Polyphenols Inhibit Hepatitis C Virus Entry by a New Mechanism of Action

Abstract

Despite the validation of direct-acting antivirals for hepatitis C treatment, the discovery of new compounds with different modes of action may still be of importance for the treatment of special patient populations. We recently identified a natural molecule, epigallocatechin-3-gallate (EGCG), as an inhibitor of hepatitis C virus (HCV) targeting the viral particle. The aim of this work was to discover new natural compounds with higher anti-HCV activity than that of EGCG and determine their mode of action. Eight natural molecules with structure similarity to EGCG were selected. HCV JFH1 in cell culture and HCV pseudoparticle systems were used to determine the antiviral activity and mechanism of action of the compounds. We identified delphinidin, a polyphenol belonging to the anthocyanidin family, as a new inhibitor of HCV entry. Delphinidin inhibits HCV entry in a pangenotypic manner by acting directly on the viral particle and impairing its attachment to the cell surface. Importantly, it is also active against HCV in primary human hepatocytes, with no apparent cytotoxicity and in combination with interferon and boceprevir in cell culture. Different approaches showed that neither aggregation nor destruction of the particle occurred. Cryo-transmission electron microscopy observations of HCV pseudoparticles treated with delphinidin or EGCG showed a bulge on particles that was not observed under control conditions. In conclusion, EGCG and delphinidin inhibit HCV entry by a new mechanism, i.e., alteration of the viral particle structure that impairs its attachment to the cell surface. IMPORTANCEIn this article, we identify a new inhibitor of hepatitis C virus (HCV) infection, delphinidin, that prevents HCV entry. This natural compound, a plant pigment responsible for the blue-purple color of flowers and berries, belongs to the flavonoid family, like the catechin EGCG, the major component present in green tea extract, which is also an inhibitor of HCV entry. We studied the mode of action of these two compounds against HCV and demonstrated that they both act directly on the virus, inducing a bulging of the viral envelope. This deformation might be responsible for the observed inhibition of virus attachment to the cell surface. The discovery of such HCV inhibitors with an unusual mode of action is important to better characterize the mechanism of HCV entry into hepatocytes and to help develop a new class of HCV entry inhibitors. H epatitis C is a major health problem, with as many as 130 million people chronically infected worldwide (1). It is caused by hepatitis C virus (HCV), which has a high propensity to establish a persistent infection. Chronic hepatitis C can lead to the development of cirrhosis and hepatocellular carcinoma. Recent improvements in the standard of care, with direct-acting antivirals (DAAs) that inhibit HCV NS3/4A protease, NS5B polymerase, or NS5A, and now without interferon (IFN), which causes severe adverse effects, have raised the hope that HCV infection can be managed efficiently in cou...

Antiviral Mechanism of Action of Epigallocatechin-3-O-gallate and Its Fatty Acid Esters

“…Regarding these biological properties, EGCG ( 1 ) has been reported to possess a broad spectrum of antiviral activities against DNA viruses such as herpes simplex virus (HSV; Herpesviridae ) [5,6,7,8,9,10,11], adenovirus ( Adenoviridae ) [10,12], human papilloma virus (HPV; Papovaviridae ) [13], and hepatitis B virus (HBV; Hepadnaviridae ) [14], and against (+)-RNA viruses such as hepatitis C virus (HCV; Flaviviridae ) [10,15,16,17,18,19], Zika virus (ZIKV; Flaviviridae ) [20,21,22,23], dengue virus (DENV; Flaviviridae ) [23,24], West Nile viruses (WNV; Flaviviridae ) [23], Chikungunya virus (CHIKV; Togaviridae ) [25], and Porcine Reproductive and Respiratory virus (PRRS; Atteriviridae ) [26], and (−)-RNA viruses such as human immunodeficiency virus (HIV; Retroviridae ) [27,28,29,30,31,32,33,34,35,36], Ebola virus (EBOV; Filoviridae ) [37] and influenza virus ( Orthomyxoviridae ) [2,10,38,39,40,41,42,43,44,45,46,47,48]. …”

Antiviral Activity of Nordihydroguaiaretic Acid and Its Derivative Tetra- O -Methyl Nordihydroguaiaretic Acid against West Nile Virus and Zika Virus

“…The difference in the virucidal ability observed between the two compounds may be because M 4 N is a methylated derivative of NDGA. In fact, supporting this view, the direct effect of other phenolic compounds on viral particles of the related HCV has been linked to the presence of certain hydroxyl groups within the molecules tested (38).…”

Strategies to Preclude Hepatitis C Virus Entry

“…Since the GAG heparan sulfate moieties dominate the capturing of HCV virions, the heparan sulfate homologue heparin and its derivatives as well as the enzyme heparinases which degrade the molecule were all shown to inhibit the viral binding to hepatoma cells [24,25]. (-)-Epigallocatechin-3-gallate (EGCG), a green tea catechin, was speculated to exert its inhibitory effect on viral attachment [99] by competing with heparan sulfate for HCV binding [100] or altering the viral shape [101]. Delphinidin, an anthocyanidin extracted from plant pigment, was also demonstrated to inactivate HCVpp by altering its shape and was particularly potent when added concurrently with the viral inoculation [101].…”

“…(-)-Epigallocatechin-3-gallate (EGCG), a green tea catechin, was speculated to exert its inhibitory effect on viral attachment [99] by competing with heparan sulfate for HCV binding [100] or altering the viral shape [101]. Delphinidin, an anthocyanidin extracted from plant pigment, was also demonstrated to inactivate HCVpp by altering its shape and was particularly potent when added concurrently with the viral inoculation [101]. The natural terpenoid saikosaponin b2 (SSb2), isolated from the root of Bupleurum kaoi, was observed to specifically block HCV particle binding and early viral entry without affecting other stages of the viral life cycle [102].…”