Bioguided isolation of secondary metabolites from Salvia cerino-pruinosa Rech. f. var. cerino-pruinosa

Abstract

Abstract: In the current study, the ethanol extracts prepared from the aerial parts and roots of an endemic species, Salvia cerino-pruinosa Rech. f. var. cerino-pruinosa were fractionated on silica gel columns and tested for determination of their antioxidant activity using DPPH free radical and ABTS cation radical scavenging, and cupric reducing antioxidant capacity (CUPRAC) test assays. Twenty known secondary metabolites were isolated from the active antioxidant fractions; rosmarinic acid (1), chlorogenic acid (2), caffeic acid (3), 4- hydroxybenzoic acid (4), benzoic acid (5), luteolin 7-O-glucoside (6), bis-(2-ethylhexyl)benzene-1,2- dicarboxylate (7), salvianolic acid A (8), salvianolic acid B (9), 7-acetylroyleanone (10), 6,7-dehydroroyleanone (11), ferruginol (12), inuroyleanol (13), 12-hydroxy-6,7-secoabieta-8,11,13-triene-6,7-dial (14), ursolic acid (15), oleanolic acid (16), taraxasterol (17), lupenone (18), β-sitosterol (19), and stigmasterol (20). Rosmarinic acid, which was obtained from the aerial parts, was found to be the best antioxidant compound among the isolated secondary metabolites in DPPH free radical and ABTS cation radical scavenging, and CUPRAC assays (IC50: 1.20±0.04 µg/mL, IC50: 1.74±0.06 µg/mL, A0.5: 1.22±0.02 µg/mL, respectively). Chlorogenic and caffeic acids, luteolin 7-O-glucoside, salvianolic acids A and B, and inuroyleanol exhibited also high antioxidant activity in the mentioned assays.