N-acyl amino acids as a new class of permeability enhancers: in vitro study on Caco-2 cells.

N-acyl amino acids are attractive anionic surfactant molecules. They are made up of an amino acid as polar head chemically linked via an amide bond to a linear fatty acid (Bordes et al, 2015). These surfactants, especially glutamate derivates, have been several times proposed in cosmetics as promising detergents and foaming agents. Generally, they are referred as “mild surfactants” because less irritant and commonly considered safer than sulfates, the most used anionic surfactants e.g. sodium dodecyl sulphate (SDS). Anionic surfactants are also commonly employed in several pharmaceutical formulations and SDS is still the most used anionic surfactant despite its not favorable toxicological profile. N-acyl amino acid surfactants could represent an alternative option to SDS. However, most of the potentialities of such surfactants as pharmaceutical excipients remained unexplored. Several studies have demonstrated the effect of SDS as permeability enhancer for the oral route using Caco-2 cell monolayer (Deli M.A, 2009; Anderberg E.K., 1993). However, its use has surely been limited by toxicity concerns. The aim of this work was to investigate the cell viability profiles (MTS assay) on Caco-2 cell of N-acyl surfactants derived from alanine and serine, in comparison to SDS. Moreover, their ability to modulate transepithelial electrical resistance (TEER) and affect the permeability of fluorescein isothiocyanate (FITC) labeled dextran as model drug across Caco-2 cell monolayer was evaluated at non-toxic concentrations (100% of cell viability) as determined by MTS assay.