The bitter taste of beer originates from resins in hops (Humulus lupulus L.), which are classified into two subtypes (soft and hard). Whereas the nature and reactivity of soft-resin-derived ...compounds, such as α-, β-, and iso-α-acids, are well studied, there is only a little information on the compounds in hard resin. For this work, hard resin was prepared from stored hops and investigated for its compositional changes in an experimental model of beer aging. The hard resin contained a series of α-acid oxides. Among them, 4′-hydroxyallohumulinones were unstable under beer storage conditions, and their transformation induced primary compositional changes of the hard resin during beer aging. The chemical structures of the products, including novel polycyclic compounds scorpiohumulinols A and B and dicyclohumulinols A and B, were determined by HRMS and NMR analyses. These compounds were proposed to be produced via proton-catalyzed cyclization reactions of 4′-hydroxyallohumulinones. Furthermore, they were more stable than their precursor 4′-hydroxyallohumulinones during prolonged storage periods.
The bitter acids in hops (Humulus lupulus L.) and beer, such as α-, β-, and iso-α-acids, are known to affect beer quality and display various physiological effects. However, these compounds readily ...oxidize, and the effect of the oxides on the properties of beer or their potential health benefits are not well understood. In this study, we developed a simple preparative method for the bitter acid oxide fraction derived from hops and designated the constituents as matured hop bitter acids (MHBA). HPLC-PDA-ESI/HRMS and MS(2) revealed that MHBA are primarily composed of α-acid-derived oxides, which possess a common β-tricarbonyl moiety in their structures similar to α-, β-, and iso-α-acids. We also developed a quantitative analytical method of whole MHBA by HPLC, which showed high precision and reproducibility. Using our newly developed method, the concentration of whole MHBA in several commercial beers was evaluated. Our results will promote the study of bitter acid oxides.
Roasted barley extract (RBE, “Mugicha”) is a traditional Japanese beverage reported to improve blood viscosity and affect food functionality. RBE is suggested to contain 2,5-diketopiperazines, which ...are the functional component with neuroprotective and immunostimulatory effects that are produced in food through roasting. In this study, we investigated the effects of RBE on blood circulation, both clinically and in rats. At first, we confirmed five 2,5-diketopiperazine derivatives in RBE by LC-MS analysis. Secondarily, we revealed that RBE affects blood flow in the rat tail and compared the efficacy on rat tail blood flow among five 2,5-diketopiperazines in RBE. Especially, cyclo(d-Phe-l-Pro) was the most effective in increasing blood flow in the rat tail. We also researched the mechanism of cyclo(d-Phe-l-Pro) with rat aorta study. As a result, we confirmed that cyclo(d-Phe-l-Pro) has an effect on vasodilatation through the release of nitric oxide in the vascular endothelium. Finally, we also confirmed that RBE affects cutaneous blood flow and increases skin temperature in humans.
Roasted barley extract (RBE) is a traditional Japanese beverage. Previously, we reported the effects of RBE containing cyclo( d -Phe- l -Pro) on blood flow in animals and humans and investigated ...rapid skin temperature recovery from cold-water immersion in women. The present randomized, double-blind study investigated the effects of RBE containing cyclo( d -Phe- l -Pro) on men’s and women’s skin temperature in excessively air-cooled conditions. Participants felt cold in the test room (25.5±0.5ºC). They ingested an RBE or placebo beverage and remained in the air-conditioned room for 100 min. Skin temperature of the left foot was measured every 5 min using infrared thermography. We evaluated effect of RBE administration by paired t-test. The skin temperature of the RBE group remained higher than that of the placebo group. The skin temperature changes 100 min after RBE or placebo ingestion were −3.67±1.14ºC and −4.59±0.89ºC, respectively in all participants. We also did subclass analysis focusing on men or women. In a previous study, RBE efficacy for skin temperature in men was not clearly demonstrated. RBE consumption was also effective not only in female participants but also in male participants. The skin temperature changes 100 min after RBE or placebo ingestion were −3.65±0.64ºC and −4.55±0.32ºC, respectively in male participants. Therefore, RBE containing cyclo( d -Phe- l -Pro) prevented skin temperature decreases in excessively air-cooled conditions in both men and women.
Extracts of Jatoba, a South American herb, when injected i.p. into a mouse model of experimental autoimmune encephalomyelitis (EAE), inhibited the aggravation of clinical symptoms. At the same time, ...production of myelin oligodendrocyte glycoprotein Ag-specific IFN-gamma and TNF-alpha by spleen cells was markedly suppressed. After administration of Jatoba there was minimal evidence of the demyelination that is characteristic of the EAE model. Decreases in clinical scores were observed when Jatoba extracts were injected just before Ag. The purified active compounds are likely to be polyphenols that are absorbable to polyvinylpolypyrrolidone. The active compounds were polymerized polyphenol polymers (procyanidins) and at least five degrees of polymerization were necessary for activity. In addition, extracts of other plant materials containing such procyanidins had similar activity. After administration of highly polymerized procyanidins, there was a decrease in both dendritic and CD4(+) T cells. Although macrophages were increased in number, the expression of CD80 and MHC class II molecules was depressed indicating that the macrophages were immature. The results indicate that the suppression of development of EAE by the highly polymerized procyanidins resulted from an inhibition of Th1 and the effects might be associated with depression of Ag-presenting capability.
Procyanidin oligomers with different degrees of polymerization (up to nonamers) were efficiently purified from the bark of Jatoba (Hymenaea courbaril) by using a recently developed chromatographic ...separation method. Purification relied on a hydrogen bonding interaction between phenolic hydroxyl groups of the procyanidins and polyethylene glycol (PEG)-coated resin in a packed column. The individual procyanidins were identified by using electrospray ionization mass spectrometry (ESI-MS) and verified by a thiolytic degradation analysis. Our results demonstrate that Jatoba bark contained a large amount of procyanidins from monomer to nonamers or higher polymers composed of only B-type linked units (flavan-3-ol units linked through C-4 to C-8 (or C-6)) of epicatechin (EC) without gallate esters.
α-Acids and β-acids, two main components of hop resin, are known to be susceptible to oxygen and degraded during hop storage, although the oxidation products in stored hops have not been fully ...identified. In this study, we developed a high-performance liquid chromatography (HPLC) analysis method suitable for separation and quantification of the oxidation products. This HPLC analysis clearly proved, for the first time, that humulinones and hulupones are major products in oxidized hops. We are also the first to identify novel 4′-hydroxy-allohumulinones, suggested to be oxidative products of humulinones, by means of NMR spectroscopy and high-resolution mass spectrometry. Using the developed analytical method, changes in α- and β-acids and their oxidation products during hop storage were clearly revealed for the first time.
The cytokine thrombopoietin (TPO), the ligand for the hematopoietic receptor c-Mpl, acts as a primary regulator of megakaryocytopoiesis and platelet production. We have determined the crystal ...structure of the receptor-binding domain of human TPO ( hTPO163) to a 2.5-Å resolution by complexation with a neutralizing Fab fragment. The backbone structure of hTPO163has an antiparallel four-helix bundle fold. The neutralizing Fab mainly recognizes the C-D crossover loop containing the species invariant residue Q111. Titration calorimetric experiments show that hTPO163interacts with soluble c-Mpl containing the extracellular cytokine receptor homology domains with 1:2 stoichiometry with the binding constants of 3.3× 109M-1and 1.1× 106M-1. The presence of the neutralizing Fab did not inhibit binding of hTPO163to soluble c-Mpl fragments, but the lower-affinity binding disappeared. Together with prior genetic data, these define the structure-function relationships in TPO and the activation scheme of c-Mpl.
The resins from hops (Humulus lupulus L.), which add the bitter taste to beer, are classified into two main sub-fractions, namely, soft and hard resins. α- and β-Acids in soft resin and their ...transformation during the wort boiling process are well-studied; however, other constituents in resins, especially hard resin, have been unidentified. In this study, we identified humulinones and hulupones as soft-resin components, in addition to 4′-hydroxyallohumulinones and tricyclooxyisohumulones A and B as hard-resin components. These compounds are all oxidation products derived from α- or β-acids. We also investigated compositional changes in the hard resin during the wort boiling process, which has a significant effect on the taste of the beer, by using model boiling experiments. The major changes were identified to be isomerization of 4′-hydroxyallohumulinones into 4′-hydroxyallo-cis-humulinones, followed by decomposition into cis-oxyhumulinic acids. These findings will be helpful in systematically evaluating and optimizing the effect of the hard resin on beer quality.
The transformation of α-acids in hops (Humulus lupulus L.) to iso-α-acids (in beer) during the brewing process is well known, but the occurrence and structure of the oxidized α-acids during hop ...storage are not well documented. Because an understanding of these oxidized compounds is essential to optimize the effects of oxidized hops on the quality of beer, we investigated the autoxidation products of humulone (a representative congener of α-acids) using a simplified autoxidation model. Among the oxidation products, tricyclooxyisohumulones A (1) and B (2), tricycloperoxyisohumulone A (3), deisopropyltricycloisohumulone (4), and the hemiacetal 5 of tricycloperoxyhumulone A (5′) were isolated, and their structures were elucidated for the first time. The occurrence of compounds 1–4 in stored hops was verified using LC/MS/MS analysis. We also monitored the levels of compounds 1–4 during hop storage using LC/MS/MS analysis.
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