Evaluation of green tea extract as a safe personal hygiene against viral infections

Lee, Yun Ha; Jang, Yo Han; Kim, Young-Seok; Kim, Jinku; Seong, Baik Lin

Green tea (Camellia sinensis) has been known to confer many benefits to human health [18] [19] [20] [21] . The polyphenolic catechins in green tea are composed of epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), epicatechin-gallate (ECG), and epicatechin (EC) (Fig. 1) , among which, EGCG is most abundant and exerts a wide range of physiological and pharmacological activities. Most prominently, EGCG exhibits antiviral activity in vitro against a variety of viruses of Retroviridae, Orthomyxoviridae, and Flaviviridae, including important human infectious pathogens such as human immunodeficiency virus (HIV), influenza A virus, and hepatitis C virus [22] . EGCG potently exerts inhibition of influenza virus replication [23, 24] , interferes with HCV entry [25, 26] , and inactivates Herpes simplex virus 1 (HSV-1) and HSV-2 at acidic and neutral pHs [27, 28] . In addition, EGCG was shown to block the enzymatic activity of the HIV-1 reverse transcriptase [29] . One of proposed mechanisms for the antiviral activity of EGCG is the covalent modification of proteins by EGCG by autoxidation process, in which EGCG is oxidized to form EGCG quinone by autoxidation, which in turn can react with the nucleophilic thiol group of a cysteine residue to form EGCG-protein complex [30] . Furthermore, it has been proposed that the autoxidation of catechins involves oxygen radical and molecular oxygen [31] . Although numerous previous studies have investigated antiviral activities of green tea extract or purified catechin components against viruses, there have been few reports with respect to developing disinfectants of public and personal hygiene. For practical use at home and in the field, a long-term stability at various working conditions is essential. Toward finding a safe and effective hygiene agent against viruses, we evaluated the durability of antiviral effects of green tea extract (GTE) as a powder type and a solution type over extended periods at various temperature conditions using human influenza A/H1N1 virus. The effect of antioxidant additive such as ascorbic acid further suggests that the virucidal function is mediated by the prooxidant activities of catechins.