PROCYANIDIN POLYMERS OF DOUGLAS FIR BARK: STRUCTURE FROM DEGRADATION WITH PHLOROGLUCINOL

Article abstract of DOI:10.1016/0031-9422(89)80303-6

Reaction of the condensed tannin polymers of Douglas fir inner bark with phloroglucinol yielded catechin, epicatechin, procyanidin B-2, catechin-(4α->2)-phloroglucinol, epicatechin-(4β->2)-phloroglucinol, the novel compound epicatechin-(4α->2)-phloroglucinol and 1,3-di-(2,4,6-trihydroxyphenyl)-1-(3,4-di-hydroxyphenyl)-propan-2-ol.Also isolated were epicatechin-(4β->8)-epicatechin-(4β->2)-phloroglucinol, epicatechin-(4β->6)-epicatechin-(4β->2)-phloroglucinol, and three other novel phloroglucinol adducts, catechin-(4α->8)-epicatechin-(4β->2)-phloroglucinol, epicatechin-(4β->8)-epicatechin-(4β->8)-epicatechin-(4β->2)-phloroglucinol and epicatechin-(4β->6)-epicatechin-(4β->8)-epicatechin-(4β->2)-phloroglucinol.The results suggest that the configuration of the extender units is almost exclusively 2,3-cis, while the terminal units are mixed, with 2,3-cis slightly predominating.The C-4 to C-8 interflavonoid linkage predominates over the C-4 to C-6 linkage by a 4:1 ratio. Key Word Index Pseudotsuga menziesii; Pinaceae; Douglas fir; procyanidin; degradation; phloroglucinol-adducts.