Antioxidant Compounds Isolated from the Roots of Phlomis umbrosa Turcz.

Two triterpenoids, arjunolic acid (1), belleric acid (2), five phenylethanoids, martynoside (3), orobanchoside (4), 3,4-dihydroxyphenethylalcohol-6-O-caffeoyl-β-D-glucoside (5), leucosceptoside B (6), lunarii-folioside (7), four phenolic acids, ferulic acid (8), syringic acid (9), vanillic acid (10), 4-hydroxybenzoic acid (11), and one lignan, (+)-syringaresinol-β-D-glucoside (12), were isolated from the roots of P. umbrosa. All isolated compounds were explored for their antioxidant potential in the DPPH and ABTS assays. In DPPH assay, compound 5 showed high antioxidant capacity. Compounds 3, 4, 6, and 7 displayed considerable antioxidant activities. In addition, compounds 5–7 exhibited potential antioxidant capacities in the ABTS assay.