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De novo generation of singlet oxygen and ammine ligands by photoactivation of a platinum anticancer complex.

Zhao Y, Farrer NJ, Li H, Butler JS, McQuitty RJ, Habtemariam A, Wang F, Sadler PJ - Angew. Chem. Int. Ed. Engl. (2013)

Bottom Line: Worth the excitement: Highly reactive oxygen and nitrogen species are generated by photoactivation of the anticancer platinum(IV) complex trans,trans,trans-[Pt(N3 )2 (OH)2 (MA)(Py)] (MA=methylamine, Py=pyridine).Singlet oxygen is formed from the hydroxido ligands and not from dissolved oxygen, and ammine ligands are products from the conversion of azido ligands to nitrenes.Both processes can induce oxidation of guanine.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (P.R. China).

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Chromatograms for the photoreactions of 1 (0.67 mm) with 5′-GMP (1.0 mm) in aqueous solution upon irradiation with A) 450 nm light, 50 mW cm−2, 60 min; B) 420 nm, 4.3 mW cm−2, 30 min; C) UVA (365 nm), 3.5 mW cm−2, 15 min; D) 5′-GMP (1.0 mm) only, UVA, 15 min.
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fig01: Chromatograms for the photoreactions of 1 (0.67 mm) with 5′-GMP (1.0 mm) in aqueous solution upon irradiation with A) 450 nm light, 50 mW cm−2, 60 min; B) 420 nm, 4.3 mW cm−2, 30 min; C) UVA (365 nm), 3.5 mW cm−2, 15 min; D) 5′-GMP (1.0 mm) only, UVA, 15 min.

Mentions: The photoreaction of 1 with 5′-GMP upon irradiation with blue light with a wavelength of 450 nm for 1 h gave (SP-4-2)-[Pt(N3)(MA)(Py)(5′-GMP)]+ (1 a+) as the major product and trans-[Pt(MA)(Py)(5′-GMP)2]2+ (1 b2+) as the minor product (Figure 1 A). A similar result has been reported for 1 under slightly different conditions, and for related compounds.2a, 4, 4 However, when the reaction mixture was irradiated at 420 nm for 30 min, two new photoproducts, 1 c and 1 e, were observed by HPLC (Figure 1 B). When the sample was irradiated with UVA (365 nm) for 15 min, one more species, 1 d, was found (Figure 1 C). The isotopic distributions observed in the ESI-MS analysis revealed that the singly charged cations of 1 c (m/z=718.1), 1 d (m/z=684.1), and 1 e (m/z=700.1) all contain a Pt atom. A control experiment with 5′-GMP in the absence of 1 and UVA irradiation for 15 min showed no reaction (Figure 1 D), thus suggesting that 5′-GMP is stable under these conditions. The photoreaction of 1 and 5′-GMP under an atmosphere of argon gave similar results, thereby excluding the possibility that dissolved oxygen is the oxidant. Hence, 1 c, 1 d, and 1 e are all produced by the photoreaction of 1.


De novo generation of singlet oxygen and ammine ligands by photoactivation of a platinum anticancer complex.

Zhao Y, Farrer NJ, Li H, Butler JS, McQuitty RJ, Habtemariam A, Wang F, Sadler PJ - Angew. Chem. Int. Ed. Engl. (2013)

Chromatograms for the photoreactions of 1 (0.67 mm) with 5′-GMP (1.0 mm) in aqueous solution upon irradiation with A) 450 nm light, 50 mW cm−2, 60 min; B) 420 nm, 4.3 mW cm−2, 30 min; C) UVA (365 nm), 3.5 mW cm−2, 15 min; D) 5′-GMP (1.0 mm) only, UVA, 15 min.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4230391&req=5

fig01: Chromatograms for the photoreactions of 1 (0.67 mm) with 5′-GMP (1.0 mm) in aqueous solution upon irradiation with A) 450 nm light, 50 mW cm−2, 60 min; B) 420 nm, 4.3 mW cm−2, 30 min; C) UVA (365 nm), 3.5 mW cm−2, 15 min; D) 5′-GMP (1.0 mm) only, UVA, 15 min.
Mentions: The photoreaction of 1 with 5′-GMP upon irradiation with blue light with a wavelength of 450 nm for 1 h gave (SP-4-2)-[Pt(N3)(MA)(Py)(5′-GMP)]+ (1 a+) as the major product and trans-[Pt(MA)(Py)(5′-GMP)2]2+ (1 b2+) as the minor product (Figure 1 A). A similar result has been reported for 1 under slightly different conditions, and for related compounds.2a, 4, 4 However, when the reaction mixture was irradiated at 420 nm for 30 min, two new photoproducts, 1 c and 1 e, were observed by HPLC (Figure 1 B). When the sample was irradiated with UVA (365 nm) for 15 min, one more species, 1 d, was found (Figure 1 C). The isotopic distributions observed in the ESI-MS analysis revealed that the singly charged cations of 1 c (m/z=718.1), 1 d (m/z=684.1), and 1 e (m/z=700.1) all contain a Pt atom. A control experiment with 5′-GMP in the absence of 1 and UVA irradiation for 15 min showed no reaction (Figure 1 D), thus suggesting that 5′-GMP is stable under these conditions. The photoreaction of 1 and 5′-GMP under an atmosphere of argon gave similar results, thereby excluding the possibility that dissolved oxygen is the oxidant. Hence, 1 c, 1 d, and 1 e are all produced by the photoreaction of 1.

Bottom Line: Worth the excitement: Highly reactive oxygen and nitrogen species are generated by photoactivation of the anticancer platinum(IV) complex trans,trans,trans-[Pt(N3 )2 (OH)2 (MA)(Py)] (MA=methylamine, Py=pyridine).Singlet oxygen is formed from the hydroxido ligands and not from dissolved oxygen, and ammine ligands are products from the conversion of azido ligands to nitrenes.Both processes can induce oxidation of guanine.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (P.R. China).

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