Antiviral activities of hydroxylated flavones on feline foamy viral proliferation

Abstract

Many hydroxylated flavones are reported to have antibacterial, anticancer, or antiviral activities. In this study, eleven hydroxylated flavones including 3,3′,4′,5,7-pentahydroxyflavone (quercetin), three polymethoxyflavones, two polyethoxyflavones, two polypropoxyflavones, one butoxyflavone, and two benzoxyflavones were tested for antiviral activity using feline foamy virus. Most of the compounds tested showed that they did not have significant cytotoxic effect on the crandell-Ress feline kidney cells. However, four compounds, including quercetin, 5,3′-dihydroxy-3,7,4′-trimethoxyflavone, 5-hydroxy-3,7,3′,4′-tetramethoxyflavone, and 3,5,7,3′,4′-pentahydroxyflavone, showed a strong inhibitory effect on feline foamy virus (FFV) proliferation, by reducing viral production to 7–24% of that in the un-treated control when they were added to the cells at a final concentration of 10 μM. These results were supported by western blot detecting viral protein in the infected cell lysate. In further analysis, quercetin was observed to have a direct inhibitory effect on reverse transcriptase and integrase in vitro, which can explain the mechanism by which quercetin inhibits FFV proliferation. These preliminary results suggest that hydroxylated flavones such as quercetin, 5,3′-dihydroxy-3,7,4′-trimethoxyflavone, 5-hydroxy-3,7,3′,4′-tetramethoxyflavone, and 3,5,7,3′,4′-pentahydroxyflavone have strong antiretroviral activities.