Secoiridoids, flavonoids and caffeoylquinic acid derivatives from the aerial parts of Scabiosa atropurpurea L

Abstract

The genus Scabiosa (Caprifoliaceae) comprises approximately 100 species worldwide, mainly distributed in the Mediterranean region. Some of these species have long been used in different folk medicines for the treatment of various disorders, particularly against bacterial and viral infections [1]. S. atropurpurea is used to treat measles and furuncles in Catalonia while its infusion is indicated as an anti-acne agent in the Iberian Peninsula [1], [2]. The extracts of this species were reported to possess in vitro antimicrobial and antioxidant activities [2]. The genus Scabiosa is represented by 36 taxa in the flora of Turkey [3]. Previous phytochemical studies showed the presence of iridoid glycosides and flavonoids in S. atropurpurea [1]. The aim of this study is to isolate and identify the secondary metabolites from the aerial parts of S. atropurpurea growing wild in Turkey. The plant material was extracted with MeOH. Successive chromatographic studies on the MeOH extract afforded 10 secondary metabolites including two secoiridoid glycosides, lonicejaposide I (1) and secologanin dimethyl acetal (2), six flavonoids, isoorientin (3) hesperidin (4), rhoifolin (5), luteolin 7-O-β-D-glucopyranoside (6), kaempferol 3-O-(3′′,6′′-di-(E)-p-coumaroyl)-β-D-glucopyranoside (7), and kaempferol 3-O-(3′′-O-Acetyl, 6′′-O-(E)-p-coumaroyl)-β-D-glycopyranoside (8), two caffeoylquinic acid derivatives, chlorogenic acid (9) and 3,5-dicaffeoylquinic acid (10). The chemical structures of the isolates were determined based on extensive 1D and 2D NMR experiments as well as ESI-MS analysis. Compounds 1, 2, 4 and 7 are being reported for the first time from the genus Scabiosa.