LAUSR

Abstract Five flavonoid glycosides were isolated from the aerial parts of Ornithopus compressus L., yellow serradella (Fabaceae). The structures of the isolated natural products were determined as kaempferol 3-O-(2,6-di-O-β-D-glucopyranosyl)-β-D-galactopyranoside (1), kaempferol 3-O-β-D-glucopyranosyl-(1→6)-[2-O-(2E)-feruloyl-β-glucopyranosyl]-(1→2)-β-D-galactopyranoside (2), quercetin 3-O-(2,6-di-O-β-D-glucopyranosyl)-β-D-galactopyranoside (3), quercetin 3-O-β-D-glucopyranosyl-(1→6)-[2-O-(2E)-feruloyl-β-glucopyranosyl]-(1→2)-β-D-galactopyranoside (4), and isorhamnetin 3-O-(2,6-di-O-β-D-glucopyranosyl)-β-D-galactopyranoside (5). While compounds 1 and 3 have been described previously, compounds 2, 4 and 5 represent formerly undescribed natural products. For structure elucidation UV, HRMS, and NMR (1H NMR, 13C NMR, H,H-COSY, HMBC, and HSQC) were employed. Absolute sugar configurations were confirmed using GLC–MS/MS after hydrolysis, octylation, and acetylation of the isolated compounds. Additionally, DPPH radical and ABTS radical cation scavenging activities as well as cytotoxic activities of the isolated compounds were assessed.