Mangosteen xanthones suppress hepatitis C virus genome replication

Roseoside Is a Bioactive Compound in Kirengeshoma koreana Nakai Extract with Potent In Vitro Antiviral Activity Against Hepatitis C Virus

Hepatitis C virus (HCV) is a pathogen that causes cirrhosis and hepatocellular carcinoma through chronic hepatitis C. This study focused on the anti-HCV activity of a 70% ethanol extract of Kirengeshoma koreana Nakai (KKE) and its bioactive chemical constituent(s). The KKE and its n-butanol (n-BuOH) fraction induced a significant reduction in HCV RNA levels without inducing cytotoxicity. A high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis revealed the presence of roseoside in the n-butanol fraction of the KKE, which inhibited HCV RNA replication in a concentration- and time-dependent manner without exerting cytotoxicity. Consistent with in silico molecular docking analysis data, roseoside targets and inhibits HCV NS5A/B replicase. Collectively, our findings demonstrate that roseoside is a chemical constituent in KKE that interferes with HCV replication by targeting NS5A/B replicase.

Identification of new benzofuran derivatives as STING agonists with broad-spectrum antiviral activity

The Stimulator of Interferon Genes (STING) is involved in cytosolic DNA sensing and type I Interferons (IFN-I) induction. Aiming to identify new STING agonists with antiviral activity and given the known biological activity of benzothiazole and benzimidazole derivatives, a series of benzofuran derivatives were tested for their ability to act as STING agonists, induce IFN-I and inhibit viral replication. Compounds were firstly evaluated in a gene reporter assay measuring luciferase activity driven by the human IFN-β promoter in cells expressing exogenous STING (HEK293T). Seven of them were able to induce IFN-β transcription while no induction of the IFN promoter was observed in the presence of a mutated and inactive STING, showing specific protein-ligand interaction. Docking studies were performed to predict their putative binding mode. The best hit compounds were then tested on human coronavirus 229E replication in BEAS-2B and MRC-5 cells and three derivatives showed EC50 values in the μM range. Such compounds were also tested on SARS-CoV-2 replication in BEAS-2B cells and in Calu-3 showing they can inhibit SARS-CoV-2 replication at nanomolar concentrations. To further confirm their IFN-dependent antiviral activity, compounds were tested to verify their effect on phospho-IRF3 nuclear localization, that was found to be induced by benzofuran derivatives, and SARS-CoV-2 replication in Vero E6 cells, lacking IFN production, founding them to be inactive. In conclusion, we identified benzofurans as STING-dependent immunostimulatory compounds and host-targeting inhibitors of coronaviruses representing a novel chemical scaffold for the development of broad-spectrum antivirals.

Drugs targeting structural and nonstructural proteins of the chikungunya virus: A review

Chikungunya virus (CHIKV) is a single positive-stranded RNA virus of the Togaviridae family and Alphavirus genus, with a typical lipid bilayer envelope structure, and is the causative agent of human chikungunya fever (CHIKF). The U.S. Food and Drug Administration has recently approved the first chikungunya vaccine, Ixchiq; however, vaccination rates are low, and CHIKF is prevalent owing to its periodic outbreaks. Thus, developing effective anti-CHIKV drugs in clinical settings is imperative. Viral proteins encoded by the CHIKV genome play vital roles in all stages of infection, and developing therapeutic agents that target these CHIKV proteins is an effective strategy to improve CHIKF treatment efficacy and reduce mortality rates. Therefore, in the present review article, we aimed to investigate the basic structure, function, and replication cycle of CHIKV and comprehensively outline the current status and future advancements in anti-CHIKV drug development, specifically targeting nonstructural (ns) proteins, including nsP1, nsP2, nsP3, and nsP4 and structural proteins such as capsid (C), E3, E2, 6K, and E1.

Identification, characterization and quantification of xanthones from Fridericia formosa leaves extract with antiviral activity

Fridericia formosa (Bureau) L.G. Lohmann (Bignonaceae) is a neotropical liana species found in the Cerrado biome in Brazil. It has been of great interest to the scientific community due to its potential as a source of new antivirals, including xanthones derived from mangiferin. In this context, the present study aimed to characterize and quantify the xanthones present in the ethanol extract of this species using high performance liquid chromatography. Additionally, the antiviral activity against Chikungunya, Zika, and Mayaro viruses was evaluated. The chromatographic analyses partially identified twenty-six xanthones, among which only fourteen had already been described in the literature. The xanthones mangiferin, 2'-O-trans-caffeoylmangiferin, and 2'-O-trans-coumaroylmangiferin, are present in higher quantities in the extract, at concentrations of 9.65%, 10.68%, and 3.41% w/w, respectively. In antiviral assays, the extract inhibited the multiplication cycle only for the Mayaro virus with a CE50 of 36.1 μg/mL. Among the isolated xanthones, 2'-O-trans-coumaroylmangiferin and 2'-O-trans-cinnamoylmangiferin inhibited the viral cytopathic effect with CE50 values of 180.6 and 149.4 μg/mL, respectively. Therefore, the extract from F. formosa leaves, which has a high content of xanthones, has antiviral potential and can be a source of new mangiferin derivatives.

Therapeutic approaches for chronic hepatitis C: a concise review

Hepatitis C virus (HCV) infection is a significant global health concern, prompting the need for effective treatment strategies. This in-depth review critically assesses the landscape of HCV treatment, drawing parallels between traditional interferon/ribavirin therapy historically pivotal in HCV management and herbal approaches rooted in traditional and complementary medicine. Advancements in therapeutic development and enhanced clinical outcomes axis on a comprehensive understanding of the diverse HCV genome, its natural variations, pathogenesis, and the impact of dietary, social, environmental, and economic factors. A thorough analysis was conducted through reputable sources such as Science Direct, PubMed, Scopus, Web of Science, books, and dissertations. This review primarily focuses on the intricate nature of HCV genomes and explores the potential of botanical drugs in both preventing and treating HCV infections.

Targeting ferroptosis with natural products in liver injury: new insights from molecular mechanisms to targeted therapies

BACKGROUND

Ferroptosis is a brand-new type of controlled cell death that is distinguished by its reliance on iron and the production of lipid peroxidation. The role of ferroptosis in damaging liver disorders has attracted a lot of attention in recent years. One effective strategy to reduce liver damage is to target ferroptosis.

PURPOSE

The purpose of this review is to clarify the connection between ferroptosis and liver damage and to look into the potential contribution of natural products to the clinical management of liver damage and the discovery of novel medications.

METHODS

To study the methods by which natural products operate on ferroptosis to cure liver damage and their main signaling pathways, we searched databases from the time of initial publication to August 2023 in PubMed, EMBASE, Web of Science, Ovid, ScienceDirect, and China National Knowledge Infrastructure. The liver illness that each natural product treats is categorized and summarized. It's interesting to note that several natural compounds, such Artemether, Fucoidan sulfate, Curcumin, etc., have the benefit of having many targets and multiple pathways of action.

RESULTS

We saw that in human samples or animal models of liver injury, ferroptosis indicators were activated, lipid peroxidation levels were elevated, and iron inhibitors had the ability to reduce liver damage. Liver damage can be treated with natural products by regulating ferroptosis. This is mostly accomplished through the modulation of Nrf2-related pathways (e.g., Conclusions and Astaxanthin), biological enzymes like GPX4 and the SIRT family (e.g., Chrysophanol and Decursin), and transcription factors like P53 (e.g., Artemether and Zeaxanthin).

CONCLUSIONS

This review proposes a promising path for the therapeutic therapy of liver damage by providing a theoretical foundation for the management of ferroptosis utilizing natural ingredients.

Unlocking STING as a Therapeutic Antiviral Strategy

Invading pathogens have developed weapons that subvert physiological conditions to weaken the host and permit the spread of infection. Cells, on their side, have thus developed countermeasures to maintain cellular physiology and counteract pathogenesis. The cyclic GMP-AMP (cGAMP) synthase (cGAS) is a pattern recognition receptor that recognizes viral DNA present in the cytosol, activating the stimulator of interferon genes (STING) protein and leading to the production of type I interferons (IFN-I). Given its role in innate immunity activation, STING is considered an interesting and innovative target for the development of broad-spectrum antivirals. In this review, we discuss the function of STING; its modulation by the cellular stimuli; the molecular mechanisms developed by viruses, through which they escape this defense system; and the therapeutical strategies that have been developed to date to inhibit viral replication restoring STING functionality.

The Phytochemical α-Mangostin Inhibits Cervical Cancer Cell Proliferation and Tumor Growth by Downregulating E6/E7-HPV Oncogenes and KCNH1 Gene Expression

Cervical cancer is the fourth most common cancer among women worldwide. The main factor associated with the onset and progression of this neoplasia is the human papillomavirus (HPV) infection. The HPV-oncogenes E6 and E7 are critical drivers of cellular transformation, promoting the expression of oncogenes such as KCNH1. The phytochemical α-mangostin (AM) is a potent antineoplastic and antiviral compound. However, its effects on HPV oncogenes and KCNH1 gene expression remain unknown. This study evaluated the effects of AM on cell proliferation, cell cycle distribution and gene expression, including its effects on tumor growth in xenografted mice. AM inhibited cell proliferation in a concentration-dependent manner, being the most sensitive cell lines those with the highest number of HPV16 copies. In addition, AM promoted G1-cell cycle arrest in CaSki cells, while led to cell death in SiHa and HeLa cells. Of interest was the finding of an AM-dependent decreased gene expression of E6, E7 and KCNH1 both in vitro and in vivo, as well as the modulation of cytokine expression, Ki-67, and tumor growth inhibition. On these bases, we suggest that AM represents a good option as an adjuvant for the treatment and prevention of cervical cancer.

Alpha-mangostin inhibits viral replication and suppresses nuclear factor kappa B (NF-κB)-mediated inflammation in dengue virus infection

Severe dengue virus (DENV) infection results from viral replication and dysregulated host immune response, which trigger massive cytokine production/cytokine storm. The result is severe vascular leakage, hemorrhagic diathesis, and organ dysfunction. Subsequent to previously proposing that an ideal drug for treatment of DENV infection should efficiently inhibit both virus production and cytokine storm, we discovered that α-mangostin (α-MG) from the pericarp of the mangosteen fruit could inhibit both DENV infection and cytokine/chemokine production. In this study, we investigated the molecular mechanisms underlying the antiviral and anti-inflammatory effects of α-MG. Time-of-drug-addition and time-of-drug-elimination studies suggested that α-MG inhibits the replication step of the DENV life cycle. α-MG inhibited polymerization activity of RNA-dependent RNA polymerase (RdRp) with IC50 values of 16.50 μM and significantly reduced viral RNA and protein syntheses, and virion production. Antiviral and cytokine/chemokine gene expression profiles of α-MG-treated DENV-2-infected cells were investigated by polymerase chain reaction array. α-MG suppressed the expression of 37 antiviral and cytokine/chemokine genes that relate to the NF-κB signaling pathway. Immunofluorescence and immunoblot analyses revealed that α-MG inhibits NF-κB nuclear translocation in DENV-2-infected cells in association with reduced RANTES, IP-10, TNF-α, and IL-6 production. These results suggest α-MG as a potential treatment for DENV infection.

The long and stumble way to find potential active compounds from plants for defeating hepatitis B and C: review

Hepatitis is a liver illness caused by virus such as hepatitis A virus, hepatitis B virus and hepatitis C virus. Hepatitis B and C are considerably more usual and induce more cirrhosis and dead worldwide than hepatitis A. Although drugs that are currently often used in the medication of hepatitis B and C, the finding of recent drug from various resources including herbal has been intensively developed. Therefore, the purpose of this review is to consider the possibility of plant’s compounds as anti-HBV and anti-HCV. From the results of a review of several articles, several plant’s compound have shown effectiveness againts HBV and HCV by in silico, in vitro and in vivo studies. In conclusion, several plant’s active compounds are possibility to be developed as anti-hepatitis B and C.

Computer Aided Drug Design Methodologies with Natural Products in the Drug Research Against Alzheimer's Disease

Natural products are compounds isolated from plants that provide a variety of lead structures for the development of new drugs by the pharmaceutical industry. The interest in these substances increases because of their beneficial effects on human health. Alzheimer's disease (AD) affects occur in about 80% of individuals aged 65 years. AD, the most common cause of dementia in elderly people, is characterized by progressive neurodegenerative alterations, as decrease of cholinergic impulse, increased toxic effects caused by reactive oxygen species and the inflammatory process that the amyloid plaque participates. In silico studies is relevant in the process of drug discovery; through technological advances in the areas of structural characterization of molecules, computational science and molecular biology have contributed to the planning of new drugs used against neurodegenerative diseases. Considering the social impairment caused by an increased incidence of disease and that there is no chemotherapy treatment effective against AD; several compounds are studied. In the researches for effective neuroprotectants as potential treatments for Alzheimer's disease, natural products have been extensively studied in various AD models. This study aims to carry out a literature review with articles that address the in silico studies of natural products aimed at potential drugs against Alzheimer's disease (AD) in the period from 2015 to 2021.

An in vitro study of an Artocarpus heterophyllus substance as a hepatitis C antiviral and its combination with current anti-HCV drugs

Background

Current therapy of chronic hepatitis C virus (HCV) with direct-acting antivirals (DAAs) has dramatically improved the sustained virologic response (SVR) of affected patients; however, treatment with DAAs remains expensive, and drug-resistant HCV variants remain a threat. As a result, there is still a need to continue to develop affordable and effective drugs for the treatment of HCV. Previously, we have demonstrated that a crude extract from Artocarpus heterophyllus leaves is a potential anti-HCV candidate. In this study, we have further purified this crude extract, examined which sub-fraction possesses the highest antiviral activity, and then explored its efficacy at different HCV life cycle stages. We also assessed synergistic antiviral effects between the A. heterophyllus extract and commercially available anti-HCV drugs.

Methods

We used vacuum liquid chromatography (VLC) and high-performance liquid chromatography (HPLC) to fractionate a dichloromethane extract of A. heterophyllus leaves. We then examined the anti-HCV activity of the fractions using HCV genotype 2a, JFH1a; the antiviral mode of action was determined by exploring adding the treatments at different times. We examined the antiviral effects on the viral entry stage through a virucidal activity test, viral adsorption examination, and pretreatment of cells with the drug. The effects on the post-viral entry stage were determined by the levels of HCV protein expression and HCV RNA expression in infected cells.

Results

Through activity guided purification, we identified the sub-fraction FR3T3 as possessing the most robust anti-HCV activity with an IC₅₀ value of 4.7 ± 1.0 μg/mL. Mode-of-action analysis revealed that FR3T3 inhibited post-viral entry stages such as HCV NS3 protein expression and HCV RNA replication with marginal effects on the viral entry stage. Thin-layer Chromatography (TLC) indicated that FR3T3 contained terpenoids and chlorophyll-related compounds. We also found a synergistic antiviral activity when the DCM extract of A. heterohyllus was used in combination therapy with commercial anti-HCV drugs; Ribavirin, Simeprevir, Cyclosporin A.

Conclusions

The extract of A. heterophyllus and its sub-fraction, FR3T3, presented here have anti-HCV activities and could be candidate drugs for add-on-therapy for treatment of chronic HCV infections.

In Vitro Antiviral Activity of α-Mangostin against Dengue Virus Serotype-2 (DENV-2)

Dengue virus (DENV), a member of the family Flaviviridae, is a threat for global health as it infects more than 100 million people yearly. Approved antiviral therapies or vaccines for the treatment or prevention of DENV infections are not available. In the present study, natural compounds were screened for their antiviral activity against DENV by in vitro cell line-based assay. α-Mangostin, a xanthanoid, was observed to exert antiviral activity against DENV-2 under pre-, co- and post-treatment testing conditions. The antiviral activity was determined by foci forming unit (FFU) assay, quantitative RT-PCR and cell-based immunofluorescence assay (IFA). A complete inhibition of DENV-2 was observed at 8 µM under the co-treatment condition. The possible inhibitory mechanism of α-Mangostin was also determined by docking studies. The molecular docking experiments indicate that α-Mangostin can interact with multiple DENV protein targets such as the NS5 methyltransferase, NS2B-NS3 protease and the glycoprotein E. The in vitro and in silico findings suggest that α-Mangostin possesses the ability to suppress DENV-2 production at different stages of its replication cycle and might act as a prophylactic/therapeutic agent against DENV-2.

Alpha-mangostin inhibits dengue virus production and pro-inflammatory cytokine/chemokine expression in dendritic cells

Dengue virus (DENV) is transmitted to humans via the bite of an Aedes mosquito, causing dengue fever, dengue hemorrhagic fever, or dengue shock syndrome. In the human skin, DENV first infects keratinocytes, dendritic cells, and macrophages. Monocytes that are recruited to the site of infection and differentiate into monocyte-derived dendritic cells (moDCs) are also infected by DENV. DENV-infected DCs secrete pro-inflammatory cytokines and chemokines to modulate the immune response. The viral load and massive pro-inflammatory cytokine/chemokine production, referred to as a 'cytokine storm', are associated with disease severity. We propose that an ideal drug for treatment of DENV infection should inhibit both virus production and the cytokine storm, and previously, we reported that alpha-mangostin (α-MG) inhibits both DENV replication and cytokine production in hepatocytes. However, the effect of α-MG on DENV-infected moDCs remains unknown. In this study, we investigated the effects of α-MG on DENV infection and pro-inflammatory cytokine/chemokine production in primary moDCs generated ex vivo from monocytes of healthy individuals. α-MG at the non-toxic concentrations of 20 and 25 μM reduced DENV production by more than 10-fold and 1,000-fold, respectively. Treatment with α-MG efficiently inhibited the infection of immature moDCs by all four serotypes of DENV. Time-of-addition studies suggested that α-MG (25 μM) inhibits DENV at the early stage of replication. In addition, α-MG markedly reduced cytokine/chemokine (TNF-α, CCL4, CCL5, CXCL10, IL6, IL1β, IL10, and IFN-α) transcription in DENV-infected immature moDCs. These findings suggest the potential of α-MG to be developed as a novel anti-DENV drug.

In vitro and in vivo studies reveal α-Mangostin, a xanthonoid from Garcinia mangostana, as a promising natural antiviral compound against chikungunya virus

Background

Chikungunya virus (CHIKV), a serious health problem in several tropical countries, is the causative agent of chikungunya fever. Approved antiviral therapies or vaccines for the treatment or prevention of CHIKV infections are not available. As diverse natural phenolic compounds have been shown to possess antiviral activities, we explored the antiviral activity of α-Mangostin, a xanthanoid, against CHIKV infection.

Methods

The in vitro prophylactic and therapeutic effects of α-Mangostin on CHIKV replication in Vero E6 cells were investigated by administering it under pre, post and cotreatment conditions. The antiviral activity was determined by foci forming unit assay, quantitative RT-PCR and cell-based immune-fluorescence assay. The molecular mechanism of inhibitory action was further proposed using in silico molecular docking studies.

Results

In vitro studies revealed that 8 µM α-Mangostin completely inhibited CHIKV infectivity under the cotreatment condition. CHIKV replication was also inhibited in virus-infected mice. This is the first in vivo study which clearly showed that α-Mangostin is effective in vivo by significantly reducing virus replication in serum and muscles. Molecular docking indicated that α-Mangostin can efficiently interact with the E2–E1 heterodimeric glycoprotein and the ADP-ribose binding cavity of the nsP3 macrodomain.

Conclusions

The findings suggest that α-Mangostin can inhibit CHIKV infection and replication through possible interaction with multiple CHIKV target proteins and might act as a prophylactic/therapeutic agent against CHIKV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01517-z.

Natural products for the management of the hepatitis C virus: a biochemical review

Chronic hepatitis C virus (HCV) infection is a significant public health problem, with a worldwide prevalence of approximately 170 million. Current therapy for HCV infection includes the prolonged administration of a combination of ribavirin and PEGylated interferon-α, for over a decade. This regimen is expensive and often associated with a poor antiviral response and unwanted side effects. A highly effective combination treatment is likely required for the future management of HCV infections and entry inhibitors could play an important role. Currently, no entry inhibitor has been licensed for the prophylactic treatment of hepatitis C. Therefore, additional agents that combat HCV infection are urgently needed and must be developed. Many phytochemical constituents have been identified that display considerable inhibition of HCV at some stage of the life cycle. This review will summarise the current state of knowledge on natural products and their possible activities in the context of HCV infection.

Recent update on anti-dengue drug discovery

Dengue is the most important arthropod-borne viral disease of humans, with more than half of the global population living in at-risk areas. Despite the negative impact on public health, there are no antiviral therapies available, and the only licensed vaccine, Dengvaxia^®, has been contraindicated in children below nine years of age. In an effort to combat dengue, several small molecules have entered into human clinical trials. Here, we review anti-DENV molecules and their drug targets that have been published within the past five years (2014-2018). Further, we discuss their probable mechanisms of action and describe a role for classes of clinically approved drugs and also an unclassified class of anti-DENV agents. This review aims to enhance our understanding of novel agents and their cognate targets in furthering innovations in the use of small molecules for dengue drug therapies.

Targeting Metabolic Reprogramming by Influenza Infection for Therapeutic Intervention

Influenza is a worldwide health and financial burden posing a significant risk to the immune-compromised, obese, diabetic, elderly, and pediatric populations. We identified increases in glucose metabolism in the lungs of pediatric patients infected with respiratory pathogens. Using quantitative mass spectrometry, we found metabolic changes occurring after influenza infection in primary human respiratory cells and validated infection-associated increases in c-Myc, glycolysis, and glutaminolysis. We confirmed these findings with a metabolic drug screen that identified the PI3K/mTOR inhibitor BEZ235 as a regulator of infectious virus production. BEZ235 treatment ablated the transient induction of c-Myc, restored PI3K/mTOR pathway homeostasis measured by 4E-BP1 and p85 phosphorylation, and reversed infection-induced changes in metabolism. Importantly, BEZ235 reduced infectious progeny but had no effect on the early stages of viral replication. BEZ235 significantly increased survival in mice, while reducing viral titer. We show metabolic reprogramming of host cells by influenza virus exposes targets for therapeutic intervention.

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.

Alpha-mangostin inhibits both dengue virus production and cytokine/chemokine expression

Since severe dengue virus (DENV) infection in humans associates with both high viral load and massive cytokine production - referred to as "cytokine storm", an ideal drug for treatment of DENV infection should efficiently inhibit both virus production and cytokine expression. In searching for such an ideal drug, we discovered that α-mangostin (α-MG), a major bioactive compound purified from the pericarp of the mangosteen fruit (Garcinia mangostana Linn), which has been used in traditional medicine for several conditions including trauma, diarrhea, wound infection, pain, fever, and convulsion, inhibits both DENV production in cultured hepatocellular carcinoma HepG2 and Huh-7 cells, and cytokine/chemokine expression in HepG2 cells. α-MG could also efficiently inhibit all four serotypes of DENV. Treatment of DENV-infected cells with α-MG (20μM) significantly reduced the infection rates of four DENV serotypes by 47-55%. α-MG completely inhibited production of DENV-1 and DENV-3, and markedly reduced production of DENV-2 and DENV-4 by 100 folds. Furthermore, it could markedly reduce cytokine (IL-6 and TNF-α) and chemokine (RANTES, MIP-1β, and IP-10) transcription. These actions of α-MG are more potent than those of antiviral agent (ribavirin) and anti-inflammatory drug (dexamethasone). Thus, α-MG is potential to be further developed as therapeutic agent for DENV infection.

Promising Anti-Hepatitis C Virus Compounds from Natural Resources

Hepatitis C virus (HCV) infection is a major worldwide problem, which involves approximately 170 million people. High morbidity of patients is caused by chronic infection, which leads to liver cirrhosis, hepatocellular carcinoma and other HCV-related diseases. The sustained virological response (SVR) has been markedly improved to be >90% by the current standard interferon (IFN)-free treatment regimens with a combination of direct-acting antiviral agents (DAAs) targeting the viral NS3 protease, NS5A multi-function protein and NS5B RNA-dependent RNA polymerase, compared with 50–70% of SVR rates achieved by the previous standard IFN-based treatment regimens with or without an NS3 protease inhibitor. However, the emergence of DAA-resistant HCV strains and the limited access to the DAAs due to their high cost could be major concerns. Also, the long-term prognosis of patients treated with DAAs, such as the possible development of hepatocellular carcinoma, still needs to be further evaluated. Natural resources are considered to be good candidates to develop anti-HCV agents. Here, we summarize anti-HCV compounds obtained from natural resources, including medicinal plant extracts, their isolated compounds and some of their derivatives that possess high antiviral potency against HCV.

Natural compounds isolated from Brazilian plants are potent inhibitors of hepatitis C virus replication in vitro

Compounds extracted from plants can provide an alternative approach to new therapies. They present characteristics such as high chemical diversity, lower cost of production and milder or inexistent side effects compared with conventional treatment. The Brazilian flora represents a vast, largely untapped, resource of potential antiviral compounds. In this study, we investigate the antiviral effects of a panel of natural compounds isolated from Brazilian plants species on hepatitis C virus (HCV) genome replication. To do this we used firefly luciferase-based HCV sub-genomic replicons of genotypes 2a (JFH-1), 1b and 3a and the compounds were assessed for their effects on both HCV replication and cellular toxicity. Initial screening of compounds was performed using the maximum non-toxic concentration and 4 compounds that exhibited a useful therapeutic index (favourable ratio of cytotoxicity to antiviral potency) were selected for extra analysis. The compounds APS (EC50=2.3μM), a natural alkaloid isolated from Maytrenus ilicifolia, and the lignans 3(∗)43 (EC50=4.0μM), 3(∗)20 (EC50=8.2μM) and 5(∗)362 (EC50=38.9μM) from Peperomia blanda dramatically inhibited HCV replication as judged by reductions in luciferase activity and HCV protein expression in both the subgenomic and infectious systems. We further show that these compounds are active against a daclatasvir resistance mutant subgenomic replicon. Consistent with inhibition of genome replication, production of infectious JFH-1 virus was significantly reduced by all 4 compounds. These data are the first description of Brazilian natural compounds possessing anti-HCV activity and further analyses are being performed in order to investigate the mode of action of those compounds.

α-Mangostin induces G1 cell cycle arrest in HCT116 cells through p38MAPK-p16INK4a pathway

α-Mangostin (α-MG), one of the active substances inGarcinia mangostana, has been shown to exhibit anti-cancer effects in HCT116 colon cancer cells.