Organic Chemistry

Section 26.9 Steroids 025

Adolf Friedrich Johann Butenandt

(1903–1995)was born in Germany.

He shared the 1939 Nobel Prize in

chemistry (with Ru i ka; see p. 14)

for isolating and determining the

structures of estrone, androsterone,

and progesterone. Forced by the Nazi

government to refuse the prize, he

accepted it after World War II. He

was the director of the Kaiser

Wilhelm Institute in Berlin and later

was a professor at the Universities of

Tübingen and Munich.

zMcM

PROBLEM 21

Is the OH substituent of the A ring of cholesterol an or a

PROBLEM 22

Aldosterone is in equilibrium with its cyclic hemiacetal. Draw the hemiacetal form of

aldosterone.

The male sex hormones, known as androgens, are secreted by the testes. They are
responsible for the development of male secondary sex characteristics during puberty.
They also promote muscle growth. Testosterone and are
androgens.

Estradiol and estrone are female sex hormones known as estrogens. They are se-
creted by the ovaries and are responsible for the development of female secondary sex
characteristics. They also regulate the menstrual cycle. Progesterone is the hormone
that prepares the lining of the uterus for implantation of an ovum and is essential for
the maintenance of pregnancy. It also prevents ovulation during pregnancy.

Although the various steroid hormones have remarkably different physiological ef-
fects, their structures are quite similar. For example, the only difference between
testosterone and progesterone is the substituent at C-17, and the only difference be-
tween and estradiol is one carbon and six hydrogens, but these
compounds make the difference between being male and being female. These exam-
ples illustrate the extreme specificity of biochemical reactions.

PROBLEM 23

The acid component of a cholesterol ester is a fatty acid such as linoleic acid. Draw the

structure of a cholesterol ester.

In addition to being the precursor of all the steroid hormones in animals, cholesterol
is the precursor of the bile acids. In fact, the word cholesterolis derived from the
Greek words cholemeaning “bile”and stereosmeaning “solid.”The bile acids—
cholic acid and chenodeoxycholic acid—are synthesized in the liver, stored in the gall-
bladder, and secreted into the small intestine, where they act as emulsifying agents so
that fats and oils can be digested by water-soluble digestive enzymes. Cholesterol is
also the precursor of vitamin D (Section 29.6).

5 a-dihydrotestosterone

H H H H H H

H 3 C

CH 3

HO

H

CO

CH 3

O CH 3

O

H

CH 3

HO

H

OH

estradiol estrone progesterone

H H

H

H

CH 3

O

H 3 C

OH

5 -dihydrotestosterone

H H

H

CH 3

O

H 3 C

OH

testosterone

5 a-dihydrotestosterone

a-substituent b-substituent?

Michael S. Brownand Joseph

Leonard Goldsteinshared the 1985

Nobel Prize in physiology or

medicine for their work on the

regulation of cholesterol metabolism

and the treatment of disease caused

by elevated cholesterol levels in the

blood. Brown was born in New York

in 1941; Goldstein, in South Carolina

in 1940. They are both professors of

medicine at the University of Texas

Southwestern Medical Center.

Pg number to be fixed