Antioxidant and antimicrobial properties of Teucrium arduini L. (Lamiaceae) flower and leaf infusions (Teucrium arduini L. antioxidant capacity)

Antioxidant and antimicrobial activities, as well as total phenol (TP, Folin-Ciocalteu method) and phenolic acid (UPLC– MS/MS) contents of leaf and flower infusions of Teucrium arduini L. from six different mountainous localities in Croatia (Ucka, Vosac, Sveti Jure, Snježnica, Vaganac, Susanj) were analyzed in this study. Antioxidant capacity was evaluated using the ferric reducing/antioxidant power (FRAP) assay, as well as 2, 2-diphenyl- 1-picrylhydrazyl (DPPH), and 2, 2´-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays. The antioxidant potency composite index (ACI), giving equal weight to all three methods used to quantify antioxidant capacity, was the highest for the sample from Vosac (96.7) among flower infusions, while maximum ACI (100) was determined for the infusion from Ucka among leaf infusions. Strong positive correlation was found between the total phenols and ACI for leaf (r= 0.953) and flower (r= 0.977) infusions. Our results point to significantly (p < 0.05) different TP content between leaf and flower infusions, as well as across localities. Leaf infusions of T. arduini from Susanj exhibited marked antibacterial activity against Staphylococus aureus, while none of the tested infusions exhibited antimicrobial activity against gram-negative bacterial species, or the tested fungal species.