Dietary Flavonols With Antiviral Efficacy: Safety and Regulatory Concerns

Globally, a variety of pharmacologically-active plant or natural products are commonly consumed as health-protective dietary supplements. These are marketed as crude formulations, isolated metabolites, multi-vitamins, essential amino acids, unsaturated fatty acids and minerals. Of these, pharmacologically-active flavonols like rutin, quercetin, kaempferol, myricetin, isorhamnetin are the most consumed dietary supplements. In addition to their broad-spectrum therapeutic benefits, these are also known for good antiviral efficacies in experimental as well as pre-clinical settings. However, though such marketed dietary supplements have gained global popularity, they are generally poorly regulated as compared to conventional drugs for their efficacy and safety. Interestingly, their experimental assessment for non-cytotoxicity as well as clinical evaluation of their intake and mortality risks in a cohort of adults have been recently reported. A comprehensive literature survey was carried out on Google Scholar, PubMed, Europe PMC, Medline and SciHub, using phrases like, herbal or natural dietary supplements, bioactive natural products, dietary flavonols, antiviral natural products, herbal hepatotoxicity and causality, etc. The present article discusses the current knowledge on the marketed dietary flavonols with antiviral efficacy as well as their safety and regulatory measures.