BIOLOGICAL AND CHEMICAL INVESTIGATION OF DRAGONS BLOOD FROM CROTON SPECIES OF SOUTH-AMERICA .1. POLYPHENOLIC COMPOUNDS FROM CROTON-LECHLERI

The blood-red sap of Croton lechleri was found to contain proanthocyanidins as major constituents which accounted for up to 90% of the dried weight. In addition to (+)-catechin, (-)-epicatechin, (+)-gallocatechin, (-)-epigallocatechin and dimeric procyanidins B-1 and B-4, five novel dimers and trimers were isolated and characterized as catechin-(4-alpha-->8)-epigallocatechin, gallocatechin-(4-alpha-->8)-epicatechin, gallocatechin-(4-alpha-->6)-epigallocatechin, catechin-(4-alpha-->8)-gallocatechin-(4-alpha-->8)-gallocatechin and gallocatechin-(4-alpha-->8)-gallocatechin-(4-alpha-->8)-epigallocatechin. Higher oligomers were also obtained. A new procedure combining chemical degradation with H-1 NMR spectroscopy has been developed for determination of the composition and molecular size of oligomeric/polymeric proanthocyanidins. The oligomers of the sap were shown to have the mean degree of polymerization of 4,5-6 and 6-7, respectively, and M(r) up to 2130. The heterogeneity of the oligomers was clearly indicated by the presence of a variety of flavan-3-ols as extension and terminal units. An exceptionally high content of gallocatechin and epigallocatechin in the oligomers was observed.