materials in their standard state
(at 25 °C, 100 kPa)
Infobox references
| Aesculin | |
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| IUPAC name | 7-hydroxy-6-{[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy- 6-(hydroxymethyl)-2-tetrahydropyranyl]oxy}-2-chromenone |
| Identifiers | |
| CAS number | 531-75-9 |
| PubChem | |
| SMILES |
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| Properties | |
| Molecular formula | C15H16O9 |
| Molar mass | 340.282 g/mol |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Aesculin is a glucoside that naturally occurs in the horse chestnut (Aesculus hippocastanum),[1] California Buckeye (Aesculus californica)[2] and in daphnin (the dark green resin of Daphne mezereum).
Contents |
Aesculin is used in a microbiology laboratory to aid in the identification of bacterial species (especially Enterococci).
Aesculin is incorporated into agar with ferric citrate and bile salts (bile aesculin agar).[3] 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.
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