Comparison of the Antioxidant and Cytoprotective Properties of Extracts from Different Cultivars of L.

L. is a rich source of vitamin C and polyphenols. Due to their health-benefit properties, L. extracts have been used in, e.g., dermatology and cosmetology, and as a food supplement. Peroxisome proliferator-activated receptor gamma (PPARγ) and its co-activator (PGC-1α) are now suspected to be the main target of active substances from . extracts, especially polyphenols. Moreover, the PPARγ pathway is involved in the development of different diseases, such as type 2 diabetes mellitus (DM2), cancers, skin irritation, and inflammation. Therefore, the aim of the present study was to evaluate the PPARγ pathway activation by the most popular water and ethanol extracts from specific L. cultivars in an in vitro model of the human normal fibroblast (BJ) cell line. We analyzed the content of biologically active compounds in the extracts using the UPLC-DAD-MS technique and revealed the presence of many polyphenols, including gallic, quinic, protocatechuic, chlorogenic, and ellagic acids as well as iridoids, with loganic acid being the predominant component. In addition, the extracts contained cyanidin 3--galactoside, pelargonidin 3--glucoside, and quercetin 3-glucuronide. The water-ethanol dark red extract (DRE) showed the strongest antioxidant activity. Cytotoxicity was assessed in a normal skin cell line, and positive effects of all the extracts with concentrations ranging from 10 to 1000 µg/mL on the cells were shown. Our data show that the studied extracts activate the PPARγ/PGC-1α molecular pathway in BJ cells and, through this mechanism, initiate antioxidant response. Moreover, the activation of this molecular pathway may increase insulin sensitivity in DM2 and reduce skin irritation.