(194n) Stability of Virucidal Effects of Green Tea Extracts

Viral infections often pose tremendous public health concerns as well as economic burdens. Despite the availability of vaccines or antivirals, personal hygiene is often considered as effective means as the first-hand measure against viral infections. The green tea polyphenols, in particular, epigallocatechin-3-gallate (EGCG), are known to exert potent antiviral activity. Here we evaluate the stability of virucidal effects of green tea extract (GTE). The temporal stability of antiviral effects of GTE was determined by measuring its virucidal activity against human influenza virus (A/H1N1) using the plague assay. The virucidal activity was observed in a dose dependent manner, and about 4–6 log₁₀ reduction of infectivity was achieved in 0.01–0.1% GT solution. >99.99% inactivation of the influenza virus was achieved within five minutes exposure to GT solution. When formulated with 0.2% ascorbic acid, the potency of virucidal activity was compromised, and the exhaustion of antiviral activity was delayed, prolonging the duration of the virucidal function over extended period. A potent antiviral activity with about 4 log₁₀ reduction of viral titers was maintained with wide range of temperatures (4–37 ºC) for two months as solution type, and for prolonged period as power. These data suggest that green tea extracts could be formulated as a safe and environmentally friendly personal hygiene against viral infections.