The aerial parts of Teucrium sandrasicum L. (Lamiaceae), an endemic species of the Turkish flora, are widely used in the daily diet. The plant is also valued as a traditional medicine and is used for diuretic, diaphoretic, tonic, antipyretic, antidiabetic, antispasmodic, and cholagogic purposes. This study investigated a methanolic extract of aerial parts of T. sandrasicum for its antioxidant and antiinflammatory effects, inhibition of thioredoxin reductase, and protection against DNA damage. The extract showed inhibitory activity against FeCl3/ascorbic acid induced phosphatidylcholine liposome oxidation (EC50 = 1.49 +/- 0.03 mg/mL), quenched stable DPPH (EC50 = 1.05 +/- 0.03 mg/mL), superoxide anion (EC50 = 1.20 +/- 0.06 mg/mL), and ABTS cation radicals (EC50 = 1.73 +/- 0.01 mg/mL). The extract also acted as a reductant, as determined by the FRAP value (2.66 +/- 0.21 mM/LFe2+), indicating its potential as an antioxidant. The T. sandrasicum species was determined to be a rich source of flavonoids (104.39 +/- 1.37 mg/g), which are likely to serve as antioxidant, anti-inflammatory, and cancer chemoprevention agents. The extract was strongly inhibitory against both cyclooxygenase-2 (COX-2) (EC50 = 1.18 +/- 0.03 mg/mL) and thioredoxin reductase (0.90 +/- 0.02 mg/mL), and it significantly and dose-dependently decreased the amount of nicked DNA, as well as increased the natural form of DNA. (C) 2015 Elsevier B.V. All rights reserved.