Xanthohumol
Chemical compound
From Wikipedia, the free encyclopedia
Xanthohumol is a natural product found in the female inflorescences of Humulus lupulus, also known as hops. This compound is also found in beer and belongs to a class of compounds that contribute to the bitterness and flavor of hops.[2] Xanthohumol is a prenylated chalconoid, biosynthesized by a type III polyketide synthase (PKS) and subsequent modifying enzymes.[3][4]
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| Preferred IUPAC name
(E)-1-[2,4-dihydroxy-6-methoxy-3-(3-methylbut-2-enyl)phenyl]-3-(4-hydroxyphenyl)prop-2-en-1-one | |
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| ECHA InfoCard | 100.123.285 |
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CompTox Dashboard (EPA) |
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| Properties | |
| C21H22O5 | |
| Molar mass | 354.402 g·mol−1 |
| Density | 1.24 g/cm3[1] |
| Melting point | 157–159 °C (315–318 °F; 430–432 K)[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Biosynthesis
Xanthohumol is a prenylated chalconoid derived from a plant type III PKS, and is synthesized in the glandular trichromes of hop cones.[2] L-Phenylalanine serves as the starting material, which is converted to cinnamic acid by the PLP-dependent phenylalanine ammonia lyase.[5][6] Cinnamic acid is oxidized by cinnamate-4-hydroxylase and loaded onto coenzyme A (CoA) by 4-coumarate CoA ligase to yield 4-hydroxy-cinnamoyl CoA, the starter unit for PKS extension.[5][6] This molecule is extended three times with malonyl CoA, cyclized through a Claisen condensation, and aromatized through tautomerization to form naringenin chalcone (chalconaringenin).[5] This intermediate has the potential to form a variety of different products depending on the enzymes that modify the core structure.[2][5] In the case of xanthohumol, a prenyltransferase called Humulus lupulus prenyltransferase 1 (HlPT-1) attaches a molecule of dimethylallyl pyrophosphate from the DXP pathway.[7] HlPT-1 has a broad substrate specificity and also participates in making other prenylated flavonoids in the hop plant.[7] Finally, an O-methyltransferase methylates a phenol substituent using S-adenosyl methionine.[6] Total syntheses of xanthohumol and derivatives have been achieved, though extraction from hops remains a primary source.[8][9]
Beer
In commercial beers, the concentration of xanthohumol ranges from about 2 μg/L – 1.2 mg/L.[10] During the brewing process, xanthohumol and other prenylated flavonoids are lost as they are converted to the corresponding flavanones.[11] Different hop varieties and different beers contain varying quantities of xanthohumol.[2]
Research
Xanthohumol is under basic research for its potential biological properties.[10] Xanthohumol can be extracted with pressurized hot water.[12] Xanthohumol may have potential as a killer of bladder cancer.[13]
See also
- Isobavachalcone, a closely related prenylated chalconoid
- Isoxanthohumol, the corresponding prenylated flavanone
- 8-Prenylnaringenin, a related prenylflavanoid with estrogenic activity
- Alpha acids, a class of bitter compounds in hops
- Myrcene, humulene, and caryophyllene, essential oils in hops