation. During resuscitation, three doses of corilagin alone (1 mg/kg, 5 mg/kg, or 10 mg/kg, intravenously) were administered. Furthermore, a single dose of corilagin (5 mg/kg) with and without Wortmannin (1 mg/kg, PI3K inhibitor), Wortmannin alone, or vehicle was administered. Twenty-four hours after resuscitation, plasma alanine aminotransferase and aspartate aminotransferase concentration and hepatic parameters were measured. One-way ANOVA was used for statistical analysis. Hepatic myeloperoxidase activity and the concentrations of plasma alanine aminotransferase and aspartate aminotransferase, interleukin-6, tumor necrosis factor-α, intercellular adhesion molecule-1, and cytokine-induced neutrophil chemoattractant-1 (CINC-1) and CINC-3 increased following hemorrhagic shock. These parameters were significantly attenuated in corilagin-treated rats following hemorrhagic shock. Hepatic phospho-Akt expression was also higher in corilagin-treated rats than in vehicle-treated rats. The elevation of phospho-Akt was abolished by combined treatment with Wortmannin and corilagin. Our results suggest that corilagin exerts its protective effects on hemorrhagic shock-induced liver injury, at least, via the Akt-dependent pathway.

A natural small molecule inhibitor corilagin blocks HCV replication and modulates oxidative stress to reduce liver damage

Hepatitis C virus (HCV) infection causes chronic liver disease, which often leads to hepatocellular carcinoma. Earlier, we have demonstrated anti-HCV property of the methanolic extract of Phyllanthus amarus, an age-old folk-medicine against viral hepatitis. Here, we report identification of a principal bioactive component 'corilagin', which showed significant inhibition of the HCV key enzymes, NS3 protease and NS5B RNA-dependent-RNA-polymerase. This pure compound could effectively inhibit viral replication in the infectious cell culture system, displayed strong antioxidant activity by blocking HCV induced generation of reactive oxygen species and suppressed up-regulation of NOX4 and TGF-β mRNA levels. Oral administration of corilagin in BALB/c mice demonstrated its better tolerability and systemic bioavailability. More importantly, corilagin could restrict serum HCV RNA levels, decrease collagen deposition and hepatic cell denaturation in HCV infected chimeric mice harbouring human hepatocytes. Taken together, results provide a basis towards developing a pure natural drug as an alternate therapeutic strategy for restricting viral replication and prevent liver damage towards better management of HCV induced pathogenesis.

An UPLC Method for Determination of Geraniin in Rat Plasma and its Application to Pharmacokinetic Studies

Introduction:

Geraniin has many biological activities including anti-osteoporotic and anti-hyperglycemic efficacies.

Materials and Methods:

A rapid and simple method for the determination of geraniin in rat plasma using ultra performance liquid chromatography coupled to ultraviolet detector was developed. The plasma sample, spiked with epicatechin as an internal standard, was subjected to ethyl acetate extraction prior to analysis. Chromatographic separation was performed on the HSS T3 column and monitored at a wavelength of 280 nm. The limit of detection and lower limit of quantification was 0.07 μg/mL and 0.2 μg/mL in rat plasma, respectively.

Conclusion:

Good linearity was obtained in the range of 0.2 - 200 μg/mL, and the correlation coefficient was better than 0.997. The intra-day and inter-day precisions decreased 9.8%. The accuracy of QC samples ranged from 84.4% to 87.1%. The extraction recovery ranged from 88.4% to 90.3% and the matrix effect ranged from 84.4% to 87.2%. The analyte was stable in rat plasma when stored at room temperature for 12 hours, 4°C for 24 hours and -20°C for 15 days. t1/2 and t1/2 for i.v. was 0.21 ± 0.10 and 7.20 ± 2.20 h, respectively. Plasma clearance (CL) was 0.03 ± 0.02 L/h/kg and apparent volume of distribution (Vz) was 0.05 + 0.01 L/kg. The developed method was successfully applied to the pharmacokinetic study of geraniin in rats.

Mechanism of Corilagin interference with IL-13/STAT6 signaling pathways in hepatic alternative activation macrophages in schistosomiasis-induced liver fibrosis in mouse model

This study tried to find the mechanism of Corilagin interference with interleukin (IL)-13/signal transducer and activator of transcription (STAT) 6 signaling pathways in IL-13-activated liver alternative activation macrophages in schistosomiasis-induced liver fibrosis in Balb/c mice. As a result, IL-13 in serum and the mRNA expression of IL-13 Receptor α1, IL-4 Receptor α and downstream mediators supressor of cytokine signaling (SOCS) 1, Kruppel-like factor (KLF) 4, peroxisome proliferator-activated receptor (PPAR) δ in the liver tissue were significantly inhibited by Corilagin (P<0.05 or 0.01). The protein expression of IL-13 Receptor α1, IL-4 Receptor α, SOCS1, KLF4, PPARγ, PPARδ and Phospho-STAT6 (P-STAT6) in Corilagin group were also markedly suppressed when compared with the model group (P<0.05 or 0.01). Furthermore, the inhibitory effect was enhanced when the concentration of Corilagin increased (P<0.05). By hematoxylin and eosin (HE) staining, when compared with the model group, the Corilagin group showed smaller granulomas (P<0.05 or 0.01). The area of positive cells and integrated optical density (IOD) of CD68, CD206 and KLF4 was significantly decreased by Corilagin stained by IHC (P<0.05 or 0.01). In conclusion, Corilagin had potential to relieve hepatic fibrosis caused by egg granuloma in Schistosoma japonicum infection by decreasing the expression of molecules associated with IL-13/STAT6 signaling pathway in liver alternative activation macrophages.

Coxsackievirus A16 induced neurological disorders in young gerbils which could serve as a new animal model for vaccine evaluation

Coxsackievirus A16 (CA16) is one of the major pathogens associated with human hand, foot, and mouth disease (HFMD) in the Asia-pacific region. Although CA16 infections are generally mild, severe neurological manifestations or even death has been reported. Studies on CA16 pathogenesis and vaccine development are severely hampered because the small animal models that are currently available show major limitations. In this study, gerbils (Meriones unguiculatus) were investigated for their suitability as an animal model to study CA16 pathogenesis and vaccine development. Our results showed that gerbils up to the age of 21 days were fully susceptible to CA16 and all died within five days post-infection. CA16 showed a tropism towards the skeletal muscle, spinal cord and brainstem of gerbils, and severe lesions, including necrosis, were observed. In addition, an inactivated CA16 whole-virus vaccine administrated to gerbils was able to provide full protection to the gerbils against lethal doses of CA16 strains. These results demonstrate that gerbils are a suitable animal model to study CA16 infection and vaccine development.

Development and validation of an UPLC-PDA method for the determination of corilagin in rat plasma and its application to pharmacokinetic study

Corilagin, which was isolated from several medical herbs, has been reported to exert many pharmacological activities. A simple and rapid liquid ultra-performance liquid chromatography (UPLC) coupled to photodiode array (PDA) method has been developed to quantify corilagin in rat plasma. In this study, plasma samples were prepared by ethyl acetate extraction. Separation was performed on a HSS T3 (100mm×2.1mm, 1.8μm) column by using a mobile phase of acetonitrile and water with 0.1% trifluoroacetic acid (v/v). Corilagin and internal standard epicatechin were detected at a wavelength of 266nm. The calibration curve was linear (r>0.998) over a concentration range of 0.2μg/mL to 20μg/mL with a lower quantification limit of 0.2μg/mL. Both intra and inter-day precision values were within 5.7% and extraction recovery were greater than 81.0%. Stability tests showed that corilagin and IS remained stable during the analytical procedure. The validated UPLC-PDA method was then used to analyze the pharmacokinetics of corilagin administered to rats intravenously (10mg/kg) or orally (50mg/kg). Oral bioavailability of corilagin was calculated to be 10.7%, indicating that this component is not suitable for oral administration. The results provide basis for further preclinical studies on corilagin.

The Genus Phyllanthus: An Ethnopharmacological, Phytochemical, and Pharmacological Review

The plants of the genus Phyllanthus (Euphorbiaceae) have been used as traditional medicinal materials for a long time in China, India, Brazil, and the Southeast Asian countries. They can be used for the treatment of digestive disease, jaundice, and renal calculus. This review discusses the ethnopharmacological, phytochemical, and pharmacological studies of Phyllanthus over the past few decades. More than 510 compounds have been isolated, the majority of which are lignins, triterpenoids, flavonoids, and tannins. The researches of their remarkable antiviral, antioxidant, antidiabetic, and anticancer activities have become hot topics. More pharmacological screenings and phytochemical investigations are required to support the traditional uses and develop leading compounds.

Activity-based and fraction-guided analysis of Phyllanthus urinaria identifies loliolide as a potent inhibitor of hepatitis C virus entry

Without a vaccine, hepatitis C virus (HCV) remains a global medical and socio-economic burden, predisposing about 170 million carriers worldwide to end-stage liver diseases including cirrhosis and hepatocellular carcinoma. Although the recently developed direct-acting antivirals (DAAs) have revolutionized hepatitis C treatment, most of them are unsuitable for monotherapy due to risks of resistance, thus necessitating combination with interferon (IFN)-alpha, ribavirin, or additional DAAs. More importantly, the high cost associated with the DAAs restricts their accessibility to most parts of the world. Developing novel cost-effective anti-HCV therapeutics may help expand the scope of antivirals and treatment strategies against hepatitis C. Herein, we applied an activity-based and fraction-guided analysis of extracts from the medicinal plant Phyllanthus urinaria (P. urinaria), which yielded fraction 13 (F13) as possessing the most potent inhibitory activity against early viral entry of cell-culture HCV infection. Chemical analysis (silica gel chromatography followed by ESI LC-MS plus (1)H and (13)C NMR) of F13 identified loliolide (LOD), a monoterpenoid lactone, as a novel inhibitor of HCV entry. Specifically, LOD could efficiently inactivate HCV free virus particles, abrogate viral attachment, and impede viral entry/fusion, with minimal effect on viral replication/translation, particle production, and induction of type I IFN host antiviral immune response. ELISA-based binding analysis confirmed the monoterpenoid's ability in efficiently blocking HCV particle attachment to the host cell surface. Furthermore, LOD could inhibit infection by several genotypic strains of HCV. This is the first report characterizing P. urinaria and its bioactive compound LOD as potent HCV entry inhibitors, which merit further evaluation for development as candidate antiviral agents against hepatitis C.

Corilagin suppresses cholangiocarcinoma progression through Notch signaling pathway in vitro and in vivo

Corilagin is a natural plant polyphenol tannic acid with antitumor, anti-inflammatory, and anti-oxidative properties. However, the mechanisms of its actions are largely unknown. Our group reported that corilagin could induce cell inhibition in human breast cancer cell line MCF-7 and human liver hepatocellular carcinoma cell lines HepG2. We report here that corilagin inhibits cholangiocarcinoma (CCA) development through regulating Notch signaling pathway. We found that, in vitro, corilagin inhibited CCA cell proliferation, migration and invasion, promoted CCA cell apoptosis, and inhibited Notch1 and Notch signaling pathway protein expression. Co-immunoprecipitation was used to establish Notch intracellular domain (NICD) interaction with MAML1 and P300 in CCA. Importantly, corilagin reduced Hes1 mRNA level through inhibiting Hes1 promoter activity. In nude mice, corilagin inhibited CCA growth and repressed the expression of Notch1 and mTOR. These results indicate that corilagin may control CCA cell growth by downregulating the expression of Notch1. Therefore, our findings suggest that corilagin may have the potential to become a new therapeutic drug for human CCA.

Chinese herbal medicines as a source of molecules with anti-enterovirus 71 activity

Enterovirus 71 (EV71) is one of the causative agents of hand, foot, and mouth disease (HFMD), which sometimes leads to severe neurological disease and death in the Asia-Pacific region. In Chinese medicine, HFMD is caused mainly by an accumulation of damp-heat and toxicity in the body. No effective drugs are currently available for the treatment and prevention of EV71 infection. This review summarizes the potential Chinese herbal extracts and isolated compounds with antiviral activity against EV71 and their clinical applications, especially those categorized as heat-clearing and detoxifying.

Anti-Enterovirus 71 Agents of Natural Products

This review, with 42 references, presents the fascinating area of anti-enterovirus 71 natural products over the last three decades for the first time. It covers literature published from 2005–2015 and refers to compounds isolated from biogenic sources. In total, 58 naturally-occurring anti-EV71 compounds are recorded.

Antiviral activity of silymarin against chikungunya virus

The mosquito-borne chikungunya virus (CHIKV) causes chikungunya fever, with clinical presentations such as severe back and small joint pain, and debilitating arthritis associated with crippling pains that persist for weeks and even years. Although there are several studies to evaluate the efficacy of drugs against CHIKV, the treatment for chikungunya fever is mainly symptom-based and no effective licensed vaccine or antiviral are available. Here, we investigated the antiviral activity of three types of flavonoids against CHIKV in vitro replication. Three compounds: silymarin, quercetin and kaempferol were evaluated for their in vitro antiviral activities against CHIKV using a CHIKV replicon cell line and clinical isolate of CHIKV of Central/East African genotype. A cytopathic effect inhibition assay was used to determine their activities on CHIKV viral replication and quantitative reverse transcription PCR was used to calculate virus yield. Antiviral activity of effective compound was further investigated by evaluation of CHIKV protein expression using western blotting for CHIKV nsP1, nsP3, and E2E1 proteins. Briefly, silymarin exhibited significant antiviral activity against CHIKV, reducing both CHIKV replication efficiency and down-regulating production of viral proteins involved in replication. This study may have important consequence for broaden the chance of getting the effective antiviral for CHIKV infection.

Therapeutic and prevention strategies against human enterovirus 71 infection

Human enterovirus 71 (HEV71) is the cause of hand, foot and mouth disease and associated neurological complications in children under five years of age. There has been an increase in HEV71 epidemic activity throughout the Asia-Pacific region in the past decade, and it is predicted to replace poliovirus as the extant neurotropic enterovirus of highest global public health significance. To date there is no effective antiviral treatment and no vaccine is available to prevent HEV71 infection. The increase in prevalence, virulence and geographic spread of HEV71 infection over the past decade provides increasing incentive for the development of new therapeutic and prevention strategies against this emerging viral infection. The current review focuses on the potential, advantages and disadvantages of these strategies. Since the explosion of outbreaks leading to large epidemics in China, research in natural therapeutic products has identified several groups of compounds with anti-HEV71 activities. Concurrently, the search for effective synthetic antivirals has produced promising results. Other therapeutic strategies including immunotherapy and the use of oligonucleotides have also been explored. A sound prevention strategy is crucial in order to control the spread of HEV71. To this end the ultimate goal is the rapid development, regulatory approval and widespread implementation of a safe and effective vaccine. The various forms of HEV71 vaccine designs are highlighted in this review. Given the rapid progress of research in this area, eradication of the virus is likely to be achieved.