Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
Tannins and Related Compounds. CXXIV. Five New Ellagitannins, Platycaryanins A, B, C, and D, and Platycariin, and a New Complex Tannin, Strobilanin, from the Fruits and Bark of Platycarya strobilacea SIEB et ZUCC., and Biomimetic Synthesis of C-Glycosidic Ellagitannins from Glucopyranose-Based Ellagitannins
Takashi TANAKAShinji KIRIHARAGen-ichiro NONAKAItsuo NISHIOKA
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1993 Volume 41 Issue 10 Pages 1708-1716

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Abstract

Five new ellagitannins, platycaryanins A (27), B (26), C (30), and D (25), and platycariin (31), and a new complex tannin, strobilanin (32), have been isolated from the fruits and bark of Platycarya strobilacea SIEB. et ZUCC. (Juglandaceae), together with twenty-six known compounds. On the basis of spectroscopic and chemical evidence, platycaryanins A, B and C, and platycariin have been characterized as the ellagitannins having a tergalloyl ester group, while platycaryanin D was found to be an unusual ellagitannin possessing (R)-hexahydroxydiphenoyl esters at the glucopyranose 2, 3- and 4, 6-positions. During these chemical studies, re-examination of the similar ellagitannins, alnusnins A and B, which were previously reported from Alnus sieboldiana, led us to revise their structures to 29 and 28, respectively, in which the tergalloyl group forms a lactone ring. Furthermore, biomimetic conversion of ellagitannins having a glucopyranose core into C-glycosidic ellagitannins was successfully achieved for the first time, and the reaction was applied to the structure elucidation of platycariin (31).

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