Antiviral and Antitumor Activity of Licorice Root Extracts.
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.


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 CC50against 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.


CONCLUSIONS
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.
Graduate School, Showa University, Tokyo, Japan sakagami@dent.meikai.ac.jp kfukuchi@med.showa-u.ac.jp.
Kunihiko
K
Fukuchi
Meikai University School of Dentistry, Sakado, Japan.
Noriyuki
N
Okudaira
Meikai University School of Dentistry, Sakado, Japan.
Kazunori
K
Adachi
Meikai University School of Dentistry, Sakado, Japan.
Reina
R
Odai-Ide
Meikai University School of Dentistry, Sakado, Japan.
Shigeru
S
Watanabe
Maruzen Pharmaceuticals, Shibuya, Japan.
Hirokazu
H
Ohno
Maruzen Pharmaceuticals, Shibuya, Japan.
Masaji
M
Yamamoto
St. Marianna University School of Medicine, Kanagawa, Japan.
Taisei
T
Kanamoto
St. Marianna University School of Medicine, Kanagawa, Japan.
Shigemi
S
Terakubo
St. Marianna University School of Medicine, Kanagawa, Japan.
Hideki
H
Nakashima
Meiji Pharmaceutical University, Kiyose, Japan.
Yoshihiro
Y
Uesawa
Meiji Pharmaceutical University, Kiyose, Japan.
Hajime
H
Kagaya
Meikai University School of Dentistry, Sakado, Japan sakagami@dent.meikai.ac.jp kfukuchi@med.showa-u.ac.jp.
Hiroshi
H
Sakagami
D000818:Animals; D000970:Antineoplastic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D000998:Antiviral Agents / Q000302:isolation & purification / Q000494:pharmacology*; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000821:virology; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology; D006035:Glycyrrhiza / Q000737:chemistry*; D015497:HIV-1 / Q000187:drug effects / Q000502:physiology; D006801:Humans; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry*; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology; D018139:Simplexvirus / Q000187:drug effects / Q000502:physiology; D014709:Vero Cells
D000970:Antineoplastic Agents; D000998:Antiviral Agents; D005419:Flavonoids; D010936:Plant Extracts; D059808:Polyphenols
Licorice root; QSAR; alkaline extract; anti-HIV; anti-HSV; flavonoids; fractionation; tumor-specificity