The origin of the wood and bark polyphenols of Eucalyptus species

Abstract

Ellagitannins are the major monomeric components in the cambium of Eucalyptus astringens and E. marginata. Flavans are the most important components of the extractives of the bark of the former and the heartwood of the latter. Also, the composition of the extractives of the sapwood and the heartwood of E. astringens are different from each other and from the above-mentioned tissues. It is concluded that polyphenols are formed in situ probably from carbohydrate. A flavan present in E. astringens bark and E. marginata heartwood has the expected chromatographic properties and color reactions of leucodelphinidin but does not yield delphinidin when heated with acid. The major stilbenes in the bark of E. astringens appear to be the previously unreported cis-trans isomers of a glucoside of 3,5,3'',4'',5''-pentahydroxystilbene. The aglucone of these stilbenes appears to be present in the heartwood of this species.