Sumac Polyphenols as Pan-Herpesvirus Inhibitors

Abstract

Pandemic preparedness is a complex of threat-agnostic countermeasures developed in advance which would be efficient against a future outbreak regardless of its causative agent, and broad-spectrum antivirals constitute a critical component of this complex. Plant polyphenols are known to suppress viruses of unrelated families by acting on multiple viral and cellular structures. We therefore searched for broad-spectrum antivirals among polyphenols that have been confirmed as safe to humans. The ellagitannin geraniin and galloylglucose constituents of the drug Rutan (1,2,3,4,6-penta-O-galloyl-β-D-glucose [R5], 3-bis-O-galloyl-1,2,4,6-tetra-O-galloyl-β-D-glucose [R6], 2,4-bis-O-galloyl-1,3,6-tri-O-galloyl-β-D-glucose [R7], 2,3,4-bis-O-galloyl-1,6-di-O-galloyl-β-D-glucose [R8]) were isolated from Geranium sanguineum and sumac (Rhus coriaria), respectively. We revealed their activity towards herpes simplex viruses (HSV-1 and HSV-2), human cytomegalovirus (CMV), and the Epstein-Barr virus (EBV). R5 suppressed HSV-1 and HSV-2 with equal efficiency, while Rutan and R7 were more active against HSV-1, and geraniin against HSV-2. Rutan and R5 also inhibited the intracellular replication of CMV and EBV (contrary to our expectations, geraniin and polyphenols R6-R8 showed no activity). Thus, we have shown for the first time that sumac polyphenols are capable of suppressing-in addition to HIV, influenza virus, and SARS-CoV-2-the reproduction of representatives of all three Orthoherpesviridae subfamilies, meeting the criteria for further development as broad-spectrum antivirals.

Keywords: Epstein–Barr virus; SARS-CoV-2; cytomegalovirus; geranium; herpes simplex virus type 1; herpes simplex virus type 2; influenza A virus; polyphenols; sumac.

Figure 1

HPLC analysis of water-soluble polyphenols of sumac.

Figure 2

Polyphenol R5 of the pharmacopeial substance of Rutan: structure, MS/MS spectrum, and fragmentation pathways.

Figure 3

HPLC of geraniin.

Figure 4

Hirschfeld surface mapped over d_norm and decomposed fingerprint plots for dominant interactions. In the fingerprint plot, the color scale denotes the relative frequency of interactions, from dark blue (low) to green/yellow (high). The densest (brightest) central zone at d_i ≈ 1.5–1.8 Å and d_e ≈ 1.5–1.9 Å indicates where intermolecular contacts occur most frequently.

Figure 5

Hirschfeld surface constructed for geraniin using the shape index.

Figure 6

Structure of geraniin.

Figure 7

Immunocytochemical detection of CMV-infected HELF, using a mixture of monoclonal antibodies to the viral proteins IE1-p72 and pp65; Olympus light microscope (Japan), 800× magnification. (a) Uninfected cells; (b) infected cells; (c) cells infected with CMV following exposure to Rutan. Brown coloration in B and C corresponds to localization of viral proteins in CMV-infected cells. Cell nuclei (purple) are stained with hematoxylin.

Figure 8

Detection of virus-specific PFU in HELF monolayers inoculated with CM from CMV-infected cells (a) or CMV-infected cells exposed to R5 (b). No PFU was found in HELF culture inoculated with CM from uninfected cells not exposed to R5 (c). Brown staining corresponds to the localization of clusters of infected cells containing CMV proteins visualized with monoclonal antibodies; 100× magnification.

Figure 9

Rutan inhibits intracellular replication and production of infectious virions of CMV_AD169. (a) Concentration-dependent reduction in the number of CMV-infected HELF cells. (b) Effect of Rutan on number of infected cells in HELF cultures (compared to untreated cells). (c) Effect of Rutan on number of infectious virions in the CM (compared to untreated cells). * p < 0.05 compared to the control.

Figure 10

Suppression by polyphenol R5 of intracellular replication (a) and production of infectious virions (b) of CMV_AD169.

Figure 11

Suppression of CMV infection by Rutan (a) and polyphenol R5 (b) in the pre-inoculation setup. CMV_AD169 strain (titer 300 PFU/mL) was used to infect HELF cells. The number of plaques in the cultures exposed to the polyphenols was counted and expressed as a percentage of the number of plaques in control cultures (not exposed to polyphenols).

Figure 12

Effect of Rutan and polyphenol R5 on the amount of EBV DNA in B95-8 cells. * p < 0.05 compared to the control.