Lanosterol
Template:Chembox Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast, plant steroids are produced via cycloartenol.[1] In the eyes of vertebrates, lanosterol is a natural constituent, having a role in maintaining health of the lens. Lanosterol is the precursor to cholesterol.[2]
Biosynthesis
The biosynthesis of lanosterol has been intensively investigated.[2]
| Description | Illustration | Enzyme |
|---|---|---|
| Two molecules of farnesyl pyrophosphate condense with reduction by NADPH to form squalene | File:Cholesterol-Synthesis-Reaction10.png | squalene synthase |
| Squalene is oxidized to 2,3-oxidosqualene (squalene epoxide) | File:Squalene epoxide biosynthesis.png | squalene monooxygenase |
| 2,3-Oxidosqualene is converted to a protosterol cation and finally to lanosterol | File:Cholesterol-Synthesis-Reaction12.png | lanosterol synthase |
| (step 2) | File:Cholesterol-Synthesis-Reaction13.png | (step 2) |
Elaboration of lanosterol under enzyme catalysis leads to other steroids. 14-Demethylation of lanosterol by CYP51 eventually yields cholesterol.
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.[3][4] Its proposed mechanism of action is to inhibit the aggregation of crystallin proteins, which contribute to the clouding of vision by forming cataracts.[3][4]
Lanosterol is under research for its potential as a therapeutic additive in eye drops to inhibit the aggregation of crystallin proteins and dissolve cataracts.[3][4] However, supplemental lanosterol in eye drops appears to have limited solubility and poor bioavailability in the eye, and has not proved effective for inhibiting cataracts, as of 2020.[3][4]
See also
- Cycloartenol
- CYP51
- Other tetracyclic triterpenes: cycloartenol, euphol, tirucallol, and cucurbitacin.[2]
References
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