Antiviral Activity of Polymethoxylated Flavones from “Guangchenpi”, the Edible and Medicinal Pericarps of Citrus reticulata ‘Chachi’

Abstract

The present study found that the supercritical fluid extract of "Guangchenpi" possessed in vitro antiviral activity against respiratory syncytial virus (RSV). Bioassay-guided isolation and identification of this extract led to obtain five active polymethoxylated flavones (1-5). Cytopathic effect (CPE) reduction assay exhibited that tangeretin (2) and nobiletin (3), two major polymethoxylated flavones in the extract, possessed better anti-RSV effect comparable to the positive control ribavirin. Plaque reduction assay revealed that tangeretin dose-dependently inhibited RSV-induced plaque formation on the HEp-2 cells. This polymethoxylated flavone mainly affected the intracellular replication of RSV, and it also could inhibit RSV entry into the HEp-2 cells. Further investigations with quantitative real-time PCR and confocal and Western blot assays indicated that tangeretin downregulated the expression of RSV phosphoprotein (P protein). Results suggest the potential application of the supercritical fluid extract of "Guangchenpi" and tangeretin in the treatment and the prevention of RSV infection.

Phenolic Compounds from the Flowers of Bombax malabaricum and Their Antioxidant and Antiviral Activities

“…As shown in Table 3, (10) showed potent anti-RSV activity comparable to the positive drug ribavirin. In our previous studies, we have found that caffeoyl acid derivatives from natural medicines had potent anti-RSV activities [36,[38][39][40]. Compound 10 is a flavonoid glycoside with a cis-coumaroyl connection.…”

“…CPE reduction assay was adopted to screen the anti-RSV activities of the isolated compounds as described in the previous reports [36,38]. First of all, the cytotoxic activities of the ethanol extract and isolates on host cells were observed under a light microscope (DP70 Olympus, Melville, NY, USA).…”

“…The samples showing anti-RSV activities in CPE assay were further determined by plaque reduction assay [38]. HEp-2 cells were inoculated in 24-well plate for 24 h. The virus suspension with 60-80 plaque forming unit (PFU) and two-fold diluted samples were added a 24-well microplate containing confluent cell monolayer.…”

“…The cytotoxicity of the anti-RSV active compounds on HEp-2 cells was detected by MTT assay in 96-well plate (Corning, Corning, NY, USA) [38]. In brief, serial two-fold dilutions of samples were added to confluent HEp-2 cell monolayers, and the medium without the sample was used as cell control.…”

Antioxidants of Maltease orange peel: comparative investigation of the efficiency of four extraction methods

“…In fact, Xu et al (2014) showed that polymethoxylaed flavones (PMF) of citrus reticulata extract (tangeretin and nobiletin), are the active components against the respiratory syncytial virus. In addition, the PMF of citrus can be used as nutraceutical supplement or as a therapeutic agent in pre-diabetic and metabolic syndrome conditions (Berim and Gang, 2015).…”