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Aesculin

Not to be confused with aescin, a saponin also found in horse chestnut.
Aesculin
Names
IUPAC name
6-(β-D-Glucopyranosyloxy)-7-hydroxy-2H-1-benzopyran-2-one
Systematic IUPAC name
7-Hydroxy-6-{[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}-2H-1-benzopyran-2-one
Other names
  • Æsculin
  • Esculin
  • Esculetin 6-β-D-glucoside
  • 6,7-Dihydroxycoumarin 6-β-D-glucoside
  • 6,7-Dihydroxychromen-2-one 6-β-D-glucoside
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.007.744 Edit this at Wikidata
EC Number
  • 208-517-5
KEGG
UNII
  • InChI=1S/C15H16O9/c16-5-10-12(19)13(20)14(21)15(24-10)23-9-3-6-1-2-11(18)22-8(6)4-7(9)17/h1-4,10,12-17,19-21H,5H2/t10-,12-,13+,14-,15-/m1/s1 checkY
    Key: XHCADAYNFIFUHF-TVKJYDDYSA-N checkY
  • InChI=1/C15H16O9/c16-5-10-12(19)13(20)14(21)15(24-10)23-9-3-6-1-2-11(18)22-8(6)4-7(9)17/h1-4,10,12-17,19-21H,5H2/t10-,12-,13+,14-,15-/m1/s1
    Key: XHCADAYNFIFUHF-TVKJYDDYBL
  • O=C/3Oc2c(cc(O[C@@H]1O[C@@H]([C@@H](O)[C@H](O)[C@H]1O)CO)c(O)c2)\C=C\3
Properties
C15H16O9
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).
checkY verify (what is checkY☒N ?)

Aesculin, also called æsculin or esculin, is a coumarin glucoside that naturally occurs in the trees horse chestnut (Aesculus hippocastanum),[1] California buckeye (Aesculus californica),[2] prickly box (Bursaria spinosa), and daphnin (the dark green resin of Daphne mezereum). It is also found in dandelion coffee and olive bark.[3] It is reported to present in olive bark, not in olive leaf, therefore, identification of aesculin (coumarin derivative) in abundance in an extract indicates that the extract has been derived from olive bark.[3]

Uses

[edit]

Aesculin is also used in a microbiology laboratory to aid in the identification of bacterial species (especially Enterococci and Listeria[4]). In fact, all strains of Group D Streptococci hydrolyze æsculin in 40% bile.

Aesculin hydrolysis test

[edit]

Aesculin is incorporated into agar with ferric citrate and bile salts (bile aesculin agar).[5] Hydrolysis of aesculin forms aesculetin (6,7-dihydroxycoumarin) and glucose. 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 (99 °F) 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) and 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 aesculin with a maximum of absorbance at 346 nm

References

[edit]
  1. ^ "Plant poisons: Aesculin". University of Bristol. Retrieved July 17, 2018.
  2. ^ C. Michael Hogan (2008) California Buckeye: Aesculus californica, GlobalTwitcher.com, N. Stromberg ed.
  3. ^ a b Lo Giudice, V.; Faraone, I.; Bruno, M. R.; Ponticelli, M.; Labanca, F.; Bisaccia, D.; Massarelli, C.; Milella, L.; Todaro, L. (2021). "Olive Trees By-Products as Sources of Bioactive and Other Industrially Useful Compounds: A Systematic Review". Molecules (Basel, Switzerland). 26 (16): 5081. doi:10.3390/molecules26165081. PMC 8399450. PMID 34443669.
  4. ^ Hussain Qadri, S. M.; Smith, Janet C.; Zubairi, Sabiha; Desilva, M. I. (1981). "Esculin hydrolysis by gram positive bacteria". Medical Microbiology and Immunology. 169 (2): 67–74. doi:10.1007/BF02171773. PMID 6783825. S2CID 21361418.
  5. ^ National Standard Methods MSOP 48 (Bile aesculin agar) and BSOPTP 2 (Aesculin hydrolysis test (UK))