Aesculin


Aesculin, also called æsculin or esculin, is a coumarin glucoside that naturally occurs in the trees horse chestnut, California buckeye, prickly box, and daphnin. It is also found in dandelion coffee.

Medical uses

As medication, aesculin is sometimes used as a vasoprotective agent.
Aesculin is also used in a microbiology laboratory to aid in the identification of bacterial species. 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. Hydrolysis of aesculin forms aesculetin 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 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 and hydrolysis of aesculin results in loss of this fluorescence.
Enterococcus will often flag positive within four hours of the agar being inoculated.

Warnings

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