Pentacyclic triterpenes responsible for photoprotection of Corema album (L.) D.Don white berries

Screening-based photoprotection is a first-line defence of plants against potentially harmful solar radiation. In the Iberian Peninsula, most natural fleshy fruits are red, purple or black, although there do exist a few plants that naturally present white fruit, such as Corema album (L.) D.Don (Ericaceae). This is a wild shrub of Atlantic coastal areas, which presents white fleshy fruit that ripens throughout the summer. We analysed the reflectance of fully ripened fruit in the field, and laboratory (before and after hexane washing and pericarp removal). The aqueous and ethyl acetate extract was successively obtained from the crushed fruit and submitted to column chromatography on Silicagel. The fractions were analysed through gas chromatography/mass spectrometry, and two compounds were separated and identified as oleanolic and ursolic acids. The reflectance measurements were taken with the UniSpec-SC Spectral Analysis System. The fruit in the field and laboratory exhibited elevated UV reflectance. The ethyl acetate extract, fractions, and isolated compounds showed high reflectance in UV, which indicated that these triterpene acids could be responsible for reflectance in natural berries. Ursolic and oleanolic acids can play a photoprotective role in berries of Corema album. In sunny environments white fruit can be more visible to dispersers.