The bioactive plant-derived epi-nutraceuticals reported in the review include apigenin, curcumin, quercetin, berberine, resveratrol, genistein and sulforaphane.
Some compounds are observed to have a broad-spectrum anti-viral activity, inhibiting both RNA and DNA viruses, with curcumin and glycyrrhizin acid are observed to be the most effective.
The ‘Nutrients’ published report emphasises: “Epigenetic therapies might be used in the future in conjunction with standard antiviral drugs or vaccines to increase their efficacy.
“By altering host factors, epigenetic therapies can create a hostile environment for viral replication and make viruses more susceptible to the direct antiviral effects of conventional drugs,” the report concluded.
Following the continued emergence of SARS-CoV-2 variants, there has been a renewed awareness of the threat of viral infections to humans, the authors note.
They point out that whilst vaccinations are essential for such wide-spread infections, drugs and natural alternatives are critical for those with compromised immune systems or those with restricted access. They add that plant-derived products with anti-viral activities present strong potential as novel therapeutics, whilst overcoming sustainability and cost challenges.
Epigenetic modification to affect gene expression within the genome presents a mechanism to silence incoming viral molecules. Thus, the researchers sought to investigate the potentials of plant-derived substances as epigenetic modifiers for anti-viral activity.
The review compared activities against 20 main viruses, whilst reviewing 33 significant bioactive compounds with anti-viral and epigenetic-altering compounds.
The researchers observe that an array of essential oils (EOs) and extracts from various families including Lamiaceae, Myrtaceae, Asteraceae, Brassicaceae, exhibit highly effective anti-viral activities. Of these, the essential oils of Illicium verum Hooker f. and Rosmarinus officinalis L. are extremely effective against HSV-1, whilst Eucalyptus globulus Labill. proves to be highly effective against Coxsackie virus B3.
Further analysis reveals that herbal EOs and extracts are more effective than pure isolated compounds in some cases.
Regarding the main contributors of the antiviral activities, its noted that most extracts responsible include polyphenols, terpenes, or alkaloids. Of these, the key bioactive substances with most noteworthy effects on epigenetic pathways include EGCG, apigenin, curcumin, quercetin, berberine, resveratrol, genistein and sulforaphane.
The report emphasises that not all bioactives exhibiting epigenetic mediation had anti-viral activities, but those also exhibiting anti-viral activities against both RNA and DNA include baicalin, sulforaphane, apigenin, ginkgolic acid, andrographolide, EGCG, resveratrol, berberine, quercetin, and curcumin.
Compounds displaying the most promising broad spectrum anti-viral activities are noted to be curcumin and glycyrrhizin.
The researchers explain the varying modes of action exhibited by the herbal products to exert their observed antiviral activities.
“These plant-derived epigenetic modifiers alter gene expression by targeting the epigenome, reversible DNA/protein modification, and chromatin remodeling. Viruses rely on epigenome modification to ensure successful replication, latency, or escape from the immune response system.
“The reversal of the epigenome by plant-derived bioactive substances could result in blocking the virus’ life cycle, disrupting latency, and activating the immune response to fight viral infections,” they add.
The report emphasises the need for further innovative in vitro and in vivo studies to explore these broad antiviral activities and overcome barriers in bioavailability which may currently limit the plant products’ therapeutic potential.
“Plant-Derived Epi-Nutraceuticals as Potential Broad-Spectrum Anti-Viral Agents”
by Rosita Gabbianelli, Ehud Shahar, Gaia de Simone, Chiara Rucci, Laura Bordoni, Giulia Feliziani, Fanrui Zhao, Marta Ferrati, Filippo Maggi, Eleonora Spinozzi and Jamal Mahajna