Common xanthene fluorescent dyes are visible-light activatable CO-releasing molecules

Area of Science:

• Photochemistry
• Chemical Biology
• Medicinal Chemistry

Background:

• Fluorescein, eosin Y, and rose bengal are widely used dyes in clinical medicine.
• These dyes are generally considered photochemically stable under typical conditions.

Purpose of the Study:

• To investigate the photochemical behavior of fluorescein, eosin Y, and rose bengal under extensive visible light irradiation.
• To explore the potential of these dyes as visible-light activatable carbon monoxide (CO)-releasing molecules (photoCORMs).

Main Methods:

• Aqueous solutions of fluorescein, eosin Y, and rose bengal were subjected to extensive irradiation with visible light.
• The release of carbon monoxide (CO) and the formation of secondary photoproducts were analyzed.

Main Results:

• Fluorescein, eosin Y, and rose bengal released carbon monoxide (CO) in high yields (40-100%) upon prolonged visible light exposure.
• A multistep degradation process was observed, producing low-mass secondary photoproducts like phthalic and formic acids.
• The photochemical reactivity challenges the assumption of their stability in certain applications.

Conclusions:

• The photochemistry of fluorescein, eosin Y, and rose bengal, including CO release, must be considered in their clinical applications.
• These dyes demonstrate potential as novel visible-light activatable CO-releasing molecules (photoCORMs) for biological studies.