A Ru(bpy)3Cl2 photocatalyst is applied to the rapid trans cis isomerization of a range alkene-containing pharmacological agents, including combretastatin A-4 (CA-4), clinical candidate in oncology, and resveratrol derivatives, switching their configuration from inactive substances potent cytotoxic agents. Selective cellulo activation CA-4 analog Res-3M demonstrated, along with its cytotoxicity ...