Cholic acid

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Structural formula
Structure of cholic acid
General
Surname Cholic acid
other names

3 α , 7 α , 12 α -trihydroxycholanic acid

Molecular formula C 24 H 40 O 5
Brief description

colorless, crystalline powder with a sweetish bitter taste

External identifiers / databases
CAS number 81-25-4
EC number 201-337-8
ECHA InfoCard 100.001.217
PubChem 221493
ChemSpider 192176
DrugBank DB02659
Wikidata Q287415
Drug information
ATC code

A05 AA03

properties
Molar mass 408.57 g mol −1
Physical state

firmly

Melting point

198 ° C

pK s value

4.98

solubility

very bad in water: 175 mg l −1 (20 ° C)

safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS labeling of hazardous substances
07 - Warning

Caution

H and P phrases H: 315-319
P: 264-280-302 + 352-332 + 313-305 + 351 + 338-337 + 313
Toxicological data

4950 mg kg −1 ( LD 50 ,  mouse ,  oral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Along with chenodeoxycholic acid, cholic acid is one of the primary bile acids . Chemically it is a steroid belonging to the group of sterols (sterols) . Their salts are called cholates .

biochemistry

education

Cholic acid is one of the four most common acids produced by the liver . It is made there from cholesterol .

function

Cholic acid and the other bile acids act as emulsifiers . During digestion, they emulsify fats , making them accessible to lipases .

The liver first converts cholic acid further into glycocholic acid (“ glycine - cholic acid amide”) and taurocholic acid (“ taurine- cholic acid amide”), which are then released into the bile and from there enter the digestive system as salts .

Bile acids are reabsorbed and reused by the body after they have performed their function in digestion. About 95% of the bile acids are absorbed in the lower ileum via a Na + symport (ASBT) in a secondary active manner. About 1–2% of the bile acids are taken up passively from the lumen in the upper small intestine by non- ionic diffusion , in the lower small and large intestine by ionic diffusion . Due to the intensive absorption, only 3-4% of the bile acids originally released into the duodenum pass into the large intestine. Then cytosolic transport proteins and anion exchangers take over their export via the basolateral membrane back into the portal blood . Thus they reach the liver again , where they are available again after conjugation in the hepatocytes . The part that has been lost through the stool (approx. 0.6 g / day) is synthesized from cholesterol in the liver .

Conversion into a secondary bile acid

Cholic acid is called primary bile acid because it is made by the liver itself. In the large intestine, cholic acid is partially converted by anaerobic bacteria into the secondary bile acid deoxycholic acid .

use

In industry, cholic acid is mainly used for the synthesis of ursodeoxycholic acid , which is used as a medicinal substance to dissolve gallstones and to prevent liver diseases.

Cholic acid is also used in traditional Chinese medicine .

Web links

Wikibooks: Biosynthesis of Bile Acids  - Learning and Teaching Materials

Individual evidence

  1. ↑ a b c Entry on cholic acid. In: Römpp Online . Georg Thieme Verlag, accessed on December 28, 2014.
  2. ↑ a b c Entry on cholic acid in the ChemIDplus database of the United States National Library of Medicine (NLM) .
  3. ↑ a b Entry on cholic acid in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
  4. ↑ Voet & Voet: Biochemistry (2nd edition), Viley-VCH, p. 783.