Triplet state characteristics and singlet oxygen generation properties of anthracyclines

Alessandra Andreoni, Edward J. Land, Vincenzo Malatesta, Andrew J. McLean, T. George Truscott

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The triplet states of adriamycin (Ad), daunomycin (D) and two daunomycin analogues, daunomycinone (Dc) and daunomycin N-trifluoroacetamide (DAc), have been studied using laser flash photolysis and pulse radiolysis techniques. Triplet lifetimes, molar absorption coefficients, energy levels and quantum yields have been obtained for Dc and DAc, and estimated for D and Ad. Time-resolved near-infrared singlet oxygen luminescence measurements have been carried out on D, Ad and 5-iminodaunomycin (5-ID) in 2H2O solution and Dc in benzene solution at room temperature. Singlet oxygen quenching by the water-soluble anthracyclines was observed and a second-order rate constant of approx. 108 M−1 · s−1 obtained. Electron spin resonance experiments have demonstrated that D photoexcited at λ < 365 nm gives rise to singlet oxygen as shown by its reaction with 2,2,6,6-tetramethyl-4-piperidone to give the corresponding nitroxyl radical. Although all the anthracyclines studied have the ability to photosensitise the formation of singlet oxygen, the quantum yields are very low (φΔ ≈ 0.02–0.03), suggesting that these anthracyclines would be poor photodynamic sensitisers.
Original languageEnglish
Pages (from-to)190-197
Number of pages8
JournalBiochimica et Biophysica Acta (BBA) - General Subjects
Volume990
Issue number2
DOIs
Publication statusPublished - 24 Feb 1989

Keywords

  • Anthracycline
  • Triplet state
  • Flash photolysis
  • ESR
  • Singlet oxygen

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