Cork extracts as bioactive compounds against UV-mediated DNA fragmentation

 The human skin is mainly composed by fibroblasts (in the dermis) and keratinocytes (in the epidermis). They are usually affected by UV radiation through the generation of reactive oxygen species (ROS) that alter the redox status of the cells’ mitochondria. [1,2] High intracellular concentration of ROS induce DNA fragmentation that may lead to photoaging or skin cancer. [3] These conditions can be generated by high doses of UVA (able to penetrate through the epidermis into the dermis) and/or UVB (only affects the epidermis) radiation. The use of antioxidants has been proposed to protect the skin from UV-mediated damage. In this context, herein we tested the capacity of cork extracts (rich in phenols - reported to be strong antioxidants) to neutralize the ROS and reduce the fragmentation of DNA from fibroblasts.

Polyphenolic fractions were extracted from the outer bark (cork) of Quercus suber L., and tested for their capacity to decrease the cellular damage (L929 fibroblasts) promoted by the ROS produced during UV exposure. At a concentration of 75μg/ml all the extracts demonstrated the capacity to preserve the cell’s metabolic activity and their typical morphology, as well as, to avoid DNA fragmentation after exposure to UV radiation. We were also able to correlate these findings with the intracellular reduction of ROS species and the presence of higher proportions of castalagin and vescalagin in the extracts. Our results prove that cork is a relevant source of bioactive compounds, protecting cells against oxidation, reducing the number of ROS species and limiting the negative impact of UV radiation.

Acknowledgements: The FP7 project POLARIS (REGPOT-2012-2013-1-316331) is acknowledged.

References: 1. Giampieri, F., et al., J Agric Food Chem, 2012. 60(9): 2322-7.; 2. Fisher, G.J., et al., New England Journal of Medicine, 1997. 337(20): 1419-1429.; 3. Armstrong, B.K. and A. Kricker, Journal of Photochemistry and Photobiology B: Biology, 2001. 63(1–3): 8-18.