2-Acetyl-5-tetrahydroxybutyl imidazole (THI)

Product Number: B-0031


THI is a trace component present in the industrially produced food colorant caramel color III. It acts as an immunosuppressant by inhibiting the enzyme sphingosine 1-phosphate lyase (S1PL) which fragments S1P to hexadecenal and phosphoethanolamine. Administration of THI in drinking water to mice (50 μg/mL) resulted in decreased S1PL activity, increased S1P levels in lymphoid tissues and reduced egress of CD4+ and CD8+ T cells (lymphopenia).


Biochemical Reagents


Inhibitor, Sphingolipid

CAS Number


Molecular Formula


Molecular Weight (g/mol)





4 °C or below

Shipping Temp

Ambient Temperature

Technical Data Sheet

1) J. T. Bagdanoff, et al. “Inhibition of Sphingosine-1-phosphate Lyase for the Treatment of Autoimmune Disorders.” J. Med. Chem. 2009, 52, 3941-3953.
2) G.F. Houben, et al. “Effects of Ammonia Caramel and Tetrahydroxybutylimidazole on the Immune System of Rats.” Arch. Toxicol., 1989, 13, 183-187.
3) S.R. Schwab, et al. “Lymphocyte Sequestration Through S1P Lyase Inhibition and Disruption of S1P Gradients.” Science 2005, 309, 1735-1739.

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