Six A-type proanthocyanidins were isolated from the water-soluble fraction of peanut skins. On the basis of spectral data, reductive cleavage with sodium cyanoborohydride, and chiral HPLC analysis, three new compounds, epicatechin-(2 beta-->O-->7, 4 beta --> 6)-catechin, epicatechin-(2 beta --> O --> 7, 4 beta --> 6)-ent-catechin and epicatechin-(2 beta --> O --> 7, 4 beta --> 6)-ent-epicatechin were unambiguously identified, together with the three known compounds, psoanthocyanidin A-1, proanthocyanidin A-2 and epicatechin-(2 beta-->O-->7, 4 beta-->8)-ent-epicatechin. (13)C NMR chemical shift rules to distinguish between [2-->O-->7, 4-->8] and [2-->O -->7,4-->6] double-linked heptamethyl ethers of A-type proanthocyanidins are proposed. Bioassay experiments showed that these six compounds possess substantial activity against hyaluronidase. (C) 1999 Elsevier Science Ltd. All rights reserved.
Nonaka, Gen-Ichiro; Morimoto, Satoshi; Kinjo, Jun-Ei, Chemical and pharmaceutical bulletin, 1987, vol. 35, # 1, p. 149 - 155
Oligomeric flavanoids. Part 25. Cleavage of the acetal functionality in A-type proanthocyanidins
作者:Petrus J. Steynberg、Annemarie Cronjé、Jan P. Steynberg、Barend C.B. Bezuidenhoudt、E.Vincent Brandt、Daneel Ferreira
DOI:10.1016/s0040-4020(96)01149-0
日期:1997.2
and A-2 2 are subject to facile cleavage of the acetal functionality with sodium cyanoboranuide in trifluoroacetic acid at 0°C. This straight forward chemical method permits the unambiguous establishment of the absolute configuration of the DEF-flavanyl unit and the D-ring carbon and oxygen atoms that are involved in the double linkage of the A-class proanthocyanidins.