Inhibitory Effect of (+)-Catechin on the Growth of Influenza A/PR/8 Virus in MDCK Cells

Abstract

We investigated whether (+)-catechin, a building block of tannins contained in the extract of Ephedrae herba (EHext), exerts an inhibitory effect on the acidification of intracellular compartments such as endosomes and lysosomes (referred to as ELS), and thereby inhibits the growth of influenza A PR/8/34 (PR8) virus (H1N1 subtype) in Madin-Darby canine kidney cells. The vital fluorescence microscopic study with acridine orange showed that 1-h treatment with (+)-catechin inhibited the acidification of ELS in a concentration-dependent manner (1.0-10.0 mM). Moreover, the growth of PR8 virus was inhibited markedly when the cells were treated with (+)-catechin (1.25-10.0 mM) for 1 h immediately after infection, or treated within as little as 5 to 10 min after infection. Conversely, virus growth resumed within 3 h concomitantly with the reappearance of acidified ELS after removal of (+)-catechin. Similar to EHext, (+)-catechin inhibited both the acidification of ELS and the influenza virus growth. It suggests that (+)-catechin is one of the active components in EHext.

Cytotoxic Activity of Crude Extracts fromAstragalus Chrysochlorus(Leguminosae)

“…The cytotoxicity assays were performed according to the microculture MTT method (11,15,16,17). The cells were harvested (4,5-5,0 x 10 4 cells/well) and inoculated in 24 well microtiter plates.…”

Synthetic Organic Chemistry Based on Small Ring Compounds

“…91) To examine whether drug 10 could exert a similar effect, acidification of intracellular compartments under influence of the drug was monitored by vital fluorescence microscopy with acridine orange. 97) This examination revealed that the amount and intensity of fluorescence in the drugtreated cells were almost identical with the control cells, implying that the drug did not affect the acidic environment of intracellular compartments, which causes the uncoating process. Although further studies may be necessary to elucidate a conclusive mechanism of action, we overall consider that the dihydrofuran-fused perhydrophenanthrenes investigated in this study exhibit anti-influenza activity by affecting a process of mRNA synthesis.…”

In Vitro Antiproliferative Activity of Aqueous Root Bark Extract of Cassia abbreviata (Holmes) Brenan

“…Formazan is an insoluble yellow colored product that is measured spectrophotometrically [18,19]. The activity of the enzyme to produce formazan is directly proportional to the level of cell viability and inversely proportional to the level of cell inhibition [20,21].…”