title: Molecular complexes of IQ and 4-hydroxy-coumarin: a mutagen-anti-mutagen system.
abstract: Molecular complexes formed between a cooked food mutagen-carcinogen (2-amino-3-methylimidazo[4,5-f] quinoline, IQ) and a potent anti-mutagen (4-hydroxy-coumarin, 4HC) were synthesized and crystallized from a solution. The active functional groups in IQ and in 4HC that may involve in the formation of these complexes are investigated by UV-visible, infrared, and NMR spectroscopy. The geometrical conformations and heat of formation of IQ:4HC complexes were optimized by semi-empirical molecular orbital calculations. The experimental and theoretical results indicate that the complexes exist in multiple conformations. The energetically favorable ones are formed via hydrogen-bonding type of interactions between amino group in IQ and carbonyl group in 4HC, and also between quinoline-nitrogen (and imidazole-nitrogen) in IQ and hydroxyl group in 4HC. The observed complex formation could serve as a model for understanding the active molecular sites responsible for the initial mutagenic activity in cooked-food mutagens as well as the anti-mutagenic activity in coumarins.
authors.affiliation: Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115-2862, USA.
authors.forename: Alberto D S
authors.initials: AD
authors.lastname: Marques
authors.forename: Chhiu-Tsu
authors.initials: CT
authors.lastname: Lin
mesh_terms: D015110:4-Hydroxycoumarins / Q000737:chemistry*; D016587:Antimutagenic Agents / Q000737:chemistry*; D004583:Electrons; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009153:Mutagens / Q000737:chemistry*; D011804:Quinolines / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D015110:4-Hydroxycoumarins; D016587:Antimutagenic Agents; D009153:Mutagens; D011804:Quinolines; C029216:2-amino-3-methylimidazo(4,5-f)quinoline; C068805:4-hydroxycoumarin