Antiviral And Anti-inflammatory Activities Of Flavonoids

Flavonoids are a class of plant secondary metabolites which have similar structures as flavones. The backbone is2-phenyl-1,4-benzopyrone. Flavonoids can be classified into flavones, flavonols, flavanones, dihydroflavones, dihydroflavonols, isoflavones, isoflavanones, chalcones, aurones, flavanes, anthocyanidins, biflavanones. Flavonoids have many kinds of bioactivities, such as antioxidant, anti-inflammatory, anti-microbial, anti-virus, anti-tumor effects and so on. In this report, pinocembrin, cryptocaryanone B, cryptochinone A and cryptocaryone were isolated from an ethanol extract of stems of Cryptocarya chingii. Here, we attempted to investigate whether these flavonoids displayed antiviral and anti-inflammatory activity.The transcription factor NF-κB plays a key role in the regulation of many inflammatory responses. IκBα degradation as a measurement of TNFa-induced NF-κB activation was determined by immunoblotting assay. To futher investigate the anti-inflammatory activity of these compounds, we tested whether these compounds can inhibit LPS induced NO production using the total nitric oxide assay kit.Quercetin, quercitrin and isoquercitrin significantly blocked HSV infection, the inhibition rate was about50%. Our studies indicated that quercetin blocked HSV infection, probably through inhibiting HSV induced ROS production. Pinocembrin, cryptocaryanone B, cryptochinone A, cryptocaryone and naringenin can significantly block NF-κB activation. Pinocembrin, cryptocaryanone B, cryptocaryone can suppress LPS-stimulated NO production, while cryptochinone A and naringenin had marginal effects.In this study, we evaluated the anti-inflammatory and anti-virus activities of flavonoids, which provided foundations for leading compounds’screenings in the future. However, further investigation is needed for more detailed mechanisms.