Structure and hypotensive effect of flavonoid glycosides in lemon peelings. Part II.

Abstract

An attempt was made to isolate hypotensive substances from hot water extracts of lemon peels. Eight flavonoid glycosides were isolated by repeated chromatography after extraction with butanol and treated with lead subacetate. Their structures were established by UV, MS, 1H-NMR and 13C-NMR spectroscopy, and sugar analysis to be : 6, 8-di-C-glucosyldiosmetin (8), 6-C-glucosyldiosmetin (9), 8-C-glucosyldiosmetin (10), isovitexine (11), apigenin 7-[6-O-α-rhamnosyl-β-glucose] (12), limocitrin 3-0-{[3-hydroxy-3-methylglutarate(1→2)]-β-glucose} (13), limocitrin 3-0-{[5-α-glucosyl-3-hydroxy-3-methylglutarate(1→2)]-β-glucose} (14) and limocitrol 3-O-{[5-α-glucosyl-3-hydroxy-3-methylglutarate(1→2)]-β-glucose} (15). Each component was intravenously injected into SHR-SP rats (1.0mg/100g body weight), and 8 was found to lower blood pressure. Among these compounds, 13, 14 and 15 were new flavonol glycosides.