One of the largest challenges associated with medicines is the occurrence of adverse effects, which are caused by their effect on healthy cells and tissues. To increase efficacy and reduce toxicity of medicines, such as chemotherapeutics, novel drugs and delivery systems for targeted therapy are being researched. The activation of drugs can be achieved by chemical or physical changes in the target area, among which light is the most practical for its precise spatial and temporal control. Light activated molecules can be divided into photoswitches and photocages, which contain a photoremovable protecting group (PPG). Three catalytic inhibitors of topoisomerase IIα were protected at pharmacophoric sites using three different PPGs. An important attribute, specific to photocaged compounds, is the rapid and complete photoactivation under the influence of appropriate irradiation. We studied the kinetics of photoactivation under weak ultraviolet radiation at 366 nm. The irradiation power was evaluated using a standard ferrioxalate actinometer. The rate of photoactivation was primarily influenced by the photoremovable group used and, to a lesser extent, by the binding site. The ciano hydroxyquinoline based caging moiety allows for a simpler and faster photoactivation compared to the quinoline and coumarin derivatives.The formation of predicted products in the fastest photodissociation reactions was confirmed by mass spectrometry. The data obtained under the described conditions serve as a basis for in vitro experiments on cancer cell lines.
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