One new natural monoterpene, 5---d-glucopyranosyl-2-hydroxy--cymene (1: ), and 11 known compounds were isolated through a biologically oriented approach from the aerial parts of L. The most active extract and fractions were selected using 3 complementary antioxidant activity assays. Results and the different methods were compared by relative antioxidant capacity index. In addition, the most active extract of was subjected to liquid chromatography coupled with electrospray ionization hybrid linear ion trap quadrupole Orbitrap mass spectrometry to quantify secondary metabolites. Antioxidant activities of ethyl acetate extract, and purified 3,4-dihydroxyacetophenone (3: ) and nebrodenside A (7: ) were demonstrated by cell free model assays, and their protective effect against HO-induced oxidative stress in a HepG2 (human hepatocellular carcinoma) cell line was established.