progesterone hormone

1. Steroid hormone-
Progesterone
Roll no- 11333
Riddhi Karnik
Riddhi karnik

2. Introduction
• Progesterone is a female sexual steroid hormone
• It is synthesized in the corpus luteum of the ovaries.
• The blood level of progesterone varies with the
menstrual cycle.
• The hormone prepares the uterus for a possible
pregnancy.
• Following fertilization, the placenta also starts to
synthesize progesterone in order to maintain the
pregnant state.
• The development of the mammary glands is also
stimulated by progesterone.
Formula C21H30O2
Molecular mass 314.46 g/mol
Riddhi karnik

3. • Progesterone consists of four
interconnected cyclic hydrocarbons.
• Progesterone contains ketone and
oxygenated functional groups, as well as
two methyl branches.
• Like all steroid hormones, it is
hydrophobic.
Riddhi karnik

4. Biosynthesis of steroid hormone
progesterone
• All steroid hormones are synthesized from
cholesterol.
• The cholesterol required for biosynthesis
of the steroid hormones is obtained from
various sources.
• It is either taken up as a constituent of
LDL lipoproteins into the hormone-
synthesizing glandular cells, or synthesized
by glandular cells themselves from acetyl-
CoA.
Riddhi karnik

5. Koolman, Color Atlas of Biochemistry, 2nd editionRiddhi karnik

6. • Pregnenolone is an important intermediate in
the biosynthesis of most steroid hormones.
• It is identical to cholesterol with the
exception of a shortened and oxidized side
chain.
• Pregnenolone is produced in three steps by
hydroxylation and cleavage in the side chain.
• Subsequent dehydrogenation of the hydroxyl
group at C-3 (b) and shifting of the double
bond from C-5 to C-4 results in the gestagen
progesterone.
Riddhi karnik

7. Riddhi karnik

8. • The conversion of pregnenolone to
progesterone takes place in two steps.
• First, the 3-hydroxyl group is oxidized to a
keto group (4) and second, the double bond
is moved to C-4, from C-5 through a
keto/enol tautomerization reaction.
• This reaction is catalyzed by 3beta-
hydroxysteroid dehydrogenase/delta(5)-
delta(4)isomerase.
Riddhi karnik

9. • Progesterone in turn is the precursor of
the mineralocorticoid aldosterone, and
after conversion to
17αhydroxyprogesterone (another
natural progestogen) of cortisol and
androstenedione. Androstenedione can
be converted to testosterone, estrone
and estradiol.
Riddhi karnik

10. Levels of Progesterone
• In women, progesterone levels are relatively low
during the preovulatory phase of themenstrual
cycle, rise afterovulation, and are elevated
during theluteal phase, as shown in diagram
below.
• Progesterone levels tend to be < 2 ng/ml prior
to ovulation, and > 5 ng/ml after ovulation.
• If pregnancy occurs, human chronionic
gonadotropin is released maintaining the corpus
luteum allowing it to maintain levels of
progesterone.
Riddhi karnik

11. Levels of progesterone
Riddhi karnik

12. Inactivation of steroid hormones
• The steroid hormones are mainly inactivated in the
liver, where they are either reduced or further
hydroxylated and then conjugated with glucuronic acid
or sulfate for excretion.
• The reduction reactions attack oxo groups and the
double bond in ring A.
• A combination of several inactivation reactions gives
rise to many different steroid metabolites that have
lost most of their hormonal activity.
• Finally, they are excreted with the urine and also partly
via the bile.
• Evidence of steroids and steroid metabolites in the
urine is used to investigate the hormone metabolism.
Riddhi karnik

13. References
• Color Atlas of Biochemistry
(Second edition, revised and enlarged) by
Jan Koolman and Klaus-Heinrich Roehm.
• Principles of biochemisty by Lehninger
• Internet
Riddhi karnik

14. Riddhi karnik