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At least 181 records · Page 10Linked to original sources

PubMed2003

Monitoring of insecticide resistance in damson hop aphid, Phorodon humuli Schrank (Hemiptera: Aphididae) from German hop gardens.

The damson hop aphid, Phorodon humuli (Schrank) (Hemiptera: Aphididae), is one of the most important sucking pests of many hop-growing areas world-wide. In this study we determined the efficacy of several insecticides against strains collected throughout the year 2001. All strains were collected in different hop gardens in the Hallertau (Bavaria), Germany, the largest hop-growing area of the world. First of all we established a leaf dip bioassay, carried out using six-well tissue culture plates and appropriate for monitoring susceptibility against imidacloprid, oxydemeton-methyl, cyfluthrin, amitraz, pymetrozine and pirimicarb. Four of these compounds, imidacloprid, cyfluthrin, pymetrozine and amitraz, are currently registered for the control of sucking pests in German hop gardens and are useful against P. humuli. The leaf-dip bioassay system turned out to be very reliable and robust. Ten P. humuli strains were collected in May 2001 and maintained in the laboratory to assess their resistance to the different insecticides in comparison with two laboratory reference strains (H2 and H5). Using diagnostic concentrations, resistance monitoring for imidacloprid and cyfluthrin was investigated during July and August 2001 on 53 populations from 30 sites around the Hallertau, an area of ca 2500 km2. Resistance to diagnostic concentrations (LC95 for reference strains) of imidacloprid, amitraz and pymetrozine was not detected in any strain received in 2001, but late-season (August) populations seemed to respond more heterogeneously than those collected mid-season (July). Overall composite mean mortalities to diagnostic concentrations of imidacloprid (13 mg litre(-1)) in collections from May, July and August were 95 (+/-2.5), 98 (+/-2.3) and 87 (+/-5.9)%, respectively. Moderate resistance to pyrethroids was observed in all strains collected in May and August using a diagnostic concentrations of 10 mg litre(-1) cyfluthrin (LC95 of the susceptible reference strain H5). Slight to moderate resistance to diagnostic concentrations of oxydemeton-methyl and pirimicarb was observed in some, but not all, strains collected early season. The results are discussed in terms of the implemention of hop aphid resistance management strategies in German hop-cultivation areas.

Animals↗

PubMed2004

Uptake, translocation and bioavailability of imidacloprid in several hop varieties.

The neonicotinoid insecticide imidacloprid is the most important insecticide in hop cultivation in Germany. A laboratory study was undertaken to investigate its systemic properties and translaminar bioavailability in hop leaves. Radiolabelled [methylene-14C]imidacloprid was applied either alone or in combination with different additives onto leaves of several hop varieties. Uptake and translocation were evaluated 1 and 7 days after foliar application under greenhouse conditions. The uptake of imidacloprid into hop leaves was most pronounced in the first 24 h after application and only negligible amounts were taken up after this period. Significant differences in the quantitative uptake occurred when imidacloprid was combined with additives, such as Amulsol, Genapol C-100, Hasten and LI 700. The uptake of imidacloprid applied without additives was less than 10% 7 days after application, whereas the combination with LI 700 provided 70-80% uptake. Genapol C-100 and Amulsol induced considerable phytotoxicity at the application site. Comparing hop varieties revealed differences up to twofold in foliar penetration of imidacloprid. The translaminar and acropetal bioavailability of imidacloprid foliarly applied to hop leaves was determined by a laboratory bioassay using the damson hop aphid, Phorodon humuli (Schrank). Significantly higher mortality was observed with laboratory formulations containing imidacloprid and the additive LI 700. In contrast to these results from systemic tests, contact mortality at the application site was constantly high over the testing period of 7 days, highlighting the importance of this mode of entry for aphid intoxication.

Animals↗

PubMed2005

A pilot trial evaluating Meta050, a proprietary combination of reduced iso-alpha acids, rosemary extract and oleanolic acid in patients with arthritis and fibromyalgia.

The aim of this open-label, 8-week observational trial was to investigate the efficacy of Meta050 (a proprietary, standardized combination of reduced iso-alpha-acids from hops, rosemary extract and oleanolic acid) on pain in patients with rheumatic disease. Osteoarthritis, rheumatoid arthritis and fibromyalgia patients were given 440 mg Meta050 three times a day for 4 weeks, which was changed to 880 mg twice a day for the subsequent 4 weeks in the majority of patients. Pain and condition-specific symptoms were assessed using a standard visual analog scale (VAS), an abridged arthritis impact measurement scale (AIMS2) and the fibromyalgia impact questionnaire. Fifty-four subjects with rheumatic disease completed the trial. Following treatment, a statistically significant decrease in pain of 50% and 40% was observed in arthritis subjects using the VAS (p < 0.0001; Wilcoxon-ranked sums) and AIMS2 (p < 0.0001), respectively. Fibromyalgia subject scores did not significantly improve. A decreasing trend of C-reactive protein, a marker for inflammation, was also observed in those subjects who presented with elevated C-reactive protein. No serious side effects were observed. These observations suggest that Meta050 at a dosage of 440 mg three times a day has a beneficial effect on pain in arthritis subjects.

Administration, Oral↗

PubMed2002

Remarkable variability of apple mosaic virus capsid protein gene after nucleotide position 141.

Eight new sequences of European isolates from almond, apple, hop, prune and pear of the Apple mosaic ilarvirus (ApMV) capsid protein gene are presented. A consensus sequence was established as having 654 nucleotides (nt) and two American and two European isolates were identified to have insertions 6 to 15 nucleotides after nt position 141. The insertion resulted in the American isolate A inframeshift repaired with two point insertions 17 and 68 nt downstream. The RNA around the insertion point can potentially form a stable secondary structure with three hairpins. The insertions could stabilise this structure or could be neutral. The predicted folding of the translated protein is not influenced by the insertions or frameshift, and we speculate that the region after nt position 141 is without reasonable selection pressure and represents a hot spot for the accumulation of insertion mutations in ApMV.

Amino Acid Sequence↗

PubMed2001

Molecular characterization of Hop mosaic virus: its serological and molecular relationships to Hop latent virus.

The 3'-terminal sequence of hop mosaic virus (HpMV) genomic RNA was determined. A cDNA of approximately 1.8 kbp was amplified from the HpMV genome by 3' RACE using a degenerate primer, which was designed to anneal to the overlapping region of open reading frames (ORFs) 2 and 3 of eight carlavirus genomes. The sequence contained three ORFs, encoding proteins of 7-, 34-, and 11-kDa, which corresponded to ORFs 4, 5, and 6 of the carlavirus genome, respectively. The amino acid sequence of ORF 5, encoding the coat protein (CP) of HpMV, shows the highest identity (67%) to that of Hop latent virus (HpLV). The HpMV CP N-terminal sequence differs from that of HpLV, but the central and C-terminal sequences of the CP of both viruses are similar. The sequence similarity possibly causes the cross-reaction of heterologous antibodies of HpMV and HpLV. Phylogenetic analyses based on the CP amino acid and 3' non-coding region sequences indicate close relationships among HpMV, HpLV, and Potato virus M. We report here the first molecular characterization of HpMV genomic RNA.

3' Untranslated Regions↗

PubMedDate not supplied

Quantifying the effects of mild sedatives.

In quantifying the effects of mild sedatives both physiological and subjective aspects of sleep must be taken into account. A questionnaire analysis on a mild sedative (400 mg of an aqueous extract of Valeriana officinalis L.) showed that by subjective criteria it is sedative (i.e. it significantly decreased perceived sleep latencies and night awakenings, and improved sleep quality). In an EEG study on the same preparation the pattern of results tended to confirm the subjective evaluation (i.e. shorter mean sleep latency, increased mean latency to first awakening) but the changes did not reach statistical significance. The discussion critically examines some of the approaches used to test putative mild sedatives and suggests a rational approach to analysing their effects.

Adult↗

PubMed2006

Fusarium graminearum on plant cell wall: no fewer than 30 xylanase genes transcribed.

The transcription of a set of 32 putative xylanase genes from Fusarium graminearum was examined by quantitative PCR after growth on different carbon sources (hop cell wall, xylan, xylose, or carboxymethylcellulose). Growing on plant cell wall medium, this fungus displays a great diversity of expression of xylan-related genes, with 30 being induced. A second level of diversity exists because expression patterns can be very different for loci encoding enzymes with the same activity (the same EC number). The wealth of xylan-degrading enzymes and the differential expression confer on the fungus a great flexibility of reaction to variation in its environment.

Cell Wall↗

PubMed2006

Analysis of xanthohumol and isoxanthohumol in different hop products by liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry.

An analytical methodology based on the sample extraction with methanol/formic acid by ultra-sonication and subsequent analysis by high-performance liquid chromatography with diode array detection is proposed for the determination of xanthohumol (XN) and isoxanthohumol (IXN) in different hop products. The identity of the compounds was confirmed by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry in positive ion mode. The performance of the method was assessed by the evaluation of parameters such as absolute recovery, repeatability, linearity and limits of detection and quantitation. This methodology was applied to investigate the impact of the extraction process of the hop products on the amount of xanthohumol and isoxanthohumol. The ethanolic extract revealed to be the hop product richest in xanthohumol (3.75+/-0.05 g/100 g) relatively to the pellets (0.62+/-0.01 g/100 g) and supercritical CO2 extract (0.089+/-0.001 g/100 g).

Chromatography, High Pressure Liquid↗

PubMed2005

Beer constituents as potential cancer chemopreventive agents.

Beer is a complex alcoholic beverage made from barley (malt), hop, water and yeast. Phenolic constituents of beer are derived from malt (70-80%) and hop (20-30%). Structural classes include simple phenols, benzoic- and cinnamic acid derivatives, coumarins, catechins, di-, tri- and oligomeric proanthocyanidins, (prenylated) chalcones and flavonoids as well as alpha- and iso-alpha-acids derived from hop. Compounds belonging to different structural classes have distinct profiles of biological activity in in vitro test systems, and in combination might lead to enhanced effects. Scientific evidence has accumulated over the past 10 years pointing to the cancer preventive potential of selected hop-derived beer constituents, i.e., prenylflavonoids including xanthohumol and isoxanthohumol, and hop bitter acids. Chemopreventive activities observed with these compounds relevant to inhibition of carcinogenesis at the initiation, promotion and progression phases, as well as results from in vivo studies on metabolism, bioavailability and efficacy are summarised in this review.

Angiogenesis Inhibitors↗

PubMed2004

Two major metabolites of 8-prenylnaringenin are estrogenic in vitro.

8-prenylnaringenin (8-PN) and preparations containing 8-prenylnaringenin have been suggested for use in medicinal and cosmetic applications like hormone replacement or bust enhancement. However, the safety of application is still under considerable debate. Recently it has been shown that human liver microsomes are converting 8-prenylnaringenin to 12 metabolites, with (E)-8-(4''-hydroxyisopentenyl)naringenin (8-PN-OH) and (E)-8-(4''-oxoisopentenyl)naringenin (8-PN=O) being among the most abundant. Applying two independent in vitro test systems we demonstrate that these two metabolites of 8-prenylnaringenin are estrogenic in vitro. These results represent an important piece of information towards the discussion of safety of use of preparations containing 8-prenylnaringenin.

Flavanones↗

PubMed2005

Regulation of osteoblastic phenotype and gene expression by hop-derived phytoestrogens.

Certain plant-derived compounds show selective estrogen receptor modulator (SERM) activity and may therefore be an alternative to the conventional hormone replacement therapy, which prevents osteoporosis but is also associated with an increased risk of breast and endometrial cancers. In the current study, we tested the effects of the hop-derived compounds 8-prenylnaringenin, 6-prenylnaringenin, xanthohumol and isoxanthohumol (1) to modulate markers of differentiation and gene expression in osteoblasts and (2) to regulate proliferation in MCF-7 breast cancer cells. Additionally, we analyzed the ER-binding affinities of these hop compounds as well as the ER-mediation of their effects. Bone-forming activity and ER-subtype specificity were investigated by measuring alkaline phosphatase (AP) activity in hFOB/ERalpha cells and regulation of gene transcription for AP, interleukin-6, pS2 and von Willebrand factor (VWF) in U-2 OS/ERalpha and U-2 OS/ERbeta cells. Our results demonstrate that AP, pS2 and VWF mRNA levels are significantly increased by the compounds in an estrogen-like manner via both ERalpha and ERbeta, while IL-6 is down-regulated in U-2 OS/ERalpha cells. Consistently, AP enzymatic activity is up-regulated by all compounds in hFOB/ERalpha9 cells. Depending on their concentration, all compounds show proliferative effects in MCF-7 cells. Except for 8-PN the hop constituents display an ERbeta-preference. Reversal of estrogen-specific AP-induction in Ishikawa cells indicates an ER-regulated mechanism. Finally, the flavonoids display cytotoxic effects only at high concentrations (> or =10(-4)M). In summary, we have demonstrated for the first time that specific phytoestrogen compounds found in hop extracts exert estrogen-like activities on bone metabolism. Regarding a potential for use in osteoporosis-prevention therapy, the dosage of a phytoestrogen, which is taken, will play an important role concerning a desired in vivo profile.

Adult↗

PubMed2005

A RT/PCR-partial restriction enzymatic mapping (PREM) method for the molecular characterisation of the large satellite RNAs of Arabis mosaic virus isolates.

The satellite RNA of the grapevine isolate NW of Arabis mosaic virus (ArMV) was cloned and sequenced, and showed 75% identity at the nucleotide level to the satellite RNA of the lilac isolate of ArMV. In order to survey ArMV isolates from various geographical origins and natural hosts for the presence of large satellite RNAs and analyse their degree of variability, a RT/PCR-partial restriction enzymatic mapping (PREM) method was developed. The method is based on the incorporation of 5-methyl-dCTP in the RT/PCR reaction, and the subsequent digestion of the RT/PCR products by methyl-sensitive restriction enzymes. Satellites RNAs were detected by RT/PCR in eight isolates out of 47, six of them originating from grapevine, one from hop and one from lilac. The partial restriction digestion patterns allowed to distinguish six different types of satellites. Cloning and sequencing of the different satellites confirmed these results, the PREM proving able to discriminate sequences with 96% identity. The sizes of the different satellites varied between 1092 and 1139 nucleotides, their encoded proteins between 338 and 360 amino acids. Conserved domains were found in the amino and carboxy-termini between the sequences of the proteins encoded by the satellites of the different isolates of ArMV.

Amino Acid Sequence↗

PubMed2004

In vitro binding experiments with a Valerian, hops and their fixed combination extract (Ze91019) to selected central nervous system receptors.

The fixed valerian-hops extract combination Ze91019 is used as a sleep aid. Although its exact mechanism of action is not well understood, earlier studies indicate that the CNS effect of valerian might occur through interaction with the GABA, melatonin and/or the adenosine systems in the brain. The use of hops in sleep remedies, however, is mainly based on traditional use and scarce scientific information. In this report, the binding of Ze91019, and the component valerian and hops extracts within, was tested on 14 subtypes of five classes of central receptors (dopamine, serotonin, melatonin, MCH and neuropeptide-Y). Binding affinities could be demonstrated at some of the screened melatonin (ML1 and ML2) and serotonin (5-HT4e, 5-HT6 and 5-HT7) receptor subtypes.

Animals↗

PubMed2004

Xanthohumol and related prenylflavonoids from hops and beer: to your good health!

Xanthohumol (3'-[3,3-dimethyl allyl]-2',4',4-trihydroxy-6'-methoxychalcone) is the principal prenylated flavonoid of the female inflorescences of the hop plant ('hops'), an ingredient of beer. Human exposure to xanthohumol and related prenylflavonoids, such as 8-prenylnaringenin and isoxanthohumol, is primarily through beer consumption. Xanthohumol has been characterized a 'broad-spectrum' cancer chemopreventive agent in in vitro studies, while 8-prenylnaringenin enjoys fame as the most potent phytoestrogen known to date. These biological activities suggest that prenylflavonoids from hops have potential for application in cancer prevention programs and in prevention or treatment of (post-)menopausal 'hot flashes' and osteoporosis. Xanthohumol and 8-prenylnaringenin are metabolized into many flavonoid derivatives with modified 3,3-dimethyl allyl (prenyl) moieties. Xanthohumol is formed in lupulin glands by a specialized branch of flavonoid biosynthesis that involves prenylation and O-methylation of the polyketide intermediate chalconaringenin. Although a lupulin gland-specific chalcone synthase is known, the aromatic prenyltransferase and O-methyltransferase participating in xanthohumol have not been identified. The prenylflavonoid pathway is a possible target for breeding or biotechnological modification of hops with the aim of increasing xanthohumol levels for beer brewing and 8-prenylnaringenin levels for pharmaceutical production.

Anticarcinogenic Agents↗

PubMed2002

Automated sample preparation by pressurized liquid extraction-solid-phase extraction for the liquid chromatographic-mass spectrometric investigation of polyphenols in the brewing process.

The analysis of polyphenols from solid plant or food samples usually requires laborious sample preparation. The liquid extraction of these compounds from the sample is compromised by apolar matrix interferences, an excess of which has to be eliminated prior to subsequent purification and separation. Applying pressurized liquid extraction to the extraction of polyphenols from hops, the use of different solvents sequentially can partly overcome these problems. Initial extraction with pentane eliminates hydrophobic compounds like hop resins and oils and enables the straightforward automated on-line solid-phase extraction as part of an optimized LC-MS analysis.

Automation↗

PubMed2002

Interactions of valerian extracts and a fixed valerian-hop extract combination with adenosine receptors.

Phytopharmaceuticals and dietary supplements containing valerian are used as mild sleep-inducing agents. An in vitro radioligand binding assay at A(1) and A(2A) adenosine receptors (ARs) was conducted with a fixed extract combination of valerian and hop (Ze 91019) to investigate a possible mechanism for the pharmacological activity of the extract. Component extracts of valerian and hop were also individually investigated. The fixed combination Ze 91019 as well as the valerian extracts therein exhibited selective affinity to A(1)ARs (K(i) = 0.15-0.37 mg/mL vs [(3)H]CCPA). The same extracts exhibited partial agonist activity at the A(1) adenosine receptor as indicated by a lower degree of stimulation of [35S]GTP gamma S binding in membrane preparations of CHO-hA(1) cells as compared to the full A(1) AR agonist N(6)-cyclopentyladenosine (CPA). In addition valerian extract inhibited cAMP accumulation in CHO-hA(1) cell membranes. The partial agonistic activity at A(1)ARs may thus play a role in the sleep inducing effect of Ze 91019 and the valerian extract therein.

Animals↗

PubMed2002

A novel multiplex RT-PCR probe capture hybridization (RT-PCR-ELISA) for simultaneous detection of six viroids in four genera: Apscaviroid, Hostuviroid, Pelamoviroid, and Pospiviroid.

A rapid and sensitive assay was developed for the detection and identification of viroids by standard or multiplex reverse transcription-polymerase chain reaction (RT-PCR)-probe capture hybridization (RT-PCR-ELISA). The assay was applied successfully for the detection and identification of the following six viroid species from infected tissues: Potato spindle tuber viroid (Pospiviroid), Peach latent mosaic viroid (Pelamoviroid), Apple scar skin viroid (Apscaviroid), Apple dimple fruit viroid (Apscaviroid), Pear blister canker viroid (Apscaviroid), and Hop stunt viroid (Hostuviroid). Total RNA was obtained from infected tissue by the Qiagen RNeasy kit and, then viroid cDNA was synthesized using viroid specific complementary DNA primer. To identify and differentiate the amplicons of the six viroids, each amplicon was digoxigenin (DIG)-labelled during the amplification process, and then detected by a colorimetric system using a biotinylated cDNA capture probe specific for each viroid. The results revealed that each capture probe hybridized only to its complementary DIG-labelled amplicon. Thus the six viroids can be detected and differentiated in a multiplex RT-PCR-ELISA assay. In the multiplex assay, cDNAs of six viroids were synthesized simultaneously in one tube, DIG-labelled during amplification, then a portion of the DIG-labelled amplified products was hybridized with selected capture probe. All the six viroid capture probes hybridized to their respective complementary DIG-labelled RT-PCR-amplified product. These findings are important for viroid detection and identification for studying host-viroid interactions and for management and control viroid diseases.

DNA Probes↗

PubMed2004

Antiviral activity of hop constituents against a series of DNA and RNA viruses.

We investigated whether crude hop extracts and purified hop components representing every major chemical class of hop compound have antiviral activity. These hop constituents were tested for antiviral activity against bovine viral diarrhea virus (BVDV) as a surrogate model of hepatitis C virus (HCV), human immunodeficiency virus (HIV), influenza A virus (FLU-A), influenza B virus (FLU-B), rhinovirus (Rhino), respiratory syncytial virus (RSV), yellow fever virus (YFV), cytomegalovirus (CMV), hepatitis B virus (HBV), and herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). The extracts all failed to prevent the replication of HIV, FLU-A, FLU-B, RSV and YFV. A xanthohumol-enriched hop extract displayed a weak to moderate antiviral activity against BVDV (therapeutic index (TI)=6.0), HSV-2 (TI=>5.3), Rhino (TI=4.0) and HSV-1 (TI=>1.9) with IC(50) values in the low microg/ml range. Pure iso-alpha-acids demonstrated low to moderate antiviral activity against both BVDV (TI=9.1) and CMV (TI=4.2) with IC(50) values in the low microg/ml range. No antiviral activity was detected using beta-acids or a hop oil extract. Ultra-pure preparations (>99% pure) were used to show that xanthohumol accounted for the antiviral activity observed in the xanthohumol-enriched hop extract against BVDV, HSV-1 and HSV-2. Xanthohumol was found to be a more potent antiviral agent against these viruses than the isomer iso-xanthohumol. With Rhino, the opposite trend was observed with iso-xanthohumol showing superior antiviral activity to that observed with xanthohumol. Xanthohumol also showed antiviral activity against CMV, suggesting that it might have a generalized anti-herpesvirus antiviral activity. Again, superior antiviral activity was observed with the xanthohumol isomer against CMV. In summary, iso-alpha-acids and xanthohumol were shown to have a low-to-moderate antiviral activity against several viruses. These hop constituents might serve as interesting lead compounds from which more active anti-HCV, anti-Rhino and anti-herpesvirus antiviral agents could be synthesized.

Animals↗