Anti-carcinogenic activity of Taraxacum plant. II.
Eleven triterpenoids (1-11) from the roots of Taraxacum japonicum (Compositae) were examined for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) induced by the tumor promoter, 12-O-tetrade-canoylphorbol-13-acetate (TPA), in Raji cells as a primary screening test for anti-tumor-promoters (cancer chemopreventive agents). Of these triterpenoids, taraxasterol (1) and taraxerol (7) exhibited significant inhibitory effects on EBV-EA induction, but the inhibitory effects of their acetates 2 and 8 were weaker than those of 1 and 7. Furthermore, 1 and 7 exhibited potent anti-tumor-promoting activity in the two-stage carcinogenesis tests of mouse skin using 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter, and 1 showed a remarkable inhibitory effect on mouse spontaneous mammary tumors using C3H/OuJ mouse. These results strongly suggested that taraxasterol (1) could be a valuable chemopreventive agent.
Kyoto Pharmaceutical University, Japan.
M
M
Takasaki
T
T
Konoshima
H
H
Tokuda
K
K
Masuda
Y
Y
Arai
K
K
Shiojima
H
H
Ageta
D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000956:Antigens, Viral / Q000096:biosynthesis; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D005260:Female; D015674:Mammary Neoplasms, Animal / Q000517:prevention & control; D051379:Mice; D008809:Mice, Inbred C3H; D013261:Sterols / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity; D014315:Triterpenes / Q000494:pharmacology*
D016588:Anticarcinogenic Agents; D000956:Antigens, Viral; D000972:Antineoplastic Agents, Phytogenic; C033305:Epstein-Barr virus early antigen; D013261:Sterols; D014315:Triterpenes; C079988:taraxasterol; D013755:Tetradecanoylphorbol Acetate