Assessment of verbascoside absorption in human colonic tissues using the Ussing chamber model

The intestinal absorption of verbascoside (VB), a phenylpropanoid glycoside, extracted and purified from olive mill waste water (OMWW), was investigated using viable and healthy human colonic tissues, mounted in an Ussing chamber. Additionally, VB absorption and transport through the intestinal mucosa were quantified using permeability coefficients. VB absorption was time-dependent and varied in relation to the specific colonic segments considered. In particular, major uptake/absorption (0.50 mu g/cm(2)) occurred between 5 and 15 min in the proximal tract of the colon, followed by descending colon (0.38 mu g/cm(2)) between 30 and 60 min, and sigmoid-rectum colon (0.34 mu g/cm(2)) at 60 min. Overall, VB was absorbed rapidly, with an average uptake of 0.29 mu g VB per cm(2), corresponding to a total accumulation efficiency of similar to 0.12%. Moreover, the presence of the VB in the basolateral side supported the hypothesis of its bioavailability in the extent of 0.1%. In addition, the permeability coefficient calculation has contributed in a deeper understanding of VB absorption and transport across the human intestinal barrier and could be utilized for other polyphenols present in food and in dietary supplements. (C) 2013 Elsevier Ltd. All rights reserved.