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PHOTOCHEMISTRY OF AQUEOUS ADRIAMYCIN AND DAUNOMYCIN. A SPIN TRAPPING STUDY WITH 17 O ENRICHED OXYGEN AND WATER
Author(s) -
Alegria Antonio E.,
Riesz Peter
Publication year - 1988
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1988.tb02799.x
Subject(s) - chemistry , adduct , aqueous solution , spin trapping , oxygen , photochemistry , photodissociation , electron paramagnetic resonance , hydroxyl radical , radical , organic chemistry , nuclear magnetic resonance , physics
— Photolyses at 485 or 490 nm of air saturated, H 2 I7 O enriched, aqueous solutions of adriamycin (ADR) in the presence of 5,5‐dimethyl‐l‐pyrroline‐l‐oxide (DMPO) produce a mixture of hydroxyl radical spin‐adducts, i.e. DMPO‐ 16 OH‐ and DMPO‐ 17 OH‐, as detected by electron spin resonance (ESR). DMPO‐ 17 OH‐ was also observed during the irradiation at these same wavelengths of aqueous solutions of ADR or daunomycin (DA) containing DMPO and 17 O enriched oxygen. Therefore, the observed hydroxyl radical spin‐adducts derive from both water and gaseous oxygen. It is concluded from the measured relative spin‐adduct concentrations and from the enrichment fractions that most of the DMPO‐OH adducts originate from water. However, if anaerobic diluted solutions of ADR (200 μ M ) or DA (600 μM) in the presence of DMPO (13 mM and 27 m M respectively) are irradiated at these same wavelengths no spin adduct is detected, indicating that oxygen is needed for the adduct formation, at these drug and spin trap concentrations. DMPO‐OH‐ is always observed if relatively high concentrations of either the drug (1.1–2.9 mM) or the spin trap(100–150 m M ) are used in argon saturated solutions. A water photooxidation mediated mechanism is proposed in order to account for these results, analogous to previous observations in the photochemistry of other water soluble anthraquinone derivatives.