Secondary metabolites from Scabiosa atropurpurea and their antioxidant and xanthine oxidase inhibitory activities

Two secoiridoid glycosides, lonicejaposide I (1) and secologanin dimethyl acetal (2), six flavonoids, isoorientin (3) hesperidin (4), apigenin 7-O-neohesperidoside (5), luteolin 7-O-b-D-glucopyranoside (6), kaempferol 3O-(3",6"-di-(E)-p-coumaroyl)-b-D-glucopyranoside (7), and kaempferol 3 -O -(3'' -O -acetyl, 6"-O-(E)-p-coumaroyl)-b-D- glycopyranoside (8), two caffeoylquinic acid derivatives, chlorogenic acid (9) and 3,5-dicaffeoylquinic acid (10) were isolated from the EtOAc and H2O subextracts of the crude MeOH extract prepared from the aerial parts of Scabiosa atropurpurea. Their structures were identified by extensive 1D and 2D NMR experiments as well as ESI-MS analysis. Xanthine oxidase (XO) inhibitory and antioxidant activities of the isolated compounds were evaluated by in vitro tests. Compounds, 3, 5, 6, 9 and 10 showed mild -to -moderate inhibitory effects on XO enzyme. The highest antioxidant activity was found for compound 10 according to results of DPPH, FRAP and CUPRAC assays. This is the first study on the XO inhibitory activities for compounds 1, 2, 5, 7 and 8.