Sex Hormones, Adrenal Cortisol, Prostaglandins
Curator: Larry H. Bernstein, MD, FCAP
Steroids
A major class of lipids, steroids, have a ring structure of three cyclohexanes and one
cyclopentane in a fused ring system as shown below. There are a variety of functional
groups that may be attached. The main feature, as in all lipids, is the large number of
carbon-hydrogens which make steroids non-polar.
Steroids include such well known compounds as cholesterol, sex hormones, birth
control pills, cortisone, and anabolic steroids.
http://www.elmhurst.edu/~chm/vchembook/images/556cholesterol.gif
The best known and most abundant steroid in the body is cholesterol. Cholesterol is
formed in brain tissue, nerve tissue, and the blood stream. It is the major compound
found in gallstones and bile salts. Cholesterol also contributes to the formation of
deposits on the inner walls of blood vessels. This topic was covered in the previous
discussion of the lipids series, and extensively in cardiovascular topics.
Cholesterol is synthesized by the liver from carbohydrates and proteins as well as fat.
Therefore, the elimination of cholesterol rich foods from the diet does not necessarily
lower blood cholesterol levels. Some studies have found that if certain unsaturated fats
and oils are substituted for saturated fats, the blood cholesterol level decreases.
The research is incomplete on this problem.
Cholesterol exists as an ester with fatty acids.What is the functional group at carbon 3
which is used to make an ester?
OH is alcohol
What is the feature on carbon 17?
Branched long hydrocarbon chain
Sex Hormones
http://www.elmhurst.edu/~chm/vchembook/images/556sexhormones.gif
The primary sex hormones, testosterone and estrogen, are responsible for the
development of secondary sex characteristics. Two female sex hormones,
progesterone and estrogen or estradiol control the ovulation cycle. Notice
that the male and female hormones have only slight differences in structures,
but yet have very different physiological effects.
Testosterone promotes the normal development of male genital organs and
is synthesized from cholesterol in the testes. It also promotes secondary male
sexual characteristics such as deep voice, facial and body hair.
Estrogen, along with progesterone regulates changes occurring in the uterus
and ovaries known as the menstrual cycle. Estrogen is synthesized from
testosterone by making the first ring aromatic which results in the loss of a
methyl group and formation of an alcohol group.
List three functional groups in progesterone?
C#3 & #17 are ketones; C#4&5 are alkenes;
What is difference between progesterone and testosterone?
testosterone has C#17 alcohol vs ketone on progesterone
What is difference between testosterone and estrogen?
Estrogen has C#3 alcohol, + aromatic first ring;
no methyl group on C#17
Adrenocorticoid Hormones
The adrenocorticoid hormones are products of the adrenal glands.
The most important mineralcorticoid is aldosterone, which regulates the
reabsorption of sodium and chloride ions in the kidney tubules and increases
the loss of potassium ions.Aldosterone is secreted when blood sodium ion
levels are too low to cause the kidney to retain sodium ions. If sodium
levels are elevated, aldosterone is not secreted, so that some sodium
will be lost in the urine. Aldosterone also controls swelling in the tissues.
Cortisol, the most important glucocortinoid, has the function of increasing
glucose and glycogen concentrations in the body. These reactions are
completed in the liver by taking fatty acids from lipid storage cells and
amino acids from body proteins to make glucose and glycogen.
In addition, cortisol is elevated in the circulation with cytokine mediated
(IL1, IL1, TNFα) inflammatory reaction, called the systemic inflammatory
response syndrome. Its ketone derivative, cortisone, has the ability
to relieve inflammatory effects. Cortisone or similar synthetic derivatives
such as prednisolone are used to treat inflammatory diseases, rheumatoid
arthritis, and bronchial asthma. There are many side effects with the use
of cortisone drugs, such as bone resorption, so there use must be
monitored carefully. Cortisol is increased pathologically with the growth
of a pituitary gland tumor that secretes adrenocorticotropic hormone
(ACTH), called Addison’s Disease, which is also associated with
hirsuit features.
What is the only difference between cortisol and aldosterone?
Aldosterone has C#13 aldehyde instead of methyl group
http://www.elmhurst.edu/~chm/vchembook/images/556cortisone.gif
Prostaglandins
Prostaglandins, are like hormones in that they act as chemical messengers,
but do not move to other sites, but work right within the cells where
they are synthesized. (PARACRINE)
Prostaglandins are unsaturated carboxylic acids, consisting of of a 20 carbon
skeleton that also contains a five member ring. They are biochemically
synthesized from the fatty acid, arachidonic acid.
http://www.elmhurst.edu/~chm/vchembook/images/551arachidonic.gif
The unique shape of the arachidonic acid caused by a series of cis double
bonds helps to put it into position to make the five member ring.
Prostaglandins are unsaturated carboxylic acids, consisting of a
- 20 carbon skeleton that also contains
- a five member ring and
- are based upon the fatty acid, arachidonic acid.
There are a variety of structures one, two, or three double bonds. On the
five member ring there may also be double bonds, a ketone, or alcohol groups.
In PGE2, list all of the functional groups.
one acid; two alkenes; two alcohols; one ketone
What is difference the C=C double bonds?
the upper is cis; the lower is trans.
http://www.elmhurst.edu/~chm/vchembook/images/556prostaglandin.gif
Functions of Prostaglandins
There are a variety of physiological effects including:
- Activation of the inflammatory response, production of pain, and fever.
When tissues are damaged, white blood cells flood to the site to
try to minimize tissue destruction. Prostaglandins are produced
as a result. - Blood clots form when a blood vessel is damaged. A type of
prostaglandin called thromboxane stimulates constriction and
clotting of platelets. Conversely, PGI2, is produced to have the
opposite effect on the walls of blood vessels where clots
should not be forming. - Certain prostaglandins are involved with the induction of labor
and other reproductive processes. PGE2 causes uterine
contractions and has been used to induce labor. - Prostaglandins are involved in several other organs such as
the gastrointestinal tract (inhibit acid synthesis and increase
secretion of protective mucus), increase blood flow in kidneys,
and leukotriens promote constriction of bronchi associated
with asthma.
When you see that prostaglandins induce inflammation, pain, and fever,
what comes to mind but aspirin. Aspirin blocks an enzyme called
cyclooxygenase, COX-1 and COX-2, which is involved with the ring
closure and addition of oxygen to arachidonic acid converting to
prostaglandins.
The acetyl group on aspirin is hydrolzed and then bonded to the
alcohol group of serine as an ester. This has the effect of blocking
the channel in the enzyme and arachidonic can not enter the active
site of the enzyme.
By inhibiting or blocking this enzyme, the synthesis of prostaglandins
is blocked, which in turn relives some of the effects of pain and fever.
http://www.elmhurst.edu/~chm/vchembook/images/556coxaspirin.gif
http://www.elmhurst.edu/~chm/vchembook/
Sphingolipids
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