Tannins and Related Compounds. CXVII. Isolation and Characterization of Three New Ellagitannins, Lagerstannins A, B and C, Having a Gluconic Acid Core, from Lagerstroemia speciosa (L.) PERS

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Lagerstannins A (6), B (11) and C (8), ellagitannins having a gluconic acid core, have been isolated from the fruits and leaves of Lagerstroemia speciosa (L.) PERS. (=L. flos-reginae RETZ.)(Lythraceae). On the basis of chemical and spectroscopic evidence, their structures were established as 2, 3;4, 6-bis-O-(S)-hexahydroxydiphenoyl-D-gluconic acid (6), 2, 3, 5-O-(S, R)-flavogallonyl-4, 6-O-(S)-hexahydroxydiphenoyl-D-gluconic acid (11), and 5-O-galloyl-4, 6-O-(S)-hexahydroxydiphenoyl-D-gluconic acid (8), respectively. Furthermore, the structure of an ellagitannin, punigluconin, previously isolated from the bark of Punica granatum L., was revised as 2, 5-di-O-galloyl-4, 6-O-(S)-hexahydroxy-diphenoyl-D-gluconic acid (10), based on spectral re-examination.