Urobilin hydrochloride

U590-9 Urobilin HCl Technical Data Sheet

Product Number: U590-9; CAS Number: 28925-89-5


SKU: U590-9 Category: Tag:

Urobilin hydrochloride CAS: 28925-89-5 MDL: MFCD00216796

Molecular weight: 627.17 g/mol

Molecular Formula: C33H42N4O6 HCl

CAS Number:  28925-89-5

Storage: Store at 0 – 4 °C, protect from light.

Synonyms: 28925-89-5, Urobilin IX hydrochloride, Urobilin hydrochloride, MFCD00216796

Field of Interest: Heme Catabolism and Phase II Metabolism

Background: Urobilin Hydrochloride is produced via the oxidation of urobilinogen, a degradation product of bilirubin, and excreted in the urine. Bilirubin is a water insoluble tetrapyrrole produced from the reduction of biliverdin in a reaction catalyzed by the enzyme bilirverdin reductase. Water insoluble bilirubin (also called indirect bilirubin) in vivo undergoes glucuronidation in the liver (addition of one or two glucuronic acids through a glycosidic bond) to form the water soluble bilirubin mono or diglucuronide (also called bilirubin conjugate or direct bilirubin). Bilirubin conjugate is excreted from the liver in bile or is converted to mesobilinogen via gut bacteria and then to urobilinogen and excreted in the urine as urobilin or stercobilinogen and excreted in the feces as stercobilin. Urobilin Hydrochloride is soluble in basic aqueous solutions (pH > 9 for intitial dissolution) and soluble down to pH 7 once in solution as well as methanol and ethanol if made slightly basic.1-4

Special Note: Urobilin in the neutral form is subject to several modes of degradation and has a very short shelf-life  unless stored under optimal conditions.  To increase the stability of Urobilin, the compound is isolated and sold as a hydrochloride salt (Urobilin hydrochloride, U590-9).  It is known that under acidic conditions the central carbon-carbon double bond can isomerize to a mixture of (E) and (Z) forms of urobilin5.  As a result, Urobilin hydrochloride will appear as a mixture of (E) and (Z) isomers when analyzed by HPLC.


1.) Sampson, D. L., Y. L. Chng, et al. (2013). “The highly abundant urinary metabolite urobilin interferes with the bicinchoninic acid assay.” Analytical Biochemistry 442(1): 110.
2.) Quinn, K. D., N. Q. T. Nguyen, et al. (2012). “Tandem mass spectrometry of bilin tetrapyrroles by electrospray ionization and collision-induced dissociation.” Rapid Communications in Mass Spectrometry 26(16): 1767.
3.) Cuperus, F. J. C., A. M. Hafkamp, et al. (2009). “Effective Treatment of Unconjugated Hyperbilirubinemia With Oral Bile Salts in Gunn Rats.” Gastroenterology 136(2): 673.

4.) Mölzer, C., H. Huber, et al. (2012). “In vitro antioxidant capacity and antigenotoxic properties of protoporphyrin and structurally related tetrapyrroles.” Free Radical Research 46(11): 1369-1377.

4.) Heirwegh, K. P. M. (1982). Bilirubin: Volume I: Chemistry. CRC Press.



Functional Groups

, , , ,

Porphyrin Family

Bilirubin Derivatives, Linear Tetra-Pyrroles

Purity %


Molecular Formula


Molecular Weight



You may also like…

Shopping Cart
Scroll to Top