3-Methylcholanthrene structure

Fluoranthenes. With the exception of 3-methylcholanthrene, much less work has been undertaken on nonalternant PAHs. Several recent studies have reported on the major metabolites and mutagenicity of various fluoranthenes (181-185), but little is known about the DNA adduct which they form. Some studies on dibenzo[a,e]fluoranthene showed that several adducts are formed by microsomal incubations (185) and additional studies will be required to provide complete structural elucidation of the products formed. 

The structure of 20-methylcholanthrene has been determined crystallographically by Iball and MacDonald (1960). Some 1600 reflections were used in the three-dimensional analysis, refinement... 

In practice, we have utilized it for the analysis of molecular systems comprised of 3 to 5 fused benzene rings. Our discussion in this document is limited to the following compounds phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(e)pyrene, benzo(a)pyrene, and dibenz(a,h)anthracene. The structures for these compounds are presented in Table I. It is important to note that the method has also been adapted to the determination of several other PAH compounds (e.g., benzo(c)phenanthrene, perylene, 3-methylcholanthrene, carbazole, 7H-dibenzo(c,g)carbazole, and indeno(l,2,3-cd)pyrene). 

Teratogen A chemical substance that causes structural defects and affects normal development, birth defects, and abnormalities in an animal Teratogenicity The biological process where chemical substances produce permanent structural and functional abnormalities to the fetus during the period of embryonic development 3MC 3-methylcholanthrene... 

The demonstration of relationships between PCB molecular structure and induction of CYP isozymes has provided a framework within which much mechanistic research has been conducted. In general, commercial mixtures of PCBs induce both 3-methylcholanthrene-type (CYPlAl and 1A2) and phenobarbital-type (CYP2B1, 2B2, and 3A) CYPs. Strong structure-activity relationships have been demonstrated between CYPl Al/1 A2 induction in rodents and non-ortho and vnono-ortho PCBs, which can assume a coplanar molecular configuration and bind to the Ah receptor (Connor et al. 1995 Hansen 1998 Safe 1994). In structure-activity studies of CYPl A induction in hepatocytes from Cynomolgus... 

Several benzo[a]cyclopentanthracenes, structurally similar to 1,2-dihydro-3-methylbenz[/]aceanthrylene (3-methylcholanthrene, a methylbenzo[a]cyclopent[ ] anthracene) have been identified in CSC These included an unmethylated benzocyclopentanthracenes, originally reported erroneously as l,2-dihydrobenz[/] aceanthrylene (cholanthrene) by Rodgman and Cook (3273), 2,3-dihydro-l//-benzo[a] cyclopent[/r]anthracene and 9,10-dihydro-9//-benzo[a]cyclopent[/]anthracene [Bonnet and Neukoimn (394, 397-399), Ahlmann (39), Bonnet (392), Pyriki (3033), Rodgman and Cook (3273)]. 

Fig. 1. Structures of benzo[<2]pyrene, 3-methylcholanthrene and dioxin. Benzo[<2]-pyrene and 3-methylcholanthrene are PAH compounds, but dioxin is not. Benzo [ ] pyrene is converted to the ultimate carcinogen BPDE by CyplAl.

The structural characteristics of individual PCB congeners influence their induction of various P450 activities. In mammals, PCB congeners have been characterized as 3-methylcholanthrene-type inducers, phenobarbital-type inducers, or mixed-type inducers of both. AHH and EROD activities (which are preferentially catalyzed by the P450IA gene subfamily) have been induced by planar PCBs in fish and mammals and by some mono- and di-ortho analogs of planar PCBs in mammals. The mechanism of toxic action of planar and mono-ortho planar PCBs is linked to an interaction with the 2,3,7,8-TCDD (or Ah) receptor protein. But this mechanism does not account for all observed PCB toxici-ties. Toxic responses uiuelated to Ah receptor effects have been reported of PCBs 4, 28, 31, 49, 52, 84, 95, 110, 136, and 153. For example, PCB 153 is less cytotoxic than PCB 169... 

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