Δ5-Androstenedione

Δ5-Androstenedione (also known as 5-Androstenedione, 5-AD, or androst-5-ene-3,17-dione) is a naturally occurring steroid and a direct precursor in the biosynthesis of the androgen and estrogen sex hormones. It is derived from dehydroepiandrosterone (DHEA) and converted to testosterone and estrone by the enzymes 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase, respectively.

Biosynthesis

Δ5-Androstenedione is synthesized from dehydroepiandrosterone (DHEA) through the action of the enzyme 3β-hydroxysteroid dehydrogenase. This conversion involves the oxidation of the 3β-hydroxy group of DHEA to a keto group and the isomerization of the Δ5 double bond to a Δ4 double bond.

Metabolism

Δ5-Androstenedione is metabolized to testosterone and estrone by the enzymes 17β-hydroxysteroid dehydrogenase and aromatase, respectively. The conversion to testosterone involves the reduction of the 17-keto group to a 17β-hydroxy group, while the conversion to estrone involves the aromatization of the A ring of the steroid.

Pharmacology

Δ5-Androstenedione has weak androgenic activity. It can act as a weak agonist of the androgen receptor (AR), but with less potency than testosterone. It can also be converted to more potent androgens and estrogens in tissues, and thus can serve as a prohormone for these sex hormones.

Clinical significance

Δ5-Androstenedione has been found to be elevated in certain conditions, such as congenital adrenal hyperplasia and polycystic ovary syndrome. It has also been used as a performance-enhancing substance, although its use is banned by most sports organizations.

See also

• Androstenedione
• Dehydroepiandrosterone
• Testosterone
• Estrone