5-Deoxyflavan-3-ol-based proanthocyanidins with antinutritional and antimicrobial properties from the forage legume Acaciella angustissima

The proanthocyanidins of Acaciella angustissima (Mill.) Britton & Rose foliage have antinutritional and antimicrobial effects as proanthocyanidin- containing extracts reduced intake and weight gain of weanling rats when added to conventional diets and caused changes in fecal bacterial diversity and metabolic activity. Purified fractions of A. angustissima were shown to be more inhibitory to rat fecal bacteria than Schinopsis spp. (quebracho) proanthocyanidin extracts. In this study, it was determined that A. angustissima proanthocyanidins consist largely of 5-deoxyflavan- 3-ols and proanthocyanidin dimers through hexamers, based on guibourtinidol, fisetinidol, and robinetinidol, with a predominance of fisetinidol units. These are accompanied by smaller amounts of higher oligomers (heptamers-decamers) and deoxyflavan-3-ols, dimers and trimers containing a p-hydroxybenzoate ester moiety.