Structure and Hypotensive Effect of Flavonoid Glycosides in Kinkan (Fortunella japonica) Peelings

Abstract

An attempt was made to isolate the hypotensive substances from a hot water extract of kinkan. Eight flavonoid glycosides were isolated by repeated chromatography and by gel filtration after extracting with n-butanol and treating with lead subacetate. Their structures were established to be 6, 8-di-C-glucosylapigenin (1), 3, 6-di-C-glucosylacacetin (2), 2''-O-α-L-rhamnosyl-4'-O-methylvitexin (3), 2''-O-α-L-rhamnosyl-4'-O-methylisovitexin (4), 2''-O-α-L-rhamnosylvitexin (5), 2''-O-α-L-rhamnosylorientin (6), 2''-O-α-L-rhamnosyl-4'-O-methylorientm (7) and ponicilin (8) by UV. MS, ¹H-NMR and ¹³C-NMR spectroscopy, and by sugar analysis. Each component was intravenously injected in SHR-SP (0.5-1.0mg/100g of body weight), 1, 2, 5 and 6 were found to lower the rat blood pressure.
Among these compounds, 2, 3, 4, 6 and 7 were new flavone glycosides.