Medicinal Flowers. XXVI. Structures of Acylated Oleanane-Type Triterpene Oligoglycosides, Yuchasaponins A, B, C, and D, from the Flower Buds of Camellia oleifera—Gastroprotective, Aldose Reductase Inhibitory, and Radical Scavenging Effects—

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The methanolic extract and its 1-butanol-soluble fraction from the flower buds of Camellia oleifera ABEL were found to exhibit inhibitory effects on ethanol- and indomethacin-induced gastric mucosal lesions in rats. The ethyl acetate- and 1-butanol-soluble fractions also showed inhibitory effects on rat lens aldose reductase and scavenging effects on 1,1-diphenylpicryl-2-hydrazyl radical and superoxide. From the 1-butanol-soluble fraction, four new acylated oleanane-type triterpene oligoglycosides, yuchasaponins A, B, C, and D, were isolated and their structures were elucidated on the basis of chemical and physicochemical evidence. On the other hand, quercetin 3-O-α-L-rhamnopyranoside and kaempferol 3-O-α-L-rhamnopyranoside were isolated from the ethyl acetate- and 1-butanol-soluble fractions as the principal constituents, and their gastroprotective effects were examined.