Enantioseparation of isoxanthohumol in beer by hydroxypropyl-gamma-cyclodextrin-modified micellar electrokinetic chromatography

The Potent Phytoestrogen 8-Prenylnaringenin: A Friend or a Foe?

8-prenylnaringenin (8-PN) is a prenylated flavonoid, occurring, in particular, in hop, but also in other plants. It has proven to be one of the most potent phytoestrogens in vitro known to date, and in the past 20 years, research has unveiled new effects triggered by it in biological systems. These findings have aroused the hopes, expectations, and enthusiasm of a “wonder-drug” for a host of human diseases. However, the majority of 8-PN effects require such high concentrations that they cannot be reached by normal dietary exposure, only pharmacologically; thus, adverse impacts may also emerge. Here, we provide a comprehensive and up-to-date review on this fascinating compound, with special reference to the range of beneficial and untoward health consequences that may ensue from exposure to it.

Triggering of dendritic cell apoptosis by xanthohumol

Xanthohumol, a flavonoid from beer with anticancer activity is known to trigger apoptosis in a variety of tumor cells. Xanthohumol further has anti-inflammatory activity. However, little is known about the effect of xanthohumol on survival and function of immune cells. The present study thus addressed the effect of xanthohumol on dendritic cells (DCs), key players in the regulation of innate and adaptive immunity. To this end, mouse bone marrow-derived DCs were treated with xanthohumol with subsequent assessment of enzymatic activity of acid sphingomyelinase (Asm), ceramide formation determined with anti-ceramide antibodies in FACS and immunohistochemical analysis, caspase activity utilizing FITC conjugated anti-active caspase 8 or caspase 3 antibodies in FACS and by Western blotting, DNA fragmentation by determining the percentage of cells in the sub-G1 phase and cell membrane scrambling by annexin V binding in FACS analysis. As a result, xanthohumol stimulated Asm, enhanced ceramide formation, activated caspases 8 and 3, triggered DNA fragmentation and led to cell membrane scrambling, all effects virtually absent in DCs from gene targeted mice lacking functional Asm or in wild-type cells treated with sphingomyelinase inhibitor amitriptyline. In conclusion, xanthohumol stimulated Asm leading to caspase activation and apoptosis of bone marrow-derived DCs.

Inhibition of suicidal erythrocyte death by xanthohumol

Xanthohumol is a proapoptotic hop-derived beer component with anticancer and antimicrobial activities. Similar to nucleated cells, erythrocytes may undergo suicidal cell death or eryptosis, which is triggered by oxidative stress (tert-butylhydroperoxide, TBOOH) or energy depletion (removal of glucose). The triggers increase cytosolic Ca(2+) concentration, leading to activation of Ca(2+)-sensitive K(+) channels with subsequent cell shrinkage and to cell membrane scrambling with subsequent phosphatidylserine exposure at the erythrocyte surface. Eryptotic cells are cleared from the circulating blood, leading to anemia, and may adhere to the vascular wall, thus impeding microcirculation. The present experiments explored whether xanthohumol influences eryptosis using flow cytometry. Exposure of human erythrocytes to 0.3 mM TBOOH or incubation in glucose-free solution significantly increased Fluo3 fluorescence (Ca(2+) concentration) as well as annexin V-binding (cell membrane scrambling) and decreased forward scatter (cell volume), effects significantly blunted by xanthohumol. In conclusion, xanthohumol is a potent inhibitor of suicidal erythrocyte death in vitro.