Photodegradation of Nabumetone in aqueous solutions

Abstract

[EN]The photolability of the anti-inflammatory drug Nabumetone (4-(6-methoxy-2-naphthyl)-butan-2-one) was studied in water. The photoproducts were followed by UV-Vis absorption, fluorescence and FTIR spectroscopies as well as gas chromatography–mass spectrometry (GC–MS). The photodegradation process in water followed first-order kinetics, with an half-life, t1/2 = 9.7min whereas leading to different products. In this medium, the side chain is photoxidised to 6-methoxy-2-naphthalene aldehyde, as major product, probably via a Nabumetone radical cation formation and the addition of singlet oxygen generated in the drug photolysis. In addition the (4-(6-methoxy-2-naphthyl)-3-buten-2-one) was detected. The most likely origin of the unsaturated compound is the dehydratation of an alcoholic derivative in alpha position of the naphthalene ring, produced via the same radical cation.