The study, performed in the Department of Biochemistry and Molecular Biology at the University of Barcelona in Spain, found that the antioxidant polyphenols in grapes protect the cells of the skin – keratinocytes – against damage from reactive oxygen species (ROS). Reactive oxygen species, also called free radicals, damage skin cells by producing lipid peroxidation. This has been shown to damage cell membranes, produce DNA mutation, skin cancer, premature aging and other skin diseases.
The study, published in the Journal of Agricultural and Food Chemistry, was carried out on cells in the laboratory. Lead researcher Dr. Marta Cascante is a Professor of Biochemistry in the Department of Biochemistry and Molecular Biology at the University of Barcelona. She explained to the Spanish National Research Council that, “These polyphenolic fractions inhibit the generation of the ROSs [reactive oxygen species] and, as a result, the subsequent activation of the JNK and p38 enzymes, meaning they have a protective effect against ultraviolet radiation emitted by the sun.”
The p38 and JNK1/2 ezymes are stimulated by both UVB or UVA radiation from the sun. In the experiment, they were inhibited by the grape extracts. These two enzymes are implicated in the production of the free radicals that harm the cells.
The phytochemicals in the grapes were described as procyanidin oligomers and gallate esters. Procyanidins have been found in a number of other plant foods, as has gallic acid.
This study confirms others that have found that certain plant antioxidants protect against sun damage. These same antioxidants also help plants protect themselves against sun damage.
Matito C, Agell N, Sanchez-Tena S, Torres JL, Cascante M. Protective effect of structurally diverse grape procyanidin fractions against UV-induced cell damage and death. J Agric Food Chem. 2011 May 11;59(9):4489-95.
Spanish Foundation for Science and Technology.