Antioxidant and anti-collagenase activity of Hypericum hircinum L.

tHypericum hircinum L. is a shrub traditionally used in some Mediterranean areas as a remedy for sev-eral diseases, mainly linked to the airway apparatus. In this work, an ethanolic extract prepared fromaerial parts of plants collected in Sardinia (Italy), and six fractions isolated by a chromatographic separa-tion of the extract, were evaluated for their antioxidant activity using three in vitro assays. Based on theethnobotanical use of the plant and in view of the emerging role that enzymes belonging to matrix metal-loproteinases (MMPs) play in the pathogenesis of some respiratory diseases, the effect of the crude extractand of several fractions on in-vitro collagenase activity was also evaluated. Results show that the ethano-lic extract and fractions containing quercetin, chlorogenic acid, and 5,7,3,5-tetrahydroxyflavanone, acomponent recently identified in this species, are endowed with the highest free radical scavengingactivity. Conversely, fractions containing shikimic acid as the main component did not show this prop-erty. The crude extract was able to inhibit in-vitro collagenase activity with an IC50value of 156 g/mL.A Lineaweaver–Burk plot, built to obtain the kinetic parameters of the enzymatic reaction, revealed thatthe inhibitory mechanism is non-competitive. Single fractions were also evaluated for their inhibitoryactivity on collagenase; fractions mainly containing flavonols and the substituted flavanone showed thehighest inhibitory effect. Thus, H. hircinum can be considered as a new natural source of molecules ableto inhibit enzymes of the MMP family, which could enter as active ingredients in wrinkle-care cosmetics.