Transepithelial taurine transport in caco-2 cell monolayers.

Here we characterized transepithelial taurine transport in monolayers of cultured human intestinal Caco-2 cells by analyzing kinetic apical and basolateral uptake and efflux parameters. Basolateral uptake was Na(+)- and Cl(-)- dependent and was inhibited by beta-amino acids. Uptake by this membrane showed properties similar to those of the apical TauT system. In both membranes, taurine uptake fitted a model consisting of a non-saturable plus a saturable component, with a higher half-saturation constant and transport capacity at the apical membrane (K(m), 17.1 micromol/L; V(max), 28.4 pmol.cm(-2).5 min(-1)) than in the basolateral domain (K(m), 9.46 micromol/L; V(max), 5.59 pmol.cm(-2).5 min(-1)). The non-saturable influx component, estimated in the absence of Na(+) and Cl(-), showed no significant differences between apical and basolateral membranes (K(D), 89.2 and 114.7 nL.cm(-2) . 5 min(-1), respectively). Taurine efflux from the cells is a diffusive process, as shown in experiments using preloaded cells and in trans-stimulation studies (apical K(D),72.7 and basolateral K(D), 50.1 nL.cm(-2).5 min(-1)). Basolateral efflux rates were significantly lower than passive influx rates. We conclude that basolateral taurine uptake in Caco-2 cells is mediated by a transport mechanism that shares some properties with the apical system TauT. Moreover, calculation of unidirectional and transepithelial taurine fluxes reveals that apical influx of this amino acid is higher than basolateral efflux rates, thereby enabling epithelial cells to accumulate taurine against a concentration gradient.

Resveratrol and piceid levels in natural and blended peanut butters.

Peanut and its derivatives, especially peanut butter, are extensively consumed in many countries, mainly in the United States, which is also the major exporter of these products. trans-Resveratrol is present in peanuts, and recently this compound has been quantified in peanut butter. It is well-known that there are beneficial effects of trans-resveratrol and its glucoside, the piceid, in health. The absorption of trans-resveratrol has been proven in animals, and certain studies show that the absorption of some phenols is enhanced by conjugation with glucose, so that it could be possible that trans-piceid would be more absorbed than its aglycon (trans-resveratrol). In our work, we have identified the presence of trans-piceid in peanut butter with a new method to quantify trans-resveratrol and trans-piceid (3-beta-glucose of trans-resveratrol). This fact is very interesting because the glucosilated form could be more easily absorbed by the intestinal gut; in this way trans-piceid would exercise its beneficial function more efficiently than trans-resveratrol. To our knowledge, this is the first time that trans-piceid has been quantified in peanut butter. Resveratrol and piceid contents in natural peanut butters were found to be significantly higher than those in blended peanut butters.