Not to be confused with aescin, a saponin also found in horse chestnut.
IUPAC name
7-hydroxy-6-{[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy- 6-(hydroxymethyl)-2-tetrahydropyranyl]oxy}-2-chromenone
Other names
Esculetin 6-β-D-glucoside
6,7-dihydroxycoumarin 6-β-D-glucoside
6,7-dihydroxychromen-2-one 6-β-D-glucoside
531-75-9 YesY
3D model (Jmol) Interactive image
ChEMBL ChEMBL482581 YesY
ChemSpider 4444765 YesY
ECHA InfoCard 100.007.744
PubChem 5281417
Molar mass 340.282 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Aesculin, also rendered Æsculin or Esculin, is a coumarin glucoside that naturally occurs in the horse chestnut (Aesculus hippocastanum),[1] California buckeye (Aesculus californica),[2] Prickly Box (Bursaria spinosa) and in daphnin (the dark green resin of Daphne mezereum). It is also found in dandelion coffee.

Medical uses

As medication, aesculin is sometimes used as a vasoprotective agent.[3]

Aesculin is also used in a microbiology laboratory to aid in the identification of bacterial species (especially Enterococci and Listeria). In fact, all strains of Group D Streptococci hydrolyze æsculin in 40% bile.

Aesculin hydrolysis test

Aesculin is incorporated into agar with ferric citrate and bile salts (bile aesculin agar).[4] Hydrolysis of the aesculin forms aesculetin (6,7-dihydroxycoumarin) and glucose. The aesculetin forms dark brown or black complexes with ferric citrate, allowing the test to be read.

The bile aesculin agar is streaked and incubated at 37 °C for 24 hours. The presence of a dark brown or black halo indicates that the test is positive. A positive test can occur with Enterococcus, Aerococcus and Leuconostoc. Aesculin will fluoresce under long wave ultraviolet light (360 nm): hydrolysis of aesculin results in loss of this fluorescence.

Enterococcus will often flag positive within four hours of the agar being inoculated.

UV visible spectrum of esculin with a maximum of absorbance at 346 nm


Aesculin ingestion can produce stomachache, spasms, diarrhea, disorientation and even death at high doses.


  1. Plant poisons: Aesculin
  2. C. Michael Hogan, 2008
  3. Esculin. Retrieved 11 June 2016.
  4. National Standard Methods (UK)


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