Tannins and Related Compounds. LXXXIV. : Isolation and Characterization of Five New Hydrolyzable Tannins from the Bark of Mallotus japonicus

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A chemical examination of the bark of Mallotus japonicus (THUNB.) MUELLER-ARG. (Euphorbiaceae) has led to the isolation of five new hydrolyzable tannins (16-20), together with fourteen known tannins (1-14). On the basis of chemical and spectroscopic evidence, the structures of compounds 16 and 17 were established as 1,2-di-O-galloyl -3,6-(R)-hexahydroxydiphenoyl-β-D-glucose and 1-O-digalloyl-3,6-(R)-hexahydroxydiphenoyl-β-D-glucose, respectively, while compounds 18 (mallojaponin) and 19 (mallonin) were shown to be 1-O-galloy-2,4-elaeocarpusinoyl-3,6-(R)-valoneayl-β-D-glucose and 1-O-galloyl-2,4-elaeocarpusinoyl-β-D-glucose. Compound 20 (mallotusinin) was characterized as a novel ellagitannin which possesses a unique 1,1'-(3,3', 4,4'-tetrahydroxy)dibenzofurandicarbozyl group. On the other hand, examination of the leaves revealed the presence of hydrolyxable tannins (8-10,12-15) all containing a β-D-glucopyranose core with ^1C_4-conformation. Furthermore, the orientation of the valoneayl group in mallotinic acid (13) and mallotusinic acid (14), which had remained unclarified, was determined on the basis of ^1H-^<13>C shift correlation spectral analysis and chemical correlations.
公益社団法人日本薬学会の論文
1989-08-25

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