New insights into the nature of short-lived paramagnetic intermediates of ketoprofen. Photo-CIDNP study

Simon V. Babenko, Polina S. Kuznetsova, Nikolay E. Polyakov, Aleksandr I. Kruppa, Tatyana V. Leshina

Research output: Contribution to journalArticlepeer-review

Abstract

The short-lived paramagnetic particles formed during the UV irradiation of nonsteroidal anti-inflammatory drug - ketoprofen (KP) have been investigated using chemically induced dynamic nuclear polarization (CIDNP). This study answers the questions about the nature of paramagnetic particles which can be responsible for KP phototoxic effects. Phototoxic side effects of NSAIDs, according modern point of view, are associated with the action of free radicals, however, there is insufficient information regarding the nature of the radical species. In contrast, most ketoprofen photodegradation schemes include carbanion as a precursor of products. CIDNP effects analysis has shown that all the major products of KP photodegradation can form via radical pairs (RPs) involving benzyl (2′), ketyl (3′) and CO2H[rad] or CO2 [rad] free radicals and solvated electron. Radical ways of KP photodegradation include: decarboxylation via RP with benzyl radical formation (I) in non-aqueous solution and both, (I) and photoreduction with formation of ketyl radicals in the presence of water. Moreover, it was found that the photoinduced radical decarboxylation of KP represents a reversible process.

Original languageEnglish
Article number112383
Number of pages7
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume392
DOIs
Publication statusPublished - 1 Apr 2020

Keywords

  • CIDNP
  • Decarboxylation
  • Free radicals
  • Ketoprofen
  • ELECTRON-SPIN-RESONANCE
  • ACID
  • MECHANISM
  • WATER-RICH
  • PHOTOSENSITIVITY
  • RESOLVED RESONANCE RAMAN
  • BENZOPHENONE
  • PHOTOCHEMISTRY
  • HYDROGEN-PEROXIDE
  • PHOTODECARBOXYLATION

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