The chemical components of Coreopsis tinctoria Nutt. and their antioxidant, antidiabetic and antibacterial activities

Seventeen compounds were isolated from the capitula of Coreopsis tinctoria Nutt. with various column chromatographic methods and semi-preparative HPLC. Their structures were identified by the spectroscopic data and comparison with literatures as 2'-hydroxy-4,4'-dimethoxy-chalcone; (1), isoliquiritigenin (2), eriodictyol (3), naringenin (4), maritimetin (5), butin (6), taxifolin (7), luteolin (8), 7,3',4'-trihydroxyflavone (9), 8,3',4'-trihydroxyflavone-7-O-β-d-glucoside (10), quercetin (11), quercetagitin-7-O-β-d-glucoside (12), quercetin-7-O-β-d-glucoside (13), 3,4-dihydroxybenzoic acid (14), caffeic acid (15), coreoside B (16), and myo-inositol (17). Compounds 1, 4, 9, 10 and 17 were isolated from C. tinctoria Nutt. for the first time. Compounds 7 and 12 possessed the highest antioxidant activity (IC₅₀ = 64.37 and 32.86 µg/ml, respectively) among the tested compounds (IC₅₀ value of positive control was 5.34 µg/ml). Compound 7 exhibited potent PTP1B enzymatic inhibition with an IC₅₀ value of 7.73 μg/ml (IC₅₀ value of positive control is 1.46 µg/ml). Furthermore, compound 5 showed strong antibacterial activity against the Gram-positive bacterium, S. aureus.