Photochemical properties of gemifloxacin: A laser flash photolysis study

• The photochemical properties of 3GEFX∗, GEFX+ and GEFX− were determined.
• The 3GEFX∗ energy was determined as 266 kJ mol−1.
• The reactions of 3GEFX∗ with dGMP and TrpH occurred via electron transfer.
• SDS–PAGE proved GEFX can cause photodamage to Lyso by electron and energy transfer.

The photochemical properties of gemifloxacin (GEFX), a fluoroquinolone antibacterial drug that exhibits phototoxicity toward biological substrates, were studied in aqueous solutions by laser flash photolysis (LFP) and pulse radiolysis. GEFX triplet state (3GEFX∗) absorption spectra showed maximum absorption at 510 nm. 3GEFX∗ was quenched by naproxen (NAP) via energy transfer with a rate constant of 1.2 × 108 dm3 mol−1 s−1. The energy of 3GEFX∗ was 266 kJ mol−1 and the transient absorption spectra showed direct evidence of electron transfer from 2′-deoxyguanosine-5′-monophosphate, N,N,N′,N′-tetramethyl-p-phenylenediamine, and tryptophan to 3GEFX∗ with bimolecular reaction rate constants of 4.1 × 106, 2.0 × 107, and 2.2 × 107 dm3 mol−1 s−1, respectively. The rate constants for reactions of GEFX with OH, eaq− were found to be 1.5 × 1010 and 1.4 × 1010 dm3 mol−1 s−1, respectively. The mechanisms and products of the photosensitive damage of lysozyme were related to the GEFX concentration, irradiation time, and ambient conditions.

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