Enzymatic triggering of C–ON bond homolysis of alkoxyamines

Alkoxyamine 1 is selectively hydrolyzed by chymotrypsin and substilisin A into alkoxyamine 2H+ for which C–ON bond homolysis occurred with a 4-fold increase in rate constants compared to 1 while non-specific proteases had no effect. This highlights the triggering effect of enzymes. This is a proof of concept for a theranostic approach for treating solid tumors using enzyme-activated alkoxyamines releasing a cytotoxic alkyl radical and a stable nitroxide as a contrast agent for Overhauser-enhanced MRI.