The compound, called sulforaphane, is found in broccoli sprout extracts and was first identified by Talalay and his colleagues more than 15 years ago. Sulforaphane has been shown to inhibit tumor development in animals.
For this study, Talalay and his colleagues tested the compound in both mice and humans.
The human experiments involved six healthy volunteers. Each participant was exposed to UV radiation on two circles on their back that were either treated or not treated with different doses of broccoli extract.
The highest doses of the extract reduced UV-induced redness and inflammation (erythema) by an average of 37 percent, although protection varied from 8 percent to 78 percent.
"If you apply an extract of broccoli sprouts that contains high levels of sulforaphane to regions of human skin, you can protect them very substantially," Talalay said. "We believe, to the best of our knowledge, that this is the first demonstration of protection against a known human carcinogen in humans."
One expert was excited by the discovery.
"There is some interesting data here," said Dr. Vijay Trisal, an assistant professor of surgical oncology at the City of Hope Cancer Center, in Duarte, Calif. "Sulforaphane compounds have been known to boost the immune system locally. This has some basic science behind it."
"The same thing happens with interferon, which we use for melanoma. It boosts the natural killer cells," Trisal explained.
The findings do need to be replicated, Talalay noted.
"It's going to take a little while to work out how this should be applied," Talalay said. "We would need to have a preparation rich in sulforaphane that would be easily absorbed through the skin, and this is not yet a reality. But, since we're dealing with a food, we're not dealing with anything likely to have a toxicity."
The study is published in this week's issue of the Proceedin
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