Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates.

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.

Mitochondria in the biology, pathogenesis, and treatment of hepatitis virus infections.

Hepatitis virus infections affect a large proportion of the global population. The host responds rapidly to viral infection by orchestrating a variety of cellular machineries, in particular, the mitochondrial compartment. Mitochondria actively regulate viral infections through modulation of the cellular innate immunity and reprogramming of metabolism. In turn, hepatitis viruses are able to modulate the morphodynamics and functions of mitochondria, but the mode of actions are distinct with respect to different types of hepatitis viruses. The resulting mutual interactions between viruses and mitochondria partially explain the clinical presentation of viral hepatitis, influence the response to antiviral treatment, and offer rational avenues for novel therapy. In this review, we aim to consider in depth the multifaceted interactions of mitochondria with hepatitis virus infections and emphasize the implications for understanding pathogenesis and advancing therapeutic development.

Direct-Acting Antiviral Therapy Restores Immune Tolerance to Patients With Hepatitis C Virus-Induced Cryoglobulinemia Vasculitis.

BACKGROUND & AIMS: Interferon-free direct-acting antiviral (DAA) therapies are effective in patients with hepatitis C virus-induced cryoglobulinemia vasculitis (HCV-CV). We analyzed blood samples from patients with HCV-CV before and after DAA therapy to determine mechanisms of these drugs and their effects on cellular immunity. METHODS: We performed a prospective study of 27 consecutive patients with HCV-CV (median age, 59 y) treated with DAA therapy (21 patients received sofosbuvir plus ribavirin for 24 weeks, 4 patients received sofosbuvir plus daclatasvir for 12 weeks, and 2 patients received sofosbuvir plus simeprevir for 12 weeks) in Paris, France. Blood samples were collected from these patients before and after DAA therapy, and also from 12 healthy donors and 12 individuals with HCV infection without CV. HCV load, cryoglobulins, and cytokines were quantified by flow cytometry, cytokine multiplex assays, and enzyme-linked immunosorbent assay. RESULTS: Twenty-four patients (88.9%) had a complete clinical response of CV to DAA therapy at week 24, defined by improvement of all the affected organs and the absence of relapse. Compared with healthy donors and patients with HCV infection without CV, patients with HCV-CV, before DAA therapy, had a lower percentage of CD4+CD25hiFoxP3+ regulatory T cells (P < .01), but higher proportions of IgM+CD21-/low memory B cells (P < .05), CD4+IFNγ+ cells (P < .01), CD4+IL17A+ cells (P < .01), and CD4+CXCR5+interleukin 21+ follicular T-helper (Tfh) cells (P < .01). In patients with HCV-CV, there was a negative correlation between numbers of IgM+CD21-/low memory B cells and T-regulatory cells (P = .03), and positive correlations with numbers of Tfh cells (P = .03) and serum levels of cryoglobulin (P = .01). DAA therapy increased patients' numbers of T-regulatory cells (1.5% ± 0.18% before therapy vs 2.1% ± 0.18% after therapy), decreased percentages of IgM+CD21-/low memory B cells (35.7% ± 6.1% before therapy vs 14.9% ± 3.8% after therapy), and decreased numbers of Tfh cells (12% ± 1.3% before therapy vs 8% ± 0.9% after therapy). Expression levels of B lymphocyte stimulator receptor 3 and programmed cell death 1 on B cells increased in patients with HCV-CV after DAA-based therapy (mean fluorescence units, 37 ± 2.4 before therapy vs 47 ± 2.6 after therapy, P < .01; and 29 ± 7.3 before therapy vs 48 ± 9.3 after therapy, P < .05, respectively). CONCLUSIONS: In a prospective clinical trial of patients with HCV-CV, DAA-based therapy restored disturbances in peripheral B- and T-cell homeostasis.

Type I Interferons: Distinct Biological Activities and Current Applications for Viral Infection.

The interferons (IFNs) are a primary defense against pathogens because of the strong antiviral activities they induce. IFNs can be classified into three groups: type I, type II and type III, according to their genetic, structural, and functional characteristics and their receptors on the cell surface. The type I IFNs are the largest group and include IFN-α, IFN-ß, IFN-ε, IFN-ω, IFN-κ, IFN-δ, IFN-τ and IFN-ζ. The use of IFNs for the treatment of viral infectious diseases on their antiviral activity may become an important therapeutic option, for example, IFN-α is well known for the successful treatment of hepatitis B and C virus infections, and interest is increasing in the antiviral efficacy of other novel IFN classes and their potential applications. Therefore, in this review, we summarize the recent progress in the study of the biological activities of all the type I IFN classes and their potential applications in the treatment of infections with immunodeficiency virus, hepatitis viruses, and influenza viruses.

Safety and efficacy of simeprevir plus sofosbuvir with or without ribavirin in patients with decompensated genotype 1 hepatitis C cirrhosis.

Combination antiviral therapy involving sofosbuvir (SOF) and simeprevir (SIM) is a treatment option in patients with genotype 1 chronic hepatitis C; however, the safety of this regimen in patients with decompensated cirrhosis is not established. Data from a combined treatment cohort of 2 large hepatology referral centers were evaluated to assess for safety and efficacy of SIM plus SOF with or without ribavirin (RBV) in patients with Child B or C cirrhosis. All (n = 42) patients included in the analysis had Child B (n = 35) or C (n = 7) cirrhosis and received 400 mg daily of SOF plus 150 mg daily of SIM, with (n = 7) or without (n = 35) RBV, for 12 weeks. Of the 42 patients in this cohort, 31 (74%) were male, 22 (52%) had failed prior treatments, and 28 (67%) were genotype 1a. Prior decompensating events included encephalopathy (57%), fluid overload (88%), or variceal hemorrhage (24%). Median Model for End-Stage Liver Disease score was 12 (range, 6-25). Treatment was well tolerated overall with more than one-half (57%) reporting no adverse events. In those reporting adverse events, the most common were fatigue (n = 6), insomnia (n = 4), headache (n = 5), nausea (n = 4), and grade 1 rash (n = 1). One patient developed chemical pancreatitis that did not require treatment discontinuation. Three of 7 patients who received RBV developed anemia, with 2 requiring blood transfusions and 1 requiring a dose reduction. No episodes of decompensation requiring hospitalization or deaths occurred on treatment. Of 42 patients, 38 (90%) patients had negative viral load at end of treatment (EOT), and 31 of 42 patients (74%) achieved sustained virological response 12 weeks after EOT; 10 of 10 patients (100%) with HCV genotype 1b achieved sustained virological response for 12 weeks (SVR12). In conclusion, SOF plus SIM was very well tolerated in patients with advanced Child B/C decompensated cirrhosis. Overall, 74% of patients achieved SVR12; 100% of patients with genotype 1b decompensated cirrhosis achieved SVR12.

Effect of scavenger receptor class B type I antagonist ITX5061 in patients with hepatitis C virus infection undergoing liver transplantation.

Hepatitis C virus (HCV) entry inhibitors have been hypothesized to prevent infection of the liver after transplantation. ITX5061 is a scavenger receptor class B type I antagonist that blocks HCV entry and infection in vitro. We assessed the safety and efficacy of ITX5061 to limit HCV infection of the graft. The study included 23 HCV-infected patients undergoing liver transplantation. The first 13 "control" patients did not receive drug. The subsequent 10 patients received 150 mg of ITX5061 immediately before and after transplant and daily for 1 week thereafter. ITX5061 pharmacokinetics and plasma HCV RNA were quantified. Viral genetic diversity was measured by ultradeep pyrosequencing (UDPS). ITX5061 was well tolerated with measurable plasma concentrations during therapy. Although the median HCV RNA reduction was greater in ITX-treated patients at all time points in the first week after transplantation, there was no difference in the overall change in the area over the HCV RNA curve in the 7-day treatment period. However, in genotype (GT) 1-infected patients, treatment was associated with a sustained reduction in HCV RNA levels compared to the control group (area over the HCV RNA curve analysis, P = 0.004). UDPS revealed a complex and evolving pattern of HCV variants infecting the graft during the first week. ITX5061 significantly limited viral evolution where the median divergence between day 0 and day 7 was 3.5% in the control group compared to 0.1% in the treated group. In conclusion, ITX5061 reduces plasma HCV RNA after transplant notably in GT 1-infected patients and slows viral evolution. Following liver transplantation, the likely contribution of extrahepatic reservoirs of HCV necessitates combining entry inhibitors such as ITX5061 with inhibitors of replication in future studies.

Prevention of hepatitis C virus infection using a broad cross-neutralizing monoclonal antibody (AR4A) and epigallocatechin gallate.

The anti-hepatitis C virus (HCV) activity of a novel monoclonal antibody (mAb; AR4A) and epigallocatechin gallate (EGCG) were studied in vitro using a HCV cell culture system and in vivo using a humanized liver mouse model capable of supporting HCV replication. Alone, both exhibit reliable cross-genotype HCV inhibition in vitro, and combination therapy completely prevented HCV infection. In vitro AR4A mAb (alone and combined with EGCG) robustly protects against the establishment of HCV genotype 1a infection. EGCG alone fails to reliably protect against an HCV challenge. In conclusion, AR4A mAb represents a safe and efficacious broadly neutralizing antibody against HCV applicable to strategies to safely prevent HCV reinfection following liver transplantation, and it lends further support to the concept of HCV vaccine development. The poor bioavailability of EGCG limits HCV antiviral activity in vitro.

Activity-based profiling of the proteasome pathway during hepatitis C virus infection.

Hepatitis C virus (HCV) infection often leads to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The stability of the HCV proteins is controlled by ubiquitin-dependent and ubiquitin-independent proteasome pathways. Many viruses modulate proteasome function for their propagation. To examine the interrelationship between HCV and the proteasome pathways we employed a quantitative activity-based protein profiling method. Using this approach we were able to quantify the changes in the activity of several proteasome subunits and found that proteasome activity is drastically reduced by HCV replication. The results imply a link between the direct downregulation of the activity of this pathway and chronic HCV infection.

Ellagic acid: Pharmacological activities and molecular mechanisms involved in liver protection.

Traditional drugs or therapies rarely have effects on regression of chronic liver diseases, which result in many cases from sustained oxidative stress. In recent years, ellagic acid (EA) has gained attention due to its multiple biological activities and several molecular targets. This is the first review focused on the pharmacological properties and on the molecular mechanisms activated by EA in terms of liver protection. EA possesses antioxidant, antihepatotoxic, antisteatosic, anticholestatic, antifibrogenic, antihepatocarcinogenic and antiviral properties that improves the hepatic architectural and functions against toxic and pathological conditions. The molecular mechanisms that EA activates include the scavenging of free radicals, regulation of phase I and II enzymes, modulation of proinflammatory and profibrotic cytokines synthesis, the regulation of biochemical pathways involved in the synthesis and degradation of lipids as well as the maintenance of essential trace elements levels. EA also inhibits hepatic stellate cells and mast cells activation, the proliferation of transformed cells, as well as viral replication by increasing antioxidant response, induction of apoptosis, downregulation of genes involved in cell cycle and angiogenesis, and stimulation of cellular immune response. Despite the enormous therapeutic potential of EA as an innovative pharmacological strategy, the number of phase I and II trials in patients is scarce, precluding its clinical application. In these sense, the use of new delivery systems that enhances EA bioavailability would improve the results already obtained. Also it remains to be determined if treatment with urolithins instead of EA would represent a better strategy in hepatic disease treatment.

Quinone derivatives from the genus Rubia and their bioactivities.

The extracts and phytochemicals of the genus Rubia have drawn much attention due to their potent effects; among them, naphthoquinone and cyclopeptide derivatives, with significant biological activities, have great potential to be developed to new drugs. This review updates and compiles a total of 142 quinone derivatives including anthraquinone and naphthoquinone derivatives, occuring in twelve Rubia species. These compounds were listed together with their sources, melting points, bioactivities, as well as 112 corresponding references. Furthermore, the structureactivity relationships of these quinone derivatives were discussed.

Current perspectives of viral hepatitis.

Viral hepatitis represents a major danger to public health, and is a globally leading cause of death. The five liver-specific viruses: Hepatitis A virus, hepatitis B virus, hepatitis C virus, hepatitis D virus, and hepatitis E virus, each have their own unique epidemiology, structural biology, transmission, endemic patterns, risk of liver complications, and response to antiviral therapies. There remain few options for treatment, in spite of the increasing prevalence of viral-hepatitis-caused liver disease. Furthermore, chronic viral hepatitis is a leading worldwide cause of both liver-related morbidity and mortality, even though effective treatments are available that could reduce or prevent most patients' complications. In 2016, the World Health Organization released its plan to eliminate viral hepatitis as a public health threat by the year 2030, along with a discussion of current gaps and prospects for both regional and global eradication of viral hepatitis. Today, treatment is sufficiently able to prevent the disease from reaching advanced phases. However, future therapies must be extremely safe, and should ideally limit the period of treatment necessary. A better understanding of pathogenesis will prove beneficial in the development of potential treatment strategies targeting infections by viral hepatitis. This review aims to summarize the current state of knowledge on each type of viral hepatitis, together with major innovations.

Effects of antiviral therapy on hepatitis B virus reactivation and liver function after resection or chemoembolization for hepatocellular carcinoma.

BACKGROUND: How hepatitis B virus (HBV) infection react to hepatocellular carcinoma (HCC) treatment remains unclear, and the roles of anti-HBV therapy were seldom reported in HCC. AIMS: To evaluate changes of HBV replication and liver function after hepatectomy or transarterial chemoembolization (TACE) for HCC, also the short-term effects of anti-viral therapy were analyzed. METHODS: Totally, 590 HBsAg (+) HCC patients were recruited into two groups: only surgical resection, and only TACE, and subgrouped according to anti-HBV therapy or none. Clinical data were analyzed for statistical significance and risk factors for adverse events. RESULTS: In the no antiviral therapy groups, rates of HBV reactivation were 15.7% and 17.5% in patients who underwent hepatectomy and TACE, respectively, while the rates of deterioration of liver function were 4.1% and 8.1%, respectively. In contrast, in the antivirus group, the rates of reactivation were 0% and 1.5% after hepatectomy and TACE respectively, while the liver function deterioration rates were 2.4% and 1.5%, respectively. For patients who underwent hepatectomy, no antiviral therapy, and long hepatic inflow occlusion times increased the risk of HBV reactivation. For TACE, no antivirus and HBeAg negativity were the risk factors for reactivation. HBV reactivation was significantly correlated to liver function exacerbation after hepatectomy, while HBV reactivation, baseline ALT (alanine aminotransferase), and α-fetoprotein levels were significantly correlated to liver function exacerbation after TACE. CONCLUSIONS: HBV reactivation can occur after hepatectomy or TACE. Anti-HBV therapy can reduce the risk of reactivation, thus reducing the risk of liver failure especially in patients undergoing TACE.

The impact of human immunodeficiency virus on viral hepatitis.

The combination of antiretroviral (ARV) therapies introduced at the end of the 1990s profoundly changed the natural history of human immunodeficiency virus (HIV) infection. Liver diseases are one of the three primary causes of 'non-AIDS-related' death in people living with HIV for three reasons: the high prevalence of hepatotropic viral co-infections, the hepatotoxicity of ARV drugs and new emerging liver diseases, including nodular regenerative hyperplasia and hepatitis E virus infection. The impact of HIV infection on the natural history of hepatitis C virus (HCV) or hepatitis B virus (HBV)/HIV co-infection has markedly changed in the past few decades with the progress made in ARV treatment and the improved definition of therapeutic strategies for HCV or HBV. Initially, HIV had a negative impact on hepatotropic infections. Today, HIV does not appear to significantly modify the natural history of HCV and HBV infection. This is associated with fair immune restoration, viral suppression associated with analogues having dual activity against HBV and HIV and with the increasing efficacy of antiviral treatments against HCV. A significant decline is expected in the morbidity and mortality associated with chronic liver infection in co-infected patients. Nevertheless, today, there are three major issues: (i) improving preventive measures including vaccination and risk reduction; (ii) screening patients infected with HBV or HCV and evaluating the impact of chronic infection on the liver and finally; (iii) early screening of hepatocellular carcinoma whose occurrence is higher and that evolves more rapidly in co-infected than in mono-infected patients.

Infections and the liver.

BACKGROUND: Hepatitis B (HBV) and hepatitis C virus (HCV) have infected nearly half a billion individuals worldwide and are major indications for liver transplantation. Key requirements to successful outcomes with modern antiviral drugs are favourable host factors. RESULTS: Single nucleotide polymorphisms near the IL28B gene location which encode for interferon (IFN)-λ3 have a large effect in determining the likelihood of patients obtaining a cure from pegylated IFN-α and ribavirin combination therapy or spontaneous clearance of the HCV. 80% of patients who carry two copies of this advantageous variant cleared the virus during IFN therapy and remained virus-free with a sustained viral response. This mutation is more common in Caucasian and Asian populations, whereas it is only found in the 40-50% of sub-Saharan Africans who are known to be more resistant to combination therapy. Similarly, host factors control tolerance to chronic HBV infection and can fluctuate over time with increased risk of progression to cirrhosis and particularly liver cancer. Loss of viral tolerance with reactivation and hepatitis is increasingly seen with the widespread use of biological treatments for diseases such as inflammatory bowel disease or rheumatoid arthritis. Natural disasters and conflicts in some parts of the world have also seen an increase in cases of hepatitis A and E virus infection and highlighted the global public health burden from viral-induced hepatitis. CONCLUSIONS: Increased appreciation of the interaction between host factors and the viral life cycles is likely to significantly alter the way we target these infections in the future.

Drugs of Abuse and Their Impact on Viral Pathogenesis.

Commonly misused substances such as alcohol, cocaine, heroin, methamphetamine, and opioids suppress immune responses and may impact viral pathogenesis. In recent years, illicit use of opioids has fueled outbreaks of several viral pathogens, including the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). This review focuses on the myriad of mechanisms by which drugs of abuse impact viral replication and disease progression. Virus-drug interactions can accelerate viral disease progression and lead to increased risk of virus transmission.

Nanostructured Copper Surface Kills ESKAPE Pathogens and Viruses in Minutes.

In the search for a fast contact-killing antimicrobial surface to break the transmission pathway of lethal pathogens, nanostructured copper surfaces were found to exhibit the desired antimicrobial properties. Compared with plain copper, these nanostructured copper surfaces with Cu(OH)2 nano-sword or CuO nano-foam were found to completely eliminate pathogens at a fast rate, including clinically isolated drug resistant species. Additionally these nanostructured copper surfaces demonstrated potential antiviral properties when assessed against bacteriophages, as a viral surrogate, and murine hepatitis virus, a surrogate for SARS-CoV-2. The multiple modes of killing, physical killing and copper ion mediated killing contribute to the superior and fast kinetics of antimicrobial action against common microbes, and ESKAPE pathogens. Prototypes for air and water cleaning with current nanostructured copper surface have also been demonstrated.

Scorpion-Derived Antiviral Peptides with a Special Focus on Medically Important Viruses: An Update.

The global burden of viral infection, especially the current pandemics of SARS-CoV-2, HIV/AIDS, and hepatitis, is a very risky one. Additionally, HCV expresses the necessity for antiviral therapeutic elements. Venoms are known to contain an array of bioactive peptides that are commonly used in the treatment of various medical issues. Several peptides isolated from scorpion venom have recently been proven to possess an antiviral activity against several viral families. The aim of this review is to provide an up-to-date overview of scorpion antiviral peptides and to discuss their modes of action and potential biomedical application against different viruses.

Advances in Nucleoside and Nucleotide Analogues in Tackling Human Immunodeficiency Virus and Hepatitis Virus Infections.

Nucleoside and nucleotide analogues are structurally similar antimetabolites and are promising small-molecule chemotherapeutic agents against various infectious DNA and RNA viruses. To date, these analogues have not been documented in-depth as anti-human immunodeficiency virus (HIV) and anti-hepatitis virus agents, these are at various stages of testing ranging from pre-clinical, to those withdrawn from trials, or those that are approved as drugs. Hence, in this review, the importance of these analogues in tackling HIV and hepatitis virus infections is discussed with a focus on the viral genome and the mechanism of action of these analogues, both in a mutually exclusive manner and their role in HIV/hepatitis coinfection. This review encompasses nucleoside and nucleotide analogues from 1987 onwards, starting with the first nucleoside analogue, zidovudine, and going on to those in current clinical trials and even the drugs that have been withdrawn. This review also sheds light on the prospects of these nucleoside analogues in clinical trials as a treatment option for the COVID-19 pandemic.

Research progress of epigallocatechin-3-gallate (EGCG) on anti-pathogenic microbes and immune regulation activities.

At the end of 2019, the COVID-19 virus spread worldwide, infecting millions of people. Infectious diseases induced by pathogenic microorganisms such as the influenza virus, hepatitis virus, and Mycobacterium tuberculosis are also a major threat to public health. The high mortality caused by infectious pathogenic microorganisms is due to their strong virulence, which leads to the excessive counterattack by the host immune system and severe inflammatory damage of the immune system. This paper reviews the efficacy, mechanism and related immune regulation of epigallocatechin-3-gallate (EGCG) as an anti-pathogenic microorganism drug. EGCG mainly shows both direct and indirect anti-infection effects. EGCG directly inhibits early infection by interfering with the adsorption on host cells, inhibiting virus replication and reducing bacterial biofilm formation and toxin release; EGCG indirectly inhibits infection by regulating immune inflammation and antioxidation. At the same time, we reviewed the bioavailability and safety of EGCG in vivo. At present, the bioavailability of EGCG can be improved to some extent using nanostructured drug delivery systems and molecular modification technology in combination with other drugs. This study provides a theoretical basis for the development of EGCG as an adjuvant drug for anti-pathogenic microorganisms.