Kratochwil, NA and Bednarski, PJ and Mrozek, H and Vogler, A and Nagle, JK (1996) Photolysis of an iodoplatinum(IV) diamine complex to cytotoxic species by visible light. ANTI-CANCER DRUG DESIGN, 11 (2). pp. 155-171. ISSN 0266-9536,
Full text not available from this repository.Abstract
The feasibility of photolyzing the Pt(IV) complex trans, cis-[PtCl2I2(en)] to cytotoxic species by visible light was evaluated. The synthesis of trans, cis-[PtCl2I2(en)] was achieved by the oxidation of [PtI2(en)] with PCl5 in tetrahydrofuran at room temperature for 30 min in the dark. The UV-Vis spectrum of trans,cis-[PtCl2I2(en)] in water showed a broad ligand-to-metal charge-transfer (LMCT) band with lambda(max) = 396 nm (epsilon = 1191/M/cm). Although trans,cis-[PtCl2I2(en)] was relatively stable in water in the dark, irradiation at lambda(irr) = 410 nm brought about its rapid decomposition. A detailed analysis of the photodecomposition products was not carried out, but two lines of evidence suggest that I-2 and [PtCl2(en)], a known antitumor agent, may be formed as a result of a reductive-elimination type reaction: (i) irradiation of trans, cis-[PtCl2I2(en)] in water at lambda(irr) = 410 nm led to the same spectral changes as when [PtCl2(en)] and I-2 together were irradiated at the same wavelength; (ii) the photoinduced loss of trans,cis-[PtCl2I2(en)] was accompanied by the covalent binding of Pt to DNA at a rate comparable to that of [PtCl2(en)] at 37 degrees C, and the presence of 100 mM chloride suppressed this DNA platination. On the other hand, the combined photolysis products, formed when trans, cis-[PtCl2I2(en)] was irradiated in culture medium at lambda(irr) > 375 nm for 60 min, were less potent than [PtCl2(en)] at inhibiting the growth of two human cancer cell lines. Two limitations make the use of trans, cis-[PtCl2I2(en)] in the therapy of cancer impractical: (i) trans, cis-[PtCl2I2(en)] was relatively unstable in the presence of serum; however, [PtI2(en)] did not appear to be a product of the reaction; (ii) the LMCT band extends only weakly into the region of the electromagnetic spectrum (i.e. lambda > 600 nm) where maximal tissue penetration would be expected. In conclusion, these investigations demonstrate that iodo-Pt(IV) diamines can be photolyzed to cytotoxic species by visible light, but the aforementioned limitations must be overcome before this new class of Pt(IV) complexes can be used as antitumor agents.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PLATINUM(IV); PHOTOCHEMISTRY; cisplatin analogue; cytotoxic photolysis products; DNA platination; iodo-Pt(IV) diamine; photoactivation; cytotoxic |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:36 |
| URI: | https://pred.uni-regensburg.de/id/eprint/51881 |
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