82801-34-1Relevant academic research and scientific papers
Procyanidins from the herb of Hypericum perforatum
Ploss,Petereit,Nahrstedt
, p. 509 - 511 (2007/10/03)
From the aqueous acetone extract of the herb of Hypericum perforatum the flavanols catechin (1) and epicatechin (2), and the procyanidins A2 (9), B1 (3), B2 (4), B3 (5), B5 (6), B7 (7) and C1 (8) were isolated. Their structures were established as their peracetate derivatives, on the basis of chemical and spectral evidence. The 13CNMR spectrum of the higher molecular weight polymer fraction revealed a 3′,4′-dihydroxylated B-ring oxidation pattern and the 2,3-cis relative stereochemistry of the constituent flavan-3-ol units. The mean average molecular size of the polymers was estimated to be 4 to 5 flavan-3-ol units. The procyanidin pattern in comparison to that of Crataegus spec. is briefly discussed.
Linkage Isomerism in Trimeric and Polymeric 2,3-cis-Procyanidins
Hemingway, Richard W.,Foo, Lai Yeap,Porter, Lawrence J.
, p. 1209 - 1216 (2007/10/02)
Four procyanidin trimers have been isolated and their structures unequivocally established as: epicatechin-(4β->8)-epicatechin-(4β->8)-catechin (5); epicatechin-(4β->6)-epicatechin-(4β->8)catechin (6); epicatechin-(4β->8)-epicatechin-(4β->6)-catechin (7); and epicatechin-(4β->8)-epicatechin-(4β->8)-epicatechin (13).The presence of the first three trimers in Pinus taeda phloem, and the isolation of both epicatechin-(4β->8)-4β-benzylepicatechin (9) and epicatechin-(4β->6)-4β-benzylthioepicatechin (10) from partial acid-catalyzed cleavage of the tannins from Pinus palustris phloem and Photinia glabrescens leaves, shows that linkage isomerism exists in natural oligomeric and polymeric procyanidins.A new system of nomenclature for proanthocyanidins is proposed.
