Transport of Cranberry A-type Procyanidin Dimers, Trimers, and Tetramers across Monolayers of Human Intestinal Epithelial Caco-2 Cells.
A-type procyanidin oligomers in cranberries are known to inhibit the adhesion of uropathogenic bacteria. B-type procyanidins dimers and trimers are absorbed by humans. The absorption of A-type procyanidins from cranberries in humans has not been demonstrated. This study examined the transport of A-type cranberry procyanidin dimers, trimers, and tetramers on differentiated human intestinal
epithelial Caco-2 cell monolayers. Procyanidins were extracted from cranberries and purified using hromatographic methods. Fraction I contained predominantly A-type procyanidin dimer A2 [epicatechin-(2-O-7, 4-8)-epicatechin]. Fraction II contained primarily A-type trimers and tetramers, with B-type trimers, A-type
pentamers, and A-type hexamers being minor components. Fraction I or II in solution were added onto the apical side of the Caco-2 cell membranes. The media at the basolateral side of the membranes were analyzed using HPLC-MSn after 2 h. Data indicated that procyanidin dimer A2 in fraction I and A-type trimers and tetramers in fraction II traversed across Caco-2 cell monolayers with transport ratio of 0.6%, 0.4%, and 0.2%, respectively. This study demonstrated A-type dimers, trimers, and tetramers were transported across Caco-2 cells at low rates, suggesting they could be absorbed by humans after cranberry consumption.