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Reduction of trans-dichloro- and trans-dibromo-tetracyanoplatinate(IV) by L-methionine

Shi, Tiesheng LU ; Berglund, Johan and Elding, Lars Ivar LU (1997) In Journal of the Chemical Society. Dalton Transactions 1997(12). p.2073-2077
Abstract (Swedish)
Reduction of trans-[Pt(CN) 4 X 2 ] 2- (X = Cl or Br) [as model compounds for antitumour-active platinum(IV) pro-drugs] to [Pt(CN) 4 ] 2- by L-methionine, MeSR, has been studied at 25 °C in the range 0 < pH < 12 (X = Cl) and 0 < pH < 6 (X = Br) by use of stopped-flow spectrophotometry. The stoichiometry is [Pt IV ] : [MeSR] ≈ 1 : 1; the reaction products are methionine S-oxide and [Pt(CN) 4 ] 2- as identified by NMR and UV spectroscopies, respectively. The kinetics is first order with respect to the platinum(IV) and methionine concentrations and the second-order rate constants have a small pH dependence. In analogy with reduction of platinum(IV) complexes by thioglycolic acid, cysteine, penicillamine and glutathione, a... (More)
Reduction of trans-[Pt(CN) 4 X 2 ] 2- (X = Cl or Br) [as model compounds for antitumour-active platinum(IV) pro-drugs] to [Pt(CN) 4 ] 2- by L-methionine, MeSR, has been studied at 25 °C in the range 0 < pH < 12 (X = Cl) and 0 < pH < 6 (X = Br) by use of stopped-flow spectrophotometry. The stoichiometry is [Pt IV ] : [MeSR] ≈ 1 : 1; the reaction products are methionine S-oxide and [Pt(CN) 4 ] 2- as identified by NMR and UV spectroscopies, respectively. The kinetics is first order with respect to the platinum(IV) and methionine concentrations and the second-order rate constants have a small pH dependence. In analogy with reduction of platinum(IV) complexes by thioglycolic acid, cysteine, penicillamine and glutathione, a mechanism is postulated in which [Pt(CN) 4 X 2 ] 2- is reduced by the various protolytic species of methionine in parallel reactions. In the transition state the thioether group of methionine is assumed to interact with co-ordinated halide, mediating the electron transfer to the platinum(IV) centre. The transition states for previously studied reactions between [Pt(CN) 4 X 2 ] 2- and thiols are discussed in view of these results. It is concluded that methionine-containing biomolecules may compete with thiol compounds for reduction of platinum(IV) pro-drugs under acidic conditions, and also in neutral solutions with low concentrations of thiol-containing biomolecules. (Less)
Abstract
Reduction of trans-[Pt(CN)4 X2]2- (X = Cl or Br) as model compounds for antitumour-active platinum(IV) pro-drugs, to [Pt(CN)4]2- by L-methionine, MeSR, has been studied at 25 °C in the range 0 < pH < 12 (X = Cl) and 0 < pH < 6 (X = Br) by use of stopped-flow spectrophotometry. The stoichiometry is [Pt IV] : [MeSR] ≈ 1 : 1; the reaction products are methionine S-oxide and [Pt(CN)4]2- as identified by NMR and UV spectroscopies, respectively. The kinetics is first order with respect to the platinum(IV) and methionine concentrations and the second-order rate constants have a small pH dependence. In analogy with reduction of platinum(IV) complexes by thioglycolic acid, cysteine, penicillamine and glutathione, a mechanism is... (More)
Reduction of trans-[Pt(CN)4 X2]2- (X = Cl or Br) as model compounds for antitumour-active platinum(IV) pro-drugs, to [Pt(CN)4]2- by L-methionine, MeSR, has been studied at 25 °C in the range 0 < pH < 12 (X = Cl) and 0 < pH < 6 (X = Br) by use of stopped-flow spectrophotometry. The stoichiometry is [Pt IV] : [MeSR] ≈ 1 : 1; the reaction products are methionine S-oxide and [Pt(CN)4]2- as identified by NMR and UV spectroscopies, respectively. The kinetics is first order with respect to the platinum(IV) and methionine concentrations and the second-order rate constants have a small pH dependence. In analogy with reduction of platinum(IV) complexes by thioglycolic acid, cysteine, penicillamine and glutathione, a mechanism is postulated in which [Pt(CN)4 X2]2- is reduced by the various protolytic species of methionine in parallel reactions. In the transition state the thioether group of methionine is assumed to interact with co-ordinated halide, mediating the electron transfer to the platinum(IV) centre. The transition states for previously studied reactions between [Pt(CN)4 X2]2- and thiols are discussed in view of these results. It is concluded that methionine-containing biomolecules may compete with thiol compounds for reduction of platinum(IV) pro-drugs under acidic conditions, and also in neutral solutions with low concentrations of thiol-containing biomolecules. (Less)
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publication status
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keywords
Tetracyanoplatinate(IV), Methionine, Reduction, Kinetics, Reaction mechanism, Platinum(IV) prodrugs, Stopped-flow, Tetraacyanoplatinates(IV), L-methionine, Reduction, Kinetics, Reaction mechanism, anti-tumor active compounds, Platinum(IV) prodrugs
in
Journal of the Chemical Society. Dalton Transactions
volume
1997
issue
12
pages
5 pages
publisher
Royal Society of Chemistry
ISSN
1472-7773
DOI
10.1039/a608507e
language
English
LU publication?
yes
id
b4ea22b1-846b-48dd-ac00-c016e58a1199
date added to LUP
2017-01-04 11:01:50
date last changed
2017-05-29 11:37:37
@article{b4ea22b1-846b-48dd-ac00-c016e58a1199,
  abstract     = {Reduction of trans-[Pt(CN)4 X2]2- (X = Cl or Br) as model compounds for antitumour-active platinum(IV) pro-drugs, to [Pt(CN)4]2- by L-methionine, MeSR, has been studied at 25 °C in the range 0 &lt; pH &lt; 12 (X = Cl) and 0 &lt; pH &lt; 6 (X = Br) by use of stopped-flow spectrophotometry. The stoichiometry is [Pt IV] : [MeSR] ≈ 1 :  1; the reaction products are methionine S-oxide and [Pt(CN)4]2- as identified by NMR and UV spectroscopies, respectively. The kinetics is first order with respect to the platinum(IV) and methionine concentrations and the second-order rate constants have a small pH dependence. In analogy with reduction of platinum(IV) complexes by thioglycolic acid, cysteine, penicillamine and glutathione, a mechanism is postulated in which [Pt(CN)4 X2]2- is reduced by the various protolytic species of methionine in parallel reactions. In the transition state the thioether group of methionine is assumed to interact with co-ordinated halide, mediating the electron transfer to the platinum(IV) centre. The transition states for previously studied reactions between [Pt(CN)4 X2]2- and thiols are discussed in view of these results. It is concluded that methionine-containing biomolecules may compete with thiol compounds for reduction of platinum(IV) pro-drugs under acidic conditions, and also in neutral solutions with low concentrations of thiol-containing biomolecules. },
  author       = {Shi, Tiesheng and Berglund, Johan and Elding, Lars Ivar},
  issn         = {1472-7773},
  keyword      = {Tetracyanoplatinate(IV),Methionine,Reduction,Kinetics,Reaction mechanism,Platinum(IV) prodrugs,Stopped-flow,Tetraacyanoplatinates(IV),L-methionine,Reduction,Kinetics,Reaction mechanism,anti-tumor active compounds,Platinum(IV) prodrugs},
  language     = {eng},
  month        = {06},
  number       = {12},
  pages        = {2073--2077},
  publisher    = {Royal Society of Chemistry},
  series       = {Journal of the Chemical Society. Dalton Transactions},
  title        = {Reduction of trans-dichloro- and trans-dibromo-tetracyanoplatinate(IV) by L-methionine},
  url          = {http://dx.doi.org/10.1039/a608507e},
  volume       = {1997},
  year         = {1997},
}