Acidity constants for cis-diaquadiammineplatinum(II), the aquated form of cisplatin

Orton, David M.; Gretton, Virginia A.; Green, Michael

doi:10.1016/s0020-1693(00)82936-9

Cited by 13 publications

(11 citation statements)

References 4 publications

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“…The properties of the latter can be qualitatively explained by applying the concept of the trans influence. [40] Thus, the pK a values for the aqua ligands (in the case of the diaqua species they refer to pK a1 ) of trans-[(NH 3 ) 2 Pt(H 2 O) 2 ] 2 (4.35), [41] trans-[(NH 3 ) 2 -Pt(Cl)(H 2 O)] (5.63), [41] cis-[(NH 3 ) 2 Pt(H 2 O) 2 ] 2 (5.93, [42] 5.37, [43] 5.24 [44] ), and cis-[(NH 3 ) 2 Pt(Cl)(H 2 O)] (6.85, [42] 6.41 [43] ) follow the expectation for the sequence of the trans influence, which is NH 3 b Cl À b OH 2 , despite differences in charge. In other words, the acidity of an aqua ligand is, to a first approximation, dependent on its binding strength to Pt 2 , which in turn is influenced by the nature of the donor atom trans to the aqua ligand.…”

Section: Resultsmentioning

confidence: 99%

Effects of (N7)-Coordinated Nickel(II), Copper(II), or Platinum(II) on the Acid-Base Properties of Guanine Derivatives and Other Related Purines[≠]

Song

Zhao

Griesser

et al. 1999

Chemistry - A European Journal

121

151

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This study is dedicated to Professor Dr. R. Bruce Martin, University of Virginia, Charlottesville (USA), on the occasion of his 70th birthday, with the very best wishes of the authors for all his future endeavors and with deep appreciation for friendship and unselfish advice provided over many years to H.S. and B.L.Abstract: The effect of Ni 2 , Cu 2 , and cis-a 2 Pt 2 or trans-a 2 Pt 2 (where a NH 3 or CH 3 NH 2 ), if coordinated to the N7 site of guanine residues, on the acid ± base properties of complexes containing guanine derivatives as ligands is considered. The various acidity constants were determined by potentiometric pH titrations. Over 60 acidity constants are listed; about half of these are new. In many instances micro acidity constants have been derived that allow a quantification of the intrinsic acid ± base properties of a certain site, which are otherwise blurred by the pK a values of overlapping buffer regions. This material allows many comparisons; among these is the observation that the acidifying properties of (N7)-coordinated divalent metal ions on the corresponding (N1)H sites in a guanine derivative decrease in the following series:The data also indicate that the effects are similar for guanine and hypoxanthine residues, but that they are more pronounced for adenine derivatives because in the latter case a (N7)-bound M 2 affects a (N1)H site; hence, a further charge effect is operative here. The available material does not yet allow certain prediction of the more subtle differences occurring between the cis and trans isomers of Pt 2 complexes, but replacement of, for example, NH 3 in the coordination sphere of Pt 2 with CH 3 NH 2 has an effect. Of course, as one might expect, the effect of (N7)-bound Pt 2 in guanine nucleotide complexes is smaller on the more remote phosphate groups than it is on the closer (N1)H sites. By evaluation (by means of micro acidity constants) of data available for hypoxanthine derivatives it is also shown that (N1) À -bound Pt 2 has an acidifying effect on the (N7)H site comparable to that of (N7)-coordinated Pt 2 on the (N1)H site.

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Section: Resultsmentioning

confidence: 99%

Effects of (N7)-Coordinated Nickel(II), Copper(II), or Platinum(II) on the Acid-Base Properties of Guanine Derivatives and Other Related Purines[≠]

Song

Zhao

Griesser

et al. 1999

Chemistry - A European Journal

121

151

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“…In fact t 1/2 in chloridefree phosphate (37°C) is about 450 h (Frey et al, 1993) compared with 2 h for cisplatin (Johnson et al, 1980;Bancroft et al, 1990;Orton et al, 1993). In vivo the difference in activity is not so dramatic: enzymatic cleavage (Cleare et al, 1978), the presence of oxygen free radicals in the cell (Tonetti et al, 1993), and differences in pharmacokinetics (Elferink et al, 1987) have been hypothesized as the cause of more efficient activation of carboplatin in vivo than in vitro.…”

Section: Carboplatinmentioning

confidence: 99%

Electrochemical biosensor evaluation of the interaction between DNA and metallo-drugs

et al. 2006

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Electrochemical techniques were used to study the interaction between a panel of antiproliferative metallo-drugs and double-stranded DNA immobilized on screen-printed electrodes as a model of the analogous interaction occurring in solution. The propensity of a given metal drug to interact with DNA was measured as a function of the decrease of guanine oxidation signal, which was detected by square wave voltammetry. Estimates of variations in experimental parameters, such as the concentration of complexes, time following dissolution (ageing time) and the presence of chloride, are provided.

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“…[23][24][25][26]. Based on these measurements, approximate values of individual pK a are as follows: pK a1 ϭ 5.5, pK a2 ϭ 7.3, pK a3 ϭ 6.6, pK a1 ϭ 4.4, pK a2 ϭ 7.3, and pK a3 ϭ5.6, respectively, for the cisplatin and transplatin complexes.…”

Section: Introductionmentioning

confidence: 99%

Hydration process as an activation of trans‐ and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

2005

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The thermodynamic and kinetic aspects of hydration reactions of cis-/transplatin were explored. The polarizable continuum model was used for estimation of solvent effects. Using the B3LYP/6-31+G(d) method, the structures were optimized and vibrational frequencies estimated. Interaction energies and activation barriers were determined at the CCSD(T)/6-31++G(d,p) level within the COSMO approach. An associative mechanism was assumed with a trigonal-bipyramidal structure of the transition state. Within the applied model, all the hydration reactions are slightly endothermic. The Gibbs energies of cisplatin hydration amount to 7.0 and 14.2 kcal/mol for the chloride and ammonium replacement, respectively. Analogous values for the transplatin reactions are 6.8 and 11.9 kcal/mol. The determined rate constants are by several (three to four) orders of magnitude larger for the dechlorination process than for deammination. The cisplatin dechlorination rate constant was established as 1.3 x 10(-4) s(-1) in excellent accord with the experiment.

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Acidity constants for cis-diaquadiammineplatinum(II), the aquated form of cisplatin

Cited by 13 publications

References 4 publications

Effects of (N7)-Coordinated Nickel(II), Copper(II), or Platinum(II) on the Acid-Base Properties of Guanine Derivatives and Other Related Purines[≠]

Effects of (N7)-Coordinated Nickel(II), Copper(II), or Platinum(II) on the Acid-Base Properties of Guanine Derivatives and Other Related Purines[≠]

Electrochemical biosensor evaluation of the interaction between DNA and metallo-drugs

Hydration process as an activation of trans‐ and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

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