6‐Hydroxycolupulon und 5‐(3‐Methyl‐2‐butenyl)isocohumulon, zwei neue Umwandlungsprodukte aus Colupulon

Reininger, W.

doi:10.1002/cber.19731060428

Cited by 10 publications

(3 citation statements)

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“…4-Hydroxycolupulone ( 6 ) has been reported in the literature already as a synthetic product, but only a fragmentary NMR characterization was provided . To the best of our knowledge, this is the first report of 4-hydroxycolupulone from a natural source.…”

Section: Results and Discussionmentioning

confidence: 99%

Humudifucol and Bioactive Prenylated Polyphenols from Hops (Humulus lupulus cv. “Cascade”)

et al. 2016

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Humulus lupulus (hop plant) has long been used in traditional medicine as a sedative and antimicrobial agent. More recently, attention has been devoted to the phytoestrogenic activity of the plant extracts as well as to the anti-inflammatory and chemopreventive properties of the prenylated chalcones present. In this study, an Italian sample of H. lupulus cv. "Cascade" has been investigated and three new compounds [4-hydroxycolupulone (6), humudifucol (7) and cascadone (8)] have been purified and identified by means of NMR spectroscopy along with four known metabolites. Notably, humudifucol (7) is the first prenylated dimeric phlorotannin discovered in nature. Because structurally related phloroglucinols from natural sources were found previously to inhibit microsomal prostaglandin E2 synthase (mPGES)-1 and 5-lipoxygenase (5-LO), the isolated compounds were evaluated for their bioactivity against these pro-inflammatory target proteins. The prenylated chalcone xanthohumol inhibited both enzymes at low μM concentrations.

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Section: Results and Discussionmentioning

confidence: 99%

Humudifucol and Bioactive Prenylated Polyphenols from Hops (Humulus lupulus cv. “Cascade”)

et al. 2016

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“…Giving peculiar, alkylated isohumulone derivatives, this reaction appears highly efficient in a buffered environment. 20,43 The radical decay of humulones is obvious but most likely differs from the lupulones process as concluded from the varying radical patterns and concentrations observed with both substrates. 25 This observation reflects in final product formation, where humulinones, as most known oxidation products from humulones, indeed are formed from another pathway than the transformation of lupulones to hulupones.…”

Section: ■ Discussionmentioning

confidence: 99%

“…The selectivity for route B to hulupones is not absolute, however, because indeed an alternative Norrish-type reaction (after tautomerization) may occur. Giving peculiar, alkylated isohumulone derivatives, this reaction appears highly efficient in a buffered environment. , …”

Section: Discussionmentioning

confidence: 99%

Radical Intermediates in the Degradation of Hop Acids

Berton¹,

Verbeke

Durme

et al. 2021

J. Agric. Food Chem.

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Radical formation in isohumulones was investigated under different types of stress, including temperature, transition metal ions, and hydrogen peroxide. Including dihydroisohumulones and tetrahydroisohumulones, as relevant analogues, allowed us to evaluate critical functionalities in radical formation. Using spin-trapping methodology with 5,5-dimethyl-1-pyrroline N-oxide and N-tert-butyl-α-phenylnitrone as relevant traps, followed by simulation of corresponding spin adducts, identification of incipient radicals was attempted. The isohexenoyl side chain in isohumulones, but not present in dihydro- and tetrahydroisohumulones, was most sensitive to radical formation. Kinetic profiles further demonstrated that radical formation in this moiety was accelerated in the presence of ferrous ions. Reactivity of parent six-membered-ring humulones in radical formation was different, as scavenging of free radical species was more important. Lupulones, despite similarity with humulones, showed a different behavior with an obvious radical decay pathway during ageing, mainly ascribed to radical formation on the ring structure. Quantification of final spin adducts allowed us to determine absolute importance of the different degradation pathways. Eventually, mechanisms are presented explaining why isohumulones are more prone to radical processes in (aut)oxidation and thermal decay than close relatives such as dihydroisohumulones.

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Oxidation products of hop bitter acids. Part VII. A further five‐membered ring product from the oxidation of colupulone

Bossche

Anteunis

Verzele

1974

Bulletin des Soc Chimique

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Oxidation of colupulone (I) produces a complex mixture, separation of which by counter current distribution gives the spiro compound IV. Support for this structure comes mainly from 'H-N.M.R. and mass spectral data.In a previous paper' we discusseG the cyclopenta /4,5-bl furan-(11) and cyclopenta I4,5-bl pyran(II1) derivatives. They were separated from the oxidation mixture of colupulone by counter current distribution (CCD) with a buffer of pH 1.90 as lower phase and iso-octane as upper phase. We now report the isolation and identification of another five-membered ring oxidation product of colupulone i.e. 5,5-bis(3-methylbut-2-enyl)-3-isobutyrylcyclopentan-2,4-dionespiro-ZH-furan-5'-one (IV) . 3.6 and all six membered hop bitter compounds proton b at 6 > 3.65 (in CC14) is given in reference 1. -

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6‐Hydroxycolupulon und 5‐(3‐Methyl‐2‐butenyl)isocohumulon, zwei neue Umwandlungsprodukte aus Colupulon

Cited by 10 publications

References 0 publications

Humudifucol and Bioactive Prenylated Polyphenols from Hops (Humulus lupulus cv. “Cascade”)

Humudifucol and Bioactive Prenylated Polyphenols from Hops (Humulus lupulus cv. “Cascade”)

Radical Intermediates in the Degradation of Hop Acids

Oxidation products of hop bitter acids. Part VII. A further five‐membered ring product from the oxidation of colupulone

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