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sun protection barrier

Arnica’s sunscreen

Like other plants, arnica can survive in the hottest areas of Brazil’s Cerrado biome. But how exactly does it withstand the sun? With this question in mind, Denise Brentan da Silva, Norberto Peporine Lopes, and other researchers at the University of São Paulo (USP) in Ribeirão Preto examined the leaves of Lychnophora salicifolia plants collected at four different sites in the states of Goiás, Minas Gerais, and Bahia and found an accumulation of a flavonoid called vicenin-2, a compound known to have anti-inflammatory properties (Scientific Reports, April 2014). Using imaging mass spectrometry (IMS), the USP team has now ascertained that unlike other flavonoids – some 5,000 of which have been identified in plants to date – vicenin-2 accumulates in abundance on the leaf surface, or epithelium of the arnica plant. The localization and UV absorption properties suggest that this compound may protect plants, or at least arnica, from the damaging effects of sunlight. “This is probably the first evidence of a sun protection barrier forming in plants through the specific localization of a substance inside a tissue,” said Lopes. Of course, it is now necessary to find out whether this or other compounds display similar behavior in other species.

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