Cai Y et. al. (1991) “”Biological and Chemical Investigations of Dragon’s Blood from Croton Species of South America” Part 1. Polyphenolic compounds from C. lecheri.” Phytochemistry 30(6), 2033-40.
Abstract: 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
→8)-
epigallocatechin, gallocatechin-(4
→8)-epicatechin,
gallocatechin-(4
→6)-epigallocatechin,
catechin-(4
→8)-
gallocatechin-(4
→8)-gallocatechin
and gallocatechin-(4
→8)-gallocatechin-(4
→8)-epigallocatechin.
Higher oligomers were also obtained. A new procedure combining chemical
degradation with 1H 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 Mr 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.