Hair Eumelanin Overview
One of the two main types of melanin pigments found in human hair, as well as virtually all mammal hair and fur (not to mention skin), eumelanin is responsible for producing black and brown hair colors. It is synthesized within specialized cells called melanocytes, located in the hair follicles.
Chemical Composition & Formation Basics
Eumelanin is formed through a complex biochemical process called melanogenesis. This process begins with the amino acid tyrosine, which is converted to dopaquinone by the enzyme tyrosinase. The specific mechanisms involved in eumelanin formation are intricate and involve several steps, regulated by various enzymes and cellular factors within melanocytes.
Eumelanin in Hair
- Color Range: Eumelanin is responsible for darker hair shades, ranging from brown to black.
- Concentration: The amount of eumelanin in hair decreases in the order of black, dark brown, brown, and light brown hair colors.
- Composition: In black and brown hair, over 95% of the total melanin content is eumelanin.
- Subtypes: Eumelanin exists in two varieties: black and brown.
Genetic Factors
The production of eumelanin is influenced by various genes, with the MC1R gene playing a crucial role. Loss-of-function variations in the MC1R gene can lead to lower eumelanin production and higher phaeomelanin production, resulting in strawberry blonde, auburn, or red hair.
Measurement & Analysis
Chemical methods have been developed to quantify eumelanin in hair. One such method involves alkaline H2O2 oxidation, which produces pyrrole-2,3,5-tricarboxylic acid (PTCA) as a eumelanin marker.
The diversity in natural human hair color phenotypes arises primarily from the varying ratios of eumelanin and phaeomelanin, with eumelanin being the dominant pigment in most hair colors except for red.
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