Rhus coriaria extract: protective effect against UVA irradiation in human dermal microvascular endothelial cells (HMEC-1)

Rhus coriaria L. (sumac) is a plant traditionally used in some countries (Turkey, Iran) as an anti- microbial and anti-inflammatory agent in skin disorders (1). Its fruits are rich in tannins, anthocyanins, flavonoids and terpenoids and gallic acid derivatives (2). Recently, different polyphenol-enriched extracts have been proposed for the prevention of UV-mediated skin damage. The extract was obtained by ethanol maceration for 48h of dried fruits. Then, the mixture was filtered and taken to dryness under reduced pressure and freezed dried. The extract (mERC) has been characterized in its components gallotannins and flavonols. UV-A rays can penetrate up to the dermal layer also affecting the microvascular endothelial cells of the papillary dermis, determining inflammation and photoaging, associated with redox imbalance. Treatment with the extract (10 and 25 µg/ml, 1h in serum-free media) was followed by the exposure to UV-A (10-15-20 J/cm2) radiation in PBS on HMEC-1 cells. Cytotoxicity (MTT and apoptosis) and DNA damage (alkaline comet test, ɣH2AX foci formation) have been evaluated at T0 and T24 after exposure. The mechanisms of UV-A mediated DNA damage on this cell line have been also studied in order to highlight the ability of the extract components to interfere with oxidative damage (oxidized base formations, SBBs, apurinic sites), but also with the formation of cyclobutane pyrimidine dimers (CPDs) by comet modified with enzymes and immunohistochemistry assays. 1) Bedi M.K. and Shenefelt P.D. (2002). Archives of Dermatology 138(2),232-242. 2) Shabbir A. (2012) J Anim Plant Sci 22(2). 505-512.