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Special Issue "Natural Products against Viral Infections II"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Bioactives and Nutraceuticals".

Deadline for manuscript submissions: closed (31 August 2020).

Special Issue Editor

Special Issue Information

Dear Colleagues,

Although immunization against viral infections has reduced or eradicated several viral diseases, including smallpox, polio, and measles, viral infections continue to be a source of human morbidity and mortality. Antiviral drug resistance has been emerging, and viral mutations present new problems for treatment of viral infections. Thus, for example, acyclovir- and penciclovir-resistant strains of HSV-1 and HSV-2 are emerging, several HIV mutants have shown resistance to reverse transcriptase inhibitors, and there are constant mutations in influenza viruses. In addition, emerging viral infectious diseases, such as severe acute respiratory syndrome (SARS), Chikungunya virus, West Nile virus, and Zika virus, are presenting new challenges. Natural products have been and will continue to be excellent sources of medicinal agents. This Special Issue is directed at natural product drug discovery of antiviral agents. We welcome contributions directed at in vitro and in vivo screening of extracts and natural products against viruses, as well as in silico efforts at antiviral drug discovery. Both original research papers and timely reviews are welcome.

Prof. Dr. William N. Setzer
Guest Editor

Manuscript Submission Information

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Keywords

  • Natural products
  • Drug discovery
  • Antiviral agents
  • In vitro screening
  • In vivo screening
  • In silico screening
  • Antiviral drug targets
  • Emerging viral diseases

Published Papers (3 papers)

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Research

Article
Essential Oils as Antiviral Agents, Potential of Essential Oils to Treat SARS-CoV-2 Infection: An In-Silico Investigation
Int. J. Mol. Sci. 2020, 21(10), 3426; https://doi.org/10.3390/ijms21103426 - 12 May 2020
Cited by 61 | Viewed by 12563
Abstract
Essential oils have shown promise as antiviral agents against several pathogenic viruses. In this work we hypothesized that essential oil components may interact with key protein targets of the 2019 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A molecular docking analysis was carried [...] Read more.
Essential oils have shown promise as antiviral agents against several pathogenic viruses. In this work we hypothesized that essential oil components may interact with key protein targets of the 2019 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A molecular docking analysis was carried out using 171 essential oil components with SARS-CoV-2 main protease (SARS-CoV-2 Mpro), SARS-CoV-2 endoribonucleoase (SARS-CoV-2 Nsp15/NendoU), SARS-CoV-2 ADP-ribose-1″-phosphatase (SARS-CoV-2 ADRP), SARS-CoV-2 RNA-dependent RNA polymerase (SARS-CoV-2 RdRp), the binding domain of the SARS-CoV-2 spike protein (SARS-CoV-2 rS), and human angiotensin−converting enzyme (hACE2). The compound with the best normalized docking score to SARS-CoV-2 Mpro was the sesquiterpene hydrocarbon (E)-β-farnesene. The best docking ligands for SARS−CoV Nsp15/NendoU were (E,E)-α-farnesene, (E)-β-farnesene, and (E,E)−farnesol. (E,E)−Farnesol showed the most exothermic docking to SARS-CoV-2 ADRP. Unfortunately, the docking energies of (E,E)−α-farnesene, (E)-β-farnesene, and (E,E)−farnesol with SARS-CoV-2 targets were relatively weak compared to docking energies with other proteins and are, therefore, unlikely to interact with the virus targets. However, essential oil components may act synergistically, essential oils may potentiate other antiviral agents, or they may provide some relief of COVID-19 symptoms. Full article
(This article belongs to the Special Issue Natural Products against Viral Infections II)
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Article
ThymicPeptides Reverse Immune Exhaustion in Patients with Reactivated Human Alphaherpesvirus1 Infections
Int. J. Mol. Sci. 2020, 21(7), 2379; https://doi.org/10.3390/ijms21072379 - 30 Mar 2020
Cited by 1 | Viewed by 920
Abstract
Recurrent infection with human alphaherpesvirus 1 (HHV-1) may be associated with immune exhaustion that impairs virus elimination. Thymic peptides enhance immune function and thus could overcome immune exhaustion. In this study, we investigated whether reactivation of herpes infections was associated with immune exhaustion. [...] Read more.
Recurrent infection with human alphaherpesvirus 1 (HHV-1) may be associated with immune exhaustion that impairs virus elimination. Thymic peptides enhance immune function and thus could overcome immune exhaustion. In this study, we investigated whether reactivation of herpes infections was associated with immune exhaustion. Moreover, we examined the impact of treatment with thymostimulin on the expression of programmed cell death protein 1 (PD-1) and its ligand (PD-L1) on T and B lymphocytes in patients suffering from recurrent HHV-1 reactivation. We also assessed the effector function of peripheral blood mononuclear cells (PBMCs) after stimulation with thymic peptides. We enrolled 50 women with reactivated HHV-1 infections and healthy volunteers. We measured the expression of various activation and exhaustion markers on the surface of PBMCs using flow cytometry. In ex vivo experiments, we measured the secretion of inflammatory cytokines by PBMCs cultured with thymostimulin. Compared with controls, patients with reactivated HHV-1 infections had increased percentages of CD3+ co-expressing CD25, an activation marker (p < 0.001). Moreover, these patients had increased percentages of CD4+ and CD8+ cells co-expressing the inhibitory markers PD-1 and PD-L1. In cultures of PBMCs from the patients, thymostimulin increased the secretion of interferon gamma (p < 0.001) and interleukin (IL)-2 (p = 0.023), but not IL-4 or IL-10.Two-month thymostimulin therapy resulted in no reactivation of HHV-1 infection during this period and the reduction of PD-1 and PD-L1 expression on the surface of T and B lymphocytes (p < 0.001). In conclusion, reactivation of herpes infection is associated with immune exhaustion, which could be reversed by treatment with thymic peptides. Full article
(This article belongs to the Special Issue Natural Products against Viral Infections II)
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Article
Less Cytotoxic Protoflavones as Antiviral Agents: Protoapigenone 1′-O-isopropyl ether Shows Improved Selectivity Against the Epstein–Barr Virus Lytic Cycle
Int. J. Mol. Sci. 2019, 20(24), 6269; https://doi.org/10.3390/ijms20246269 - 12 Dec 2019
Cited by 1 | Viewed by 1279
Abstract
Protoflavones, a rare group of natural flavonoids with a non-aromatic B-ring, are best known for their antitumor properties. The protoflavone B-ring is a versatile moiety that might be explored for various pharmacological purposes, but the common cytotoxicity of these compounds is a limitation [...] Read more.
Protoflavones, a rare group of natural flavonoids with a non-aromatic B-ring, are best known for their antitumor properties. The protoflavone B-ring is a versatile moiety that might be explored for various pharmacological purposes, but the common cytotoxicity of these compounds is a limitation to such efforts. Protoapigenone was previously found to be active against the lytic cycle of Epstein–Barr virus (EBV). Further, the 5-hydroxyflavone moiety is a known pharmacophore against HIV-integrase. The aim of this work was to prepare a series of less cytotoxic protoflavone analogs and study their antiviral activity against HIV and EBV. Twenty-seven compounds, including 18 new derivatives, were prepared from apigenin through oxidative de-aromatization and subsequent continuous-flow hydrogenation, deuteration, and/or 4′-oxime formation. One compound was active against HIV at the micromolar range, and three compounds showed significant activity against the EBV lytic cycle at the medium-low nanomolar range. Among these derivatives, protoapigenone 1′-O-isopropyl ether (6) was identified as a promising lead that had a 73-times selectivity of antiviral over cytotoxic activity, which exceeds the selectivity of protoapigenone by 2.4-times. Our results open new opportunities for designing novel potent and safe anti-EBV agents that are based on the natural protoflavone moiety. Full article
(This article belongs to the Special Issue Natural Products against Viral Infections II)
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