Synthesis and structural characterization of a novel phenoxazinone dye by use of a fungal laccase

Laccase, isolated from Cerrena unicolor, is able to transform 3-amino-4-hydroxybenzensulfonic acid into a water soluble phenoxazine dye with an extinction coefficient (ɛ) of 8600 M−1 cm−1. The dye has been characterized using a variety of different analytic and spectroscopic techniques like UV–vis spectroscopy, HPLC (High Performance Liquid Chromatography), ESI/MS (Electrospray Ionization Mass Spectrometry) and the following NMR experiments: 1H, 13C, TOCSY (Total Correlation Spectroscopy), HSQC (Heteronuclear Single Quantum Coherence), HMBC (Heteronuclear Multiple Bond Coherence) showing the structure of 2-amino-3-oxo-3H-phenoxazine-8-sulfonic acid. The advantages of the presented biocatalytic system, in alignment with chemical system to obtain Curie_22, are eco-sustainability and one step performance.