The Chemistry of Hop Constituents

Stevens, Roger

doi:10.1021/cr60245a002

Cited by 121 publications

(73 citation statements)

References 203 publications

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“…It is in the lupulin glands of the female hop cone that the main brewing principles, the resins and the essential oils, are synthesized . The characteristic resins of hops include many substances; Hayduck originally separated the hop resins into α ‐, β ‐ and γ ‐fractions on the basis of their solubility in different solvents and their ability to form a precipitate with lead acetate .…”

Section: Hop Chemistrymentioning

confidence: 99%

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Humulus lupulus- a story that begs to be told. A review

Schönberger²,

et al. 2014

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The hop cones of the female plant of the common hop species Humulus lupulus L. are grown almost exclusively for the brewing industry. Only the cones of the female plants are able to secrete the fine yellow resinous powder (i.e. lupulin glands). It is in these lupulin glands that the main brewing principles of hops, the resins and essential oils, are synthesized and accumulated. Hops are of interest to the brewer since they impart the typical bitter taste and aroma to beer and are responsible for the perceived hop character. In addition to the comfortable bitterness and the refreshing hoppy aroma delivered by hops, the hop acids also contribute to the overall microbial stability of beer. Another benefit of the hop resins is that they help enhance and stabilize beer foam and promote foam lacing. In an attempt to understand these contributions, the very complex nature of the chemical composition of hops is reviewed. First, a general overview of the hop chemistry and nomenclature is presented. Then, the different hop resins found in the lupulin glands of the hop cones are discussed in detail. The major hop bitter acids (α-and β-acids) and the latest findings on the absolute configuration of the cis and trans iso-α-acids are discussed. Special attention is given to the hard resins; the known δ-resin is reviewed and the ε-resin is introduced. Recent data on the bittering potential and the antimicrobial properties of both hard resin fractions are disclosed. Attention is also given to the numerous essential oil constituents as well as their contributions to beer aroma. In addition to the aroma contribution of the well-known essential oil compounds, a number of recently identified sulfur compounds and their impact on beer aroma are reviewed. The hop polyphenols and their potential health benefits are also addressed. Subsequently, the importance of hops in brewing is examined and the contributions of hops to beer quality are explained. Finally, the beer and hop market of the last century, as well as the new trends in brewing, are discussed in detail. Hop research is an ever growing field of central importance to the brewing industry, even in areas that are not traditionally associated with hops and brewing. This article attempts to give a general overview of the different areas of hop research while assessing the latest advances in hop science and their impact on brewing.

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Section: Hop Chemistrymentioning

confidence: 99%

“…β ‐Myrcene is the main component responsible for imparting the pungent smell to fresh hops . Other monoterpenes present in the hop oil fraction in significantly lower amounts are ocimene, β ‐pinene, limonene and ρ ‐cymene, among others .…”

Section: Hop Essential Oilsmentioning

confidence: 99%

Humulus lupulus- a story that begs to be told. A review

Schönberger²,

et al. 2014

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“…These so-called ortho-quinols constitute the main structural element of the architecture of many natural products such as humulone (86) and its congeners, 92,93 wasabidienones 87/88 94,95 and related fungal metabolites such as aspersitin (89), 96 as well as the polyketide sorbicillinol (90) Several other natural products feature bicyclo[2.2.2]octane systems that can be synthetically derived from the Diels-Alder cyclodimerization of ortho-quinols. The bis(monoterpene) biscarvacrol (92), 101 the shikimate-derived grandifloracin (93), 102 the bis(sesquiterpenes) aquaticol (94) 103 and bacchopetiolone (95), 104 the polyketide bisorbicillinol (96), 105 the bis(diterpene) maytenone (97) 106 and the bis(dinorditerpene) hugonone A (98), 107 shown in Figure 6, are just a few illustrative examples of these natural products, whose retrosynthetic analysis at once reveals an ortho-quinol route for their construction. It is then obviously tempting to propose that these natural products are biosynthetically derived from ortho-quinol intermediates, themselves generated by some enzymatic hydroxylative dearomatization of phenolic precursors.…”

Section: Scheme 27mentioning

confidence: 99%

Oxidative Dearomatization of Phenols: Why, How and What For?

Quideau¹,

Pouységu²,

Deffieux³

2008

Synlett

438

122

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“…Hops extracts are currently marketed as a source of phytoestrogens to alleviate menopausal symptoms and as an alternative to hormone replacement therapy (Bowe et al, 2006; Milligan et al, 2002; Milligan et al, 1999; Milligan et al, 2000), and have also been applied to treating insomnia and anxiety (Hoffmann, 2003). In addition to plant fibrous material and proteins, hops contain a number of small molecules including volatile oils, flavonoids, and, primarily, the so-called bitter resins or acids, which comprise 12–15% of all components (Stevens, 1967). Bitter acids have exhibited several antineoplastic properties, including inhibition of tumor transition to malignancy (Chen and Lin, 2004).…”

mentioning

confidence: 99%

Structural Basis of Human Pregnane X Receptor Activation by the Hops Constituent Colupulone

Teotico¹,

Bischof²,

Li³

et al. 2008

Mol Pharmacol

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Hops extracts are used to alleviate menopausal symptoms and as an alternative to hormone replacement therapy, but they can produce potentially harmful drug-drug interactions. The nuclear xenobiotic receptor pregnane X receptor (PXR) is promiscuously activated by a range of structurally distinct chemicals. It has a key role in the transcriptional regulation of genes that encode xenobiotic metabolism enzymes. In this study, hops extracts are shown to induce the expression of numerous drug metabolism and excretion proteins. The ␤-bitter acid colupulone is demonstrated to be a bioactive component and direct activator of human PXR. The 2.8-Å resolution crystal structure of the ligand binding domain of human PXR in complex with colupulone was elucidated, and colupulone was observed to bind in a single orientation stabilized by both van der Waals and hydrogen bonding contacts. The crystal structure also indicates that related ␣-and ␤-bitter acids have the capacity to serve as PXR agonists as well. Taken together, these results reveal the structural basis for drug-drug interactions mediated by colupulone and related constituents of hops extracts.

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The Chemistry of Hop Constituents

Cited by 121 publications

References 203 publications

Humulus lupulus- a story that begs to be told. A review

Humulus lupulus- a story that begs to be told. A review

Oxidative Dearomatization of Phenols: Why, How and What For?

Structural Basis of Human Pregnane X Receptor Activation by the Hops Constituent Colupulone

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