The bitter acids of hops (Humulus lupulus L.) mainly consist of humulones or α-acids and lupulones or β-acids. We aimed to evaluate the antiproliferative mechanisms of lupulones on a human metastatic ...colon carcinoma-derived cell line (SW620 cells) and to assess their chemopreventive effects in a model of colon carcinogenesis. SW620 cell growth was inhibited by 70% after a 48 h exposure to lupulones (40 μg/ml). Lupulones up-regulated the expression of Fas receptor (Fas) and Fas ligand (FasL) as well as TNF-related apoptosis inducing ligand (TRAIL)-R1 (DR4) and -R2 (DR5) receptor proteins, suggesting the involvement of Fas and TRAIL receptors-mediated pathways in lupulone-induced apoptosis. Lupulones also increased the mitochondrial membrane permeability. Colon carcinogenesis was initiated in Wistar rats by intra-peritoneal injections of azoxymethane (AOM), once a week for 2 weeks. One week after the last injection, rats received lupulones (0.001 or 0.005%) in drinking water, and AOM-control rats received the excipient. After 7 months of treatment, the colon of rats receiving 0.001 and 0.005% lupulones showed, respectively, a 30 and a 50% reduction (P < 0.05) of the number of preneoplastic lesions (aberrant crypt foci). In addition, we observed a drastic reduction (70–80%) of the total number of tumors in the colon of rats treated with lupulones when compared with the AOM control group. Lupulones induced apoptosis in SW620 colon-derived metastatic cells by activating both Fas and TRAIL death receptor signaling pathways, and antagonize at a low dose (4 mg/kg/day) colon cancer development. These observations suggest the use of lupulones for colon cancer chemoprevention trials.
We report here that small but numerous foliar glands are present near the base of the abaxial leaf blades of hop (
Humulus lupulus
L.) at about 2.6 times the density found in the more distal regions, ...and this concentration of glands appear to protect the basal region from damage by insects. Distinctive wild taxa of
H. lupulus
are native to distinctive regions of the north temperate world. The much higher presence of protective glands in the three native North American
Humulus
taxonomic varieties in comparison with the varieties native to Europe and Asia suggests specialized leaf feeders in North America have been responsible for the evolution of greater gland density. Commercial domesticated hop cultivars trace most of their germplasm to the European hop (
H. lupulus
var.
lupulus
), which possesses a much lower concentration of leaf glands than the native hops of all other regions of the world, and therefore is likely relatively susceptible to damage. We suggest that breeding for increased density of protective foliage glands may be a non-chemical way of alleviating foliar feeding damage in cultivated hops.
AIMS: The goals of this study were to determine if β‐acid from hops (Humulus lupulus L.) could be used to control fructan fermentation by equine hindgut micro‐organisms, and to verify the ...antimicrobial mode of action on Streptococcus bovis, which has been implicated in fructan fermentation, hindgut acidosis and pasture‐associated laminitis (PAL) in the horse. METHODS AND RESULTS: Suspensions of uncultivated equine faecal micro‐organisms produced fermentation acids when inulin (model fructan) was the substrate, but β‐acid (i.e. lupulone) concentrations ≥9 ppm inhibited lactate production and mitigated the decrease in pH. Inulin‐fermenting Strep. bovis was isolated from the β‐acid‐free suspensions after enrichment with inulin. The isolates were sensitive to β‐acid, which decreased the viable number of streptococci in faecal suspensions, as well as growth, lactate production and the intracellular potassium of Strep. bovis in pure culture. CONCLUSIONS: These results are consistent with the hypothesis that hops β‐acid prevented the growth of fructan‐fermenting equine faecal bacteria, and that the mechanism of action was dissipation of the intracellular potassium of Strep. bovis. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacterial hindgut fermentation of grass fructans has been linked to PAL and other metabolic disorders in horses. Hops β‐acid is a potential phytochemical intervention to decrease the growth of bacteria responsible for PAL.
Herbal extracts targeting at the brain remain a continuous challenge to pharmacology. Usually, a number of different animal tests have to be performed in order to find a potential clinical use. Due ...to manifold possibly active ingredients biochemical approaches are difficult. A more holistic approach using a neurophysiological technique has been developed earlier in order to characterise synthetic drugs. Stereotactic implantation of four semi-microelectrodes into frontal cortex, hippocampus, striatum and reticular formation of rats allowed continuous wireless monitoring of field potentials (EEG) before and after drug intake. After frequency analysis (Fast Fourier Transformation) electric power was calculated for 6 ranges (delta, theta, alpha1, alpha2, beta1 and beta2). Data from 14 synthetic drugs – tested earlier and representative for different clinical indications – were taken for construction of discriminant functions showing the projection of the frequency patterns in a six-dimensional graph. Quantitative analysis of the EEG frequency pattern from the depth of the brain succeeded in discrimination of drug effects according to their known clinical indication (Dimpfel and Schober, 2003). Extracts from Valerian root, Ginkgo leaves, Paullinia seed, Hop strobile, Rhodiola rosea root and Sideritis scardica herb were tested now under identical conditions. Classification of these extracts based on the matrix from synthetic drugs revealed that Valerian root and hop induced a pattern reminiscent of physiological sleep. Ginkgo and Paullinia appeared in close neighbourhood of stimulatory drugs like caffeine or to an analgesic profile (tramadol). Rhodiola and Sideritis developed similar frequency patterns comparable to a psychostimulant drug (methylphenidate) as well to an antidepressive drug (paroxetine).
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MicroRNAs are 21- to 24-nucleotide-long, non-coding RNA molecules that regulate gene expression at the post-transcriptional level. They can modulate various biological processes, including plant ...response and resistance to fungal pathogens. Hops are grown for use in the brewing industry and, recently, also for the pharmaceutical industry. Severe Verticillium wilt caused by the phytopathogenic fungus Verticillium nonalfalfae, is the main factor in yield loss in many crops, including hops (Humulus lupulus L.). In our study, we identified 56 known and 43 novel miRNAs and their expression patterns in the roots of susceptible and resistant hop cultivars after inoculation with V. nonalfalfae. In response to inoculation with V. nonalfalfae, we found five known and two novel miRNAs that are differentially expressed in the susceptible cultivar and six known miRNAs in the resistant cultivar. Differentially expressed miRNAs target 49 transcripts involved in protein localization and pigment synthesis in the susceptible cultivar, whereas they are involved in transcription factor regulation and hormone signalling in the resistant cultivar. The results of our study suggest that the susceptible and resistant hop cultivars respond differently to V. nonalfalfae inoculation at the miRNA level and that miRNAs may contribute to the successful defence of the resistant cultivar.
In hops (Humulus lupulus L.), irrigation by flooding the inter-row can carry away suspended particles and minerals, causing gradients in soil fertility. The effect of more than 20 years of flooding ...irrigation on soil and plants was evaluated in two hop fields by measuring soil and plant variables in multiple points along the rows. In a second experiment 1000 kg ha−1 of lime was applied and incorporated into the soil to assess whether liming could moderate any gradient created by the irrigation. At different sampling points along the rows, significant differences were recorded in soil properties, plant elemental composition and dry matter yield, but this was not found to exist over a continuous gradient. The variations in cone yield were over 50% when different sampling points were compared. However, this difference cannot be attributed to the effect of irrigation, but rather to an erratic spatial variation in some of the soil constituents, such as sand, silt and clay. Flooding irrigation and frequent soil tillage resulted in lower porosity and higher soil bulk density in the 0.0–0.10 m soil layer in comparison to the 0.10–0.20 m layer. In turn, porosity and bulk density were respectively positively and negatively associated with crop productivity. Thus, irrigation and soil tillage may have damaged the soil condition but did not create any gradient along the row. The ridge appeared to provide an important pool of nutrients, probably caused by mass flow due to the evaporation from it and a regular supply of irrigation water to the inter-row. Liming raised the soil pH slightly, but had a relevant effect on neither soil nor plants, perhaps because of the small amounts of lime applied.
Abscisic acid (ABA) is one of the most common stress signals that appear in plant organs in response to soil drying. Equilibrium between ABA biosynthesis and catabolism regulates ABA accumulation in ...plants under water stress. The aim of our work was to explore the dynamics of changes in ABA metabolites as well as other stress-induced phytohormones such as jasmonic acid, indole-3-acetic acid, and their respective metabolites in hop Humulus lupulus (L.) plants during drying and to identify among them potential signals involved in drought signalling. We showed that the concentrations of all ABA metabolites (except the concentration of ABA glucosyl ester in leaves) increased in the same manner in leaves and xylem sap approximately at the same level of soil water content when the relative water content of leaves decreased. The predominant metabolites in leaves and xylem sap were phaseic acid and dihydroxyphaseic acid. ABA glucosyl ester was not a source of the increased concentration of ABA in leaves and xylem sap because of its considerably lower concentration compared to ABA. The concentration of jasmonates decreased in leaves of hop plants. Changes in auxin concentration suggest that this hormone is involved in the response of hop plants to soil drying.
BACKGROUND AND AIMS: Soil drying leads to the generation of chemical signals in plants that regulate water use via control of the stomatal aperture. The aim of our work was to identify the presence ...and identity of potential chemical signals, their dynamics, and their relationship with transpiration rate during soil drying in hop (Humulus lupulus (L.)) plants. METHODS: We used pressure chamber technique for measurement of shoot water potential and collection of shoot xylem sap. We analyzed concentrations of abscisic acid (ABA), nitrate, phosphate, sulphate and malate in sap and also the rate of whole plant transpiration. RESULTS: Transpiration rate decreased prior to changes in shoot water potential. The concentration of ABA in xylem sap continuously increased from early to later stages of water stress, whereas in leaves it increased only at later stages. Shoot sap pH increased simultaneously with the decrease of transpiration rate. Xylem sap alkalization was in some cases accompanied by a decrease in nitrate concentration and an increase in malate concentration. Concentration of sulphate increased in xylem sap during drying and sulphate in combination with a higher ABA concentration enhanced stomatal closure. CONCLUSIONS: Several early chemical signals appear in sap of hop plants during soil drying and their impact on transpiration may vary according to the stage of soil drying.
Hop (Humulus lupulus L., Cannabaceae family) is prized for its essential oil contents, used in beer production and, more recently, in biological and pharmacological applications. In this work, a ...method involving headspace solid‐phase microextraction and gas chromatography–mass spectrometry was developed and optimized to establish the terpenoid (monoterpenes and sesquiterpenes) metabolomic pattern of hop‐essential oil derived from Saaz variety as a mean to explore this matrix as a powerful biological source for newer, more selective, biodegradable and naturally produced antimicrobial and antioxidant compounds.
Different parameters affecting terpenoid metabolites extraction by headspace solid‐phase microextraction were considered and optimized: type of fiber coatings, extraction temperature, extraction time, ionic strength, and sample agitation. In the optimized method, analytes were extracted for 30 min at 40°C in the sample headspace with a 50/30 μm divinylbenzene/carboxen/polydimethylsiloxane coating fiber. The methodology allowed the identification of a total of 27 terpenoid metabolites, representing 92.5% of the total Saaz hop‐essential oil volatile terpenoid composition. The headspace composition was dominated by monoterpenes (56.1%, 13 compounds), sesquiterpenes (34.9%, 10), oxygenated monoterpenes (1.41%, 3), and hemiterpenes (0.04%, 1) some of which can probably contribute to the hop of Saaz variety aroma. Mass spectrometry analysis revealed that the main metabolites are the monoterpene β‐myrcene (53.0 ± 1.1% of the total volatile fraction), and the cyclic sesquiterpenes, α‐humulene (16.6 ± 0.8%), and β‐caryophyllene (14.7 ± 0.4%), which together represent about 80% of the total volatile fraction from the hop‐essential oil. These findings suggest that this matrix can be explored as a powerful biosource of terpenoid metabolites.
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