Xanthohumol, a hop-derived prenylated flavonoid, promotes macrophage reverse cholesterol transport.

Xanthohumol, a prominent prenyl flavonoid from the hop plant (Humulus lupulus L.), is suggested to be antiatherogenic since it reportedly increases high-density lipoprotein (HDL) cholesterol levels. It is not clear whether xanthohumol promotes reverse cholesterol transport (RCT), the most important antiatherogenic property of HDL; therefore, we investigated the effects of xanthohumol on macrophage-to-feces RCT using a hamster model as a CETP-expressing species. In vivo RCT experiments showed that xanthohumol significantly increased fecal appearance of the tracer derived from intraperitoneally injected [3H]-cholesterol-labeled macrophages. Ex vivo experiments were then employed to investigate the detailed mechanism by which xanthohumol enhanced RCT. Cholesterol efflux capacity from macrophages was 1.5-fold higher in xanthohumol-fed hamsters compared with the control group. In addition, protein expression and lecithin-cholesterol acyltransferase activity in the HDL fraction were significantly higher in xanthohumol-fed hamsters compared with the control, suggesting that xanthohumol promoted HDL maturation. Hepatic transcript analysis revealed that xanthohumol increased mRNA expression of abcg8 and cyp7a1. In addition, protein expressions of liver X receptor α and bile pump export protein were increased in the liver by xanthohumol administration when compared with the control, implying that it stimulated bile acid synthesis and cholesterol excretion to feces. In conclusion, our data demonstrate that xanthohumol improves RCT in vivo through cholesterol efflux from macrophages and excretion to feces, leading to antiatherosclerosis effects. It remains to be elucidated whether enhancement of RCT by xanthohumol could prove valuable in humans.

Rational identification of a novel soy-derived anxiolytic-like undecapeptide acting via gut-brain axis after oral administration.

Here we found that the chymotryptic digest of soy ß-conglycinin, a major storage protein, exhibited anxiolytic-like effects in mice. We then searched for anxiolytic-like peptides in the digest. Based on a comprehensive peptide analysis of the chymotryptic digest by high performance liquid chromatograph connected to an LTQ Orbitrap mass spectrometer and the structure-activity relationship of known peptides, we explored anxiolytic-like peptides present in the digest. FLSSTEAQQSY, which corresponds to 323-333 of the ß-conglycinin α subunit [ßCGα(323-333)] emerged as a candidate. Oral administration of synthetic ßCGα(323-333) exhibited anxiolytic-like effects in the elevated plus-maze and open-field test in male mice. Orally administered ßCGα(323-333) exhibited anxiolytic-like effects in sham-operated control mice but not in vagotomized mice. In addition, oral administration of ßCGα(323-333) increased the expression of c-Fos, a marker of neuronal activity, in the nucleus of the solitary tract, which receives inputs from the vagus nerve. These results suggest that the anxiolytic-like effects were mediated by the vagus nerve. The anxiolytic-like effects of ßCGα(323-333) were also blocked by antagonists of the serotonin 5-HT1A, dopamine D1 and GABAA receptors. However ßCGα(323-333) had no affinity for these receptors, suggesting it stimulates the release of endogenous neurotransmitters to activate the receptors. Taken together, a soy-derived undecapeptide, ßCGα(323-333), may exhibit anxiolytic-like effects after oral administration via the vagus nerve and 5-HT1A, D1 and GABAA systems.

Aromatic amino acid-leucine dipeptides exhibit anxiolytic-like activity in young mice.

We previously reported that Tyr-Leu (YL) exhibits potent anxiolytic-like activity comparable to diazepam in mice. In the current study, we revealed that aromatic amino acid-Leu, Phe-Leu and Trp-Leu (FL and WL, respectively), exhibited anxiolytic-like activity in the elevated plus-maze and open-field tests. FL and WL were orally active. Retro-sequence peptides of FL and WL were inactive. Similarly to YL, the anxiolytic-like activities of FL and WL were inhibited by WAY100135, SCH-23390 and bicuculline, antagonists of serotonin 5-HT1A, dopamine D1 and GABAA receptors, respectively, implying that FL and WL activate a common anxiolytic pathway to that of YL. Taken together, aromatic amino acid-Leu dipeptides such as YL, FL, and WL may exhibit anxiolytic-like activity in a manner dependent on the activation of 5-HT1A, D1 and GABAA receptors.