Coronaviruses are responsible for a growing economic, social and mortality burden, as the causative agent of diseases such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), avian infectious bronchitis virus (IBV) and COVID-19. However, there is a lack of effective antiviral agents for many coronavirus strains. Naturally existing compounds provide a wealth of chemical diversity, including antiviral activity, and thus may have utility as therapeutic agents against coronaviral infections. The PubMed database was searched for papers including the keywords coronavirus, SARS or MERS, as well as traditional medicine, herbal, remedy or plants, with 55 primary research articles identified. The overwhelming majority of publications focussed on polar compounds. Compounds that show promise for the inhibition of coronavirus in humans include scutellarein, silvestrol, tryptanthrin, saikosaponin B 2 , quercetin, myricetin, caffeic acid, psoralidin, isobavachalcone, and lectins such as griffithsin. Other compounds such as lycorine may be suitable if a therapeutic level of antiviral activity can be achieved without exceeding toxic plasma concentrations. It was noted that the most promising small molecules identified as coronavirus inhibitors contained a conjugated fused ring structure with the majority being classified as being polyphenols.

Phenolic acid and flavonoid glycosides form a varied class of naturally occurring compounds, characterised by high polarity-resulting from the glycone moiety-and the presence of multiple phenol functionalities, which often leads to strong antioxidant activity.Phenolic glycosides, and in particular flavonoid glycosides, may possess strong bioactive properties with broad spectrum activity. This systematic literature review provides a detailed overview of 28 studies examining the biological activity of phenolic and flavonoid glycosides from plant sources, highlighting the potential of these compounds as therapeutic agents. The activity of glycosides depends upon the biological activity type, identity of the aglycone and the identity and specific location of the glycone moiety. From studies reporting the activity of both glycosides and their respective aglycones, phenolic glycosides appear to generally be a storage/reserve pool of precursors of more bioactive compounds. The glycosylated compounds are likely to be more bioavailable compared to their aglycone forms, due to the presence of the sugar moieties. Hydrolysis of the glycoside in the in vivo environment would release the free aglycone, potentiating their biological activity. However, further high-quality studies are needed to firmly establish the clinical efficacy of glycosides from many of the plant species studied.

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Objectives The pathophysiology of chronic wounds typically involves redox imbalance and inflammation pathway dysregulation, often with concomitant microbial infection. Endogenous antioxidants such as glutathione and tocopherols are notably reduced or absent, indicative of significant oxidative imbalance. However, emerging evidence suggests that polyphenols could be effective agents for the amelioration of this condition. This review aims to summarise the current state of knowledge surrounding redox imbalance in the chronic wound environment and the potential use of polyphenols for the treatment of chronic wounds. Key findings Polyphenols provide a multi-faceted approach towards the treatment of chronic wounds. Firstly, their antioxidant activity allows direct neutralisation of harmful free radicals and reactive oxygen species, assisting in restoring redox balance. Upregulation of pro-healing and anti-inflammatory gene pathways and enzymes by specific polyphenols further acts to reduce redox imbalance and promote wound healing actions, such as proliferation, extracellular matrix deposition and tissue remodelling. Finally, many polyphenols possess antimicrobial activity, which can be beneficial for preventing or resolving infection of the wound site. Summary Exploration of this diverse group of natural compounds may yield effective and economical options for the prevention or treatment of chronic wounds.