Urtica dioica L. and Parietaria judaica L. subsp. judaica (Urticaceae): A Comparative Screening of the Phytochemical Profile and In Vitro Biological Potential

Urtica dioica L. and Parietaria judaica L. subsp. judaica are two members of the Urticaceae family well-known for their sensitization and allergenic potential. Nevertheless, both species were used in traditional medicine, and various pharmacological properties have been described so far. Here, the dried aerial parts from Southern Italy were extracted through maceration, and a preliminary comparative study focused on the in vitro antioxidant and anti-denaturation properties, as well as on the pancreatic lipase inhibitory effects, was carried out. The most apolar constituents were extracted by means of liquid–liquid extraction, and the phytochemical profile of the two species was verified with gas chromatography–mass spectrometry (GC–MS) analyses and compared using principal component analysis (PCA). The correlation between detected phytochemicals and observed biological properties was also verified. A positive correlation was observed between lipase inhibition and the compounds mainly abundant in the U. dioica dichloromethane fraction, which showed the best activity (IC50 = 1.67 ± 0.01 mg/mL). The two P. judaica fractions instead showed the best anti-denaturation effects (IC50 = 321.6 ± 3.3 and 424.4 ± 1.8 μg/mL). Further studies are needed to optimize the solvent partitioning method and to deeply study the interesting biological properties of investigated species.