title: The Biological Effects of Bilirubin Photoisomers.
abstract: Although phototherapy was introduced as early as 1950's, the potential biological effects of bilirubin photoisomers (PI) generated during phototherapy remain unclear. The aim of our study was to isolate bilirubin PI in their pure forms and to assess their biological effects in vitro. The three major bilirubin PI (ZE- and EZ-bilirubin and Z-lumirubin) were prepared by photo-irradiation of unconjugated bilirubin. The individual photoproducts were chromatographically separated (TLC, HPLC), and their identities verified by mass spectrometry. The role of Z-lumirubin (the principle bilirubin PI) on the dissociation of bilirubin from albumin was tested by several methods: peroxidase, fluorescence quenching, and circular dichroism. The biological effects of major bilirubin PI (cell viability, expression of selected genes, cell cycle progression) were tested on the SH-SY5Y human neuroblastoma cell line. Lumirubin was found to have a binding site on human serum albumin, in the subdomain IB (or at a close distance to it); and thus, different from that of bilirubin. Its binding constant to albumin was much lower when compared with bilirubin, and lumirubin did not affect the level of unbound bilirubin (Bf). Compared to unconjugated bilirubin, bilirubin PI did not have any effect on either SH-SY5Y cell viability, the expression of genes involved in bilirubin metabolism or cell cycle progression, nor in modulation of the cell cycle phase. The principle bilirubin PI do not interfere with bilirubin albumin binding, and do not exert any toxic effect on human neuroblastoma cells.
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Jasprova
authors.affiliation: Italian Liver Foundation, CSF, Trieste, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Dal Ben
authors.affiliation: Italian Liver Foundation, CSF, Trieste, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Vianello
authors.affiliation: Institute of Chemical Technology Prague, Prague, Czech Republic.
authors.forename: Iryna
authors.initials: I
authors.lastname: Goncharova
authors.affiliation: Institute of Chemical Technology Prague, Prague, Czech Republic.
authors.forename: Marie
authors.initials: M
authors.lastname: Urbanova
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Karolina
authors.initials: K
authors.lastname: Vyroubalova
authors.affiliation: Italian Liver Foundation, CSF, Trieste, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Gazzin
authors.affiliation: Italian Liver Foundation, CSF, Trieste, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Tiribelli
authors.affiliation: Faculty of Science, Charles University in Prague, Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Sticha
authors.affiliation: The Institute for Mother and Child, Prague, Czech Republic.
authors.forename: Marcela
authors.initials: M
authors.lastname: Cerna
authors.affiliation: Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.|4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Libor
authors.initials: L
authors.lastname: Vitek
mesh_terms: D001663:Bilirubin / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D005786:Gene Expression Regulation / Q000187:drug effects; D006418:Heme / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D007700:Kinetics; D008024:Ligands; D008027:Light; D010789:Phototherapy; D012709:Serum Albumin / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008024:Ligands; D012709:Serum Albumin; D006418:Heme; D001663:Bilirubin
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