A resveratrol analog termed 3,3',4,4',5,5'-hexahydroxy-trans-stilbene is a potent HIV-1 inhibitor

The potential role of resveratrol as supportive antiviral in treating conditions such as COVID-19 - A formulator's perspective

With an increased transmissibility but milder form of disease of the omicron variant of COVID-19 and the newer antivirals often still out of reach of many populations, a refocus of the current treatment regimens is required. Safe, affordable, and available adjuvant treatments should also be considered and known drugs and substances need to be repurposed and tested. Resveratrol, a well-known antioxidant of natural origin, shown to act as an antiviral as well as playing a role in immune stimulation, down regulation of the pro-inflammatory cytokine release and reducing lung injury by reducing oxidative stress, is such an option. New initiatives and collaborations will however need to be found to unleash resveratrol's full potential in the pharmaceutical market.

Active Components from Cassia abbreviata Prevent HIV-1 Entry by Distinct Mechanisms of Action

Cassia abbreviata is widely used in Sub-Saharan Africa for treating many diseases, including HIV-1 infection. We have recently described the chemical structures of 28 compounds isolated from an alcoholic crude extract of barks and roots of C. abbreviata, and showed that six bioactive compounds inhibit HIV-1 infection. In the present study, we demonstrate that the six compounds block HIV-1 entry into cells: oleanolic acid, palmitic acid, taxifolin, piceatannol, guibourtinidol-(4α→8)-epiafzelechin, and a novel compound named as cassiabrevone. We report, for the first time, that guibourtinidol-(4α→8)-epiafzelechin and cassiabrevone inhibit HIV-1 entry (IC₅₀ of 42.47 µM and 30.96 µM, respectively), as well as that piceatannol interacts with cellular membranes. Piceatannol inhibits HIV-1 infection in a dual-chamber assay mimicking the female genital tract, as well as HSV infection, emphasizing its potential as a microbicide. Structure-activity relationships (SAR) showed that pharmacophoric groups of piceatannol are strictly required to inhibit HIV-1 entry. By a ligand-based in silico study, we speculated that piceatannol and norartocarpetin may have a very similar mechanism of action and efficacy because of the highly comparable pharmacophoric and 3D space, while guibourtinidol-(4α→8)-epiafzelechin and cassiabrevone may display a different mechanism. We finally show that cassiabrevone plays a major role of the crude extract of CA by blocking the binding activity of HIV-1 gp120 and CD4.

Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals

With the growing demand for sustainability and reducing CO₂ footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.

Resveratrol, Rapamycin and Metformin as Modulators of Antiviral Pathways

Balanced nutrition and appropriate dietary interventions are fundamental in the prevention and management of viral infections. Additionally, accurate modulation of the inflammatory response is necessary to achieve an adequate antiviral immune response. Many studies, both in vitro with mammalian cells and in vivo with small animal models, have highlighted the antiviral properties of resveratrol, rapamycin and metformin. The current review outlines the mechanisms of action of these three important compounds on the cellular pathways involved with viral replication and the mechanisms of virus-related diseases, as well as the current status of their clinical use.

Natural and nature-inspired stilbenoids as antiviral agents

Viruses continue to be a major threat to human health. In the last century, pandemics occurred and resulted in significant mortality and morbidity. Natural products have been largely screened as source of inspiration for new antiviral agents. Within the huge class of plant secondary metabolites, resveratrol-derived stilbenoids present a wide structural diversity and mediate a great number of biological responses relevant for human health. However, whilst the antiviral activity of resveratrol has been extensively studied, little is known about the efficacy of its monomeric and oligomeric derivatives. The purpose of this review is to provide an overview of the achievements in this field, with particular emphasis on the source, chemical structures and the mechanism of action of resveratrol-derived stilbenoids against the most challenging viruses. The collected results highlight the therapeutic versatility of stilbene-containing compounds and provide a prospective insight into their potential development as antiviral agents.

Progress to Improve Oral Bioavailability and Beneficial Effects of Resveratrol

Resveratrol (3,5,4'-trihydroxystilbene; RSV) is a natural nonflavonoid polyphenol present in many species of plants, particularly in grapes, blueberries, and peanuts. Several in vitro and in vivo studies have shown that in addition to antioxidant, anti-inflammatory, cardioprotective and neuroprotective actions, it exhibits antitumor properties. In mammalian models, RSV is extensively metabolized and rapidly eliminated and therefore it shows a poor bioavailability, in spite it of its lipophilic nature. During the past decade, in order to improve RSV low aqueous solubility, absorption, membrane transport, and its poor bioavailability, various methodological approaches and different synthetic derivatives have been developed. In this review, we will describe the strategies used to improve pharmacokinetic characteristics and then beneficial effects of RSV. These methodological approaches include RSV nanoencapsulation in lipid nanocarriers or liposomes, nanoemulsions, micelles, insertion into polymeric particles, solid dispersions, and nanocrystals. Moreover, the biological results obtained on several synthetic derivatives containing different substituents, such as methoxylic, hydroxylic groups, or halogens on the RSV aromatic rings, will be described. Results reported in the literature are encouraging but require additional in vivo studies, to support clinical applications.

Strategic Syntheses of Vine and Wine Resveratrol Derivatives to Explore their Effects on Cell Functions and Dysfunctions

Trans-resveratrol, the most well-known polyphenolic stilbenoid, is found in grapes and accordingly in wine and it is considered to be beneficial for human health, especially towards the aging-linked cell alterations by providing numerous biological activities, such as anti-oxidant, antitumoral, antiviral, anti-inflammatory, neuroprotective, and platelet anti-aggregation properties. Although trans-resveratrol is a promising molecule, it cannot be considered as a drug, due to its weak bio-availability and fast metabolism. To overcome these weaknesses, several research teams have undertaken the synthesis of innovative trans-resveratrol derivatives, with the aim to increase its solubility in water and pharmacological activities towards cell targets. The aim of this review is to show the chronological evolution over the last 25 years of different strategies to develop more efficient trans-resveratrol derivatives towards organism physiology and, therefore, to enhance various pharmacological activities. While the literature on the development of new synthetic derivatives is impressive, this review will focus on selected strategies regarding the substitution of trans-resveratrol phenyl rings, first with hydroxy, methoxy, and halogen groups, and next with functionalized substituents. The effects on cell functions and dysfunctions of interesting resveratrol analogs will be addressed in this review.

The antimalarial drug amodiaquine possesses anti-ZIKA virus activities

Zika virus (ZIKV) outbreak has emerged as a global health threat, particularly in tropical areas, over the past few years. No antiviral therapy or vaccine is available at present. For these reasons, repurposing clinically approved drugs against ZIKV infection may provide rapid and cost-effective global health benefits. Here, we explored this strategy and screened eight FDA-approved drugs for antiviral activity against ZIKV using a cell-based assay. Our results show that the antimalarial drug amodiaquine has anti-ZIKV activity with EC₅₀ at low micromolar concentrations in cell culture. We further characterized amodiaquine antiviral activity against ZIKV and found that it targets early events of the viral replication cycle. Altogether, our results suggest that amodiaquine may be efficacious for the treatment of ZIKV infection.

Therapeutic Versatility of Resveratrol Derivatives

Resveratrol, a natural phytoalexin, exhibits a remarkable range of biological activities, such as anticancer, cardioprotective, neuroprotective and antioxidant properties. However, the therapeutic application of resveratrol was encumbered for its low bioavailability. Therefore, many researchers focused on designing and synthesizing the derivatives of resveratrol to enhance the bioavailability and the pharmacological activity of resveratrol. During the past decades, a large number of natural and synthetic resveratrol derivatives were extensively studied, and the methoxylated, hydroxylated and halogenated derivatives of resveratrol received particular more attention for their beneficial bioactivity. So, in this review, we will summarize the chemical structure and the therapeutic versatility of resveratrol derivatives, and thus provide the related structure activity relationship reference for their practical applications.

HIV-1 Resistance to Dolutegravir Is Affected by Cellular Histone Acetyltransferase Activity

Integrase strand transfer inhibitors (INSTIs) are the newest class of antiretrovirals to be approved for the treatment of HIV infection. Canonical resistance to these competitive inhibitors develops through substitutions in the integrase active site that disrupt drug-protein interactions. However, resistance against the newest integrase inhibitor, dolutegravir (DTG), is associated with an R263K substitution at the C terminus of integrase that causes resistance through an unknown mechanism. The integrase C-terminal domain is involved in many processes over the course of infection and is posttranslationally modified via acetylation of three lysine residues that are important for enzyme activity, integrase multimerization, and protein-protein interactions. Here we report that regulation of the acetylation of integrase is integral to the replication of HIV in the presence of DTG and that the R263K mutation specifically disrupts this regulation, likely due to enhancement of interactions with the histone deacetylase I complex, as suggested by coimmunoprecipitation assays. Although no detectable differences in the levels of cell-free acetylation of the wild-type (WT) and mutated R263K enzymes were observed, the inhibition of cellular histone acetyltransferase enzymes sensitized the NL4.3_WT virus to DTG, while NL4.3_R263K was almost completely unaffected. When levels of endogenous acetylation were manipulated in virus-producing cells, inhibitors of acetylation enhanced the replication of NL4.3_R263K, whereas inhibition of deacetylation greatly diminished the replication of NL4.3_WT Taken together, these results point to a pivotal role of acetylation in the resistance mechanism of HIV to some second-generation integrase strand transfer inhibitors, such as DTG.IMPORTANCE This is, to our knowledge, the first report of the influence of posttranslational modifications on HIV drug resistance. Both viral replication and resistance to second-generation integrase strand transfer inhibitors of both WT and INSTI-resistant HIV strains were differentially affected by acetylation, likely as a result of altered interactions between integrase and the cellular deacetylation machinery. Many "shock and kill" strategies to eradicate HIV manipulate endogenous levels of acetylation in order to reactivate latent HIV. However, our results suggest that some drug-resistant viruses may differentially respond to such stimulation, which may complicate the attainment of this goal. Our future work will further illuminate the mechanisms involved.

Identification of resveratrol analogs as potent anti-dengue agents using a cell-based assay

Dengue virus (DENV) causes a variety of difficult-to-treat diseases that threaten almost half of the world's population. Currently, no effective vaccine or antiviral therapy is available. We have examined a series of synthetic resveratrol analogs to identify potential anti-DENV agents. Here, we demonstrate that two resveratrol analogs, PNR-4-44 and PNR-5-02, possess potent anti-DENV activity with EC₅₀ values in the low nanomolar range. These two resveratrol analogs were shown to mainly target viral RNA translation and viral replication, but PNR-5-02 is also likely to target cellular factors inside host cells. Although the precise molecular mechanism(s) mediating anti-DENV activities have not been elucidated, further structure-guided design might lead to the development of newer improved resveratrol derivatives that might have therapeutic value. J. Med. Virol. 89:397-407, 2017. © 2016 Wiley Periodicals, Inc.