• nanoparticle (NP);
  • β-sitosterol β-d-glucoside (Sit-G);
  • endocytosis;
  • in situ loop;
  • intestinal absorption;
  • transepithelial resistance (TEER)


Nanoparticles (NP) are potential carriers for drug delivery to the targeted intestine. NP based on β-sitosterol β-D-glucoside (Sit-G) enhanced the colon-specific absorption of FITC–dextran 4,400 (FD-4), because the concentration-dependent increase of bioavailability appeared in only the colon. In a permeation study, the absorption enhancement in the colon was suppressed in the following conditions: (1) the addition of Sit-G NP to serosa; (2) a permeation study at 4°C; (3) the addition of endocytosis inhibitor, cytochalasin B. NP based on sitosterol, the aglycon of Sit-G, did not increase the FD-4 colonic permeation. The addition of Sit-G NP to the mucosal side induced a decrease of transepithelial resistance (TEER), but this phenomenon was suppressed by an inhibitor of Na+-dependent specific glucose transporter, phrolidzin, which did not affect FD-4 permeation. These findings suggested that absorption enhancement by Sit-G NP may not be due to opening of a tight junction, but might be related to endocytosis via glucose residue of Sit-G. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:311–318, 2003