Polyhydroxylated sulfated steroids derived from 5α-cholestanes as antiviral agents against herpes simplex virus

Anti-HSV-1 agents: an update

Herpes simplex virus type I (HSV-1) is a member of the α-herpesvirus subfamily and is capable of causing herpes simplex keratitis, herpes labialis, and herpes simplex encephalitis. HSV-1 is well known for its lytic infections at the primary sites and for establishing latency in the sensory neuronal ganglia, with occasional recurrent infections. To date, there are no approved commercially available vaccines, and anti-HSV-1 drugs such as specific or non-specific nucleotide (nucleoside) analogs and helicase-primase inhibitors have become the main clinical agents for the treatment of HSV-1 infections despite challenges from resistance. Therefore, development of new anti-HSV-1 compounds or therapies is key to addressing the issue of resistance. The present review provides an update on the progress made over approximately 60 years regarding anti-HSV-1 agents while also highlighting future perspectives for controlling HSV-1 infections.

Elaeocarpus sylvestris var. ellipticus Extract and Its Major Component, Geraniin, Inhibit Herpes Simplex Virus-1 Replication

Elaeocarpus sylvestris var. ellipticus (ES), which our research group had confirmed inhibits influenza A and SARS-CoV-2 viruses, was investigated to identify new potent and selective inhibitors of herpes simplex virus-1 (HSV-1) replication. To clarify the optimal condition for ES extract (ESE), ES was extracted at different concentrations of 0, 30, 50, 70, and 100%, to screen for its anti-HSV-1 effect. Among these ESE samples, ESE50 (50% concentration) exhibited the strongest inhibition of HSV-1 replication (EC50 23.2 μg/mL) while showing low cytotoxicity on host cells (IC50 342.8 μg/mL). The treatment of ESE50 clearly demonstrated a decrease in the expression of ICP0 in the lungs of HSV-1-infected BALB/c nude mice, compared to the MOCK group. Geraniin, which was isolated from ESE50 and analyzed using ESI-MS and 1D-(1H- and 13C-) and 2D-NMR, showed greater potency in inhibiting HSV-1 replication, as determined by the plaque reduction assay (EC50 8.3 μg/mL) and luciferase inhibition (EC50 36.9 μg/mL). The results demonstrate that ESE50 and geraniin show great potential as candidates for new drug discovery in the treatment of HSV-1 and related diseases.

In-vitro and in-silico anti-HSV-1 activity of a marine steroid from the jellyfish Cassiopea andromeda venom

In this study, we investigated the potential in vitro anti-HSV-1 activities of the Cassiopea andromeda jellyfish tentacle extract (TE) and its fractions, as well as computational work on the thymidine kinase (TK) inhibitory activity of the identified secondary metabolites. The LD50, secondary metabolite identification, preparative and analytical chromatography, and in silico TK assessment were performed using the Spearman-Karber, GC-MS, silica gel column chromatography, RP-HPLC, LC-MS, and docking methods, respectively. The antiviral activity of TE and the two purified compounds Ca2 and Ca7 against HSV-1 in Vero cells was evaluated by MTT and RT-PCR assays. The LD50 (IV, mouse) values of TE, Ca2, and Ca7 were 104.0 ± 4, 5120 ± 14, and 197.0 ± 7 (μg/kg), respectively. They exhibited extremely effective antiviral activity against HSV-1. The CC50 and MNTD of TE, Ca2, and Ca7 were (125, 62.5), (25, 12.5), and (50, 3.125) μg/ml, respectively. GC-MS analysis of the tentacle extract revealed seven structurally distinct chemical compositions. Four of the seven compounds had a steroid structure. According to the docking results, all compounds showed binding affinity to the active sites of both thymidine kinase chains. Among them, the steroid compound Pregn-5-ene-3,11-dione, 17,20:20,21 bis [methylenebis(oxy)]-, cyclic 3-(1,2-ethane diyl acetal) (Ca2) exhibited the highest affinity for both enzyme chains, surpassing that of standard acyclovir. In silico data confirmed the experimental results. We conclude that the oxosteroid Ca2 may act as a potent agent against HSV-1.

A Systematic Review of Second-Line Treatments in Antiviral Resistant Strains of HSV-1, HSV-2, and VZV

Drug-resistant variants of herpes simplex viruses (HSV) have been reported that are not effectively treated with first-line antiviral agents. The objective of this study was to evaluate available literature on the possible efficacy of second-line treatments in HSV and the use of second-line treatments in HSV strains that are resistant to first-line treatments. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a final search was conducted in six databases on November 5, 2021 for all relevant literature using terms related to antiviral resistance, herpes, and HSV. Eligible manuscripts were required to report the presence of an existing or proposed second-line treatment for HSV-1, HSV-2, or varicella zoster virus (VZV); have full-text English-language access; and potentially reduce the rate of antiviral resistance. Following screening, 137 articles were included in qualitative synthesis. Of the included studies, articles that examined the relationship between viral resistance to first-line treatments and potential second-line treatments in HSV were included. The Cochrane risk-of-bias tool for randomized trials was used to assess risk of bias. Due to the heterogeneity of study designs, a meta-analysis of the studies was not performed. The dates in which accepted studies were published spanned from 2015-2021. In terms of sample characteristics, the majority (72.26%) of studies used Vero cells. When looking at the viruses on which the interventions were tested, the majority (84.67%) used HSV-1, with (34.31%) of these studies reporting testing on resistant HSV strains. Regarding the effectiveness of the proposed interventions, 91.97% were effective as potential managements for resistant strains of HSV. Of the papers reviewed, nectin in 2.19% of the reviews had efficacy as a second-line treatments in HSV, amenamevir in 2.19%, methanol extract in 2.19%, monoclonal antibodies in 1.46%, arbidol in 1.46%, siRNA swarms in 1.46%, Cucumis melo sulfated pectin in 1.46%, and components from Olea europeae in 1.46%. In addition to this griffithsin in 1.46% was effective, Morus alba L. in 1.46%, using nucleosides in 1.46%, botryosphaeran in 1.46%, monoterpenes in 1.46%, almond skin extracts in 1.46%, bortezomib in 1.46%, flavonoid compounds in 1.46%, andessential oils were effective in 1.46%, but not effective in 0.73%. The available literature reviewed consistently supports the existence and potentiality of second-line treatments for HSV strains that are resistant to first-line treatments. Immunocompromised patients have been noted to be the population most often affected by drug-resistant variants of HSV. Subsequently, we found that HSV infections in this patient population are challenging to manage clinically effectively. The goal of this systematic review is to provide additional information to patients on the potentiality of second-line treatment in HSV strains resistant to first-line treatments, especially those who are immunocompromised. All patients, whether they are immunocompromised or not, deserve to have their infections clinically managed in a manner supported by comprehensive research. This review provides necessary information about treatment options for patients with resistant HSV infections and their providers.

The Structural Diversity and Biological Activity of Steroid Oximes

Steroids and their derivatives have been the subject of extensive research among investigators due to their wide range of pharmacological properties, in which steroidal oximes are included. Oximes are a chemical group with the general formula R1R2C=N-OH and they exist as colorless crystals and are poorly soluble in water. Oximes can be easily obtained through the condensation of aldehydes or ketones with various amine derivatives, making them a very interesting chemical group in medicinal chemistry for the design of drugs as potential treatments for several diseases. In this review, we will focus on the different biological activities displayed by steroidal oximes such as anticancer, anti-inflammatory, antibacterial, antifungal and antiviral, among others, as well as their respective mechanisms of action. An overview of the chemistry of oximes will also be reported, and several steroidal oximes that are in clinical trials or already used as drugs are described. An extensive literature search was performed on three main databases-PubMed, Web of Science, and Google Scholar.

Ten-Year Research Update Review: Antiviral Activities from Marine Organisms

Oceans cover more than 70 percent of the surface of our planet and are characterized by huge taxonomic and chemical diversity of marine organisms. Several studies have shown that marine organisms produce a variety of compounds, derived from primary or secondary metabolism, which may have antiviral activities. In particular, certain marine metabolites are active towards a plethora of viruses. Multiple mechanisms of action have been found, as well as different targets. This review gives an overview of the marine-derived compounds discovered in the last 10 years. Even if marine organisms produce a wide variety of different compounds, there is only one compound available on the market, Ara-A, and only another one is in phase I clinical trials, named Griffithsin. The recent pandemic emergency caused by SARS-CoV-2, also known as COVID-19, highlights the need to further invest in this field, in order to shed light on marine compound potentiality and discover new drugs from the sea.

Improving Encapsulation of Hydrophilic Chloroquine Diphosphate into Biodegradable Nanoparticles: A Promising Approach against Herpes Virus Simplex-1 Infection

Chloroquine diphosphate (CQ) is a hydrophilic drug with low entrapment efficiency in hydrophobic nanoparticles (NP). Herpes simplex virus type 1 (HSV-1) is an enveloped double-stranded DNA virus worldwide known as a common human pathogen. This study aims to develop chloroquine-loaded poly(lactic acid) (PLA) nanoparticles (CQ-NP) to improve the chloroquine anti- HSV-1 efficacy. CQ-NP were successfully prepared using a modified emulsification-solvent evaporation method. Physicochemical properties of the NP were monitored using dynamic light scattering, atomic force microscopy, drug loading efficiency, and drug release studies. Spherical nanoparticles were produced with modal diameter of <300 nm, zeta potential of −20 mv and encapsulation efficiency of 64.1%. In vitro assays of CQ-NP performed in Vero E6 cells, using the MTT-assay, revealed different cytotoxicity levels. Blank nanoparticles (B-NP) were biocompatible. Finally, the antiviral activity tested by the plaque reduction assay revealed greater efficacy for CQ-NP compared to CQ at concentrations equal to or lower than 20 µg mL⁻¹ (p < 0.001). On the other hand, the B-NP had no antiviral activity. The CQ-NP has shown feasible properties and great potential to improve the antiviral activity of drugs.