Bis-N-nitroso-caged nitric oxides: photochemistry and biological performance test by rat aorta vasorelaxation Original Research Article

Three new caged nitric oxides (NOs)—BNN3, BNN5Na, and BNN5M—were tested for biological use. BNNs have a strong ultraviolet (UV) absorption band (λmax: 300 nm, ε: 13.5 mM−1 cm−1) extended to 420 nm and produce NO upon irradiation with 300–360 nm light in quantum yields about 2. A photoexcited BNN molecule yields two NOs with time constants of less than 10 ns for phase 1 and less than 20 μs for phase 2 at 37°C, suggesting usefulness of BNNs for measuring in vivo and in vitro fast NO reactions. Upon irradiating with UV light, caged nitric oxides-loaded rat aortic strips maintained in a state of active tonic contraction effectively relaxed (<3 μM BNN5M loading solution concentration). BNN3 is incorporated in the lipid membrane. BNN5Na, insoluble in organic solvents but water soluble, localizes in the water phase. BNN5M, is muscle-cell-permeable and hydrolysed to BNN5Na to remain in cytosol. BNNs were thermally stable and demonstrated no observable toxicity.