Flavonoids in Citrus and Related Genera

Part II. Isolation and Identification of Isonaringin and Neoeriocitrin from Citrus

抄録

Chemical structure of isonaringin (I), originally isolated from C. pseudogulgul and C. tengu, was studied. Permethylation of I followed by acid hydrolysis yielded 2, 3, 4-tri-O-methyl L-rhamnose and 2, 3, 4-tri-O-methyl D-glucose which were identified by comparing with authentic specimens by paper and thin-layer chromatographies. Partial methylation of I with dimethyl sulfate afforded didymin (II), 7-rutinoside of isosakuranetin, which could further be dehydrogenated to linarin (V), 7-rutinoside of acacetin. II and V were identified by mp, mixed mp, UV, IR, and comparison with authentic specimens, respectively. Thus I was proved to be identical with narirutin, 7-rutinoside of naringenin. Isolation of I from many species of citrus was also carried out. Neoeriocitrin, 7-neohes-peridoside of eriodictyol, was isolated from two Japanese miscellaneous varieties of citrus and a poncirus hybrid. The structure was assigned by degradative, spectral and thin-layer chromatographic evidences.