啤酒花的萃取

本文综述了使用啤酒花萃取物的优点以及啤酒花的超临界二氧化碳萃取和液态二氧化碳萃取的特点。     

Monoprenylierte acylphloroglucine

The incorporation of labeled precursors into hop bitter compounds is presented and a scheme for the biosynthesis of these substances via 1-acyl-3-prenyl phloroglucinols is proposed.     

新疆啤酒花新品种阜北—1的成分分析比较

分析了新疆阜北农场培育的啤酒花新品种阜北－１的主要化学成分,与新疆现有的２个有规模的香型花余乐比特、札一进行比较。新品种酒花中苦味树脂的含量为１８．９％,α－酸为５．６３％,β－酸为２．２６％,合律草酮占总α－酸的３０．７３％,新品种的酒花油含量为０．９０％,其中法呢稀相对含量高达１１．０３％。从这些表征啤酒花品种特性的数据得知,新酒花属于香型花,与现有的２个香型花一样,品质较佳,应该大力推广。     

Einbau von 14C-mevalonsäurelacton in hopfenbitterstoffe

Labeled mevalonate is incorporated into terpenes and hop bitter compounds by Humulus lupulus. The role of mevalonate as a precursor for the prenyl (3-methyl-but-2-enyl) side chain of the hop bitter compounds is discussed.     

Chalcone synthase homologues from Humulus lupulus: some enzymatic properties and expression

The enzymatic properties of four chalcone synthase homologues CHS_H1, VPS, CHS 2 and CHS 4 from Humulus lupulus L. were investigated after heterologous expression in Escherichia coli. It was found that both VPS and CHS_H1 can utilize isovaleryl-CoA and isobutyryl-CoA as substrates producing compounds with positions in thin layer chromatography characteristic for phloroisovalerophenone and phloroisobutyrophenone. These reactions are accompanied by the formation of associated byproducts. The formation of naringenin chalcone can be catalyzed primarily by CHS_H1. Comparatively the ability of VPS to perform chalcone synthase reaction is very limited. Since only CHS_H1 has true chalcone synthase activity, this enzyme can be considered a key enzyme in prenylflavonoid biosynthesis. Both CHS 2 and CHS 4 utilize isovaleryl-CoA and isobutyryl-CoA as substrates, but the reactions were prematurely terminated. In comparison with VPS and CHS_H1, the optimum pH of CHS 2 was shifted to lower value. High expression of chalcone synthase-like genes were found in maturating hop cones of cultivars with high bitter acid content (Agnus, Magnum, Target) by Northern and Western blotting using probes specific for vps, chs_H1, chs 4 and polyspecific serum risen against recombinant protein CHS4, respectively. It was also found that these cultivars maintained expression of CHS homologues for a longer period of time during cone development in contrast to time-limited expression of CHS homologues in cultivars with low bitter acids content.     

High throughput isolation of microsatellites in hop (Humulus lupulus L.)

Procedures to generate usable microsatellite marker sequences should be optimized for cost-effectiveness in each species. For hop, we have used a cocktail of several restriction enzymes to digest the genomic DNA. This is followed by capture of microsatellite-containing sequences with long microsatellite probes attached to a membrane. The enrichment level for GA and GT libraries was 37% and 35%, respectively, and 100% of the clones contained microsatellite sequences. Libraries can be generated from genomic DNA in approximately 10 d.     

In vitro gas production kinetics and short-chain fatty acid production from rumen incubation of diets supplemented with hop cones (Humulus lupulus L.)

The aim of this study was to assess the effects of hop cones (Humulus lupulus L.) from two varieties Aurora and Dana, differing in their α- and β-acid contents, on rumen microbial activity measured with in vitro gas production kinetics and short-chain fatty acids (SCFA) production. Hop cones were added to the total mixed dairy cow ration (CONT) in concentrations simulating a cow’s daily intake of 50, 100 and 200 g of hop cones – the concentrations of hop cones expressed on a substrate basis were 43, 82 and 153 mg/g of substrate. Substrates were anaerobically incubated in glass syringes, and gas production kinetic parameters were determined by fitting data with the Gompertz model. Gas produced after 24 h (Gas24), maximum fermentation rate (MFR) and time of maximum fermentation rate (TMFR) were calculated from the estimated gas production kinetic parameters. After 24 h of incubation, the fermentation liquids of each substrate were taken for the determination of SCFA. Increasing the hop cone concentration decreased the total potential gas production, Gas24, MFR and shortened TMFR. The highest hop cone concentration significantly decreased acetic and butyric acid productions and total SCFA production after 24 h of incubation, but not propionic acid production, resulting in a decreased ratio between acetic acid and propionic acid.     

Bildung und weiterreaktion von acylvorstufen der hopfenbitterstoffe

Isobutyric acid is incorporated into desoxycohumulone, cohumulone and colupulone and isovaleric acid is incorporated into desoxyhumulone, humulone and lupulone. The compound 1-isobutyryl-3-(3,3-dimethylallyl)-phloroglucinol (CoX) can be considered as an intermediate for the first three components of the hop resins while isovaleryl-3-(3,3-dimethylallyl)-phloroglucinol (X) is an intermediate in the biosynthesis of the parent compounds.     

Efficient In Vitro Micropropagation and Regeneration of Humulus Lupulus on Low Sugar, Starch-Gelrite Media

Several Czech and foreign hop mericlones were tested in vitro for efficiency of green callus formation and plant regeneration from internodal or nodal explants. Modified MS media gelled either with agar, starch or a mixture of potato starch and Gelrite, supplemented with different concentrations of either glucose or maltose, were investigated. Two mericlones of Czech hop (Osvald 72 no. 5216 and Sládek no. 6908) were studied in more details because of their different regeneration capacities. The HPLC analysis of medium sugar concentrations after the explant cultivation has revealed slow uptake of sugar from the medium. Presence of glucose at concentration of 45 g dm^–3 in agar medium resulted in a decreased number of nodes compared to the control with 30 g dm^–3 of glucose. The use of a mixture of potato starch plus Gelrite instead of routinely used agar and decreasing the medium glucose concentration to 15 g dm^–3 proved to be most efficient for multiplication rate. The use of this medium results in lower cost of micropropagation of healthy hop cultures without exhibition of vitrification.     

Vertical dispersal of the two-spotted spider mite Tetranychus urticae, and the predatory mite Phytoseiulus persimilis on dwarf hops

1 The pattern of dispersion within plants of the two-spotted spider mite, Tetranychus urticae, and its predator, the phytoseiid Phytoseiulus persimilis, was studied on the dwarf hop variety First Gold from May to September in 1997 and 1998. 2 Spider mite populations developed on the lower leaves initially but, by late July, as the numbers of mites increased, most were found towards the top of plants. From early August, the numbers of spider mites decreased most rapidly on the upper parts of plants. 3 Where P. persimilis was released, the predator maintained the numbers of T. urticae below those found on non-release plots throughout the season. 4 By early August, the predator’s pattern of dispersion was similar to that of the pest. 5 Predators spread to non-release plots by 20 June in 1997 and 24 July in 1998 and eventually became more numerous than on the plots where they had been released.     

Isolation and characterization of polymorphic microsatellites for assessment of genetic variation of hops (Humulus lupulus L.)

Hop (Humulus lupulus L.) cultivars are vegetatively propagated and it is difficult to differentiate them during the process of propagation. Fingerprinting with molecular markers based on DNA could be a useful means of identifying different cultivars. Simple sequence repeats, or microsatellite markers, are the most suitable marker for genetic fingerprinting because they are multi‐allelic and co‐dominant. For this purpose, we have developed primers for 10 new polymorphic microsatellite loci that are suitable for genetic fingerprinting in hop.     

Application of in vivo bioluminescence to the study of lonophoretic action

Ionophores (carbonyl cyanide m-chlorophenylhydrazone; valinomycin; and the hopderived compounds colupulone, trans-isohumulone and trans-humulinic acid) reduced the rate of dodecanal-dependent light emission from luxA/B-transformed cells of Lactococcus lactis subsp. diacetylactis F712 when the cells were suspended in a buffered medium (pH 6.4) containing glucose. This allowed an assay for ionophores to be devised and permitted measurement of the effects of such compounds on the test organism by the use of a non-destructive technique in real time.     

Detection of resistance of lactic acid bacteria to a mixture of the hop analogue compounds tetrahydroiso-alpha-acids by noninvasive measurement of intracellular pH

AIMS: To examine the resistance of beer isolates of lactic acid bacteria (LAB) towards a mixture of tetrahydroiso-alpha-acids (Tetra) by growth experiments as well as by measurement of intracellular pH. METHODS AND RESULTS: Beer LAB isolates were identified to species level by SDS-PAGE of whole-cell proteins. Beer isolates of Lactobacillus brevis showed better ability for growth in the presence of Tetra than nonbeer isolates of the L. brevis or other species of LAB including beer and nonbeer isolates. The antimicrobial effect of Tetra was also examined by noninvasive measurement of intracellular pH by fluorescence ratio imaging microscopy for selected beer isolates of L. brevis and Pediococcus inopinatus. Strains of L. brevis showing limited decrease of intracellular pH during exposure to Tetra also showed better ability for growth in the presence of these compounds as well as in commercial beer products. CONCLUSIONS: It was possible to apply a method for noninvasive measurement of intracellular pH to predict the resistance of beer spoilage LAB towards the Tetra hop analogue compounds. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the usability of a new rapid method for detecting hop-resistant variants of known beer spoilage LAB species.     

Development of preparative and analytical methods of the hop bitter acid oxide fraction and chemical properties of its components

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 MS² 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.     

Einbau von [14C]-Essigsäure in hopfenbitterstoffe

Labeled acetic acids are incorporated by hops into desoxycohumulone, desoxyhumulone, humulone, colupulone and lupulone. The incorporation of acetic acid is considered in relation to the mixed isoprenoid-polyketide origin of these bitter principles.     

Aminosäuren als vorstufe der acylseitenkette der hopfenbitterstoffe

In Humulus lupulus, leucine undergoes transamination, and incorporation into desoxyhumulone and lupulone. We therefore propose that leucine is the precursor for the isovaleryl residue of the hop bitter compounds; the same appears to be true for valine and isoleucine as precursors for the isobutyryl and 2-methyl butyryl residues.     

Enzymatic Reactions by Five Chalcone Synthase Homologs from Hop (Humulus lupulus L.)

The enzyme activities encoded in five cDNAs for chalcone synthase (CHS) homologs from hop were investigated. Only valerophenone synthase (VPS) and CHS_H1 showed both naringenin-chalcone and phlorisovalerophenone forming activity. Narigenin-chalcone production by VPS was much lower than by CHS_H1. Therefore, it is highly possible that flavonoid depends mainly on CHS_H1, while bitter acid biosynthesis depends mainly on VPS and CHS_H1.     

Biochemical Preparation of (R)-Sulcatol

The antiallergic properties of a hop water extract (HWE) were studied by evaluating the Evans blue leakage from ICR mice caused by compound 48/80 stimulation, and the histamine release from ovalbumin (OVA)-sensitized BALB/c mice. An oral administration of HWE significantly inhibited the vascular permeability and histamine release. HWE itself did not have any influence on the total and antigen-specific immunoglobulin E (IgE) production in OVA-sensitized mice. These results indicate that HWE exerted an antiallergic effect by inhibiting the release of chemical mediators from mast cells and basophiles.