Structure determination of clinofibrate photoproducts generated by ultraviolet-light irradiation in aqueous media

Abstract

Abstract Photodegradation of clinofibrate, which is one of the fibrate drugs, was evaluated and chemical structures of its photoproducts were determined. Clinofibrate in aqueous media was photodegraded gradually by the UV light emission with the generation of several photoproducts. The result of HPLC analysis indicated that some photoproducts were more photostable compared with the parent compound. After 14 days irradiation, clinofibrate was degraded completely while several photoproducts were remained in the test solution. Structure determination of nine photoproducts was performed by means of ESI-LC/MS/MS analysis. Main photoproduct of clinofibrate was 2-(4-(1-(4-hydroxyphenyl)cyclohexyl)phenoxy)-2-methylbutanoic acid. Structure determination of clinofibrate photoproducts made it possible the estimation of the photodegradation pathway. It was tempting to speculate that the main photoproduct was generated by the elimination of 2-methylbutanoic acid and other photoproducts were generated through several photochemical reactions including further elimination of 2-methylbutanoic acid and decarboxylation. The obtained results will be helpful for the further research focused on the evaluation of biological activities of clinofibrate photoproducts, photostability of clinofibrate in commercial tablets and changed formulations, and the photostabilization of them.

Keywords

• Photoproduct
• ESI-LC/MS/MS
• Clinofibrate
• Photodegradation