Structure–activity relationships of anabolic steroids

Testosterone molecule structure

The structure–activity relationships (SAR) of anabolic steroids refer to the relationship between the chemical structure of anabolic steroids and their biological activity. Anabolic steroids are synthetic derivatives of the hormone testosterone, which is the primary male sex hormone and an anabolic steroid itself. These compounds are designed to enhance the anabolic effects (such as muscle growth) while minimizing androgenic effects (such as the development of male characteristics).

Chemical Structure

Anabolic steroids are characterized by a core structure of four fused carbon rings, known as the cyclopentanoperhydrophenanthrene ring system. This structure is shared with other steroids, including cholesterol and corticosteroids. Modifications to this core structure can significantly alter the activity of the steroid.

Modifications to the A-Ring

The A-ring of the steroid nucleus can be modified to enhance anabolic activity. For example, the introduction of a 1-dehydro modification (a double bond between carbon 1 and 2) can increase the anabolic to androgenic ratio. This modification is seen in steroids like nandrolone.

Modifications to the B-Ring

Alterations to the B-ring, such as the addition of a 9α-fluoro group, can also affect the activity of the steroid. These modifications can enhance the binding affinity to the androgen receptor, thereby increasing anabolic effects.

Modifications to the C-Ring

The C-ring can be modified by adding a 17α-alkyl group, which increases oral bioavailability by preventing hepatic metabolism. However, this modification can also increase hepatotoxicity, as seen in steroids like methandrostenolone.

Modifications to the D-Ring

The D-ring modifications, such as the addition of a 17β-hydroxy group, are crucial for the anabolic activity of the steroid. This group is essential for binding to the androgen receptor and is present in all active anabolic steroids.

Steroid nomenclature

Mechanism of Action

Anabolic steroids exert their effects by binding to the androgen receptor, a type of nuclear receptor that regulates gene expression. Upon binding, the steroid-receptor complex translocates to the cell nucleus, where it binds to specific DNA sequences, leading to the transcription of genes involved in muscle growth and other anabolic processes.

Clinical Applications

Anabolic steroids are used clinically to treat conditions such as hypogonadism, delayed puberty, and muscle wasting diseases. They are also used illicitly to enhance athletic performance and physical appearance.

Adverse Effects

The use of anabolic steroids can lead to a range of adverse effects, including liver damage, cardiovascular disease, and endocrine disorders. The risk of these effects is increased with higher doses and prolonged use.

Related Pages

• Anabolic steroid
• Testosterone
• Androgen receptor
• Steroid hormone