Dynamics of Irreversible NO Release from Photoexcited Molsidomine

Molsidomine (SIN-10), an orally administered NO-delivery drug for vasodilation, cannot be used to alleviate hypertensive crisis because it releases NO at a slow rate. SIN-10 may be used to treat sudden cardiac abnormalities if the rapid and immediate release of NO is achieved via photoactivation. The photodissociation dynamics associated with the NO release process from SIN-10 in CHCl₃ was investigated using time-resolved infrared spectroscopy. Approximately 41% of photoexcited SIN-10 at 360 nm decomposed into CO₂, CH₂CH₃ radical, and the remaining radical fragment [SIN-1A(-H)] with a time constant of 43 ps. All SIN-1A(-H) released NO spontaneously with a time constant of 68 ns, becoming N-morpholino-aminoacetonitrile, resulting in 41% for the quantum yield of immediate NO release from SIN-10. The results obtained can be used to realize the quantitative control of the NO administration at a specific time, and SIN-10 can be potentially used to address the phenomenon of hypertensive crisis.