Pitfalls in cell culture work with xanthohumol.

Xanthohumol, the most abundant prenylated chalcone in hop (Humulus lupulus L.) cones, is well known to exert several promising pharmacological activities in vitro and in vivo. Among these, the chemopreventive, anti-inflammatory and anti-cancer effects are probably the most interesting. As xanthohumol is hardly soluble in water and able to undergo conversion to isoxanthohumol we determined several handling characteristics for cell culture work with this compound. Recovery experiments revealed that working with xanthohumol under cell culture conditions requires a minimal amount of 10% FCS to increase its solubility to reasonable concentrations (-50-75 micromol/l) for pharmacological in vitro tests. Additionally, more than 50% of xanthohumol can be absorbed to various plastic materials routinely used in the cell culture using FCS concentrations below 10%. In contrast, experiments using fluorescence microscopy in living cells revealed that detection of cellular intake of xanthohumol is hampered by concentrations above 1% FCS.