Evaluation of the in vitro antioxidant activity of three Lamiaceae often used in Portuguese folk medicine

This study reports the first approach to the antioxidant potential evaluation of three Lamiaceae often used in Portuguese folk medicine, The lipid peroxidation inhibition capacity of ground ivy, oregano and mastic thyme was accessed by biochemical assays used as models for the lipid peroxidation damage in biomembranes, n=ely inhibition of ~-carotene bleaching in the presence of linoleic acid radicals and inhibition of thiobarbituric acid reactive substances (TBARS) formation in brain homogenates, The antioxidant properties were also evaluated through the reducing power determination and radical scavenging activity of 2,2-diphenyl-I-picrylllydrazyl (DPPH) radicals. Bioactive compowlds such as phenolics, flavonoids and ascorbic acid were also determined. Oregano proved to have the highest radical scavenging and lipid peroxidation inhibition capacity (EC,. values lower than 0.45 mg/ml). This species also revealed the highest content in antioxidants such as phenolics (368.58 ± 18.18 mg/g), flavonoids (224.15 ± 0.96 mg/g) and ascorbic acid (1 70,69 ± 5,29 J.Ig/g), Significantly negative linear correlations were observed between the bioactive compounds and antioxidant activity EC50 values of the three Lamiaceae