Changes in the intestinal absorption mechanism of icariin in the nanocavities of cyclodextrins.
Icariin is a bioactive herbal ingredient isolated from Herba epimedii, which has been widely used for the treatment of osteoporosis and male sexual dysfunction in traditional Chinese medicine. The major objective of this work is to investigate the different enhancing effects of β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) on the intestinal absorption of icariin, and to identify the molecular mechanisms of this action. Host-guest-type interactions of icariin with cyclodextrins nanocavities were unambiguously demonstrated by the phase-solubility diagram, ultraviolet spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffractometry, and two dimensional proton nuclear magnetic resonance rotating-frame Overhauser effect spectroscopy. These results were further supported using molecular modeling studies. The rat single-pass intestinal perfusion model showed that the absorption of icariin was affected by P-glycoprotein (Pgp). The icariin/HP-β-CD inclusion complex provided greater enhancement in the intestinal absorption than the icariin/β-CD inclusion complex. Therefore, the enhancing effect was involved in a solubilizing effect and/or Pgp inhibitory effect. Finally, fluorescence anisotropy measurements and Pgp adenosine triphosphatase (ATPase) assay demonstrated that β-CD exhibited no effect on Pgp, while HP-β-CD showed inhibition by restraining the Pgp ATPase activity rather than changing the fluidity of cell membrane.
Tianjin State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.
Ye
Y
Zhang
Qiang-Song
QS
Wang
Yuan-Lu
YL
Cui
Fan-Cui
FC
Meng
Ke-Ming
KM
Lin
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors; D000704:Analysis of Variance; D000818:Animals; D002152:Calorimetry, Differential Scanning; D004347:Drug Interactions; D005419:Flavonoids / Q000737:chemistry* / Q000493:pharmacokinetics*; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility; D013057:Spectrum Analysis; D047392:beta-Cyclodextrins / Q000737:chemistry / Q000494:pharmacology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D005419:Flavonoids; D047392:beta-Cyclodextrins; C056599:icariin