Prorobinetidin
Introduction '''Prorobinetidins''' are a type of condensed tannins formed from robinetinidol. They form robinetinidin when depolymerized under oxidative conditions. ''Mimosa'' and quebracho tannins are, according to a comparative 13C NMR study of polyflavonoids, found to be predominantly profisetinidin/prorobinetidin-type tannins. ''Stryphnodendron adstringens'' ( the barbatimão), a species of legume found in Brazil, produces prorobinetinidins in its stem bark. These are robinetinidol-(4β → 8)-epigallocatechin, robinetinidol-(4α → 8)-epigallocatechin, robinetinidol-(4β → 8)-epigallocatechin 3-O-gallate, robinetinidol-(4α → 8)-epigallocatechin 3-O-gallate, robinetinidol-(4α → 6)-gallocatechin and robinetinidol-(4α → 6)-epigallocatechin, in addition to the tentatively characterized, robinetinidol 4β → 6(8)-gallocatechin and robinetinidol-(4α → 8)-gallocatechin.
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