Androstenol, also known as 5α-androst-16-en-3α-ol (shortened to 3α,5α-androstenol or 3α-androstenol), is a 16-androstene class
steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...
al
pheromone
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
and
neurosteroid
Neurosteroids, also known as neuroactive steroids, are endogenous or exogenous steroids that rapidly alter neuronal excitability through interaction with ligand-gated ion channels and other cell surface receptors. The term ''neurosteroid'' was co ...
in humans and other mammals, notably pigs.
It possesses a characteristic
musk
Musk ( Persian: مشک, ''Mushk'') is a class of aromatic substances commonly used as base notes in perfumery. They include glandular secretions from animals such as the musk deer, numerous plants emitting similar fragrances, and artificial sub ...
-like odor.
Androstenol, or a derivative, is found in
black truffles
''Tuber melanosporum'', called the black truffle, Périgord truffle or French black truffle, is a species of truffle native to Southern Europe. It is one of the most expensive edible mushrooms in the world.
Taxonomy
Italian naturalist Carlo Vi ...
. This was offered as an explanation for how pigs locate them deep in the ground: Androstenol is produced in the saliva of male pigs. However, experiments in France using pigs to scent truffles, truffle scent extract, and purified androstenol showed that pigs responded to the first two (actually trying to eat dirt containing the truffle extract), but ignored the androstenol.
A
positional isomer
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct bonds between them. The term meta ...
of androstenol,
3β-androstenol (5α-androst-16-en-3β-ol), is also endogenous to humans (as well as to pigs), behaving as a pheromone and contributing to axillary odor.
Biosynthesis
In humans and boars, androstenol is
biosynthesized in the
testes
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoste ...
.
Pregnenolone
Pregnenolone (P5), or pregn-5-en-3β-ol-20-one, is an endogenous steroid and precursor/metabolic intermediate in the biosynthesis of most of the steroid hormones, including the progestogens, androgens, estrogens, glucocorticoids, and mineralocor ...
is metabolized into
androstadienol by the 16-ene-synthetase activity of
CYP17A1
Cytochrome P450 17A1 (steroid 17α-monooxygenase, 17α-hydroxylase, 17-alpha-hydroxylase, 17,20-lyase, 17,20-desmolase) is an enzyme of the hydroxylase type that in humans is encoded by the ''CYP17A1'' gene on chromosome 10. It is ubiquitously exp ...
.
Androstadienol is then sequentially converted into androstenol by
3β-hydroxysteroid dehydrogenase (
androstadienol to
androstadienone),
5α-reductase
5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes o ...
(androstadienone to
androstenone
Androstenone (5α-androst-16-en-3-one) is a 16-androstene class steroidal pheromone. It is found in boar's saliva, celery cytoplasm, and truffle fungus. Androstenone was the first mammalian pheromone to be identified. It is found in high concent ...
), and
3α-hydroxysteroid dehydrogenase (androstenone to androstenol), in a manner analogous to the biosynthesis of
3α-androstanediol from
dehydroepiandrosterone (DHEA).
Androstenol may also be synthesized in the
adrenal gland
The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex ...
s and the
ovaries
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...
in humans.
In addition, androstenol may be synthesized in the human
nasal mucosa
The nasal mucosa lines the nasal cavity. It is part of the respiratory mucosa, the mucous membrane lining the respiratory tract. The nasal mucosa is intimately adherent to the periosteum or perichondrium of the nasal conchae. It is continuous ...
from androstenone, and likely also from androstadienol and androstadienone in this area.
Distribution
Considerable amounts of androstenol are present in human urine, and it is also present in the blood plasma and saliva of humans and pigs as well as in the
axilla
The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superior ...
ry
sweat
Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals.
Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distrib ...
of humans.
Due to its ability to cross the
blood-brain-barrier, androstenol is likely present in the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
as well.
Biological activity
Androstenol, similarly to the related endogenous steroids
3α-androstanediol and
androsterone
Androsterone, or 3α-hydroxy-5α-androstan-17-one, is an endogenous steroid hormone, neurosteroid, and putative pheromone. It is a weak androgen with a potency that is approximately 1/7 that of testosterone. Androsterone is a metabolite of tes ...
, has been found to act as a potent
positive allosteric modulator of the
GABAA.
It has been proposed that this action may mediate the pheromone effects of androstenol.
Moreover, as androstadienol, androstadienone, and androstenone are all converted into androstenol, it could mediate their pheromone effects as well.
In animals, androstenol has been found to produce
anxiolytic
An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiet ...
-like,
antidepressant
Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common Side effect, side-effects of antidepressants include Xerostomia, dry mouth, weig ...
-like, and
anticonvulsant
Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of ...
effects.
Androstenol has also been found to modify the behavioral and social responses of humans.
In addition, androstenol has been found to decrease
luteinizing hormone
Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...
(LH) pulse frequency during the
follicular phase
The follicular phase, also known as the preovulatory phase or proliferative phase, is the phase of the estrous cycle (or, in primates for example, the menstrual cycle) during which follicles in the ovary mature from primary follicle to a fully ...
of the human
menstrual cycle
The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs ...
.
In accordance, it has been proposed that androstenol may be involved in the
menstrual synchrony of women.
In contrast to androstenol (3α-androstenol), its 3β-epimer, 3β-androstenol, does not potentiate the GABA
A receptor, even at high concentrations.
This is in accordance with other 3β-hydroxy steroids, including
isopregnanolone
Isopregnanolone, also known as isoallopregnanolone and epiallopregnanolone, as well as sepranolone (), and as 3β-hydroxy-5α-pregnan-20-one or 3β,5α-tetrahydroprogesterone (3β,5α-THP), is an endogenous neurosteroid and a natural 3β-epimer of ...
,
epipregnanolone
Epipregnanolone, also known as 3β-hydroxy-5β-pregnan-20-one, 3β,5β-tetrahydroprogesterone, or 3β,5β-THP, is an endogenous neurosteroid. It acts as a negative allosteric modulator of the GABAA receptor and reverses the effects of potentiato ...
,
3β-dihydroprogesterone, and
3β-androstanediol, which similarly do not act as such, in contrast to their 3α-hydroxy variants.
Androstenol, along with several isomers of
androstanol, is an
antagonist
An antagonist is a character in a story who is presented as the chief foe of the protagonist.
Etymology
The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, ri ...
of the
constitutive androstane receptor
The constitutive androstane receptor (CAR) also known as nuclear receptor subfamily 1, group I, member 3 is a protein that in humans is encoded by the ''NR1I3'' gene. CAR is a member of the nuclear receptor superfamily and along with pregnan ...
(CAR).
Androstenol has minimal or no
androgen
An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
ic activity.
See also
*
List of neurosteroids § Pheromones and pherines
*
C19H30O
References
{{Xenobiotic-sensing receptor modulators
Androstanes
Cyclopentenes
GABAA receptor positive allosteric modulators
Human pheromones
Mammalian pheromones
Neurosteroids