title: Bis-benzimidazole dyes, Hoechst 33258 and Hoechst 33342: radioiodination, facile purification and subcellular distribution.
abstract: A simple HPLC method is presented for the purification of DNA binding bis-benzimidazole dyes Hoechst 33258, Hoechst 33342 and 131I-iodoHoechst 33258. The mobile phase, consisting of methanol and aqueous ammonia (0.2%) in the ratio 2:3, resolved and separated the radiochemical from unlabeled ligand and other reagents used in the reaction, thereby resulting in high radiochemical purity and yield. The iodinated Hoechst 33258 did not show any selective binding to nuclear DNA when cell fractionation studies were performed with cultured mammalian cells as well as in mice testes. Fluorescence microscopy studies with V79 cells stained with these dyes, showed the superiority of Hoechst 33342 in selective localization in nuclear DNA compared to Hoechst 33258. The difference in behavior of these two dyes in terms of binding to nuclear DNA, and hence their ability to provide protection against damage caused by ionizing radiation, may be explained on the basis of the molecular charge. The high chemotoxicity of Hoechst 33342 observed in the present studies suggests that its usefulness as a radioprotector against chronic irradiation of tissue by incorporated radionuclides may be limited.
authors.affiliation: Department of Radiology, University of Medicine & Dentistry of New Jersey, Newark 07103, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Harapanhalli
authors.forename: R W
authors.initials: RW
authors.lastname: Howell
authors.forename: D V
authors.initials: DV
authors.lastname: Rao
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D006690:Bisbenzimidazole / Q000138:chemical synthesis* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003412:Cricetulus; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D007457:Iodine Radioisotopes / Q000737:chemistry* / Q000302:isolation & purification; D007553:Isotope Labeling / Q000379:methods*; D008297:Male; D051379:Mice; D011837:Radiation-Protective Agents / Q000138:chemical synthesis* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D001562:Benzimidazoles; D005456:Fluorescent Dyes; D007457:Iodine Radioisotopes; D011837:Radiation-Protective Agents; D006690:Bisbenzimidazole; C017807:bisbenzimide ethoxide trihydrochloride