Efficacy of Black Tea Extracts on Inhibition of Herpes Simplex Virus Type 2

¹ Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand Master of Science Program in Applied Microbiology (International Program), Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand
² Natural Extracts and Innovative Products for Alternative Healthcare Research Group, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand

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Abstract

Herpes simplex viruses (HSV) are divided into two types: HSV-1 and HSV-2. HSV-1 typically causes infections in the oral and ocular regions, whereas HSV-2 is mainly transmitted sexually and predominantly affects the genital area. Current antiviral drugs, such as acyclovir, valacyclovir, and famciclovir may cause undesirable side effects. Therefore, natural extracts should be used as an anti-viral agent for the treatment of HSV infections. Camellia sinensis, or tea, is globally consumed as a beverage that is rich in bioactive compounds, including polyphenols, catechins, and theaflavins. These bioactive compounds exhibit strong antioxidants and anti-inflammatory properties. In this study, black tea leaves were extracted using distilled water and 95% ethanol, yielding aqueous and ethanolic extracts. Cytotoxicity on Vero cells was assessed by MTT assay. The CC50 values of black tea leaf aqueous and ethanolic extracts were 70.5 and 237.97 μg/mL, respectively. Antioxidant activities of aqueous and ethanolic extracts of black tea leaves were 271.07 and 85.47 mg gallic acid equivalent/g extract when determined by DPPH assay. Non-toxic concentrations of black tea aqueous extract (30 μg/mL) and ethanolic extract (120 μg/mL) inhibited HSV-2 when treatment after viral infection by 97.79% and 96.62%, respectively. Therefore, both extracts were potent against HSV-2. The ethanolic extract exhibited a remarkably high SI value of 72.99 and aqueous extract showed SI value of 18.70. These findings suggest that black tea extracts possess potent antioxidants and antiviral activities and could serve as promising natural alternatives for managing HSV infections.