Abstract
The generic term “melanin“ describes a black pigment of biological origin, although some melanins can be brown or even yellow. The pigment is characterized as a heterogenic polymer of phenolic or indolic nature, and the classification of eu-, pheo- and allo- melanin is broadly accepted. This classification is based on the chemical composition of the monomer subunit structure of the pigment. Due to the high heterogeneity of melanins, their analytical characterization can be a challenging task. In the present work, we synthesized the current information about the analytical methods which can be applied in melanin analysis workflow, from extraction and purification to high-throughput methods, such as matrix-assisted laser desorption/ionization mass-spectrometry or pyrolysis gas chromatography. Our thorough comparative evaluation of analytical data published so far on melanin analysis has proven to be a difficult task in terms of finding equivalent results, even when the same matrix was used. Moreover, we emphasize the importance of prior knowledge of melanin types and properties in order to select a valid experimental design using analytical methods that are able to deliver reliable results and draw consistent conclusions.
Highlights
Melanins, one of the most widespread pigments in the animal kingdom, represent a group of biopolymers with distinctive physicochemical and biological properties
We synthesized the current information about the analytical methods which can be applied in melanin analysis workflow, from extraction and purification to high-throughput methods, such as matrix-assisted laser desorption/ionization mass-spectrometry or pyrolysis gas chromatography
The present paper aims to provide relevant information regarding the most commonly applied methods in melanin analysis, from extraction and purification to high-throughput methods such as matrix-assisted laser desorption/ionization mass-spectrometry or pyrolysis gas chromatography
Summary
One of the most widespread pigments in the animal kingdom, represent a group of biopolymers with distinctive physicochemical and biological properties. Melanins can be categorized in eumelanin (dark brown/black), pheomelanin (yellow/red) and allomelanin, specific to the plant kingdom. Both eumelanin and pheomelanin derive from the common precursor dopaquinone, which is obtained through tyrosine or L-Dopa oxidation (Figure 1). Clear differences in synthetic DHI and DHICA melanins exists, the former being a weak H-atom donor and a poor free radical scavenger, while the latter is a strong H-atom donor and a strong free radical scavenger These are consequences of the different electron delocalization, absorption and paramagnetic properties, as well as the aggregation mode at the supramolecular level [3]. The overall purpose is to guide specialists in selecting the proper analytical methods for melanin analysis in order to correlate the results with existing literature and draw reliable conclusions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
