title: Tannins and related compounds. LXXXIV. Isolation and characterization of five new hydrolyzable tannins from the bark of Mallotus japonicus.
abstract: 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-beta-D-glucose and 1-O-digalloyl-3,6-(R)-hexahydroxydiphenoyl-beta-D-glucose, respectively, while compounds 18 (mallojaponin) and 19 (mallonin) were shown to be 1-O-galloyl-2,4-elaeocarpusinoyl-3,6-(R)-valoneayl-bet a-D-glucose and 1-O-galloyl-2,4-elaeocarpusinoyl-beta-D-glucose. Compound 20 (mallotusinin) was characterized as a novel ellagitannin which possesses a unique 1,1'-(3,3',4,4'-tetrahydroxy)dibenzofurandicarboxyl group. On the other hand, examination of the leaves revealed the presence of hydrolyzable tannins (8-10, 12-15) all containing a beta-D-glucopyranose core with 1C4-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-13C shift correlation spectral analysis and chemical correlations.
authors.forename: R
authors.initials: R
authors.lastname: Saijo
authors.forename: G
authors.initials: G
authors.lastname: Nonaka
authors.forename: I
authors.initials: I
authors.lastname: Nishioka
mesh_terms: D000897:Anti-Ulcer Agents / Q000032:analysis / Q000302:isolation & purification*; D007564:Japan; D010946:Plants, Medicinal / Q000032:analysis*; D013634:Tannins / Q000032:analysis / Q000302:isolation & purification*
chemical_list: D000897:Anti-Ulcer Agents; D013634:Tannins