Binding of the hop (Humulus lupulus L.) chalcone xanthohumol to cytosolic proteins in Caco-2 intestinal epithelial cells.

Abstract

Used in the brewing of beer, hops (Humulus lupulus L.) contain the prenylated chalcone xanthohumol, which is under investigation as a cancer chemoprevention agent and as a precursor for the estrogenic flavanones isoxanthohumol and 8-prenylnaringenin. The uptake, transport and accumulation of xanthohumol were studied using the human intestinal epithelial cell line Caco-2 to help understand the poor bioavailability of this chalcone. Studies were carried out using Caco-2 cell monolayers 18-21 days after seeding. The apparent K(m) and V(max) values of xanthohumol accumulation in Caco-2 cells were determined, and the protein binding of xanthohumol in sub-cellular fractions of Caco-2 cells was investigated. Approximately 70% of xanthohumol added to the apical side of Caco-2 cells accumulated inside the cells, while 93% of the intracellular xanthohumol was localized in the cytosol. Xanthohumol accumulation was temperature dependent and saturable with an apparent K(m )value of 26.5 +/- 4.66 muM and an apparent V(max) of 0.215 +/- 0.018 nmol/mg protein/min. Facilitated transport was not responsible for the uptake of xanthohumol, instead, accumulation inside the Caco-2 cells was apparently the result of specific binding to cytosolic proteins. These data suggest that specific binding of xanthohumol to cytosolic proteins in intestinal epithelial cells contributes to the poor oral bioavailability observed previously in vivo.

• Authors: Yan Pang, Dejan Nikolic, Dongwei Zhu, Lucas R Chadwick, Guido F Pauli, Norman R Farnsworth, Richard B van Breemen
• Journal: Molecular nutrition & food research (Mol Nutr Food Res) Vol. 51 Issue 7 Pg. 872-9 (Jul 2007) ISSN: 1613-4125 [Print] Germany
• PMID: 17579893 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Flavonoids
• Propiophenones
• Proteins
• xanthohumol

Topics

• Biological Availability
• Caco-2 Cells
• Cell Membrane Permeability
• Cytosol (chemistry)
• Flavonoids
• Humans
• Humulus (chemistry)
• Intestinal Absorption
• Intestinal Mucosa (ultrastructure)
• Intestines (ultrastructure)
• Propiophenones (metabolism, pharmacokinetics)
• Proteins (metabolism)