title: Reaction of polynuclear platinum antitumor compounds with reduced glutathione studied by multinuclear (1H, 1H-15N gradient heteronuclear single-quantum coherence, and 195Pt) NMR spectroscopy.
abstract: A possible explanation for the low bioavailability of platinum antitumor compounds is their high reactivity with the sulfur-containing tripeptide glutathione (GSH; deprotonated GSH = SG). GSH is located in the intracellular matrix of the cell with a normal concentration of 5-10 mM. In vivo, only a small fraction of the administered drug will migrate into the cell, resulting in relatively high concentrations of GSH compared to that of the drug. The products of the reactions of [[trans-PtCl(NH(3))(2)](2)-mu-[trans-Pt(NH(3))(2)(NH(2)(CH(2))(6)NH(2))(2)]](NO(3))(4) (BBR3464; 1,0,1/t,t,t, n = 6), [[trans-PtCl(NH(3))(2)](2)-mu-(H(2)N(CH(2))(6)NH(2))](NO(3))(2) (BBR3005; 1,1/t,t, n = 6), [[trans-PtCl(NH(3))(2)](2)-mu-(H(2)N(CH(2))(3)NH(2)(CH(2))(4)NH(2))]Cl(3) (BBR3571; 1,1/t,t-spermidine, n = 3, 4), and trans-[PtCl(2)(NH(3))(2)] (t-DDP) with reduced GSH in phosphate-buffered saline (pH 7.35) have been characterized by (1)H, (195)Pt, and (1)H(-)(15)N gradient heteronuclear single-quantum coherence NMR spectroscopy and high-performance liquid chromatography (HPLC) coupled with electrospray ionization time-of-flight mass spectrometry to determine likely metabolites of the complexes with GSH. Chemical shifts (NMR) and retention times (HPLC) established via analysis of the t-DDP profile served as a fingerprint to compare results obtained for the products afforded by the degradation of the polynuclear compounds by GSH. Identical kinetic profiles and chemical shifts between the metabolites and the t-DDP/GSH products allowed identification of the final product for the 1:2 Pt:GSH reaction as a dinuclear species [[trans-Pt(SG)(NH(3))(2)](2)-mu-SG], in which glutathione bridges the two platinum centers via only the sulfur atom.
authors.affiliation: Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Oehlsen
authors.forename: Yun
authors.initials: Y
authors.lastname: Qu
authors.forename: Nicholas
authors.initials: N
authors.lastname: Farrell
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D005978:Glutathione / Q000737:chemistry*; D007202:Indicators and Reagents; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009944:Organoplatinum Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D011786:Quality Control; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000970:Antineoplastic Agents; D007202:Indicators and Reagents; D009944:Organoplatinum Compounds; D005978:Glutathione