Mechanistic Understanding of the Antiviral Properties of Pistachios and Zeaxanthin against HSV-1

Antiviral Potential and In Silico Insights of Polyphenols as Sustainable Phytopharmaceuticals: A Comprehensive Review

Polyphenols, particularly flavonoids, are reported to have health-promoting, disease-preventing abilities and several polyphenols having a wide spectrum of antiviral activities can be explored for preventive and/or therapeutic purposes. We have compiled the updated literature of diverse polyphenols active against common viral diseases, including herpes, hepatitis, influenza, rota and SARS-corona-viruses. The antiviral activity of bioactive polyphenols depends on the hydroxyl and ester groups of polyphenol molecules, as compounds with five or more hydroxyl groups and three specific methoxy groups showed antiviral potential, like anti-rabies activity. This comprehensive review will explore selective polyphenols isolated from common ethnomedicinal or food plants. Comparing bioactivities of structurally related polyphenols and using bioinformatics studies, we have explored the three most promising phyto-antivirals, including chrysin, resveratrol and quercetin, available in many foods and medicinal plants. Quercetin showed a maximum interaction score with human genes. We also explore the intricate structure-activity relationship between these polyphenols and pathogenic viruses with their mechanisms of antiviral action in selected virus models. Here, we report the promising potential of some phyto-polyphenols in the management of viral diseases through an in-depth analysis of the structure and bioactivity of these compounds.

Selective Control by Pistacia vera L. and Its Carotenoid Zeaxanthin on SARS-CoV-2 Virus

Since the onset of the COVID-19 (COronaVIrus Disease 19) pandemic, SARS-CoV-2 has exhibited a high transmission rate, further enhanced by new variants able to better adapt to humans. Addressing this issue has been challenging due to viral resistance and side effects associated with antiviral drugs and vaccines. As a result, there has been a growing interest in plant-derived compounds with antiviral properties. Our study revealed that pistachio extracts significantly inhibited SARS-CoV-2 viral entry. Employing pseudotyped particles bearing the S protein of SARS-CoV-2, we demonstrated that treatment with pistachio extracts inhibited binding of alpha (α) and omicron (ο) SARS-CoV-2 variants. Furthermore, our study revealed that the pistachio carotenoid zeaxanthin exhibited a different inhibitory activity against two SARS-CoV-2 variants. In silico analyses demonstrated a strong interaction between zeaxanthin and the receptor-binding domain (RBD) domain of the omicron spike (S) protein, thus reducing pseudovirus entry. However, zeaxanthin's weaker interaction with the alpha variant's RBD was insufficient to inhibit entry. Additionally, zeaxanthin suppressed the expression of the host protease TMPRSS2 at the protein level, thereby limiting the internalization of the alpha variant, which relies on TMPRSS2 for cellular entry.

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.

Pistacia vera L. as natural source against antimicrobial and antiviral resistance

Increased global research is focused on the development of novel therapeutics to combat antimicrobial and antiviral resistance. Pistachio nuts represent a good source of protein, fiber, monounsaturated fatty acids, minerals, vitamins, and phytochemicals (carotenoids, phenolic acids, flavonoids and anthocyanins). The phytochemicals found in pistachios are structurally diverse compounds with antimicrobial and antiviral potential, demonstrated as individual compounds, extracts and complexed into nanoparticles. Synergistic effects have also been reported in combination with existing drugs. Here we report an overview of the antimicrobial and antiviral potential of pistachio nuts: studies show that Gram-positive bacterial strains, such as Staphylococcus aureus, are the most susceptible amongst bacteria, whereas antiviral effect has been reported against herpes simplex virus 1 (HSV-1). Amongst the known pistachio compounds, zeaxanthin has been shown to affect both HSV-1 attachment penetration of human cells and viral DNA synthesis. These data suggest that pistachio extracts and derivatives could be used for the topical treatment of S. aureus skin infections and ocular herpes infections.

Microbial pigments: Sources, current status, future challenges in cosmetics and therapeutic applications

Color serves as the initial attraction and offers a pleasing aspect. While synthetic colorants have been popular for many years, their adverse environmental and health effects cannot be overlooked. This necessitates the search for natural colorants, especially microbial colorants, which have proven and more effective. Pigment-producing microorganisms offer substantial benefits. Natural colors improve product marketability and bestow additional benefits, including antioxidant, antiaging, anticancer, antiviral, antimicrobial, and antitumor properties. This review covers the various types of microbial pigments, the methods to enhance their production, and their cosmetic and therapeutic applications. We also address the challenges faced during the commercial production of microbial pigments and propose potential solutions.

An Integrated In Silico and In Vitro Approach for the Identification of Natural Products Active against SARS-CoV-2

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has provoked a global health crisis due to the absence of a specific therapeutic agent. 3CLpro (also known as the main protease or Mpro) and PLpro are chymotrypsin-like proteases encoded by the SARS-CoV-2 genome, and play essential roles during the virus lifecycle. Therefore, they are recognized as a prospective therapeutic target in drug discovery against SARS-CoV-2 infection. Thus, this work aims to collectively present potential natural 3CLpro and PLpro inhibitors by in silico simulations and in vitro entry pseudotype-entry models. We screened luteolin-7-O-glucuronide (L7OG), cynarin (CY), folic acid (FA), and rosmarinic acid (RA) molecules against PLpro and 3CLpro through a luminogenic substrate assay. We only reported moderate inhibitory activity on the recombinant 3CLpro and PLpro by L7OG and FA. Afterward, the entry inhibitory activity of L7OG and FA was tested in cell lines transduced with the two different SARS-CoV-2 pseudotypes harboring alpha (α) and omicron (o) spike (S) protein. The results showed that both compounds have a consistent inhibitory activity on the entry for both variants. However, L7OG showed a greater degree of entry inhibition against α-SARS-CoV-2. Molecular modeling studies were used to determine the inhibitory mechanism of the candidate molecules by focusing on their interactions with residues recognized by the protease active site and receptor-binding domain (RBD) of spike SARS-CoV-2. This work allowed us to identify the binding sites of FA and L7OG within the RBD domain in the alpha and omicron variants, demonstrating how FA is active in both variants. We have confidence that future in vivo studies testing the safety and effectiveness of these natural compounds are warranted, given that they are effective against a variant of concerns.