50562-99-7Relevant academic research and scientific papers
DIMERIC AND TRIMERIC PROANTHOCYANIDINS POSSESSING A DOUBLY LINKED STRUCTURE FROM PAVETTA OWARIENSIS
Balde, A. M.,Pieters, L. A.,Wray, V.,Kolodziej, H.,Berghe, D. A. Vanden,et al.
, p. 4129 - 4136 (1991)
Pavetannin A-2, a new A-type proanthocyanidin, along with the trimers cinnamtannin B-1, pavetannin B-1, B-2, B-3, B-5 and B-6 have been isolated in their free phenolic form from the stem bark of Pavetta owariensis.Spectral data and partial acid-catalysed degradation established their structures as ent-epicatechin-(4α->8,2α->O->7)-catechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4α->8)-epicatechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4β->8)-ent-epicatechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4β->8)-epicatechin, epicatechin-(4β->6,2β->O->7)-epicatechin-(4β->8)-epicatechin, epicatechin-(4β->6,2β->O->7)-catechin-(4β->8)-epicatechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4α->8)-catechin, respectively. Key Word Index - Pavetta owariensis; Rubiaceae; stem bark; proanthocyanidins; doubly linked structures; dimer; trimer; thiolytic degradation.
Polyphenols from peanut skins and their free radical-scavenging effects
Lou, Hongxiang,Yuan, Huiqing,Ma, Bin,Ren, Dongmei,Ji, Mei,Oka, Syuichi
, p. 2391 - 2399 (2007/10/03)
Separation of the water-soluble fraction of peanut skins led to the isolation of five proanthocyanidins. Based on the spectroscopic investigation and partial acid catalyzed degradation, their structures were determined to be epicatechin-(2β→O→7, 4β→6)-[epicatechin- (4β→8)]-catechin (1), epicatechin-(2β→O→7, 4β→8) epicatechin-(4β→8)-catechin-(4β→8)- epicatechin (2), and procyanidins B2 (3), B3 (4) and B4 (5). The absolute configuration of the new compounds was determined from their circular dichroism curves and the 1H NMR spectra of analysis of flavan-3-ols formed by thiolytic degradation of 1 and 2 in the presence of a chiral dirhodium complex (dirhodium tetra-(R)-(trifluoromethyl) phenyl acetate).
Studies on the constituents of bark of Parameria laevigata Moldenke
Kamiya,Watanabe,Endang,Umar,Satake
, p. 551 - 557 (2007/10/03)
One new trimeric proanthocyanidin, epicatechin-(2β→O→7,4β→6)-epicatechin- (2β→O→7, 4β→8)epicatechin (5) and two new tetrameric proanthocyanidins, epicatechin-(2β→O→7, 4β→8)-[epicatechin-(4β6)]epicatechin-(4β→8)- epicatechin, named as parameritannin A-1 (6), and epicatechin-(2β→O→5, 4β→6)[epicatechin-(2β→O→7, 4β→8)]-epicatechin-(4β→8)-epicatechin, named as parameritannin A-2 (7), have been isolated from the bark of Parameria laevigata Moldenke (Apocynaceae) along with the two known dimers, proanthocyanidin A-2 (1) and proanthocyanidin A-6 (2), and two dimers, cinnamtannin B-1 (3) and aesculitannin B (4). These structures were elucidated by spectral and chemical evidence.
Tannins and Related Compounds. LX. Isolation and Characterization of Proanthocyanidins with a Doubly-Linked Unit from Vaccinium vitis-idaea L.
Morimoto, Satoshi,Nonaka, Gen-Ichiro,Nishioka, Itsuo
, p. 33 - 38 (2007/10/02)
New proanthocyanidin trimers (14 and 15) and tetramers (16 and 17) have been isolated from the whole body of Vaccinium vitis-idaea L. (Ericaceae).The structures of these proanthocyanidins were established by thiolytic degradation and by analyses of the proton and carbon-13 nuclear magnetic resonance spectra.In addition, the presence of (-)-epicatechin (1), (+)-catechin (2), (-)-epigallocatechin (3), (+)-gallocatechin (4), procyanidins B-1 (5), B-3 (6), A-1 (8) and A-2 (9), and cinnamtannins B1 (10), D1 (11), B2 (12) and D2 (13) in this plant was demonstrared.Keywords - Vaccinium vitis-idaea; Ericaceae; doubly-bonded proanthocyanidin; procyanidin; condensed tannin; flavan-3-ol; thiolytic degradation
Tannins and Related Compounds. LIX. Aesculitannins, Novel Proanthocyanidins with Doubly-Bonded Structures from Aesculus hippocastanum L.
Morimoto, Satoshi,Nonaka, Gen-ichiro,Nishioka, Itsuo
, p. 4717 - 4729 (2007/10/02)
A chemical examination of the seed shells of Aesculus hyppocastanum L.has led to the isolation of proanthocyanidins A-6 (10) and A-7 (11), and aesculitannins A (12), B (13), C (14), D (15), E (16), F (17) and G (18).On the basis of chemical and spectroscopic evidence, proanthocyanidins A-6 (10) and A-7 (11) have been determined to be A-type dimers each possessing a C-4, C-6 interflavanoid linkage, while aesculitannins A (12), B (13), C (14), D (15), E (16), F (17) and G (18) have been characterized as oligomeric proanthocyanidins possessing A-type unit(s) in each molecule.In addition, the presence of (-)-epicatechin (1), proanthocyanidins B-5 (3), A-2 (4), A-4 (5) and C-1 (6), epicatechin-(4β->6)-epicatechin-(4β->6)-epicatechin (7), and cinnamtannins B1 (8) and B2 (9) was also demonstrated Keywords---Aesculus hippocastanum; Hippocastanaceae; aesculitannin; doubly-bonded proanthocyanidin; procyanidin; condensed tannin; flavan-3-ol; thiolytic degradation; epimerization; hydrogen peroxide oxidation
Tannins and Related Compounds. Part 13. Isolation and Structures of Trimeric, Tetrameric, and Pentameric Proanthicyanidins from Cinnamon
Nonaka, Gen-ichiro,Morimoto, Satoshi,Nishioka, Itsuo
, p. 2139 - 2145 (2007/10/02)
A proanthocyanidin trimer, two tetramers, and a pentamer have been isolated in their free phenolic forms from cinnamon, the bark of Cinnamomum zeylanicum (Lauraceae).Partial acid-catalysed degradation of these tannins with phenylmethanethiol, in conjunction with 1H- and 13C-n.m.r. analysis, has unequivocally established their structures as epicatechin-(4β->8, 2β->7)epicatechin-(4α->8)-epicatechin (5); epicatechin-(4β->8)epicatechin-(4β->8, 2β->7)-epicatechin-(4α->8)-epicatechin (6); epicatechin-(4β->6)-epicatechin-(4β->8, 2β->7)-epicatechin-(4α->8)-epicatechin (7); and epicatechin-(4β->8)-epicatechin-(4β->8)epicatechin-(4β->8, 2β->7)-epicatechin-(4α->8)-epicatechin (8).
