Structure Identification: |
Agricultural & Biological Chemistry, 1986, 50(8):2061-2067. | Isolation and structures of procyanidins (condensed tannins) from Rhaphiolepis umbellata.[Reference: WebLink] | METHODS AND RESULTS:
Two new procyanidin trimers (1, 3) and one tetramer (2) were isolated in their free phenolic forms from the bark of Rhaphiolepis umbellata, which is used as the dyeing agent for Oshima Tsumugi. On the basis of 1H- and 13C-NMR spectral examinations and the results of partially acidcatalyzed degradation, 1, 2 and 3 were characterized as epicatechin-(4β→8)-epicatechin-(4β→6)-epicatechin, epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin-(4β→6)-epicatechin andcatechin(4α→6)-epicatechin-(4β→8)-epicatechin, respectively. In addition, the occurrence of the known compounds, i.e., (-)-epicatechin (4), procyanidins B-l (9), B-2 (5), B-5 (6) and C-l (7), proanthocyanidin A-2 (10), cinnamtannin A1 (8) and Cinnamtannin A2 (14), cinchonains la (11) and lib (12), and (-)-catechin 7-O-β-D-glucopyranoside (13) in the bark of Rhaphiolepis umbellata was confirmed. |
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