TY - JOUR T1 - Antiviral and Antitumor Activity of Licorice Root Extracts JF - In Vivo JO - In Vivo SP - 777 LP - 785 VL - 30 IS - 6 AU - KUNIHIKO FUKUCHI AU - NORIYUKI OKUDAIRA AU - KAZUNORI ADACHI AU - REINA ODAI-IDE AU - SHIGERU WATANABE AU - HIROKAZU OHNO AU - MASAJI YAMAMOTO AU - TAISEI KANAMOTO AU - SHIGEMI TERAKUBO AU - HIDEKI NAKASHIMA AU - YOSHIHIRO UESAWA AU - HAJIME KAGAYA AU - HIROSHI SAKAGAMI Y1 - 2016/11/01 UR - http://iv.iiarjournals.org/content/30/6/777.abstract N2 - Background: In the search for anti-viral and antitumor substances from natural resources, antiviral and antitumor activities of licorice root extract and purified ingredients were investigated. Materials and Methods: Viability of cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Antiviral activity was quantified by the selectivity index, defined as the ratio of the 50% cytotoxic concentration (CC50) to the 50% effective concentration against human immunodeficiency virus (HIV) or herpes simplex virus (HSV)-infected cells (EC50). The tumor specificity was calculated by the ratio of CC50 against human normal oral cells to that against human oral squamous cell carcinoma cell lines. Licorice flavonoids and lower molecular polyphenols were subjected to quantitative structure–activity relationship analysis. Results: Alkaline extract of licorice root had higher anti-HIV activity than did water extracts, confirming our previous reports. On the other hand, water extract, especially the flavonoid-rich fraction, had higher anti-HSV activity than did the alkaline extract. The flavonoid-rich fraction was more cytotoxic against human oral squamous cell carcinoma cell lines compared to normal oral cells, suggesting their tumor-specific cytotoxicity. Conclusion: The present study suggests that water and alkaline extracts of licorice root exert different mechanisms of actions against these two viruses. Physicochemical properties, rather than the category of compounds, may be important in determining their anti-HSV activity. ER -