Protective mechanism of quercetin and its derivatives in viral-induced respiratory illnesses

Abstract

Globally, acute respiratory illnesses are the most commonly manifesting illness in all age group. The disease mostly affects the upper respiratory tract (URT) and is self-limiting. However, a small percentage progresses to lower respiratory tract infections (LRTI). The most important causative agents of severe LRTIs are bacteria and viruses. Various viruses can cause respiratory tract infections, being the most essential belonging to the Orthomyxoviridae, Paramyxoviridae, Picornaviridae, coronaviruses, and adenoviruses. Quercetin is classified as a flavonoid compound and was previously known to have antiviral, antibacterial, antioxidant, and anti-inflammatory activities. Some preclinical studies highlight quercetin could also interfere with coronavirus infection and modulate the release of pro-inflammatory cytokines. Since there is no comprehensive compilation addressing the antiviral activities of quercetin and its derivatives, this narrative review provides a summary of the preclinical evidence of their antiviral activities on respiratory illnesses induced by viruses other than coronaviruses. The literature research was performed in PubMed, Scopus, and Google Scholar. The results explain that quercetin has a wide range of actions in viral-induced respiratory illnesses including, but not limited to suppressing pro-inflammatory cytokines and chemokines, promoting antioxidant-related genes expression, blocking viral entry and replication, accelerating viral clearance, reducing the accumulation of alveolar macrophages, and reducing goblet cells marker and mucin gene expression.

Natural photosensitizers potentiate the targeted antimicrobial photodynamic therapy as the Monkeypox virus entry inhibitors: An in silico approach

“…Numerous studies support the antiviral properties of these natural photosensitizers in both in vitro and in vivo investigations due to their promising antiviral effects in inhibiting polymerases, reverse transcriptase, proteases, suppressing DNA gyrase, and binding viral capsid proteins [27] , [28] , [29] , [30] . Rib has high quantum yields for triplet formation (0.375±0.05 in aqueous solution at pH=7) [31] .…”

Pharmacokinetics of Quercetin

“…QUE is the most studied phytochemical and an important flavonoid for research [4]. Specifically, a growing body of well-documented evidence suggests numerous therapeutic and prophylactic roles of QUE in various diseases (e.g., neurodegenerative, infectious, and cardiovascular) and other bioactive processes (e.g., antimicrobial, antiviral, antioxidants, and antiaging) [5,6]. Most recently, numerous clinical trials have been conducted to examine the roles of QUE as an adjunct therapy for the coronavirus disease 2019 (COVID-19) [7].…”