Objective:

Laurate is a medium-chain fatty acid which is an ingredient of a variety of nutrients including milk and coconut oil, and which currently is discussed for pharmaceutically applications as an absorption enhancer in intestine, as e.g. chitosan and caprate. However, information on laurate effects on intestinal epithelial cells is scarce.

Methods:

Confluent monolayers of HT-29/B6 human colon cells were grown on permeable supports, and mounted in Ussing-type chambers. Transepithelial resistance and apparent permeability for paracellular flux markers were measured using standard techniques. Two-path impedance spectroscopy was employed to differentiate between transcellular (R^trans) and paracellular resistance (R^para), and tight junction proteins were analyzed by Western blotting and confocal laser-scanning microscopy.

Results:

3.5 mM Na⁺-laurate resulted in a strong and reversible decrease of transepithelial resistance to 50% of initial values, which was identified to be based on a marked drop in R^para. In contrast, permeability for 4 kDa FITC-dextran was not increased. In accordance with these results, tricellulin, a barrier former of tricellular cell contacts, was unchanged regardíng expression or distribution. However, a slightly higher laurate concentration (4.5 mM) resulted in a generally fractured pattern of the tight junction architecture, and LDH assays indicated adverse effects on cell viability.

Conclusion:

Within the non-toxic concentration range, laurate induces specific opening of the paracellular pathway for ions but not for potential drug molecules. Therefore, in comparison to other compounds such as caprate and chitosan, clinical applicability appears to be rather limited in context with development of novel drug delivery strategies.