Steroid Hormones

Steroid basic structure

Saturated tetracyclic carbon skeleton derived from cyclopentanoperhydrophenanthrene

Steroid ring labels

Four rings labeled A B C D

Steroid numbering

Carbon atoms numbered according to standard steroid convention

Steroid surfaces

Top = β surface bottom = α surface

β‑orientation

Solid line bond pointing toward reader

α‑orientation

Dotted line bond pointing away from reader

Steroid ring junctions B‑C and C‑D

Usually trans

A‑B ring junction

May be cis or trans

5α‑series definition

A‑B ring junction trans hydrogen at C5 trans to C10 methyl

5β‑series definition

A‑B ring junction cis hydrogen at C5 cis to C19 methyl

Angular methyl groups

Carbon 18 (C13) and carbon 19 (C10)

Estrane skeleton

C18 steroids

Estrane example

Estrogen

Androstane skeleton

C19 steroids

Androstane example

Testosterone

Pregnane skeleton

C21 steroids

Pregnane example

Progesterone

Progesterone role

Precursor to testosterone

Testosterone role

Precursor to estrogen

Sex hormone biosynthesis

All steroid hormones synthesized in both males and females