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|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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Aesculin, also rendered Æsculin or Esculin, is a coumarin glucoside that naturally occurs in the horse chestnut (Aesculus hippocastanum), California Buckeye (Aesculus californica), Prickly Box (Bursaria spinosa) and in daphnin (the dark green resin of Daphne mezereum). It is also found in dandelion coffee.
Aesculin is 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). 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.
- Plant poisons: Aesculin]
- C. Michael Hogan, 2008
- National Standard Methods (UK)
- Plant poisons: Aesculin
- National Standard Methods MSOP 48 (Bile aesculin agar) and BSOPTP 2 (Aesculin hydrolysis test (UK)).
- C. Michael Hogan (2008) California Buckeye: Aesculus californica, GlobalTwitcher.com, N. Stromberg ed.