Characteristics of the excited states of Nitrofurantoin, an anti-inflammatory and photoactive nitrofuran derivative

• Published in: Journal of luminescence 2017-05, Vol.185, p.10-16
• Main Authors: Parra, Gustavo G., Ferreira, Lucimara P., Codognato, Débora C.K., Cavalheiro, Carla C.S., Borissevitch, Iouri
• Format: Article
• Language: English
• Subjects: Fluorescence; Nitrofurantoin; Singlet oxygen; Triplet state
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2017.01.001

Spectral characteristics of bio and photoactive nitrofuran derivative drug [N-(5-nitro-2-furfurylidene)−1-aminohydantoin], (Nitrofurantoin, NFT) were investigated using optical absorption and fluorescence spectroscopies, both in “steady-state” and time resolved forms. The irradiation of the NFT in the UV region in aqueous solution induces the fluorescence with quantum yield Φfl≈0.03% and lifetime τfl≈1ns with these values being practically independent of the NFT protonation state. The NFT transient absorption spectrum and lifetime (τT) depend on the NFT protonation state with τT being 0.04 μs for mono-protonated NFT state, 0.22 μs for its non-protonated one, and with quantum yield, ΦT ≈ 0.0001% which is practically independent of its protonation state. The quenching of this transient by molecular oxygen accompanied by simultaneous singlet oxygen formation (1O2) allows associate this specie with the NFT molecules in the triplet state being the efficiency of this process dependent of NFT protonation state, ηpH10≈0.53 and ηpH2.5≈0.07. The extremely low quantum yields, Φfl and ΦT, and short τfl and τT are, probably, associated with alternative ways of the dissipation of the NFT excited state energy: the NFT photoisomerization and NO• photorelease. The synergic action of two highly reactive species such as 1O2 and NO• in biological medium is extremely valuable for applications in photochemotherapy, thus making NFT a potential candidate for further studies in vitro and in vivo.