Prenylflavonol, acylated flavonol glycosides and related compounds from Epimedium sagittatum

Chemical examination of the n-BuOH extract from the aerial parts of Epimedium sagittatum led to isolation of three prenylated flavonol glycosides sagittasine A-C, two acylated flavonol glycosides kaempferol-3-O-(2 ''-E-p-coumaroyl,4 ''-Z-p-coumaroyl)-alpha-L-rhamnopyranoside and kaempferol-3-O-(3 ''-Z-p-coumaroyl,4 ''-E-alpha-coumaroyl)-alpha-L-rhamnopyranoside, together with known flavonoids, flavonolignans, 2-phenoxychromones, a lignan, and aromatic acid derivatives. Flavonolignans were identified for the first time in this plant. The vasorelaxing properties of the n-BuOH extract of E. sagittatum and 13 isolated compounds were tested using pre-contracted rat aorta rings in an organ bath apparatus. The results indicated that the n-BuOH extract of E sagittatum produced a partial endothelial nitric oxide-dependent vasorelaxation, with EC50 of 0.16 +/- 0.03 mg/ml. However, the 13 compounds tested, generated only a mild or moderate relaxation, and did not possess significant vasorelaxing effect individually. (C) 2007 Elsevier Ltd. All rights reserved.