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Structural formula
Structure of pregnenolone
Surname Pregnenolone
other names

3 β- hydroxypregn-5-en-20-one

Molecular formula C 21 H 32 O 2
Brief description

colorless needles

External identifiers / databases
CAS number 145-13-1
EC number 205-647-4
ECHA InfoCard 100.005.135
PubChem 8955
ChemSpider 8611
DrugBank DB02789
Wikidata Q412158
Molar mass 316.48 g mol −1
Physical state


Melting point

193 ° C


almost insoluble in water (7.06 mg l −1 at 37 ° C)

safety instructions
GHS labeling of hazardous substances
no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Pregnenolone is a derivative of the pregnane (C 21 - Steroid ) and is selected from cholesterol formed.


Pregnenolone is formed from cholesterol by hydroxylation at C 20 and C 22 with subsequent cleavage of the side chain . The conversion is catalyzed by the enzyme cholesterol monooxygenase in the mitochondria and controlled by the pituitary hormones ACTH , FSH , LH .

P450scc catalyzes the conversion of cholesterol ( 1 ) to pregnenolone ( 3 ) via the intermediate compound 20 α , 22 β -Dihydroxycholesterin ( 2 ).

The necessary transport of cholesterol from the cytosol into the mitochondria takes place by binding to the StAR protein , a transport protein in the mitochondrial membrane. Nothing is yet known about the exact transport of pregnenolone from the mitochondria.


Pregnenolone is a prohormone of the steroid hormones and can be further converted to progesterone or 17-hydroxypregnenolone .

Use and therapeutic effectiveness

In animal experiments on mice and rats, pregnenolone blocks the activation of the cannabinoid receptor type 1 (CB1). a. is activated by ∆ 9 - tetrahydrocannabinol (THC), the main active ingredient of hemp ( Cannabis sativa ). It could thus act as an antagonist .

Web links

Individual evidence

  1. a b Entry on pregnenolone. In: Römpp Online . Georg Thieme Verlag, accessed on November 12, 2014.
  2. Entry on pregnenolone in the ChemIDplus database of the United States National Library of Medicine (NLM) .
  3. Data sheet 5-Pregnen-3β-ol-20-one from Sigma-Aldrich , accessed on May 29, 2011 ( PDF ).
  4. Pregnenolone biosynthesis on Reactome.Org (R-HSA-196108), accessed July 28, 2020
  5. Antidote to cannabis high discovered. Der Standard, January 3, 2014, accessed January 5, 2014 .
  6. M. Vallee, S. Vitiello et al. a .: Pregnenolone Can Protect the Brain from Cannabis Intoxication. In: Science. 343, 2014, pp. 94–98, doi : 10.1126 / science.1243985 .