Evaluation of pranoprofen photodegradation induced by ultraviolet-light irradiation in aqueous media

Abstract

The photodegradation of pranoprofen (PP), which is a member of the 2-arylpropionic acid family of non-steroidal anti-inflammatory drugs, in aqueous media under ultraviolet light (UV) irradiation was studied herein. Our purpose is to clarify the photostability and photochemical behavior of PP. The photodegradation of PP and the generation of its photoproducts were monitored by means of high-performance liquid chromatography (HPLC). PP was degraded completely after 2 h of UV irradiation with the generation of several photoproducts identified in HPLC analysis. The chemical structures of nine PP photoproducts were elucidated based on the mass/charge ratio (m/z) values and fragmentation patterns of protonated ions obtained from electrospray ionization liquid chromatography mass spectrometry (ESI-LC/MS/MS). Among these nine PP photoproducts, the main product was 7-acetyl-5H-[1]benzopyrano[2,3-b]pyridin-5-one, which was the final oxidized form of PP. The photodegradation pathways are proposed, showing that oxidation of excited PP might be an initial process. This is the first study showing the photochemical behavior of PP, and these results allow further research focused on the photostability of PP in commercial tablets and its changed formulation, the toxicological potencies of photoproducts and photostabilization approaches.

Graphical Abstract

Highlights

• The photodegradation of pranoprofen and the generation of its photoproducts by UV irradiation were examined.

• HPLC and ESI-LC/MS/MS were utilized as analytical tools for achieving this purpose.

• Pranoprofen was degraded completely after UV irradiation for 2 h with the generation of several photoproducts.

• Up to nine photoproducts were detected, and their structures were proposed by examining UV absorption and MS spectral profiles.

• The photodegradation pathways in aqueous media were proposed.

Keywords:

• ESI-LC/MS/MS
• HPLC
• pranoprofen
• photodegradation
• photoproducts

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by JSPS KAKENHI Grant [Number JP 20K15980].