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[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Lanosterol

Lanosterol is the first sterol of the pathway: it already has the four rings but carries three extra methyl groups.

Updated 2026-11-01

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## Key facts

- Lanosterol synthase makes it from 2,3-oxidosqualene in one reaction that closes four rings.
- It has 30 carbons; losing three methyls (C30 → C27) and shifting double bonds takes it to cholesterol in about twenty reactions.
- The first, 14α-demethylation, is done by CYP51, the same enzyme azoles inhibit in fungi.

**Formula**
C₃₀H₅₀O

**PubChem**
[CID 246983](https://pubchem.ncbi.nlm.nih.gov/compound/246983)

## Structure

- A steroid nucleus with an OH on C3, two methyls on C4 and one on C14, which cholesterol lacks.
- Its name comes from lanolin, the wool grease where it was found.

## Clinical notes

- Lanosterol synthase variants cause congenital cataracts; lanosterol has been studied to dissolve lens aggregates, with no clinical use yet.
- Lanosterol promotes degradation of HMG-CoA reductase (feedback).

## Pathways

- [Cholesterol synthesis (mevalonate pathway)](https://durgical.com/en/biochemistry/pathways/cholesterol-synthesis/)

## Related conditions

- [Cataract](https://durgical.com/en/conditions/cataract/)

## Related

- [Squalene](https://durgical.com/en/biochemistry/molecules/squalene/)
- [Cholesterol](https://durgical.com/en/biochemistry/molecules/cholesterol/)
- [Squalene epoxidase](https://durgical.com/en/biochemistry/enzymes/squalene-epoxidase/)
- [HMG-CoA reductase](https://durgical.com/en/biochemistry/enzymes/hmg-coa-reductase/)

## Test yourself

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## Which enzyme makes lanosterol?

Lanosterol synthase (oxidosqualene cyclase), which cyclises 2,3-oxidosqualene.

## How does lanosterol differ from cholesterol?

It has 30 carbons: three extra methyls (two on C4, one on C14) and different double bonds.

## Which human enzyme of the lanosterol-to-cholesterol stretch resembles the azole target?

CYP51 (lanosterol 14α-demethylase); azoles mainly inhibit the fungal one.

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Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Lanosterol (CID 246983)](https://pubchem.ncbi.nlm.nih.gov/compound/246983) (PubChem, NCBI, 2026) · Public domain; [Cholesterol biosynthesis (R-HSA-191273)](https://reactome.org/PathwayBrowser/#/R-HSA-191273) (Reactome, 2026); [1W6K: Structure of human OSC in complex with Lanosterol](https://www.rcsb.org/structure/1W6K) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/molecules/lanosterol/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/lanosterol/