Page - (000322) - in Biomedical Chemistry: Current Trends and Developments

a The results are expressed as mean ± SD. b Papp = apparent permeability coefficient. c a–b = apical to basolateral. d b–a = basolateral to apical. A Papp value below 0.2 × 10-6 cm s-1 indicates low permeability, a Papp value ranging from 0.2 × 10-6 cm s-1 to 1.6 × 10-6 cm s-1 indicates moderate permeability and a Papp value above 1.6 × 10-6 cm s-1 indicates high permeability, in this particular setting (Bergström, 2003). The permeability in the a–b direction increased substantially for all the methylated analogs (ranging from 0.3 × 10-6 cm s-1 to 20 × 10-6 cm s-1) compared to H-Phe-Phe-NH2 (26, 0.02 × 10-6 cm s-1). All the compounds,