Phytochemistry p. 109 - 120 (1996)
Update date:2022-09-26
Topics:
Hoer, Michaela
Heinrich, Michael
Rimpler, Horst
Bioassay-guided fractionation of a crude extract of Guazuma ulmifolia bark led to the isolation of polymeric proanthocyanidins which inactivated cholera toxin (CT).The average degree of polymerization (DP) of the active compounds ranged from 14.4 to 32.0.The polymers consisted mainly of (-)-epicatechin units.In polymers of a representative fraction, the flavanol units were connected by <4 -> 8> bonds and, less frequently, by <4 -> 6> bonds.Inhibition of CT by tannins increased with Mr and conformation flexibility of the tannin molecule.Several known procyanidin oligomers were also isolated. 1H NMR shift rules to distinguish between <4 -> 8> and <4 -> 6> linked proanthocyanidin peracetates, that have been proposed for dimers, were extended to trimers and a tetramer.A further diagnostic shift parameter to determine the interflavanoid bonding position is presented and the conformation of oligomeric proanthocyanidin peracetates is discussed. - Key Word Index: Guazuma ulmifolia; Sterculiaceae; bark; proanthocyanidins; tannins; polymers; gel permeation chromatography; NMR; thiolytic degradation; (-)-epicatechin; peracetates; antisecretory activity.
View Moresuzhou chukai pharmateach co,.ltd
Contact:86-512-88812511
Address:Building 3, Wujiang Scientific Innovation Park, 2358 Changan Rd, Wujiang 215200, Jiangsu Province, P. R. China
website:http://www.shtopchem.com/
Contact:0086-0576-87776998
Address:room no 1608,xuhui business building yude road,xujiahui street, xuhui district
Changzhou Ruiping Chemical Co., Ltd
website:http://www.wishchem.com
Contact:+86-519-82324280
Address:No.288-1 Huacheng Road, Jintan
Shanghai Forever Synthesis Co.,Ltd.
Contact:021-61124658
Address:Zhoukang Road,Pudong New District,Shanghai,China
Shanghai Send Pharmaceutical Technology Co., Ltd.
website:http://www.shsendpharma.com
Contact:021-58088081, +8613585868794
Address::Room A601, Building 1,NO. 800 Qingdai Road Pudong District Shanghai,China
Doi:10.1039/a607308e
(1997)Doi:10.1080/00397911.2012.680569
(2013)Doi:10.1021/jo00152a039
(1983)Doi:10.1248/cpb.40.770
(1992)Doi:10.1021/ol047594l
(2005)Doi:10.1016/j.tetasy.2004.11.027
(2005)