In vitro activity: Suprofen inactivates the diclofenac-4-hydroxylase activity of baculovirus-expressed P450 2C9 in a time- and concentration-dependent manner, which is consistent with mechanism-based inactivation. Suprofen is a known generator of singlet oxygen whose participation in the reaction is supported by the effects of quenchers and scavengers. Suprofen photosensitizes the production of alkali-labile cleavage sites in DNA much more efficiently than direct strand breaks. Suprofen sensitizes photo-oxidation of cholesterol, producing 7 alpha- and 7 beta-hydroperoxides but not 5 alpha-hydroperoxide of cholesterol. Suprofen-sensitized photo-oxidation of membrane lipids of liposomes increases leakage of trapped glucose, suggesting photosensitized destabilization of the membrane structure. Suprofen incorporation in the phosphatidylcholine (PC) evaporation vesicles (REV) membrane leads to approximately 5% increase in the encapsulation efficiency (34%) in comparison to standard REV (29%).