Detail of "215-58-7"

Reference

Dibenz[a,c]anthracene: a potent inhibitor of skin-tumor initiation by 7,12-dimethylbenz[a]anthracene

Dibenz[a,c]anthracene: a potent inhibitor of skin-tumor initiation by 7,12-dimethylbenz[a]anthracene. Slaga, Thomas J.; Viaje, Aurora; Buty, Steven G.; Bracken, William M. (Biol. Div., Oak Ridge Natl. Lab., Oak Ridge, Tenn., USA). Res. Commun. Chem. Pathol. Pharmacol., 19(3), 477-83 (English) 1978. CODEN: RCOCB8. ISSN: 0034-5164. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) The mechanism by which the weak tumor initiator dibenz[a,c]anthracene (I) [215-58-7] inhibits the skin-tumor-initiating activity of 7,12-dimethylbenz[a]anthracene (DMBA) [57-97-6] was investigated. I was a potent inhibitor of DMBA initiation when given either 5 min, or 1, 12, or 36 h before DMBA. Pretreatment of mice with unlabeled I at either 1, 12, or 36 h before killing increased the in vitro epidermally mediated covalent binding of [3H]DMBA to DNA more than pretreatment with unlabeled DMBA at comparable times. Only when the tumor expts. were mimicked did a decrease in DMBA covalent binding to DNA in vitro occur. The results suggest that some competition at the level of polycyclic hydrocarbon metab. or at the genome level may exist between metabolites of the weak carcinogen and those of the strong carcinogen.

Hepatic and extrahepatic metabolism of carbon-14-styrene oxide

Hepatic and extrahepatic metabolism of carbon-14-styrene oxide. Ryan, Adrian J.; James, Margaret O.; Ben-Zvi, Zvi; Law, Francis C. P.; Bend, John R. (Pharmacol. Branch, Natl. Inst. Environ. Health Sci., Research Triangle Park, N. C., USA). Environ. Health Perspect., 17, 135-44 (English) 1976. CODEN: EVHPAZ. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) With 8-14C-labeled styrene oxide [96-09-3] as substrate, specific glutathione S-transferase [50812-37-8] and epoxide hydrase [9048-63-9] activities were detd. in subcellular fractions of liver, lungs, kidney, and intestinal mucosa from rabbit, rat, and guinea pig. Liver had the highest enzyme activities in each species. Rat and guinea pig had higher glutathione S-transferase activity in both liver and kidney than rabbit. Rat testis also had appreciable glutathione S-transferase activity. The perinatal development of epoxide hydrase and glutathione S-transferase was followed in liver and several extrahepatic tissues of fetal and neonatal guinea pigs and rabbits. The rates at which enzyme activities reached adult levels in the extrahepatic tissues differed from the liver in both species. Epoxide hydrase and glutathione S-transferase developed at different rates in each organ, demonstating that the relative importance of these 2 detoxifying pathways for styrene oxide may shift before and after birth. The effects of pretreating male and female rats with phenobarbital (PB) [50-06-6], 1,2,3,4-dibenzanthracene (DBA) [215-58-7], pregnenolone-16a-carbonitrile (PCN) [1434-54-4], or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) [1746-01-6] on hepatic and extrahepatic epoxide hydrase and glutathione S-transferase activities toward styrene oxide were detd. PB increased both enzyme activities in liver of both sexes. PCN induced only glutathione S-transferase activity in female liver. Extrahepatic epoxide hydrase and glutathione S-transferase activities were unaffected except that TCDD doubled female renal epoxide hydrase activity and PB increased intestinal epoxide hydrase activity in both sexes. Styrene oxide biotransformation was studied in isolated, perfused rat liver and rabbit lung prepns. Conjugation with glutathione was a major metabolic pathway although significant amts. of diol were also formed in each instance. In rat liver, 27-40% of the administered styrene oxide was excreted via the bile mainly as S-(1-phenyl-2-hydroxyethyl)glutathione [64186-97-6].