Kunihiko Fukuchi, Noriyuki Okudaira, Kazunori Adachi, Reina Odai-Ide, Shigeru Watanabe, Hirokazu Ohno, Masaji Yamamoto, Taisei Kanamoto, Shigemi Terakubo, Hideki Nakashima, Yoshihiro Uesawa, Hajime Kagaya, Hiroshi Sakagami 

Because there is a search to derive antiviral and anti-tumor substances from natural resources, an investigation was done into the antiviral and anti-tumor activities of licorice root extract. The method included a ratio of 50% cytotoxic concentration to 50% effective concentration against human immunodeficiency virus (HIV) or herpes simplex virus (HSV)-infected cells. The experiment found that alkaline extract of licorice rot had higher anti-HIV activity than did water extracts. However, especially found in the flavonoid-rich fraction, water extract had higher anti-HSV activity than did the alkaline extract. In conclusion, the study suggested that alkaline and water extracts of licorice root apply different mechanisms  off actions against HIV and HSV.