title: Intestinal formation of trans-crocetin from saffron extract (Crocus sativus L.) and in vitro permeation through intestinal and blood brain barrier.
abstract: OBJECTIVE
  Extracts of saffron (Crocus sativus L.) have traditionally been used against depressions. Recent preclinical and clinical investigations have rationalized this traditional use. Trans-crocetin, a saffron metabolite originating from the crocin apocarotenoids, has been shown to exert strong NMDA receptor affinity and is thought to be responsible for the CNS activity of saffron. Pharmacokinetic properties of the main constituents from saffron have only been described to a limited extent. Therefore the present in vitro study aimed to determine if crocin-1 and trans-crocetin are able to pass the intestinal barrier and to penetrate the blood brain barrier (BBB). Additionally, the intestinal conversion of glycosylated crocins to the lipophilic crocetin had to be investigated. Experiments with Caco-2 cells and two different porcine BBB systems were conducted. Further on, potential intestinal metabolism of saffron extract was investigated by ex vivo experiments with murine intestine.
  
  
  METHODS
  In vitro Caco-2 monolayer cell culture was used for investigation of intestinal permeation of crocin-1 and trans-crocetin. In vitro models of porcine brain capillary endothelial cells (BCEC) and blood cerebrospinal fluid barrier (BCSFB) were used for monitoring permeation characteristics of trans-crocetin through the blood brain barrier (BBB). Intestine tissue and feces homogenates from mice served for metabolism experiments.
  
  
  RESULTS
  Crocin-1, even at high concentrations (1000 µM) does not penetrate Caco-2 monolayers in relevant amounts. In contrast, trans-crocetin permeates in a concentration-independent manner (10-114 µM) the intestinal barrier by transcellular passage with about 32% of the substrate being transported within 2 h and a permeation coefficient of Papp 25.7 × 10(-)(6) ± 6.23 × 10(-)(6) cm/s. Trans-crocetin serves as substrate for pGP efflux pump. Trans-crocetin permeates BBB with a slow but constant velocity over a 29 h period (BCEC system: Papp 1.48 × 10(-)(6) ± 0.12 × 10(-)(6) cm/s; BCSFB system Papp 3.85 × 10(-)(6) ± 0.21 × 10(-)(6) cm/s). Conversion of glycosylated crocins from saffron extract to trans-crocetin occurs mainly by intestinal cells, rather than by microbiological fermentation in the colon.
  
  
  CONCLUSIONS
  The here described in vitro studies have shown that crocins from saffron are probably not bioavailable in the systemic compartment after oral application. On the other side the investigations clearly have pointed out that crocins get hydrolyzed in the intestine to the deglycosylated trans-crocetin, which subsequently is absorbed by passive transcellular diffusion to a high extend and within a short time interval over the intestinal barrier. Crocetin will penetrate in a quite slow process the blood brain barrier to reach the CNS. The intestinal deglycosylation of different crocins in the intestine is mainly due to enzymatic processes in the epithelial cells and only to a very minor extent due to deglycosylation by the fecal microbiome. On the other side the fecal bacteria degrade the apocarotenoid backbone to smaller alkyl units, which do not show any more the typical UV absorbance of crocins. As previous studies have shown strong NMDA receptor affinity and channel opening activity of trans-crocetin the use of saffron for CNS disorders seems to be justified from the pharmacokinetic and pharmacodynamic background.
authors: University of Münster, Institute for Pharmaceutical Biology and Phytochemistry, Corrensstraße 48, D-48149 Münster, Germany.
authors: M
authors: M
authors: Lautenschläger
authors: University of Münster, Institute for Pharmaceutical Biology and Phytochemistry, Corrensstraße 48, D-48149 Münster, Germany.
authors: J
authors: J
authors: Sendker
authors: University of Münster, Institute for Biochemistry, Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany.
authors: S
authors: S
authors: Hüwel
authors: University of Münster, Institute for Biochemistry, Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany.
authors: H J
authors: HJ
authors: Galla
authors: University of Münster, Institute for Pharmaceutical Biology and Phytochemistry, Corrensstraße 48, D-48149 Münster, Germany.
authors: S
authors: S
authors: Brandt
authors: University of Münster, Institute for Pharmaceutical and Medical Chemistry, Department of Pharmacology, Corrensstraße 48, D-48149 Münster, Germany.
authors: M
authors: M
authors: Düfer
authors: Center for Nanotechnology/Institute of Physics, Heisenbergstraße 11, D-48149 Münster, Germany.
authors: K
authors: K
authors: Riehemann
authors: University of Münster, Institute for Pharmaceutical Biology and Phytochemistry, Corrensstraße 48, D-48149 Münster, Germany. Electronic address: ahensel@uni-muenster.de.
authors: A
authors: A
authors: Hensel
mesh_terms: D000818:Animals; D001682:Biological Availability; D001692:Biological Transport; D001812:Blood-Brain Barrier / Q000187:drug effects*; D018938:Caco-2 Cells; D002338:Carotenoids / Q000493:pharmacokinetics*; D027622:Crocus / Q000737:chemistry*; D006031:Glycosylation; D006801:Humans; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010936:Plant Extracts / Q000737:chemistry*; D013552:Swine; D014801:Vitamin A / Q000031:analogs & derivatives
chemical_list: D010936:Plant Extracts; C487773:trans-sodium crocetinate; D014801:Vitamin A; D002338:Carotenoids; C029036:crocin
keywords: Absorption; Blood brain barrier; Caco-2; Crocetin; Crocus sativus L.; Metabolism