Trend of Antioxidant Activity and Total Phenolic Content in Wild Edible Plants as Part of the Environmental Quality Assessment of Some Areas in the Central Italy

Polyphenols are secondary metabolites of interest due to their potential application in various fields. This study is supposed to analyse the content of total polyphenols, total tannins, condensed tannins and antioxidant activity of ten wild plant species of nutritive interest to better understand their potential applications. Furthermore, the effect of heavy metals on the production of the investigated secondary metabolites was analysed. The different phenolic compounds were determined in methanol extracts obtained from edible plants collected during three sampling periods (June, September and November–December) in four areas of the Central Italy. Analyses were carried out by applying standard methodologies. In particular, total polyphenols were determined by the Folin–Ciocalteu method, total tannins by the polyvinylpolypyrrolidone (PVPP) reagent and condensed tannins by the 4-(dimethylamino)cinnamaldehyde (DMCA). Antioxidant activity was determined by assessing the scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). The results showed a satisfactory content of phenolic compounds and antioxidant activity for all species analysed. Furthermore, the existence of a negative correlation between the presence of heavy metals and phenolic compounds was found. Results proved the potential use of these plants for balanced feeding of ruminants.