Antiviral Research 68 (2005) 66–74
Antiviral effect of catechins in green tea on influenza virus
Jae-Min Song, Kwang-Hee Lee, Baik-Lin Seong ∗
Department of Biotechnology, College of Engineering, Yonsei University, 134, Shinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea
Received 22 February 2005; accepted 28 June 2005
Polyphenolic compound catechins ((−)-epigallocatechin gallate (EGCG), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin (EGC))
from green tea were evaluated for their ability to inhibit influenza virus replication in cell culture and for potentially direct virucidal effect.
Among the test compounds, the EGCG and ECG were found to be potent inhibitors of influenza virus replication in MDCK cell culture
and this effect was observed in all influenza virus subtypes tested, including A/H1N1, A/H3N2 and B virus. The 50% effective inhibition
concentration (EC50) of EGCG, ECG, and EGC for influenza A virus were 22–28, 22–40 and 309–318 M, respectively. EGCG and ECG
exhibited hemagglutination inhibition activity, EGCG being more effective. However, the sensitivity in hemagglutination inhibition was widely
different among three different subtypes of influenza viruses tested. Quantitative RT-PCR analysis revealed that, at high concentration, EGCG
and ECG also suppressed viral RNA synthesis in MDCK cells whereas EGC failed to show similar effect. Similarly, EGCG and ECG inhibited
the neuraminidase activity more effectively than the EGC. The results show that the 3-galloyl group of catechin skeleton plays an important
role on the observed antiviral activity, whereas the 5′-OH at the trihydroxy benzyl moiety at 2-position plays a minor role. The results, along
with the HA type-specific effect, suggest that the antiviral effect of catechins on influenza virus is mediated not only by specific interaction
with HA, but altering the physical properties of viral membrane.
© 2005 Elsevier B.V. All rights reserved.
Keywords: Influenza virus