On the antioxidant activity of eumelanin biopigments: a quantitative comparison between free radical scavenging and redox properties

Abstract

The antioxidant activity of eumelanin, a ubiquitous pigment in flora and fauna, constitutes one of its most fascinating physicochemical properties. To shed light on free radical scavenging vs redox facets of such activity, we applied hydrogen atom transfer- and electron transfer-based assays to pristine Sepia ink, eumelanin from Sepia ink, chemically controlled eumelanins and their precursor building blocks. Our work contributes to the rational use of the antioxidant properties of eumelanin for health, cosmetics and environmental applications.

Graphical Abstract

Keywords:

• Eumelanin
• biopigment
• DHI (5,6‐dihydroxyindole)
• DHICA (5,6‐dihydroxyindole-2‐carboxylic acid)
• Sepia ink
• Briggs-Rauscher assay
• Folin Ciocalteu assay

Acknowledgements

S.C., D.G., M.L. and A.R. gratefully acknowledge financial support from ITT Montani Fermo (Italy), and in particular Margherita Bonanni, during their internship at Polytechnique Montreal.

Disclosure statement

No potential conflict of interest was reported by the authors.