| Abstract: | The electrostatic molecular potential contour maps were calculated for carcinogenic 3-methylcholanthrene (3-MCA) and a number of its metabolites {3-MCA 7,8-oxide and 3-MCA 9,10-oxide; 3-MCA 7,8-dihydrodiolsseveral stereoisomers: A trans(equatorial, equatorial) and A cis(equatorial, axial)]; 3-MCA 9,10-dihydrodiol–7,8-epoxide A βββ and 3-MCA 9,10-dihydrodiol–7,8-epoxide A αβα}. The maps were generated from our ab initio MODPOT/VRDDO/MERGE wave functions calculated for these species. The results of these maps for 3-MCA similarly to our results for the maps we generated for benzo(a)pyrene (BP)] show that these electrostatic molecular potential contour maps can be used to indicate favored positions of attack for electrophilic species, such as “electrophilic” oxygen to form an epoxide as well as for positive ion attack. The 3-MCA maps indicate the favored site for attack and the pathways. The maps around 3-MCA 9,10-oxide and around 3-MCA 9,10-dihydrodiol-7,8-epoxide indicate the directional preferences for proton assisted epoxide ring opening. The maps around the 3-MCA dihydrodiols indicate that while for certain stereoisomers the “electrophilic” oxygen will prefer to attack from below, for other isomers it will prefer to attack from above. This gives great insight into the stereochemical preference for formation of different 3-MCA 9,10-dihydrodiol–7,8-epoxides. |
