Chemopreventive effects of 2-(allylthio)pyrazine on hepatic lesion, mutagenesis and tumorigenesis induced by vinyl carbamate or vinyl carbamate epoxide.
2-(Allylthio)pyrazine (2-AP), synthesized for its possible use as a hepatoprotective agent, has been found to selectively inhibit rat hepatic cytochrome P450 2E1 (Kim et al., Biochem. Pharmacol., 53, 261-269, 1997), while it enhances the activities of phase II detoxification enzymes such as glutathione S-transferase and epoxide hydrolase. As part of a program in evaluating the chemopreventive potential of 2-AP, we have determined its effects on hepatotoxicity, mutagenicity and tumorigenicity of vinyl carbamate (VC), a prototypic hepatocarcinogen preferentially activated by P450 2E1 to the ultimate carcinogenic metabolite vinyl carbamate epoxide (VCO), which undergoes detoxification by glutathione conjugation and oxirane hydrolysis. Administration of 2-AP (100 mg/kg body wt) to male Sprague-Dawley rats by gavage, 2 days, 1 day and 4 h prior to VC or VCO, markedly ameliorated the hepatotoxicity of these compounds as determined by decreased serum aspartate aminotransferase and alanine aminotransferase activities. Furthermore, 2-AP pre-treatment significantly suppressed the VC-induced hepatocarcinogenesis in infant male B6C3F1 mice. In a separate experiment, the multiplicities of skin tumors formed in female ICR mice treated with 5.8 micromol of VC or VCO were inhibited 58 and 70%, respectively, by pre-treatment with 2-AP by oral administration. The mutational spectrum of ras-oncogene in papillomas was not altered by 2-AP pre-treatment. 2-AP also inhibited the mutagenicity of VC in the Salmonella-microsome assay. Taken together, these findings suggest that 2-AP is a potential chemopreventive agent.
Seoul National University College of Pharmacy, South Korea. surh@plaza.snu.ac.kr
Y J
YJ
Surh
S G
SG
Kim
K K
KK
Park
Y
Y
Sohn
J M
JM
Lee
N D
ND
Kim
J A
JA
Miller
D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D002273:Carcinogens / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D009153:Mutagens / Q000633:toxicity*; D011719:Pyrazines / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014520:Urethane / Q000031:analogs & derivatives* / Q000633:toxicity
C104935:2-(allylthio)pyrazine; D016588:Anticarcinogenic Agents; D002273:Carcinogens; D004791:Enzyme Inhibitors; D009153:Mutagens; D011719:Pyrazines; D014520:Urethane; C017963:vinyl carbamate; C064746:vinyl carbamate epoxide