The Experts below are selected from a list of 642 Experts worldwide ranked by ideXlab platform
R. M. Kamens - One of the best experts on this subject based on the ideXlab platform.
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Gas and Particulate Products Distribution from the Photooxidation of α-Humulene in the Presence of NO_x, Natural Atmospheric Air and Sunlight
Journal of Atmospheric Chemistry, 2003Co-Authors: M. Jaoui, R. M. KamensAbstract:The photooxidation of α-humulene in the presence of NO_x, natural sunlight, and rural background air was investigated using a combination of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Identification and quantification of gas and particulate reaction products were reported over the course of the reaction. The daytime photooxidation was carried out in a large outdoor smog chamber (190 m^3). A wide range of ring retaining and ring opening products in the gas and particle phase are reported. On average, measured gas and particle phase products accounted for ∼ 44% of the reacted α-humulene carbon. Measurements show that a number of reaction products with low vapor pressures (e.g. 3-seco-α-Humulone aldehyde, 7-seco-α-Humulone aldehyde, α-humulal aldehyde, α-humulene 3-oxide or α-humulene 7-oxide, α-humulaic/alic acid isomers, and 3-seco-α-14-hydroxyHumulone aldehyde) were found in the early stage of the reaction and may play an important role in the early formation of secondary organic aerosol. A detailed mechanism is proposed to account for most products observed in this investigation.
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Gas and Particulate Products Distribution from the Photooxidation of α-Humulene in the Presence of NOx, Natural Atmospheric Air and Sunlight
Journal of Atmospheric Chemistry, 2003Co-Authors: M. Jaoui, R. M. KamensAbstract:The photooxidation of α-humulene in the presence of NOx, natural sunlight, and rural background air was investigated using a combination of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Identification and quantification of gas and particulate reaction products were reported over the course of the reaction. The daytime photooxidation was carried out in a large outdoor smog chamber (190 m3). A wide range of ring retaining and ring opening products in the gas and particle phase are reported. On average, measured gas and particle phase products accounted for ∼ 44% of the reacted α-humulene carbon. Measurements show that a number of reaction products with low vapor pressures (e.g. 3-seco-α-Humulone aldehyde, 7-seco-α-Humulone aldehyde, α-humulal aldehyde, α-humulene 3-oxide or α-humulene 7-oxide, α-humulaic/alic acid isomers, and 3-seco-α-14-hydroxyHumulone aldehyde) were found in the early stage of the reaction and may play an important role in the early formation of secondary organic aerosol. A detailed mechanism is proposed to account for most products observed in this investigation.
Wolfgang Eisenreich - One of the best experts on this subject based on the ideXlab platform.
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Biosynthetic experiments with tall plants under field conditions. 18O2 incorporation into Humulone from Humulus lupulus.
Phytochemistry, 2004Co-Authors: Stefan Hecht, Klaus Kammhuber, Adelbert Bacher, Josef Reiner, Wolfgang EisenreichAbstract:Abstract Five segments of a large hop plant ( Humulus lupulus var. Hallertauer Magnum) carrying several cones were enclosed in sealed glass vessels that were gassed with 18 O 2 . After 14 days, the segments were harvested and Humulone and coHumulone were analysed by NMR spectroscopy and mass spectroscopy. The oxygen atoms in position 6 of Humulone and coHumulone showed 9% 18 O enrichment, respectively. It follows that the C-6 hydroxy groups were introduced by oxygenase catalysis.
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Biosynthesis of bitter acids in hops
European journal of biochemistry, 1999Co-Authors: Markus Goese, Klaus Kammhuber, Adelbert Bacher, Meinhart H. Zenk, Wolfgang EisenreichAbstract:The biosynthesis of Humulone, an antibacterial bitter acid from hops, was studied by isotope-incorporation experiments using 13 C-labelled glucose or 2 H2O. 13 C enrichments, 2 H enrichments and 13 C 13 C coupling patterns identify isovaleryl-CoA, malonyl-CoA and dimethylallyl pyrophosphate as precursors for Humulone. Dimethylallyl pyrophosphate, which serves as a building block for the bitter acid, is generated via the deoxyxylulose pathway of terpenoid biosynthesis. The data confirm that a symmetrical intermediate is involved in Humulone formation.
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biosynthesis of bitter acids in hops a 13 c nmr and 2 h nmr study on the building blocks of Humulone
FEBS Journal, 1999Co-Authors: Markus Goese, Klaus Kammhuber, Adelbert Bacher, Meinhart H. Zenk, Wolfgang EisenreichAbstract:The biosynthesis of Humulone, an antibacterial bitter acid from hops, was studied by isotope-incorporation experiments using 13 C-labelled glucose or 2 H2O. 13 C enrichments, 2 H enrichments and 13 C 13 C coupling patterns identify isovaleryl-CoA, malonyl-CoA and dimethylallyl pyrophosphate as precursors for Humulone. Dimethylallyl pyrophosphate, which serves as a building block for the bitter acid, is generated via the deoxyxylulose pathway of terpenoid biosynthesis. The data confirm that a symmetrical intermediate is involved in Humulone formation.
M. Jaoui - One of the best experts on this subject based on the ideXlab platform.
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Gas and Particulate Products Distribution from the Photooxidation of α-Humulene in the Presence of NO_x, Natural Atmospheric Air and Sunlight
Journal of Atmospheric Chemistry, 2003Co-Authors: M. Jaoui, R. M. KamensAbstract:The photooxidation of α-humulene in the presence of NO_x, natural sunlight, and rural background air was investigated using a combination of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Identification and quantification of gas and particulate reaction products were reported over the course of the reaction. The daytime photooxidation was carried out in a large outdoor smog chamber (190 m^3). A wide range of ring retaining and ring opening products in the gas and particle phase are reported. On average, measured gas and particle phase products accounted for ∼ 44% of the reacted α-humulene carbon. Measurements show that a number of reaction products with low vapor pressures (e.g. 3-seco-α-Humulone aldehyde, 7-seco-α-Humulone aldehyde, α-humulal aldehyde, α-humulene 3-oxide or α-humulene 7-oxide, α-humulaic/alic acid isomers, and 3-seco-α-14-hydroxyHumulone aldehyde) were found in the early stage of the reaction and may play an important role in the early formation of secondary organic aerosol. A detailed mechanism is proposed to account for most products observed in this investigation.
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Gas and Particulate Products Distribution from the Photooxidation of α-Humulene in the Presence of NOx, Natural Atmospheric Air and Sunlight
Journal of Atmospheric Chemistry, 2003Co-Authors: M. Jaoui, R. M. KamensAbstract:The photooxidation of α-humulene in the presence of NOx, natural sunlight, and rural background air was investigated using a combination of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Identification and quantification of gas and particulate reaction products were reported over the course of the reaction. The daytime photooxidation was carried out in a large outdoor smog chamber (190 m3). A wide range of ring retaining and ring opening products in the gas and particle phase are reported. On average, measured gas and particle phase products accounted for ∼ 44% of the reacted α-humulene carbon. Measurements show that a number of reaction products with low vapor pressures (e.g. 3-seco-α-Humulone aldehyde, 7-seco-α-Humulone aldehyde, α-humulal aldehyde, α-humulene 3-oxide or α-humulene 7-oxide, α-humulaic/alic acid isomers, and 3-seco-α-14-hydroxyHumulone aldehyde) were found in the early stage of the reaction and may play an important role in the early formation of secondary organic aerosol. A detailed mechanism is proposed to account for most products observed in this investigation.
Mikko Uusi-oukari - One of the best experts on this subject based on the ideXlab platform.
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Humulone Modulation of GABAA Receptors and Its Role in Hops Sleep-Promoting Activity.
Frontiers in neuroscience, 2020Co-Authors: Ali Y. Benkherouf, Kim Eerola, Sanna L. Soini, Mikko Uusi-oukariAbstract:Humulus lupulus L. (hops) is a major constituent of beer. It exhibits neuroactive properties that make it useful as a sleeping aid. These effects are hypothesized to be mediated by an increase in GABAA receptor function. In the quest to uncover the constituents responsible for the sedative and hypnotic properties of hops, recent evidence revealed that Humulone, a prenylated phloroglucinol derivative comprising 35-70% of hops alpha acids, may act as a positive modulator of GABAA receptors at low micromolar concentrations. This raises the question whether Humulone plays a key role in hops pharmacological activity and potentially interacts with other modulators such as ethanol, bringing further enhancement in GABAA receptor-mediated effects of beer. Here we assessed electrophysiologically the positive modulatory activity of Humulone on recombinant GABAA receptors expressed in HEK293 cells. We then examined Humulone interactions with other active hops compounds and ethanol on GABA-induced displacement of [3H]EBOB binding to native GABAA receptors in rat brain membranes. Using BALB/c mice, we assessed Humulone's hypnotic behavior with pentobarbital- and ethanol-induced sleep as well as sedation in spontaneous locomotion with open field test. We demonstrated for the first time that Humulone potentiates GABA-induced currents in α1β3γ2 receptors. In radioligand binding to native GABAA receptors, the inclusion of ethanol enhanced Humulone modulation of GABA-induced displacement of [3H]EBOB binding in rat forebrain and cerebellum as it produced a leftward shift in [3H]EBOB displacement curves. Moreover, the additive modulatory effects between Humulone, isoxanthohumol and 6-prenylnaringenin were evident and corresponded to the sum of [3H]EBOB displacement by each compound individually. In behavioral tests, Humulone shortened sleep onset and increased the duration of sleep induced by pentobarbital and decreased the spontaneous locomotion in open field at 20 mg/kg (i.p.). Despite the absence of Humulone effects on ethanol-induced sleep onset, sleep duration was increased dose-dependently down to 10 mg/kg (i.p.). Our findings confirmed Humulone's positive allosteric modulation of GABAA receptor function and displayed its sedative and hypnotic behavior. Humulone modulation can be potentially enhanced by ethanol and hops modulators suggesting a probable enhancement in the intoxicating effects of ethanol in hops-enriched beer.
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Hops compounds modulatory effects and 6-prenylnaringenin dual mode of action on GABAA receptors.
European journal of pharmacology, 2020Co-Authors: Ali Y. Benkherouf, Sanna L. Soini, Nora Logrén, Tamara Somborac, Maaria Kortesniemi, Baoru Yang, Outi M. H. Salo-ahen, Oskar Laaksonen, Mikko Uusi-oukariAbstract:Abstract Hops (Humulus lupulus L.), a major component of beer, contain potentially neuroactive compounds that made it useful in traditional medicine as a sleeping aid. The present study aims to investigate the individual components in hops acting as allosteric modulators in GABAA receptors and bring further insight into the mode of action behind the sedative properties of hops. GABA-potentiating effects were measured using [3H]ethynylbicycloorthobenzoate (EBOB) radioligand binding assay in native GABAA receptors. Flumazenil sensitivity of GABA-potentiating effects, [3H]Ro 15–4513, and [3H]flunitrazepam binding assays were used to examine the binding to the classical benzodiazepines site. Humulone (alpha acid) and 6-prenylnaringenin (prenylflavonoid) were the most potent compounds displaying a modulatory activity at low micromolar concentrations. Humulone and 6-prenylnaringenin potentiated GABA-induced displacement of [3H]EBOB binding in a concentration-dependent manner where the IC50 values for this potentiation in native GABAA receptors were 3.2 μM and 3.7 μM, respectively. Flumazenil had no significant effects on Humulone- or 6-prenylnaringenin-induced displacement of [3H]EBOB binding. [3H]Ro 15–4513 and [3H]flunitrazepam displacements were only minor with Humulone but surprisingly prominent with 6-prenylnaringenin despite its flumazenil-insensitive modulatory activity. Thus, we applied molecular docking methods to investigate putative binding sites and poses of 6-prenylnaringenin at the GABAA receptor α1β2γ2 isoform. Radioligand binding and docking results suggest a dual mode of action by 6-prenylnaringenin on GABAA receptors where it may act as a positive allosteric modulator at α+β- binding interface as well as a null modulator at the flumazenil-sensitive α+γ2- binding interface.
Klaus Kammhuber - One of the best experts on this subject based on the ideXlab platform.
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Biosynthetic experiments with tall plants under field conditions. 18O2 incorporation into Humulone from Humulus lupulus.
Phytochemistry, 2004Co-Authors: Stefan Hecht, Klaus Kammhuber, Adelbert Bacher, Josef Reiner, Wolfgang EisenreichAbstract:Abstract Five segments of a large hop plant ( Humulus lupulus var. Hallertauer Magnum) carrying several cones were enclosed in sealed glass vessels that were gassed with 18 O 2 . After 14 days, the segments were harvested and Humulone and coHumulone were analysed by NMR spectroscopy and mass spectroscopy. The oxygen atoms in position 6 of Humulone and coHumulone showed 9% 18 O enrichment, respectively. It follows that the C-6 hydroxy groups were introduced by oxygenase catalysis.
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Biosynthesis of bitter acids in hops
European journal of biochemistry, 1999Co-Authors: Markus Goese, Klaus Kammhuber, Adelbert Bacher, Meinhart H. Zenk, Wolfgang EisenreichAbstract:The biosynthesis of Humulone, an antibacterial bitter acid from hops, was studied by isotope-incorporation experiments using 13 C-labelled glucose or 2 H2O. 13 C enrichments, 2 H enrichments and 13 C 13 C coupling patterns identify isovaleryl-CoA, malonyl-CoA and dimethylallyl pyrophosphate as precursors for Humulone. Dimethylallyl pyrophosphate, which serves as a building block for the bitter acid, is generated via the deoxyxylulose pathway of terpenoid biosynthesis. The data confirm that a symmetrical intermediate is involved in Humulone formation.
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biosynthesis of bitter acids in hops a 13 c nmr and 2 h nmr study on the building blocks of Humulone
FEBS Journal, 1999Co-Authors: Markus Goese, Klaus Kammhuber, Adelbert Bacher, Meinhart H. Zenk, Wolfgang EisenreichAbstract:The biosynthesis of Humulone, an antibacterial bitter acid from hops, was studied by isotope-incorporation experiments using 13 C-labelled glucose or 2 H2O. 13 C enrichments, 2 H enrichments and 13 C 13 C coupling patterns identify isovaleryl-CoA, malonyl-CoA and dimethylallyl pyrophosphate as precursors for Humulone. Dimethylallyl pyrophosphate, which serves as a building block for the bitter acid, is generated via the deoxyxylulose pathway of terpenoid biosynthesis. The data confirm that a symmetrical intermediate is involved in Humulone formation.