Antioxidant and anti-collagenase activity of Hypericum hircinum L

Hypericum hircinum L. is a shrub traditionally used in some Mediterranean areas as a remedy for several diseases, mainly linked to the airway apparatus. In this work, an ethanolic extract prepared from aerial parts of plants collected in Sardinia (Italy), and six fractions isolated by a chromatographic separation of the extract, were evaluated for their antioxidant activity using three in vitro assays. Based on the ethnobotanical use of the plant and in view of the emerging role that enzymes belonging to matrix metalloproteinases (MMPs) play in the pathogenesis of some respiratory diseases, the effect of the crude extract and of several fractions on in-vitro collagenase activity was also evaluated. Results show that the ethanolic extract and fractions containing quercetin, chlorogenic acid, and 5,7,3′,5′-tetrahydroxyflavanone, a component recently identified in this species, are endowed with the highest free radical scavenging activity. Conversely, fractions containing shikimic acid as the main component did not show this property. The crude extract was able to inhibit in-vitro collagenase activity with an IC50 value of 156 μg/mL. A Lineaweaver–Burk plot, built to obtain the kinetic parameters of the enzymatic reaction, revealed that the inhibitory mechanism is non-competitive. Single fractions were also evaluated for their inhibitory activity on collagenase; fractions mainly containing flavonols and the substituted flavanone showed the highest inhibitory effect. Thus, H. hircinum can be considered as a new natural source of molecules able to inhibit enzymes of the MMP family, which could enter as active ingredients in wrinkle-care cosmetics.