Humulone

Source: Wikipedia, the free encyclopedia.
Not to be confused with humulene.
Humulone
Names
Preferred IUPAC name
(6S)-3,5,6-Trihydroxy-2-(3-methylbutanoyl)-4,6-bis(3-methylbut-2-en-1-yl)cyclohexa-2,4-dien-1-one[1]
Other names
α-Lupulic acid; α-Bitter acid
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.043.371 Edit this at Wikidata
UNII
  • InChI=1S/C21H30O5/c1-12(2)7-8-15-18(23)17(16(22)11-14(5)6)20(25)21(26,19(15)24)10-9-13(3)4/h7,9,14,23-24,26H,8,10-11H2,1-6H3/t21-/m1/s1
  • O=C(\C1=C(/O)\C(=C(\O)[C@](O)(C1=O)C\C=C(/C)C)C\C=C(/C)C)CC(C)C
Properties
C21H30O5
Molar mass 362.466 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Humulone (α-lupulic acid), a

bitter-tasting chemical compound found in the resin of mature hops (Humulus lupulus).[2] Humulone is a prevalent member of the class of compounds known as alpha acids
, which collectively give hopped beer its characteristic bitter flavor.

Chemistry

In terms of structure, humulone is a

isoprenoid side-chains. Two side-chains are prenyl groups and one is an isovaleryl group. The acidity of the ring enol moieties that give rise to its designation as an acid lie in their vinylogous relationship with the ring and side chain carbonyl functional groups.[citation needed
]

Isohumulone

Main article: Isohumulone

During the brewing process, humulone degrades to cis- and trans-isohumulone.[1] These “alpha acids” survive the boiling process, although numerous oxidized derivatives are produced.[3] The iso-alpha acids are significantly more soluble than humulone at the pH levels typically present in the brewing process.[4]

Degradation of humulone to cis- and trans-isohumulone
Degradation of humulone to cis- and trans-isohumulone

Laboratory synthesis

Humulone can be synthesized by the acylation of benzene-1,2,3,5-tetrol with isovaleryl chloride to give 2,3,4,6-tetrahydroxyisovalerophenone. This step is followed by prenylation with 1-bromo-3-methyl-2-butene to give humulone.[5]

Synthesis of humulone from benzene-1,2,3,5-tetrol

Biosynthesis

As determined by

INADEQUATE 2D NMR, the biosynthesis of humulone in Humulus lupulus starts with an isovaleryl-CoA unit and 3 malonyl-CoA units catalyzed by phlorovalerophenone synthase. This conversion yields the benzenoid 3-methyl-1-(2,4,6-trihydroxyphenyl)butan-1-one. Dimethylallyl pyrophosphate is then obtained from the deoxyxylulose pathway, where prenylation of the benzenoid occurs, yielding humulone.[6]

isovaleryl-CoA + 3 malonyl-CoA → 4 CoASH + 3 CO2 + 3-methyl-1-(2,4,6-trihydroxyphenyl)butan-1-one
3-methyl-1-(2,4,6-trihydroxyphenyl)butan-1-one + 2 DMAPP →C21H30O5

Research

Humulone is under

antibacterial effects.[9]

References

  1. ^
    PMID 23239507
    .
  2. PMID 12848522
    .
  3. doi:10.1016/j.tifs.2005.11.012
    .
  4. doi:10.1002/14356007.a03_421
  5. doi:10.1246/bcsj.62.3034
    .
  6. PMID 10406953
    .
  7. PMID 33177986
    .
  8. PMID 32001220
    .
  9. PMID 19201179
    .
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