Structural Elements Which Govern the Resistance of Intestinal Tissues to Compound Transport

Abstract
The series of cyclized RGD peptides in this study demonstrated a very low partition into octanol as judged by HPLC. Thus, these molecules are likely to move predominantly through the paracellular pathway. Permeability across Caco-2 monolayers was determined using reversed phase HPLC and found to be restricted by molecular weight and possibly charge-charge interactions between the solute and charged moieties within the paracellular shunt. When normalized for molecular weight, molecules with a net charge between -1 and -2 demonstrated the highest permeabilities, which suggests an optimal net charge with respect to permeability.