Structure-efficiency relationship of photoinduced electron transfer-triggered nitric oxide releasers.

Spatiotemporally controllable nitric oxide (NO) releasers are required for biological studies and as candidate therapeutic agents. Here, we investigate the structure-efficiency relationship of a series of photoinduced electron transfer-triggered NO releasers based on our reported yellowish-green light-controllable NO releaser, NO-Rosa. The distance between the NO-releasing N-nitrosoaminophenol moiety and the rosamine antenna moiety was critical for efficient NO release. Notably, substitution at the phenolic hydroxyl group blocked NO release. We synthesized NO-Rosa-Gal bearing D-galactose (Gal) at this location, and showed that hydrolysis by β-galactosidase restored the photoresponse. This represents proof-of-concept of a strategy for highly specific control of NO release by using a double-lock system involving both enzymatic reactivation and photo-control.