Sunlight continues to damage people's skin and increase the risk of cancer for hours after they leave the beach and head indoors. BBC News reports that scientists at Yale University, in the US, discovered it was the supposedly protective pigment melanin that was causing the damage. The team say the findings may lead to better sunscreens that can prevent the extra damage.
When UV radiation pummels our skin cells, it can cause mutations in the DNA. Melanin, the pigment behind a tan or natural skin tone, is the body's defence as it absorbs the radiation. What scientists did not know previously was what happens to all the energy that the melanin has absorbed. The Yale team showed that the high-energy version of melanin supercharges a series of chemical reactions.
A cocktail of superoxides and peroxynitrites culminate in a "very high-energy molecule breaking apart and releasing the energy that was holding it together", said lead researcher Prof Douglas Brash. He said: "It's what happens in fireflies when they (use the energy to) produce light and glow, except the energy is just transferred to the DNA."
In laboratory tests, the whole damage in skin was still taking place four hours after UV exposure was stopped. "Half or more of this kind of DNA damage is not happening on the beach, it's on the car on the way home," Brash said. The team hope they can develop a sunscreen that combines the usual protection with absorbing any energy from the melanin.
Science Daily reports that new research has introduced a new plant-derived agent which protects skin from the harmful effects of UV irradiation. "We found out that the antioxidant active Licochalcone A, which is the main component of the root extract of the plant Glycyrrhiza inflata (Chinese Licorice), is able to protect the skin from subsequent UV irradiation damage from within by strengthening the skin's own defence systems. Thus plant extracts with the described profile are able to provide a protective shield from sun exposure supporting and going beyond the action of sunscreens regarding sun protection," said Gitta Neufang, a researcher involved in the work from Beiersdorf AG, Hamburg, Germany.
In order to test the effects of the plant-derived active Licochalcone A in cell culture, Neufang and colleagues isolated human skin cells and irradiated them with solar simulated light mimicking sun exposure. They were able to show that skin cells pre-treated with Licochalcone A produced a higher amount of 'self-protecting', antioxidant molecules. Consequently, significantly less harmful radicals were detected in Licochalone A treated human skin cells. In addition, they also conducted a study with healthy volunteers demonstrating that the application of a lotion containing Licochalcone A-rich root extract on the inner forearms for two weeks protected the skin from damage after UV irradiation.
These findings show that the skin's own defence system can be stimulated by the application of licorice extract. In combination with UV-filters this approach therefore might provide superior sun protection by not only offering physical but also biological sun protection. "Even with the best sun-protecting filter system (SPF50+) 2% of UV-rays still reach the skin and cause damage. We hope that our study helps to improve the effectiveness of sunscreens to protect from the harmful aspects of sun exposure." concluded Gitta Neufang.
[link url="http://www.bbc.com/news/health-31533553"]Full BBC News report[/link]
[link url="http://www.sciencemag.org/content/347/6224/842.abstract?sid=0b39aaab-70a0-4b68-87c8-ca38420d4ca4"]Science abstract[/link]
[link url="http://www.sciencedaily.com/releases/2015/02/150218191909.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed:+sciencedaily/top_news/top_health+(ScienceDaily:+Top+Health+News)"]Full Science Daily report[/link]
[link url="http://onlinelibrary.wiley.com/doi/10.1111/exd.12588/abstract;jsessionid=A464EEAC1BBC944D0188251CEA4AB80E.f04t04"]Experimental Dermatology abstract[/link]