Lanosterol is a
tetracyclic
Tetracyclics are cyclic compound, cyclic chemical compounds that contain four fused ring (chemistry), rings of atoms, for example, Tröger's base.
Some tricyclic compounds having three fused and one tethered ring (connected to main nucleus by ...
triterpenoid
Triterpenes are a class of terpenes composed of six isoprene units with the molecular formula C30H48; they may also be thought of as consisting of three terpene units. Animals, plants and fungi all produce triterpenes, including squalene, the pre ...
and is the compound from which all animal and fungal
steroid
A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration.
Steroids have two principal biological functions: as important components of cell membranes t ...
s are derived. By contrast, plant steroids are produced via
cycloartenol
Cycloartenol is an important triterpenoid often found in plants. It belongs to the sterol class of steroids. It is the starting point for the synthesis of almost all plant steroids, making them chemically distinct from the steroids of fungi and a ...
.
In the eyes of vertebrates, lanosterol is a natural constituent, having a role in maintaining health of the
lens
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...
. Lanosterol is the precursor to
cholesterol
Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils.
Cholesterol is biosynthesis, biosynthesized by all anima ...
.
[
]
Biosynthesis
The biosynthesis of lanosterol has been intensively investigated.Demethylation
Demethylation is the chemical process resulting in the removal of a methyl group (CH3) from a molecule. A common way of demethylation is the replacement of a methyl group by a hydrogen atom, resulting in a net loss of one carbon and two hydrogen at ...
of lanosterol by CYP51
In enzymology, a sterol 14-demethylase () is an enzyme of the cytochrome P450 (CYP) superfamily. It is any member of the CYP51 family. It catalysis, catalyzes a chemical reaction such as:
:obtusifoliol + 3 O2 + 3 NADPH + 3 H+ \rightleftharpoons 4 ...
eventually yields cholesterol
Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils.
Cholesterol is biosynthesis, biosynthesized by all anima ...
.
Research as an eye drop supplement
As a molecule naturally enriched in the eye lens, lanosterol is a component involved in maintenance of lens clarity.mechanism of action
In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical Drug interaction, interaction through which a Medication, drug substance produces its pharmacological effect. A mechanism of action usually includes mention o ...
is to inhibit the aggregation of crystallin proteins, which contribute to the clouding of vision by forming cataract
A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...
s.[
Lanosterol is under research for its potential as a therapeutic additive in ]eye drop
Eye drops or eyedrops are liquid drops applied directly to the surface of the eye usually in small amounts such as a single drop or a few drops. Eye drops usually contain saline to match the salinity of the eye. Drops containing only saline ...
s to inhibit the aggregation of crystallin proteins and dissolve cataract
A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...
s.[ However, supplemental lanosterol in eye drops appears to have limited solubility and poor ]bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation.
By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...
in the eye, and has not proved effective for inhibiting cataracts, as of 2020.[
]
See also
*Cycloartenol
Cycloartenol is an important triterpenoid often found in plants. It belongs to the sterol class of steroids. It is the starting point for the synthesis of almost all plant steroids, making them chemically distinct from the steroids of fungi and a ...
*CYP51
In enzymology, a sterol 14-demethylase () is an enzyme of the cytochrome P450 (CYP) superfamily. It is any member of the CYP51 family. It catalysis, catalyzes a chemical reaction such as:
:obtusifoliol + 3 O2 + 3 NADPH + 3 H+ \rightleftharpoons 4 ...
*Other tetracyclic triterpene
Triterpenes are a class of terpenes composed of six isoprene units with the molecular formula C30H48; they may also be thought of as consisting of three terpene units. Animals, plants and fungi all produce triterpenes, including squalene, the pre ...
s: cycloartenol
Cycloartenol is an important triterpenoid often found in plants. It belongs to the sterol class of steroids. It is the starting point for the synthesis of almost all plant steroids, making them chemically distinct from the steroids of fungi and a ...
, euphol, tirucallol, and cucurbitacin
Cucurbitacins are a class of biochemistry, biochemical compounds that some plants – notably members of the pumpkin and gourd family, Cucurbitaceae – produce and which function as a defense against herbivores. Cucurbitacins and their deriva ...
.[
]
References
{{Cholesterol metabolism intermediates
Sterols
Triterpenes
Lanostanes