TY - JOUR
T1 - Pt(IV) complexes as prodrugs for cisplatin
AU - Shi, Yi
AU - Liu, Shu An
AU - Kerwood, Deborah J.
AU - Goodisman, Jerry
AU - Dabrowiak, James C.
N1 - Funding Information:
We wish to thank the Department of Chemistry of Syracuse University for its continued support of this research. We are also grateful to the National Science Foundation iREU Program , grant OISE- 0456116 , (to S. L.) for supporting this research.
PY - 2012/2
Y1 - 2012/2
N2 - The antitumor effects of platinum(IV) complexes, considered prodrugs for cisplatin, are believed to be due to biological reduction of Pt(IV) to Pt(II), with the reduction products binding to DNA and other cellular targets. In this work we used pBR322 DNA to capture the products of reduction of oxoplatin, c,t,c-[PtCl 2(OH) 2(NH 3) 2], 3, and a carboxylate-modified analog, c,t,c-[PtCl 2(OH)(O 2CCH 2CH 2CO 2H)(NH 3) 2], 4, by ascorbic acid (AsA) or glutathione (GSH). Since carbonate plays a significant role in the speciation of platinum complexes in solution, we also investigated the effects of carbonate on the reduction/DNA-binding process. In pH 7.4 buffer in the absence of carbonate, both 3 and 4 are reduced by AsA to cisplatin (confirmed using 195Pt NMR), which binds to and unwinds closed circular DNA in a manner consistent with the formation of the well-known 1, 2 intrastrand DNA crosslink. However, when GSH is used as the reducing agent for 3 and 4, 195Pt NMR shows that cisplatin is not produced in the reaction medium. Although the Pt(II) products bind to closed circular DNA, their effect on the mobility of Form I DNA is different from that produced by cisplatin. When physiological carbonate is present in the reduction medium, 13C NMR shows that Pt(II) carbonato complexes form which block or impede platinum binding to DNA. The results of the study vis-à-vis the ability of the Pt(IV) complexes to act as prodrugs for cisplatin are discussed.
AB - The antitumor effects of platinum(IV) complexes, considered prodrugs for cisplatin, are believed to be due to biological reduction of Pt(IV) to Pt(II), with the reduction products binding to DNA and other cellular targets. In this work we used pBR322 DNA to capture the products of reduction of oxoplatin, c,t,c-[PtCl 2(OH) 2(NH 3) 2], 3, and a carboxylate-modified analog, c,t,c-[PtCl 2(OH)(O 2CCH 2CH 2CO 2H)(NH 3) 2], 4, by ascorbic acid (AsA) or glutathione (GSH). Since carbonate plays a significant role in the speciation of platinum complexes in solution, we also investigated the effects of carbonate on the reduction/DNA-binding process. In pH 7.4 buffer in the absence of carbonate, both 3 and 4 are reduced by AsA to cisplatin (confirmed using 195Pt NMR), which binds to and unwinds closed circular DNA in a manner consistent with the formation of the well-known 1, 2 intrastrand DNA crosslink. However, when GSH is used as the reducing agent for 3 and 4, 195Pt NMR shows that cisplatin is not produced in the reaction medium. Although the Pt(II) products bind to closed circular DNA, their effect on the mobility of Form I DNA is different from that produced by cisplatin. When physiological carbonate is present in the reduction medium, 13C NMR shows that Pt(II) carbonato complexes form which block or impede platinum binding to DNA. The results of the study vis-à-vis the ability of the Pt(IV) complexes to act as prodrugs for cisplatin are discussed.
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U2 - 10.1016/j.jinorgbio.2011.10.012
DO - 10.1016/j.jinorgbio.2011.10.012
M3 - Article
C2 - 22169035
AN - SCOPUS:83055168314
SN - 0162-0134
VL - 107
SP - 6
EP - 14
JO - Journal of Inorganic Biochemistry
JF - Journal of Inorganic Biochemistry
IS - 1
ER -