Anti-influenza virus activity of green tea by-products in vitro and efficacy against influenza virus infection in chickens

Poult Sci. 2012 Jan;91(1):66-73. doi: 10.3382/ps.2011-01645.


Polyphenolic compounds present in green tea, particularly catechins, are known to have strong anti-influenza activity. The goal of this study was to determine whether green tea by-products could function as an alternative to common antivirals in animals compared to original green tea. Inhibition of viral cytopathic effects ascertained by neutral red dye uptake was examined with 50% effective (virus-inhibitory) concentrations (EC₅₀)determined. Against the H1N1 virus A/NWS/33, we found the anti-influenza activity of green tea by-products (EC₅₀ = 6.36 µg/mL) to be equivalent to that of original green tea (EC₅₀= 6.72 µg/mL). The anti-influenza activity of green tea by-products was further examined in mouse and chicken influenza infection models. In mice, oral administration of green tea by-products reduced viral titers in the lungs in the early phase of infection, but they could not protect these animals from disease and death. In contrast, therapeutic administration of green tea by-products via feed or water supplement resulted in a dose-dependent significant antiviral effect in chickens, with a dose of 10 g/kg of feed being the most effective (P < 0.001). We also demonstrated that unidentified hexane-soluble fractions of green tea by-products possessed strong anti-influenza activity, in addition to ethyl acetate-soluble fractions, including catechins. This study revealed green tea by-product extracts to be a promising novel antiviral resource for animals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Intranasal / veterinary
  • Administration, Oral
  • Animals
  • Antiviral Agents / administration & dosage*
  • Antiviral Agents / chemistry
  • Antiviral Agents / pharmacology
  • Camellia sinensis / chemistry*
  • Catechin / analogs & derivatives
  • Catechin / chemistry
  • Catechin / pharmacology
  • Cell Line
  • Chickens
  • Hemagglutination Inhibition Tests / veterinary
  • Influenza A Virus, H1N1 Subtype / drug effects*
  • Influenza A Virus, H9N2 Subtype / drug effects*
  • Mice
  • Mice, Inbred BALB C
  • Neuraminidase / antagonists & inhibitors
  • Neutral Red / chemistry
  • Orthomyxoviridae Infections / drug therapy
  • Orthomyxoviridae Infections / veterinary*
  • Plant Extracts / administration & dosage*
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology
  • Plant Leaves / chemistry
  • Reverse Transcriptase Polymerase Chain Reaction / veterinary
  • Specific Pathogen-Free Organisms


  • Antiviral Agents
  • Plant Extracts
  • Neutral Red
  • Catechin
  • Neuraminidase