The photochemistry of dipyridamole

The photochemical reactions of dipyridamole (DIP), a healing agent, was studied to predict the photobiological implications of its use which will be the subject of a future article. Its photolysis product under UV-A and aerobic conditions was isolated and identified. DIP was shown to be photostable under inert atmosphere (argon). On the other hand, under the same conditions a process of electron transfer was detected in the presence of nitro blue tetrazolium (NBT) which can be inhibited by oxygen. The photodegradation of DIP occurs probably via a type II mechanism involving irreversible trapping of self-photogenerated reactive oxygen species (ROS). This fact could be indicative of its antioxidant activity. The formation of singlet oxygen and superoxide during the DIP photodegradation makes one suspicious of a possibility that DIP could also be involved in oxidative stress in biological systems. Further studies on biological systems will contribute to elucidate this probable dual behavior.