37687-33-5Relevant articles and documents
Ring D modifications of ellipticine. Part 2. Chlorination of ellipticine via its N-oxide and synthesis and selective acetylation of 5,6,11-trimethyl-5H-benzo[b]carbazole
Boogaard, Adrian T.,Pandit, Upendra K.,Koomen, Gerrit-Jan
, p. 4811 - 4828 (1994)
The N-oxide of ellipticine can be used for the introduction of a chlorine atom at carbon-3 of the ellipticine nucleus. According to model studies with 5,8-dimethylisoquinoline-N-oxide the reaction is guided both by steric hindrance and by nitrogen-6 of th
Cytochrome b5 increases cytochrome P450 3A4-mediated activation of anticancer drug ellipticine to 13-hydroxyellipticine whose covalent binding to DNA is elevated by sulfotransferases and N,O-acetyltransferases
Stiborova, Marie,Indra, Radek,Moserova, Michaela,Cerna, Vera,Rupertova, Martina,Martinek, Vaclav,Eckschlager, Tomas,Kizek, Rene,Frei, Eva
experimental part, p. 1075 - 1085 (2012/08/13)
The antineoplastic alkaloid ellipticine is a prodrug, whose pharmacological efficiency is dependent on its cytochrome P450 (P450)- and/or peroxidase-mediated activation in target tissues. The P450 3A4 enzyme oxidizes ellipticine to five metabolites, mainly to 13-hydroxy- and 12- hydroxyellipticine, the metabolites responsible for the formation of ellipticine-13-ylium and ellipticine-12-ylium ions that generate covalent DNA adducts. Cytochrome b5 alters the ratio of ellipticine metabolites formed by P450 3A4. While the amounts of the detoxication metabolites (7-hydroxy- and 9-hydroxyellipticine) were not changed with added cytochrome b5, 12-hydroxy- and 13-hydroxyellipticine, and ellipticine N 2-oxide increased considerably. The P450 3A4-mediated oxidation of ellipticine was significantly changed only by holo-cytochrome b5, while apo-cytochrome b5 without heme or Mn-cytochrome b5 had no such effect. The change in amounts of metabolites resulted in an increased formation of covalent ellipticine-DNA adducts, one of the DNA-damaging mechanisms of ellipticine antitumor action. The amounts of 13-hydroxy- and 12-hydroxyellipticine formed by P450 3A4 were similar, but more than 7-fold higher levels of the adduct were formed by 13-hydroxyellipticine than by 12-hydroxyellipticine. The higher susceptibility of 13-hydroxyellipticine toward heterolytic dissociation to ellipticine-13-ylium in comparison to dissociation of 12-hydroxyellipticine to ellipticine-12-ylium, determined by quantum chemical calculations, explains this phenomenon. The amounts of the 13- hydroxyellipticine-derived DNA adduct significantly increased upon reaction of 13-hydroxyellipticine with either 3′-phosphoadenosine-5′- phosphosulfate or acetyl-CoA catalyzed by human sulfotransferases 1A1, 1A2, 1A3, and 2A1, or N,O-acetyltransferases 1 and 2. The calculated reaction free energies of heterolysis of the sulfate and acetate esters are by 10-17 kcal/mol more favorable than the energy of hydrolysis of 13-hydroxyellipticine, which could explain the experimental data.
