title: Photobehaviour of methyl-pyridinium and quinolinium iodide derivatives, free and complexed with DNA. A case of bisintercalation.
abstract: Excited state dynamics of four azinium salts were studied in buffered water and in the presence of salmon testes DNA. Complexation with DNA changes the photobehaviour of the free ligands lowering the photoreactivity and emission in favor of internal conversion. The interaction of these four dyes with DNA was studied with different techniques with the aim to establish the affinity and the type of binding between the ligands and DNA. The results from spectrophotometric and fluorimetric titrations provided evidence of a strong interaction between the azinium salts and the polynucleotide, with a binding constant of about 10(6) M(-1), making them interesting for therapeutical applications. Dichroic measurements allowed us to determine the possible modes of binding for each complex. Short living excited states of the free dyes were detected and characterized by ultrafast absorption spectroscopy. A further decrease of transient lifetimes was observed upon interaction with DNA. The bicationic pyridinium iodide was found to act as a bisintercalative agent, potentially increasing the cytotoxicity with low dose and less collateral effects.
authors.affiliation: Department of Chemistry, Biology and Biotechnology, University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy. anna.spalletti@unipg.it.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Mazzoli
authors.forename: Benedetta
authors.initials: B
authors.lastname: Carlotti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Consiglio
authors.forename: Cosimo G
authors.initials: CG
authors.lastname: Fortuna
authors.forename: Giorgia
authors.initials: G
authors.lastname: Miolo
authors.forename: Anna
authors.initials: A
authors.lastname: Spalletti
mesh_terms: D000818:Animals; D004396:Coloring Agents / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D005470:Fluorometry; D006847:Hydrocarbons, Iodinated / Q000737:chemistry*; D007700:Kinetics; D008297:Male; D011726:Pyridinium Compounds / Q000737:chemistry*; D011806:Quinolinium Compounds / Q000737:chemistry*; D012474:Salmon; D013053:Spectrophotometry; D013057:Spectrum Analysis
chemical_list: D004396:Coloring Agents; D006847:Hydrocarbons, Iodinated; D011726:Pyridinium Compounds; D011806:Quinolinium Compounds; D004247:DNA