Urolithin A

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Urolithin A
Chemical structure of urolithin A
Names
Preferred IUPAC name
3,8-Dihydroxy-6H-dibenzo[b,d]pyran-6-one
Other names
Uro-A
Identifiers
3D model (
JSmol
)
ChEMBL
ChemSpider
DrugBank
KEGG
UNII
  • InChI=1S/C13H8O4/c14-7-1-3-9-10-4-2-8(15)6-12(10)17-13(16)11(9)5-7/h1-6,14-15H
    Key: RIUPLDUFZCXCHM-UHFFFAOYSA-N
  • InChI=1/C13H8O4/c14-7-1-3-9-10-4-2-8(15)6-12(10)17-13(16)11(9)5-7/h1-6,14-15H
    Key: RIUPLDUFZCXCHM-UHFFFAOYAT
  • Oc1ccc2c3ccc(O)cc3OC(=O)c2c1
Properties
C13H8O4
Molar mass 228.203 g·mol−1
Melting point 17
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Urolithin A is a metabolite compound resulting from the transformation of ellagitannins by the gut bacteria.[1] It belongs to the class of organic compounds known as benzo-coumarins or dibenzo-α-pyrones. Its precursors – ellagic acids and ellagitannins – are ubiquitous in nature, including edible plants, such as pomegranates, strawberries, raspberries, walnuts, and others.[2]

Urolithin A is not known to be found in any food source. Its bioavailability mostly depends on individual microbiota composition, as only some bacteria are able to convert ellagitannins into urolithins.[3]

Chemistry

Urolithin A belongs to the class of organic compounds known as benzo-coumarins or dibenzo-α-pyrones. These are polycyclic aromatic compounds containing a 1-benzopyran moiety with a ketone group at the C2 carbon atom (1-benzopyran-2-one).

Biochemistry and metabolism

For Gordonibacter, see Eggerthellaceae.

hydroxyl groups.[7]

While studies have shown that Gordonibacter urolithinfaciens and Gordonibacter pamelaeae play a role in the conversion of ellagic acids and ellagitannins into urolithin A, the microorganisms responsible for the complete transformation into the final urolithins are still unknown.[3] The efficiency of the conversion of ellagitannins into urolithin A significantly varies in humans, and some individuals do not show any conversion.[8]

When synthesized and absorbed in the intestines, urolithin A enters the systemic circulation where it becomes available to tissues throughout the body where it is further subjected to additional chemical transformations (including glucuronidation, methylation, sulfation, or a combination of them) within the enterocytes and hepatocytes.[9] Urolithin A and its derivatives - urolithin A glucuronide and urolithin A sulfate being most abundant - release into the circulation, before being excreted in the urine.[10]

Safety

In vivo studies did not determine any toxicity or specific adverse effects following dietary intake of urolithin A.[11] Safety studies in elderly humans indicated urolithin A was well tolerated.[12] In 2018, the US Food and Drug Administration listed urolithin A as a safe ingredient for food or dietary supplement products having content in the range of 250 mg to one gram per serving.[13]

Dietary sources

Urolithin A is not known to be found in any food but rather forms as the result of transformation of ellagic acids and ellagitannins by the gut microflora in humans.[citation needed] Sources of ellagitannins are: pomegranates, nuts, some berries (raspberries, strawberries, blackberries, cloudberries), tea, muscadine grapes, many tropical fruits, and oak-aged wines (table below).

The conversion of the ellagic acids into urolithin A depends on individual microflora composition and can vary significantly.[8][14]

Dietary source Ellagic Acid[15]
Fruits (mg/100g fresh weight)
Blackberries 150
Black raspberries 90
Boysenberries 70
Cloudberries 315.1
Pomegranate 269.9[16]
Raspberries 270
Rose hip 109.6
Strawberries 77.6
Strawberry jam 24.5
Yellow raspberries 1900
Nuts (mg/g)
Pecans 33
Walnuts 59
Beverages (mg/L)
Pomegranate juice 811.1[16]
Cognac 31-55
Oak-aged red wine 33
Whiskey 1.2
Seeds (mg/g)
Black raspberries 6.7
Red raspberries 8.7
Boysenberries 30
Mango 1.2

See also

References

  1. S2CID 5387712
    .
  2. PMID 15656654
    .
  3. ^
    PMID 28824607
    .
  4. PMID 22129380
    .
  5. S2CID 19611576
    .
  6. PMID 26475039
    .
  7. PMID 23781257
    .
  8. ^
    PMID 27158799
    .
  9. S2CID 43139238
    .
  10. PMID 22126674
    .
  11. PMID 28757461
    .
  12. PMC 6183836
    .
  13. ^ "FDA GRAS notice GRN No. 791: urolithin A". US Food and Drug Administration. 20 December 2018. Retrieved 25 August 2020.
  14. PMID 26597167
    .
  15. doi:10.1016/j.foodres.2011.04.027
    .
  16. ^
    PMID 26341594
    .

External links
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