Radicaloid‐Type Oxidative Decomposition Of Beer Bittering Agents Revealed

Huvaere, Kevin; Andersen, Mogens L.; Olsen, Karsten; Skibsted, Leif H.; Heyerick, Arne; Keukeleire, Denis De

doi:10.1002/chem.200305050

Cited by 37 publications

(39 citation statements)

References 22 publications

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“…Some of these compounds have been detected in the flowers of the hops plant ( Humulus lupulus L.), which are used primarily for flavoring and preserving beer (Huvaere et al, 2003). Due to the resemblance to other plant-derived antioxidants and ability to inhibit CYPs that activate carcinogens, hops constituents have been studied for their chemopreventive properties.…”

Section: Inhibition Of Intestinal Biochemical Processesmentioning

confidence: 99%

Mechanisms underlying food–drug interactions: Inhibition of intestinal metabolism and transport

Won

Oberlies

Paine

2012

Pharmacology & Therapeutics

118

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Food-drug interaction studies are critical to evaluate appropriate dosing, timing, and formulation of new drug candidates. These interactions often reflect prandial-associated changes in the extent and/or rate of systemic drug exposure. Physiologic and physicochemical mechanisms underlying food effects on drug disposition are well-characterized. However, biochemical mechanisms involving drug metabolizing enzymes and transport proteins remain underexplored. Several plant-derived beverages have been shown to modulate enzymes and transporters in the intestine, leading to altered pharmacokinetic (PK) and potentially negative pharmacodynamic (PD) outcomes. Commonly consumed fruit juices, teas, and alcoholic drinks contain phytochemicals that inhibit intestinal cytochrome P450 and phase II conjugation enzymes, as well as uptake and efflux transport proteins. Whereas myriad phytochemicals have been shown to inhibit these processes in vitro, translation to the clinic has been deemed insignificant or undetermined. An overlooked prerequisite for elucidating food effects on drug PK is thorough knowledge of causative bioactive ingredients. Substantial variability in bioactive ingredient composition and activity of a given dietary substance poses a challenge in conducting robust food-drug interaction studies. This confounding factor can be addressed by identifying and characterizing specific components, which could be used as marker compounds to improve clinical trial design and quantitatively predict food effects. Interpretation and integration of data from in vitro, in vivo, and in silico studies require collaborative expertise from multiple disciplines, from botany to clinical pharmacology (i.e., plant to patient). Development of more systematic methods and guidelines is needed to address the general lack of information on examining drug-dietary substance interactions prospectively.

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Section: Inhibition Of Intestinal Biochemical Processesmentioning

confidence: 99%

Mechanisms underlying food–drug interactions: Inhibition of intestinal metabolism and transport

Won

Oberlies

Paine

2012

Pharmacology & Therapeutics

118

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“…In recent years, some storage-induced changes in the fraction of volatile aroma compounds have been successfully characterized and the corresponding off-flavor compounds identified. [3][4][5] In particular, photodegradation [6] and radical-assisted oxidation of iso-a-acids [7] are generally accepted to be responsible for the generation of potent off-odor compounds, but the available information on nonvolatile off-taste is rather fragmentary. Although aging of beer has long been known to induce a significant decrease in the intensity of the bitterness as well as a change of the bitter taste quality towards a long-lasting, lingering, and harsh bitterness and, in consequence, continues to cause severe quality problems for the brewing industry, [8][9][10] the molecular basis of the deterioration of that bitterness is not known.…”

Section: Introductionmentioning

confidence: 99%

Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

Intelmann

Kummerlöwe

Haseleu

et al. 2009

Chemistry A European J

108

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Besides undesirable changes in the attractive aroma, a significant decrease in the intensity of the bitterness as well as a change of the taste into a lingering, harsh bitterness has long been known as a shelf-life limiting factor of beer. Multiple studies have demonstrated that the aging of beer induces a decrease of the total amount of cis- and trans-iso-alpha-acids, the well-known bitter principles of beer. Although the trans-iso-alpha-acids exclusively, not the cis-iso-alpha-acids, were found to be degraded upon storage of beer, the key transformation products formed exclusively from the trans isomers in beer are not known. In the present study, suitable model experiments followed by LC-MS/MS and sophisticated NMR spectroscopic experiments, including the measurement of residual dipolar couplings (RDCs) in gel-based alignment media as well as a novel broadband and B(1)-field-compensated incredible natural abundance double-quantum transfer experiment (INADEQUATE) pulse sequence, enabled the identification of a series of previously unknown trans-specific iso-alpha-acid transformation products, namely, tricyclocohumol, tricyclocohumene, isotricyclocohumene, tetracyclocohumol, and epitetracyclocohumol, respectively. HPLC-MS/MS analysis of these compounds, which exhibit the aforementioned harsh lingering bitter taste and have threshold concentrations ranging from 5 to 70 micromol L(-1), confirmed their generation during aging of beer and, for the first time, explained the storage-induced changes of the beer's bitter taste on a molecular level.

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“…29 Reaction with molecular oxygen leads to the formation of the corresponding hydroperoxy radical. After abstraction of hydrogen, the hydroperoxide undergoes a Fenton-like redox reaction to form the alkoxy radical and subsequently the alcohol after a second abstraction of hydrogen.…”

Section: ■ Discussionmentioning

confidence: 99%

Oxidation of Isohumulones Induces the Formation of Carboxylic Acids by Hydrolytic Cleavage

Rakete

Berger

Böhme

et al. 2014

J. Agric. Food Chem.

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The degradation of isohumulones in mechanistic experiments was investigated. Incubation of trans-isohumulone in the presence of l-proline led to the formation of carboxylic acids and their corresponding proline amides. In the context of isohumulones unknown amides were verified first in model incubations and then in beer for the first time by comparison with authentic reference standards via LC-MS analyses. Carboxylic acids and amides were formed preferably under oxidative conditions and increasing pH. Stable isotope experiments excluded the incorporation of molecular oxygen into carboxylic acids, strongly indicating a hydrolytic mechanism via β-dicarbonyl cleavage. The proposed mechanism includes oxidation and thereby incorporation of molecular oxygen to the isohumulone ring structure followed by hydrolytic cleavage leading to acids and amides.

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Radicaloid‐Type Oxidative Decomposition Of Beer Bittering Agents Revealed

Cited by 37 publications

References 22 publications

Mechanisms underlying food–drug interactions: Inhibition of intestinal metabolism and transport

Mechanisms underlying food–drug interactions: Inhibition of intestinal metabolism and transport

Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

Oxidation of Isohumulones Induces the Formation of Carboxylic Acids by Hydrolytic Cleavage

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