A phytochemical investigation of Diplotaxis virgata D.C. and D. erucoides (L.) D.C. (Brassicaceae) offered to the isolation of two new flavonoids isorhamnetin-3-O-α-l-glucopyranoside (1) and rhamnetin-3,3'-di-O-β-d-glucopyranoside (2), respectively. Their structures have been elucidated from the extended spectroscopic methods, including 1D- and 2D-NMR, UV and mass spectrometry analysis and by comparison with literature data. The fatty acid composition of the hexane extracts of the two species was also investigated by using GC-MS. The antioxidant activity of ethanol, ethyl acetate, n-butanol extracts and the isolated compounds from the two species was evaluated using DPPH and ABTS⁺ scavenging assays. All the tested samples showed an efficient radical scavenging ability, with IC50 values ranging from 16-40 µg/mL for the DPPH and from 17-44 µg/mL for the ABTS⁺ assays. In addition, the antibacterial activity of the prepared extracts and compounds 1 and 2, determined by well diffusion agar method against two Gram positive and five Gram negative bacteria, was evaluated and the results showed significant effects against all strains used.
Keywords: D. erucoides; D. virgata; NMR; antimicrobial activity; antioxidant activity; fatty acids; flavonoids.