Research by Lund University and colleagues in France and Italy looked into two different types of melanin found in skin and hair, called eumelanin and pheomelanin.
Eumelanin makes us develop a sun tan and gives colour to brown and black hair, whereas those with red hair and pale skin instead have high levels of pheomelanin.
"By understanding how the body naturally protects itself against UV light, we can develop better sun protection products based on the same principles. This would provide better protection against skin cancer," says Villy Sundström, Professor of Chemistry at Lund University.
"We found that eumelanin converts harmful UV radiation into heat with almost 100% efficiency. The chemical reaction is incredibly quick, taking less that a thousandth of a billionth of a second.”
Eumelanin is considered to be the pigment that protects against UV radiation while pheomelanin is believed to cause skin cancer in some way.
However, researchers have not previously been aware of what chemical reactions UV light causes in the pigment. There has therefore also been a lack of knowledge of the pigment processes that lead to protection against or development of cancer.
In their research the scientists observed this chemical reaction, in which a proton is ejected from the pigment at the same moment the UV light reaches the pigment molecule.
This projectile in turn gives off energy to the surrounding membrane tissue in the form of heat. It has therefore converted dangerous UV energy into harmless heat.
"In this way, the pigment disarms the energy in the UV light and prevents it causing harmful chemical reactions," adds Sundström.
The next steps for the scientists is to find treatment methods and substances that replace natural pigment for those with defective production of eumelanin.
Eumelanin is composed of two similar building blocks, but only one of them produces the protective effect, meaning the effect is very specific. This insight could prove important in the development of substances for treatment and sun protection products.
Alice Corani, Annemarie Huijser, Thomas Gustavsson, Dimitra Markovitsi, Per-Åke Malmqvist, Alessandro Pezzella, Marco d’Ischia, Villy Sundström. Superior Photoprotective Motifs and Mechanisms in Eumelanins Uncovered. Journal of the American Chemical Society, 2014; 136 (33): 11626 DOI: 10.1021/ja501499q