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|piperazine, 1-acetyl-4-(4-((2-(2,4-dichlorophenyl)-2-(1H- imidazol-1-ylmethyl)-1,3-dioxolan-4-yl)methoxy)phenyl)-, cis-|
|Piperazine, 1-acetyl-4-(4-((2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl)methoxy)phenyl)-, cis-|
|Ki: ||Kd:||Ic 50:||Ec50/Ic50:|
Highly selective inhibition of human CYP3Aa in vitro by azamulin and evidence that inhibition is irreversible.. David M Stresser; Marc I Broudy; Thuy Ho; Catherine E Cargill; Andrew P Blanchard; Raman Sharma; Andre A Dandeneau; Joseph J Goodwin; Stephanie D Turner; John C L Erve; Christopher J Patten; Shangara S Dehal; Charles L Crespi (2004) Drug metabolism and disposition: the biological fate of chemicals display abstract
Azamulin [14-O-(5-(2-amino-1,3,4-triazolyl)thioacetyl)-dihydromutilin] is an azole derivative of the pleuromutilin class of antiinfectives. We tested the inhibition potency of azamulin toward 18 cytochromes P450 using human liver microsomes or microsomes from insect cells expressing single isoforms. In a competitive inhibition model, IC(50) values for CYP3A (0.03-0.24 microM) were at least 100-fold lower than all other non-CYP3A enzymes except CYP2J2 ( approximately 50-fold lower). The IC(50) value with heterologously expressed CYP3A4 was 15-fold and 13-fold less than those of CYP3A5 and CYP3A7, respectively. The reference inhibitor ketoconazole was less selective and exhibited potent inhibition (IC(50) values 300 microM. Azamulin represents an important new chemical tool for use in characterizing the contribution of CYP3A to the metabolism of xenobiotics.
Induction of cytochrome P450 1A1 by ketoconazole and itraconazole but not fluconazole in murine and human hepatoma cell lines.. Hesham M Korashy; Anooshirvan Shayeganpour; Dion R Brocks; Ayman O S El-Kadi (2007) Toxicological sciences : an official journal of the Society of Toxicology display abstract
Azole antifungal agents are widely prescribed drugs for the treatment of systemic fungal infections; however, since their introduction into the market, increasing evidences of hepatotoxicity have been reported. Therefore, we examined here the ability of three structurally different antifungal drugs, ketoconazole (KTZ), itraconazole (ITZ), and fluconazole (FLZ) to induce the CYP1A1, an enzyme known to play an important role in chemical activation of xenobiotics to toxic metabolites. KTZ and ITZ, but not FLZ, induced the CYP1A1 in murine Hepa 1c1c7 and human HepG2 hepatoma cells at the mRNA, protein and activity levels in a concentration- and time-dependent manner. The increases in Cyp1a1 mRNA levels mediated by KTZ and ITZ were completely blocked by the RNA synthesis inhibitor, actinomycin D, whereas the level of existing mRNA was not altered, implying a requirement of de novo RNA synthesis through a transcriptional mechanism. The ability of these drugs to directly activate the aryl hydrocarbon receptor (AhR) transformation and hence xenobiotic responsive element's binding was strongly correlated with their abilities to induce luciferase activity. Inhibition studies showed that KTZ and ITZ, in addition to being CYP1A1 inducers, are substrates and competitive inhibitors. This study provides the first evidence for the ability of KTZ and ITZ to induce the CYP1A1 gene expression through an AhR-dependent mechanism, and suggests a novel mechanism of the KTZ- and ITZ-mediated toxicities.