Xanthohumol, a main prenylated chalcone from hops, reduces liver damage and modulates oxidative reaction and apoptosis in hepatitis C virus infected Tupaia belangeri

Modulation of the replication of positive-sense RNA viruses by the natural plant metabolite xanthohumol and its derivatives

The COVID-19 pandemic has highlighted the importance of identifying new potent antiviral agents. Nutrients as well as plant-derived substances are promising candidates because they are usually well tolerated by the human body and readily available in nature, and consequently mostly cheap to produce. A variety of antiviral effects have recently been described for the hop chalcone xanthohumol (XN), and to a lesser extent for its derivatives, making these hop compounds particularly attractive for further investigation. Noteworthy, mounting evidence indicated that XN can suppress a wide range of viruses belonging to several virus families, all of which share a common reproductive cycle. As a result, the purpose of this review is to summarize the most recent research on the antiviral properties of XN and its derivatives, with a particular emphasis on the positive-sense RNA viruses human hepatitis C virus (HCV), porcine reproductive and respiratory syndrome virus (PRRSV), and severe acute respiratory syndrome corona virus (SARS-CoV-2).

Antiviral and antimicrobial applications of chalcones and their derivatives: From nature to greener synthesis

Chalcones and their derivatives have been widely studied due to their versatile pharmacological and biological activities, such as anti-inflammatory, antibacterial, antiviral, and antitumor effects. These compounds have shown suitable antiviral effects through the selective targeting of a variety of viral enzymes, including lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fumarate reductase, protein tyrosine phosphatase, topoisomerase-II, protein kinases, integrase/protease, and lactate/isocitrate dehydrogenase, among others. Chalcones and their derivatives have displayed excellent potential for combating pathogenic bacteria and fungi (especially, multidrug-resistant bacteria). However, relevant mechanisms should be further explored, focusing on inhibitory effects against DNA gyrase B, UDP-N-acetylglucosamine enolpyruvyl transferase (MurA), and efflux pumps (e.g., NorA), among others. In addition, the antifungal and antiparasitic activities of these compounds (e.g., antitrypanosomal and antileishmanial properties) have prompted additional explorations. Nonetheless, systematic analysis of the relevant mechanisms, biosafety issues, and pharmacological properties, as well as clinical translation studies, are vital for practical applications. Herein, recent advancements pertaining to the antibacterial, antiviral, antiparasitic, and antifungal activities of chalcones and their derivatives are deliberated, focusing on the relevant mechanisms of action, crucial challenges, and future prospects. Furthermore, due to the great importance of greener and more sustainable synthesis of these valuable compounds, especially on an industrial scale, the progress made in this field has been briefly discussed. Hopefully, this review can serve as a catalyst for researchers to delve deeper into the exploration and designing of novel chalcone compounds with medicinal properties, especially against pathogenic viruses and multidrug-resistant bacteria as major causes of concern for human health.

Flavonoids as Potential Antiviral Agents for Porcine Viruses

Flavonoids are types of natural substances with phenolic structures isolated from a variety of plants. Flavonoids have antioxidant, anti-inflammatory, anticancer, and antiviral activities. Although most of the research or applications of flavonoids are focused on human diseases, flavonoids also show potential applicability against porcine virus infection. This review focuses on the recent progress in antiviral mechanisms of potential flavonoids against the most common porcine viruses. The mechanism discussed in this paper may provide a theoretical basis for drug screening and application of natural flavonoid compounds and flavonoid-containing herbs to control porcine virus infection and guide the research and development of pig feed additives.

Isolation and Characterization of Two Chalcone Derivatives with Anti-Hepatitis B Virus Activity from the Endemic Socotraen Dracaena cinnabari (Dragon’s Blood Tree)

Hepatitis B virus (HBV) infection is prevalent and continues to be a global health concern. In this study, we determined the anti-hepatitis B virus (HBV) potential of the Socotra-endemic medicinal plant Dracaena cinnabari and isolated and characterized the responsible constituents. A bioassay-guided fractionation using different chromatographic techniques of the methanolic extract of D. cinnabari led to the isolation of two chalcone derivatives. Using a variety of spectroscopic techniques, including ¹H-, ¹³C-, and 2D-NMR, these derivatives were identified as 2,4’-dihydroxy-4-methoxydihydrochalcone (compound 1) and 2,4’-dihydroxy-4-methoxyhydrochalcone (compound 2). Both compounds were isolated for the first time from the red resin (dragon’s blood) of D. cinnabari. The compounds were first evaluated for cytotoxicity on HepG2.2.15 cells and 50% cytotoxicity concentration (CC50) values were determined. They were then evaluated for anti-HBV activity against HepG2.2.15 cells by assessing the suppression of HBsAg and HBeAg production in the culture supernatants and their half maximum inhibitory concentration (IC₅₀) and therapeutic index (TI) values were determined. Compounds 1 and 2 indicated inhibition of HBsAg production in a dose- and time-dependent manner with IC₅₀ values of 20.56 and 6.36 μg/mL, respectively.

Xanthohumol Is a Potent Pan-Inhibitor of Coronaviruses Targeting Main Protease

Coronaviruses cause diseases in humans and livestock. The SARS-CoV-2 is infecting millions of human beings, with high morbidity and mortality worldwide. The main protease (M^pro) of coronavirus plays a pivotal role in viral replication and transcription, which, in theory, is an attractive drug target for antiviral drug development. It has been extensively discussed whether Xanthohumol is able to help COVID-19 patients. Here, we report that Xanthohumol, a small molecule in clinical trials from hops (Humulus lupulus), was a potent pan-inhibitor for various coronaviruses by targeting M^pro, for example, betacoronavirus SARS-CoV-2 (IC₅₀ value of 1.53 μM), and alphacoronavirus PEDV (IC₅₀ value of 7.51 μM). Xanthohumol inhibited M^pro activities in the enzymatical assays, while pretreatment with Xanthohumol restricted the SARS-CoV-2 and PEDV replication in Vero-E6 cells. Therefore, Xanthohumol is a potent pan-inhibitor of coronaviruses and an excellent lead compound for further drug development.

The Role of Bcl-xL Protein in Viral Infections

Bcl-xL represents a family of proteins responsible for the regulation of the intrinsic apoptosis pathway. Due to its anti-apoptotic activity, Bcl-xL co-determines the viability of various virally infected cells. Their survival may determine the effectiveness of viral replication and spread, dynamics of systemic infection, and viral pathogenesis. In this paper, we have reviewed the role of Bcl-xL in the context of host infection by eight different RNA and DNA viruses: hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), influenza A virus (IAV), Epstein-Barr virus (EBV), human T-lymphotropic virus type-1 (HTLV-1), Maraba virus (MRBV), Schmallenberg virus (SBV) and coronavirus (CoV). We have described an influence of viral infection on the intracellular level of Bcl-xL and discussed the impact of Bcl-xL-dependent cell survival control on infection-accompanying pathogenic events such as tissue damage or oncogenesis. We have also presented anti-viral treatment strategies based on the pharmacological regulation of Bcl-xL expression or activity.

A comprehensive review on the antiviral activities of chalcones

Some viral outbreaks have plagued the world since antiquity, including the most recent COVID-19 pandemic. The continuous spread and emergence of new viral diseases have urged the discovery of novel treatment options that can overcome the limitations of currently marketed antiviral drugs. Chalcones are natural open chain flavonoids that are found in various plants and can be synthesised in labs. Several studies have shown that these small organic molecules exert a number of pharmacological activities, including antiviral, anti-inflammatory, antimicrobial and anticancer. The purpose of this review is to provide a summary of the antiviral activities of chalcones and their derivatives on a set of human viral infections and their potential for targeting the most recent COVID-19 disease. Accordingly, we herein review chalcones activities on the following human viruses: Middle East respiratory syndrome coronavirus, severe acute respiratory syndrome coronavirus, human immunodeficiency, influenza, human rhinovirus, herpes simplex, dengue, human cytomegalovirus, hepatitis B and C, Rift Valley fever and Venezuelan equine encephalitis. We hope that this review will pave the way for the design and development of potentially potent and broad-spectrum chalcone based antiviral drugs.

Xanthohumol Inhibits TGF-β1-Induced Cardiac Fibroblasts Activation via Mediating PTEN/Akt/mTOR Signaling Pathway

Background

Xanthohumol (Xn) is the most abundant prenylated flavonoid in Hops (Humulus lupulus L.), and exhibits a range of pharmacological activities. This study aimed to investigate the effect of Xn on TGF-β1-induced cardiac fibroblasts activation and elucidate the underlying mechanism.

Materials and Methods

The cellTiter 96^® AQueous one solution cell proliferation assay kit was adopted to determine the cell viability of cardiac fibroblasts, and the proliferation was detected through 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay. The α-SMA protein expression was measured by using immunofluorescence and Western blotting. Western blotting was conducted to test the protein expressions of collagen I and III, PTEN, p-Akt, Akt, p-mTOR, mTOR, p-Smad3, Smad3 and GAPDH. The mRNA levels of α-SMA, collagen I and III were determined by quantitative real-time polymerase chain reaction (PCR).

Results

Xn inhibited the TGF-β1-induced proliferation, differentiation and collagen overproduction of cardiac fibroblasts. TGF-β1 induced the down-regulated PTEN expression, Akt and mTOR phosphorylation. These effects of TGF-β1 were suppressed by Xn, while blocking of PTEN reduced Xn-mediated inhibitory effect on cardiac fibroblasts activation induced by TGF-β1.

Conclusion

Xn inhibits TGF-β1-induced cardiac fibroblasts activation via mediating PTEN/Akt/mTOR signaling pathway.

Discovery and Development of Inflammatory Inhibitors from 2-Phenylchromonone (Flavone) Scaffolds

Flavonoids are compounds based on a 2-phenylchromonone scaffold. Flavonoids can be divided into flavonoids, flavonols, dihydroflavones, anthocyanins, chalcones and diflavones according to the oxidation degree of the central tricarbonyl chain, the connection position of B-ring (2-or 3-position), and whether the tricarbonyl chain forms a ring or not. There are a variety of biological activities about flavonoids, such as anti-inflammatory activity, anti-oxidation and anti-tumor activity, and the antiinflammatory activity is apparent. This paper reviews the anti-inflammatory activities and mechanisms of flavonoids and their derivatives reported in China and abroad from 2011 till date (2011-2020), in order to find a good drug scaffold for the study of anti-inflammatory activities.

Micellar solubilization enhances the anti-inflammatory effect of xanthohumol

BACKGROUND

Xanthohumol is known to exert anti-inflammatory properties but has poor oral bioavailability. Using advanced micellization technology, it has been possible to markedly enhance its bioavailability.

PURPOSE

In the present study, we compared the chronic anti-inflammatory activities of native and micellar xanthohumol in the rat adjuvant arthritis model, using diclofenac as a reference drug.

METHODS

Adjuvant arthritis was induced by injecting Freund's complete adjuvant into the right hind paw of rats and monitoring paw volume over 3 weeks. The drugs were given daily for 3 weeks, starting from the day of adjuvant inoculation. Serum was collected at the end of the experiment to measure inflammatory and oxidative stress parameters. Statistical comparisons between different groups were carried out by one-way analysis of variance followed by Tukey-Kramer multiple comparison test.

RESULTS

Micellar solubilized xanthohumol showed a better anti-inflammatory activity than its native form. The reduction in paw volume was reflected in corresponding changes in relevant mediators of inflammation like tumor necrosis factor-α, interleukin-6 and C-reactive protein, myloperoxidase and lipid peroxidation markers.

CONCLUSION

The findings confirm that micellar solubilization of xanthohumol enhances its anti-inflammatory activity, probably as a result of improving its bioavailabilty. The solubilized xanthohumol may prove to be a promising adjuvant tool for anti-inflammatory treatment and a potential anti-inflammatory alternative to synthetic drugs.

Biochemical composition of the hops and quality of the finished beer

The large varieties of hops and hop products used in the brewing industry. Various in the biochemical composition, individual approaches to the brewing technology of each hop product are required in order to obtain a high-quality beer with a characteristic bitter taste and aroma. The purpose of this work was to study the biochemical composition of pressed conical hops, pellets of hop type 90, type 45, ethanolic and CO2 extracts of hop of various varieties, and their influence on the quality of the finished beer. As a result of comprehensive research on hops and hop products of various varieties, using the modern biochemical methods were determined differences in their biochemical composition depend on the absolute values such parameters as the mass fraction of α-acids, b-acids and their composition, xanthohumol, general polyphenols, essential oils, the ratio of their valuable components of hops: b-acids to a-acids and also for quantity of general polyphenols, essential oils per unit of α-acids. Based on the results of the biochemical composition of hops and hop products were investigated their influence on the quality of beer and were determined their using in brewing.

Xanthohumol from Humulus lupulus L. potentiates the killing of Mycobacterium tuberculosis and mitigates liver toxicity by the combination of isoniazid in mouse tuberculosis models

Anti-tuberculosis drug induced hepatotoxicity is the main problem in tuberculosis patients. Xanthohumol, a major prenyl chalcone present in hops, has diverse biological activities including antibacterial and hepatoprotective activities. The present research aimed to investigate the combined effect of xanthohumol with isoniazid against Mycobacterium tuberculosis-infected mice. The liver damage was induced by treatment with isoniazid daily for 8 weeks. During the experiment, the uninfected group and the normal control group received an equal volume of saline, the xanthohumol group received an equal volume of xanthohumol only, and the isoniazid group received an equal volume of isoniazid only. The combination therapy group received not only isoniazid but also the corresponding xanthohumol. Experimental results showed that isoniazid combined with xanthohumol resulted in the lowest lung and spleen colony-forming unit counts compared to other groups. Furthermore, other positive outcomes implied that isoniazid combined with xanthohumol obviously alleviated anti-tuberculosis drug induced liver damage as indicated by the declined levels of ALT, AST, ALP, bilirubin and MDA and the increased levels of SOD, GSH-Px and ATPases. The study of the mechanisms underlying the hepatoprotective activity showed that xanthohumol was able to activate the antioxidative defense system and protect the hepatocellular membrane. The combination of isoniazid and xanthohumol had more effective bacteriostatic and hepatoprotective activities on Mycobacterium tuberculosis-infected mice than isoniazid alone. In conclusion, xanthohumol has the potential to be an effective adjuvant in tuberculosis treatment.

Anti-tuberculosis drug induced hepatotoxicity is the main problem in tuberculosis patients.

Beneficial and Deleterious Effects of Female Sex Hormones, Oral Contraceptives, and Phytoestrogens by Immunomodulation on the Liver

The liver is considered the laboratory of the human body because of its many metabolic processes. It accomplishes diverse activities as a mixed gland and is in continuous cross-talk with the endocrine system. Not only do hormones from the gastrointestinal tract that participate in digestion regulate the liver functions, but the sex hormones also exert a strong influence on this sexually dimorphic organ, via their receptors expressed in liver, in both health and disease. Besides, the liver modifies the actions of sex hormones through their metabolism and transport proteins. Given the anatomical position and physiological importance of liver, this organ is evidenced as an immune vigilante that mediates the systemic immune response, and, in turn, the immune system regulates the hepatic functions. Such feedback is performed by cytokines. Pro-inflammatory and anti-inflammatory cytokines are strongly involved in hepatic homeostasis and in pathological states; indeed, female sex hormones, oral contraceptives, and phytoestrogens have immunomodulatory effects in the liver and the whole organism. To analyze the complex and interesting beneficial or deleterious effects of these drugs by their immunomodulatory actions in the liver can provide the basis for either their pharmacological use in therapeutic treatments or to avoid their intake in some diseases.

Therapeutic Application of Micellar Solubilized Xanthohumol in a Western-Type Diet-Induced Mouse Model of Obesity, Diabetes and Non-Alcoholic Fatty Liver Disease

Xanthohumol (XN), a prenylated chalcone from hops, has been reported to exhibit a variety of health-beneficial effects. However, poor bioavailability may limit its application in the prevention and therapy of diseases. The objective of this study was to determine whether a micellar solubilization of xanthohumol could enhance the bioavailability and biological efficacy of xanthohumol in a Western-type diet (WTD) induced model of obesity, diabetes and non-alcoholic fatty liver disease (NAFLD). After 3 weeks feeding with WTD, XN was additionally applied per oral gavage as micellar solubilizate (s-XN) or native extract (n-XN) at a daily dose of 2.5 mg/kg body weight for a further 8 weeks. Control mice received vehicle only in addition to the WTD. WTD-induced body weight-gain and glucose intolerance were significantly inhibited by s-XN application. Furthermore, WTD-induced hepatic steatosis, pro-inflammatory gene expression (MCP-1 and CXCL1) and immune cell infiltration as well as activation of hepatic stellate cells (HSC) and expression of collagen alpha I were significantly reduced in the livers of s-XN-treated mice compared to WTD controls. In contrast, application of n-XN had no or only slight effects on the WTD-induced pathological effects. In line with this, plasma XN concentration ranged between 100–330 nmol/L in the s-XN group while XN was not detectable in the serum samples of n-XN-treated mice. In conclusion, micellar solubilization enhanced the bioavailability and beneficial effects of xanthohumol on different components of the metabolic syndrome including all pathological steps of NAFLD. Notably, this was achieved in a dose more than 10-fold lower than effective beneficial doses of native xanthohumol reported in previous in vivo studies.

Xanthohumol Protects Morphology and Function in a Mouse Model of Retinal Degeneration

Purpose

To investigate whether treatment with xanthohumol (XN), the principal prenylated chalconoid from Humulus lupulus (hops), is protective in a mouse model of light-induced retinal degeneration (LIRD).

Methods

Mice (129S2/SvPasCrl) were intraperitoneally injected with vehicle or XN prior to toxic light exposure and every 3 days thereafter. Retinal function was assessed by electroretinograms at 1, 2, and 4 weeks following toxic light exposure. Visual acuity was tested by optokinetic tracking 1 week and 4 weeks after toxic light exposure. Retina sections were stained with hematoxylin and eosin for morphologic analysis or by TUNEL. Redox potentials were assessed in retinal tissue by measuring levels of cysteine (CYS), cystine (CYSS), glutathione (GSH), and glutathione disulfide (GSSG) using HPLC with fluorescence detection.

Results

Toxic light significantly suppressed retinal function and visual acuity, severely disrupted the photoreceptor cell layer, and significantly decreased the number of nuclei and increased the accumulation of TUNEL-labeled cells in the outer nuclear layer. These effects were prevented by XN treatment. Treatment with XN also maintained GSSG and CYSS redox potentials and the total CYS pool in retinas of mice undergoing toxic light exposure.

Conclusions

XN treatment partially preserved visual acuity and retinal function in the LIRD mouse. Preservation of retinal CYS and of GSSG and CYSS redox potentials may indicate that XN treatment induces an increased antioxidant response, but further experiments are needed to verify this potential mechanism. To our knowledge, this is the first study to report protective effects of XN in a model of retinal degeneration.

Plant-derived antivirals against hepatitis c virus infection

Hepatitis C virus (HCV) infection is a worldwide public health burden and it is estimated that 185 million people are or have previously been infected worldwide. There is no effective vaccine for prevention of HCV infection; however, a number of drugs are available for the treatment of infection. The availability of direct-acting antivirals (DAAs) has dramatically improved therapeutic options for HCV genotype 1. However, the high costs and potential for development of resistance presented by existing treatment demonstrate the need for the development of more efficient new antivirals, or combination of therapies that target different stages of the viral lifecycle. Over the past decades, there has been substantial study of compounds extracted from plants that have activity against a range of microorganisms that cause human diseases. An extensive variety of natural compounds has demonstrated antiviral action worldwide, including anti-HCV activity. In this context, plant-derived compounds can provide an alternative approach to new antivirals. In this review, we aim to summarize the most promising plant-derived compounds described to have antiviral activity against HCV.

Antifibrotic effect of xanthohumol in combination with praziquantel is associated with altered redox status and reduced iron accumulation during liver fluke-associated cholangiocarcinogenesis

Cholangiocarcinoma (CCA) caused by infection of the liver fluke Opisthorchis viverrini, (Ov) is the major public health problem in northeast Thailand. Following Ov infection the subsequent molecular changes can be associated by reactive oxygen species (ROS) induced chronic inflammation, advanced periductal fibrosis, and cholangiocarcinogenesis. Notably, resistance to an activation of cell death in prolonged oxidative stress conditions can occur but some damaged/mutated cells could survive and enable clonal expansion. Our study used a natural product, xanthohumol (XN), which is an anti-oxidant and anti-inflammatory compound, to examine whether it could prevent Ov-associated CCA carcinogenesis. We measured the effect of XN with or without praziquantel (PZ), an anti-helminthic treatment, on DNA damage, redox status change including iron accumulation and periductal fibrosis during CCA genesis induced by administration of Ov and N-dinitrosomethylamine (NDMA) in hamsters. Animals were randomly divided into four groups: group I, Ov infection and NDMA administration (ON); group II, Ov infection and NDMA administration and PZ treatment (ONP); the latter 2 groups were similar to group I and II, but group III received additional XN (XON) and group IV received XN plus PZ (XONP). The results showed that high 8-oxodG (a marker of DNA damage) was observed throughout cholangiocarcinogenesis. Moreover, increased expression of CD44v8-10 (a cell surface in regulation of the ROS defense system), whereas decreased expression of phospho-p38^MAPK (a major ROS target), was found during the progression of the bile duct cell transformation. In addition, high accumulation of iron and expression of transferrin receptor-1 (TfR-1) in both malignant bile ducts and inflammatory cells were detected. Furthermore, fibrosis also increased with the highest level being on day 180. On the other hand, the groups of XN with or without PZ supplementations showed an effective reduction in all the markers examined, including fibrosis when compared with the ON group. In particular, the XONP group, in which a significant reduction DNA damage occurred, was also found to have iron accumulation and fibrosis compared to the other groups. Our results show that XN administered in combination with PZ could efficiently prevent CCA development and hence provide potential chemopreventive benefits in Ov-induced cholangiocarcinogenesis.

Piperidylmethyloxychalcone improves immune-mediated acute liver failure via inhibiting TAK1 activity

Mice deficient in the toll-like receptor (TLR) or the myeloid differentiation factor 88 (MyD88) are resistant to acute liver failure (ALF) with sudden death of hepatocytes. Chalcone derivatives from medicinal plants protect from hepatic damages including ALF, but their mechanisms remain to be clarified. Here, we focused on molecular basis of piperidylmethyloxychalcone (PMOC) in the treatment of TLR/MyD88-associated ALF. C57BL/6J mice were sensitized with D-galactosamine (GalN) and challenged with Escherichia coli lipopolysaccharide (LPS, TLR4 agonist) or oligodeoxynucleotide containing unmethylated CpG motif (CpG ODN, TLR9 agonist) for induction of ALF. Post treatment with PMOC sequentially ameliorated hepatic inflammation, apoptosis of hepatocytes, severe liver injury and shock-mediated death in ALF-induced mice. As a mechanism, PMOC inhibited the catalytic activity of TGF-β-activated kinase 1 (TAK1) in a competitive manner with respect to ATP, displaced fluorescent ATP probe from the complex with TAK1, and docked at the ATP-binding active site on the crystal structure of TAK1. Moreover, PMOC inhibited TAK1 auto-phosphorylation, which is an axis in the activating pathways of nuclear factor-κB (NF-κB) or activating protein 1 (AP1), in the liver with ALF in vivo or in primary liver cells stimulated with TLR agonists in vitro. PMOC consequently suppressed TAK1-inducible NF-κB or AP1 activity in the inflammatory injury, an early pathogenesis leading to ALF. The results suggested that PMOC could contribute to the treatment of TLR/MyD88-associated ALF with the ATP-binding site of TAK1 as a potential therapeutic target.

Sec24C-Dependent Transport of Claudin-1 Regulates Hepatitis C Virus Entry

Claudin-1 is a hepatitis C virus (HCV) coreceptor required for viral entry. Although extensive studies have focused on claudin-1 as an anti-HCV target, little is known about how the level of claudin-1 at the cell surface is regulated by host vesicular transport. Here, we identified an interaction between claudin-1 and Sec24C, a cargo-sorting component of the coat protein complex II (COPII) vesicular transport system. By interacting with Sec24C through its C-terminal YV, claudin-1 is transported from the endoplasmic reticulum (ER) and is eventually targeted to the cell surface. Blocking COPII transport inhibits HCV entry by reducing the level of claudin-1 at the cell surface. These findings provide mechanistic insight into the role of COPII vesicular transport in HCV entry.IMPORTANCE Tight junction protein claudin-1 is one of the cellular receptors for hepatitis C virus, which infects 185 million people globally. Its cellular distribution plays important role in HCV entry; however, it is unclear how the localization of claudin-1 to the cell surface is controlled by host transport pathways. In this paper, we not only identified Sec24C as a key host factor for HCV entry but also uncovered a novel mechanism by which the COPII machinery transports claudin-1 to the cell surface. This mechanism might be extended to other claudins that contain a C-terminal YV or V motif.

Chalcone: A Privileged Structure in Medicinal Chemistry

Privileged structures have been widely used as an effective template in medicinal chemistry for drug discovery. Chalcone is a common simple scaffold found in many naturally occurring compounds. Many chalcone derivatives have also been prepared due to their convenient synthesis. These natural products and synthetic compounds have shown numerous interesting biological activities with clinical potentials against various diseases. This review aims to highlight the recent evidence of chalcone as a privileged scaffold in medicinal chemistry. Multiple aspects of chalcone will be summarized herein, including the isolation of novel chalcone derivatives, the development of new synthetic methodologies, the evaluation of their biological properties, and the exploration of the mechanisms of action as well as target identification. This review is expected to be a comprehensive, authoritative, and critical review of the chalcone template to the chemistry community.

Xanthohumol Modulates Calcium Signaling in Rat Ventricular Myocytes: Possible Antiarrhythmic Properties

Cardiac arrhythmia is a major cause of mortality in cardiovascular pathologies. A host of drugs targeted to sarcolemmal Na⁺, Ca²⁺, and K⁺ channels has had limited success clinically. Recently, Ca²⁺ signaling has been target of pharmacotherapy based on finding that leaky ryanodine receptors elevate local Ca²⁺ concentrations causing membrane depolarizations that trigger arrhythmias. In this study, we report that xanthohumol, an antioxidant extracted from hops showing therapeutic effects in other pathologies, suppresses aberrant ryanodine receptor Ca²⁺ release. The effects of xanthohumol (5-1000 nM) on Ca²⁺ signaling pathways were probed in isolated rat ventricular myocytes incubated with Fluo-4 AM using the perforated patch-clamp technique. We found that 5-50 nM xanthohumol reduced the frequency of spontaneously occurring Ca²⁺ sparks (>threefold) and Ca²⁺ waves in control myocytes and in cells subjected to Ca²⁺ overload caused by the following: 1) exposure to low K⁺ solutions, 2) periods of high frequency electrical stimulation, 3) exposures to isoproterenol, or 4) caffeine. At room temperatures, 50-100 nM xanthohumol reduced the rate of relaxation of electrically- or caffeine-triggered Ca²⁺transients, without suppressing I_Ca, but this effect was small and reversed by isoproterenol at physiologic temperatures. Xanthohumol also suppressed the Ca²⁺ content of the SR and its rate of recirculation. The stabilizing effects of xanthohumol on the frequency of spontaneously triggered Ca²⁺ sparks and waves combined with its antioxidant properties, and lack of significant effects on Na⁺ and Ca²⁺ channels, may provide this compound with clinically desirable antiarrhythmic properties.

Synthesis, characterization, and antioxidant activity of Zn2+ and Cu2+ coordinated polyhydroxychalcone complexes

ABSTRACT

Four new metal complexes [Cu(ISO)₂], [Cu(BUT)₂] and [Zn(ISO)₂], [Zn(BUT)₂] of the polyhydroxychalcones (isoliquiritigenin and butein) are synthesized, structurally characterized and their antioxidant activity is investigated. The formation of the complexes [Cu(ISO)₂] and [Zn(ISO)₂] is followed by Job's plot using NMR titration. The resulting compounds are characterized by mass spectrometry, IR spectroscopy, and elemental analysis. Studies on the radical scavenging activity are performed using DPPH as substrate. The results showed that the antioxidant activities of isoliquiritigenin and butein are enhanced after binding to copper or zinc.

GRAPHICAL ABSTRACT

Characterization of hepatitis E virus infection in tree shrew (Tupaia belangeri chinensis)

Background

Hepatitis E virus (HEV) is a major cause of hepatitis in developing countries and poses a threat to public health worldwide. Tree shrew (Tupaia belangeri chinensis) is a useful animal model in studies on hepatitis viruses, such as hepatitis B and C viruses. However, the use of this animal model for HEV research is yet to be developed.

Methods

Tree shrews were intravenously (IV) injected with swine genotype 4 HEV or infected by contact-exposure to IV infected tree shrews. RT-nPCR was performed to detect HEV RNA in the feces, tissues, and blood. HEV capsid protein in the different tissues was detected by Western blot and estimated by quantitative RT-PCR. Anti-HEV antibodies were determined by ELISA. Liver damages were evaluated by histopathologic examination and analysis of liver-specific enzymes activities.

Results

Both negative and positive strands of HEV RNA were detected in the feces of the HEV-infected or contact-exposed tree shrews 3–4 days post-inoculation. HEV RNA was detectable in the liver, spleen, kidneys, and bile. Virusemia developed in all the HEV-infected tree shrews. HEV capsid protein was expressed in the liver, spleen, and kidneys. The histological examination and analysis of liver-specific enzymes activities showed that HEV caused acute liver lesions in the tree shrews. Meanwhile, the infected tree shrews showed positive IgG and IgM antibodies.

Conclusions

Tree shrews are susceptible to HEV and may be useful animal models for HEV experimental infection studies on pathogenesis or preclinical drug development.

The chalcone compound isosalipurposide (ISPP) exerts a cytoprotective effect against oxidative injury via Nrf2 activation

The chalcone compound isosalipurposide (ISPP) has been successfully isolated from the native Korean plant species Corylopsis coreana Uyeki (Korean winter hazel). However, the therapeutic efficacy of ISPP remains poorly understood. This study investigated whether ISPP has the capacity to activate NF-E2-related factor (Nrf2)-antioxidant response element (ARE) signaling and induce its target gene expression, and to determined the protective role of ISPP against oxidative injury of hepatocytes. In HepG2 cells, nuclear translocation of Nrf2 is augmented by ISPP treatment. Consistently, ISPP increased ARE reporter gene activity and the protein levels of glutamate cysteine ligase (GCL) and hemeoxygenase (HO-1), resulting in increased intracellular glutathione levels. Cells pretreated with ISPP were rescued from tert-butylhydroperoxide-induced reactive oxygen species (ROS) production and glutathione depletion and consequently, apoptotic cell death. Moreover, ISPP ameliorated the mitochondrial dysfunction and apoptosis induced by rotenone which is an inhibitor of complex 1 of the mitochondrial respiratory chain. The specific role of Nrf2 activation by ISPP was demonstrated using an ARE-deletion mutant plasmid and Nrf2-knockout cells. Finally, we observed that extracellular signal-regulated kinase (ERK) and AMP-activated protein kinase (AMPK), but not protein kinase C (PKC)-δ or other mitogen-activated protein kinases (MAPKs), are involved in the activation of Nrf2 by ISPP. Taken together, our results demonstrate that ISPP has a cytoprotective effect against oxidative damage mediated through Nrf2 activation and induction of its target gene expression in hepatocytes.

Xanthohumol inhibits Notch signaling and induces apoptosis in hepatocellular carcinoma

Despite improvement in therapeutic strategies, median survival in advanced hepatocellular carcinoma (HCC) remains less than one year. Therefore, molecularly targeted compounds with less toxic profiles are needed. Xanthohumol (XN), a prenylated chalcone has been shown to have anti-proliferative effects in various cancers types in vitro. XN treatment in healthy mice and humans yielded favorable pharmacokinetics and bioavailability. Therefore, we determined to study the effects of XN and understand the mechanism of its action in HCC. The effects of XN on a panel of HCC cell lines were assessed for cell viability, colony forming ability, and cellular proliferation. Cell lysates were analyzed for pro-apoptotic (c-PARP and cleaved caspase-3) and anti-apoptotic markers (survivin, cyclin D1, and Mcl-1). XN concentrations of 5μM and above significantly reduced the cell viability, colony forming ability and also confluency of all four HCC cell lines studied. Furthermore, growth suppression due to apoptosis was evidenced by increased expression of pro-apoptotic and reduced expression of anti-apoptotic proteins. Importantly, XN treatment inhibited the Notch signaling pathway as evidenced by the decrease in the expression of Notch1 and HES-1 proteins. Ectopic expression of Notch1 in HCC cells reverses the anti-proliferative effect of XN as evidenced by reduced growth suppression compared to control. Taken together these results suggested that XN mediated growth suppression is appeared to be mediated by the inhibition of the Notch signaling pathway. Therefore, our findings warrants further studies on XN as a potential agent for the treatment for HCC.

The hop constituent xanthohumol exhibits hepatoprotective effects and inhibits the activation of hepatic stellate cells at different levels

Xanthohumol is the principal prenylated flavonoid of the female inflorescences of the hop plant. In recent years, various beneficial xanthohumol effects including anti-inflammatory, antioxidant, hypoglycemic activities, and anticancer effects have been revealed. This review summarizes present studies indicating that xanthohumol also inhibits several critical pathophysiological steps during the development and course of chronic liver disease, including the activation and pro-fibrogenic genotype of hepatic stellate cells. Also the various mechanism of action and molecular targets of the beneficial xanthohumol effects will be described. Furthermore, the potential use of xanthohumol or a xanthohumol-enriched hop extract as therapeutic agent to combat the progression of chronic liver disease will be discussed. It is notable that in addition to its hepatoprotective effects, xanthohumol also holds promise as a therapeutic agent for treating obesity, dysregulation of glucose metabolism and other components of the metabolic syndrome including hepatic steatosis. Thus, therapeutic xanthohumol application appears as a promising strategy, particularly in obese patients, to inhibit the development as well as the progression of non-alcoholic fatty liver disease.

Experimental infection of tree shrews (Tupaia belangeri) with Coxsackie virus A16

Coxsackie virus A16 (CA16) is commonly recognized as one of the main human pathogens of hand-foot-mouth disease (HFMD). The clinical manifestations of HFMD include vesicles of hand, foot and mouth in young children and severe inflammatory CNS lesions. In this study, experimentally CA16 infected tree shrews (Tupaia belangeri) were used to investigate CA16 pathogenesis. The results showed that both the body temperature and the percentages of blood neutrophilic granulocytes / monocytes of CA16 infected tree shrews increased at 4-7 days post infection. Dynamic distributions of CA16 in different tissues and stools were found at different infection stages. Moreover, the pathological changes in CNS and other organs were also observed. These findings indicate that tree shrews can be used as a viable animal model to study CA16 infection.

Pharmacological profile of xanthohumol, a prenylated flavonoid from hops (Humulus lupulus)

The female inflorescences of hops (Humulus lupulus L.), a well-known bittering agent used in the brewing industry, have long been used in traditional medicines. Xanthohumol (XN) is one of the bioactive substances contributing to its medical applications. Among foodstuffs XN is found primarily in beer and its natural occurrence is surveyed. In recent years, XN has received much attention for its biological effects. The present review describes the pharmacological aspects of XN and summarizes the most interesting findings obtained in the preclinical research related to this compound, including the pharmacological activity, the pharmacokinetics, and the safety of XN. Furthermore, the potential use of XN as a food additive considering its many positive biological effects is discussed.

Tupaia belangeri as an experimental animal model for viral infection

Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development.

Hepatitis C virus infection and related liver disease: the quest for the best animal model

Hepatitis C virus (HCV) is a major cause of cirrhosis and hepatocellular carcinoma (HCC) making the virus the most common cause of liver failure and transplantation. HCV is estimated to chronically affect 130 million individuals and to lead to more than 350,000 deaths per year worldwide. A vaccine is currently not available. The recently developed direct acting antivirals (DAAs) have markedly increased the efficacy of the standard of care but are not efficient enough to completely cure all chronically infected patients and their toxicity limits their use in patients with advanced liver disease, co-morbidity or transplant recipients. Because of the host restriction, which is limited to humans and non-human primates, in vivo study of HCV infection has been hampered since its discovery more than 20 years ago. The chimpanzee remains the most physiological model to study the innate and adaptive immune responses, but its use is ethically difficult and is now very restricted and regulated. The development of a small animal model that allows robust HCV infection has been achieved using chimeric liver immunodeficient mice, which are therefore not suitable for studying the adaptive immune responses. Nevertheless, these models allowed to go deeply in the comprehension of virus-host interactions and to assess different therapeutic approaches. The immunocompetent mouse models that were recently established by genetic humanization have shown an interesting improvement concerning the study of the immune responses but are still limited by the absence of the complete robust life cycle of the virus. In this review, we will focus on the relevant available animal models of HCV infection and their usefulness for deciphering the HCV life cycle and virus-induced liver disease, as well as for the development and evaluation of new therapeutics. We will also discuss the perspectives on future immunocompetent mouse models and the hurdles to their development.