Development of Photoredox-reaction-driven NO-releasing Reagents and Application for Photomanipulation of Vasodilation

Abstract

Nitric oxide (NO) is a signaling molecule that mediates vasodilation, neurotransmission, and immune response. Due to its instability in biological environments, NO-releasing small-molecular compounds have been developed for biological experiments and also as therapeutic reagents for vascular diseases. Although photocontrollable NO releasers are very useful chemical tools because of their precise operability in response to light irradiation, their biological applications have been limited, mainly because they require UV light irradiation or contain metal ions with the potential to cause cytotoxicity. In order to overcome these problems, our group has developed visible-light-responsive NO releasers based on photoreodox reaction. These compounds are composed of two moieties, an NO-releasing moiety and a light-harvesting antenna moiety. After photoirradiation, photoinduced electron transfer from the NO releasing moiety to the antenna takes place, followed by NO release. Based on this system, we developed a blue-light-controllable NO releaser and a yellowish-green-light-controllable one, which are applicable for cellular and ex vivo experiments. This account focuses on recent developments in photoredox-driven NO releasers and their applications for spatiotemporally controlled NO release in cells and ex vivo.