Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
In vitro digestion/Caco-2 cell model for assessing dietary folate bioavailability
Humans are dependent on folate uptake from exogenous sources through intestinal absorption. Plant-based foods appear to be the richest source of folate. Pinto bean (Phaseolus vulgaris L.), was chosen for this study because of its abundance in Nebraska and is a commonly consumed dry bean. In vitro digestion coupled to the Caco-2 cell culture model was used to assess and evaluate the permeability of dietary 5-methyltetrahydrofolate (5–methyl–THF) from pinto beans. Two models were used to estimate absorption of 5-methyl-THF: folate-depleted and folate-sufficient cell monolayers. Confluence and integrity of Caco-2 cell monolayers grown on inserts were validated with the use of transepithelial electrical resistance measurements and red phenol exclusion assay. In vitro digestion method was applied to estimate the bioaccessible 5-methyl-THF from pinto beans. The bean extract was applied to the apical side of Caco-2 cell monolayers. Samples were collected in a solution, containing 2% (v/v) ascorbic acid. The differentiated Caco-2 cell monolayers grown on inserts were treated with increasing concentrations of: 5-methyl-THF (190 μM); 5-methyl-THF+2.5%, v/v legume extract (193 μM); 5-methyl-THF+5%, v/v legume extract (202 μM); 2.5%, v/v legume extract (4 μM); or 5%, v/v legume extract (7 μM) for 80 min at 37°C without agitation. Transport experiments were performed under “sink” conditions. The permeability coefficients were determined in the apical-to-basolateral direction. 5-methyl-THF was transported across the intestinal mucosa with permeability coefficients of 1.03–1.79×10–5 cm/s in folate-depleted and with permeability coefficients of 0.99–1.32×10 –5 cm/s in folate-sufficient cell monolayers. The cumulative fractions of transported 5-methyl-THF increased linearly for both folate-depleted and folate-sufficient cell monolayers. The results of these studies demonstrate that 5-methyl-THF is bioaccessible from pinto bean extract and taken up by the intestinal Caco-2 cells. The experimental conditions were established for the use of in vitro digestion/Caco-2 cell culture model to assess intestinal absorption of 5–methyl–THF from pinto beans. The in vitro digestion method mimics the in vivo digestion process and provides an estimation of bioavailable 5-methyl-THF from pinto beans, which mimics the human gastrointestinal physiology.^
Health Sciences, Nutrition
Yarbaeva, Shakhlo N, "In vitro digestion/Caco-2 cell model for assessing dietary folate bioavailability" (2009). ETD collection for University of Nebraska - Lincoln. AAI3386607.