LANOSTEROL

Description

Lanosterol is a naturally-occurring sterol and biosynthetic precursor of several animal, fungal, and protozoan steroids, including cholesterol and ergosterol. Defects in the processing of lanosterol contribute to a wide variety of disorders, including the formation of cataracts. Similarly, certain fungicides act by blocking lanosterol processing by fungi.

Description

According to the?Merck Index, lanosterol is “the core structure from which all others are derived by biological modification”. It has the mysterious alternative name “kryptosterol”.
Lanosterol was isolated from sheep’s wool in 1930 by German researchers A. Windhaus and R. Tschesche. In 1958, Nobel Prize–winner K. E. Block and associates at Harvard University reported its synthesis from isocholesterol. It was subsequently prepared from squalene in 1966 by E. E. van Tamelen and co-workers at Stanford University
Until recently, lanosterol was primarily of historical and biosynthetic interest. But earlier this year, K. Zhang and colleagues at the University of California, San Diego, discovered that?lanosterol is involved in the genetics of cataracts in humans. They traced the genetic roots of severe cataracts to a mutation of the gene that encodes lanosterol synthase, one of the enzymes that produce lanosterol.
Based on this finding, Zhang’s group investigated whether lanosterol might be used to prevent cataracts. They found that treating cells that express disordered crystallin proteins with lanosterol reduces the incidence of crystallin clumps that cause cataracts. In early animal studies, administering lanosterol-containing eye drops reduced the severity of cataracts.
Some ophthalmology researchers have challenged the validity of Zhang’s results. Zhang’s group is conducting additional studies to verify whether humans with cataracts will benefit from lanosterol treatment.

The Uses of LANOSTEROL

Lanosterol has been used:

• as a standard in HPLC for the quantification in testis samples
• in S-adenosyl-L-methionine:Δ²⁴-sterol-C-methyltransferase (SMT) assay
• to treat wild-type cells growing in rich medium to know its effects on Sre1 protein

What are the applications of Application

Lanosterol is a precursor of cholesterol

Definition

ChEBI: A tetracyclic triterpenoid that is lanosta-8,24-diene substituted by a beta-hydroxy group at the 3beta position. It is the compound from which all steroids are derived.

General Description

Lanosterol, an amphipathic molecule, that is produced by?lanosterol?synthase (LSS). It is enriched in the lens.

Biochem/physiol Actions

Cholesterol precursor sterol.Lanosterol serves as an endogenous selective modulator of macrophage immunity.

Purification Methods

If very impure, then it should be acetylated, converted to the dibromide acetate [crystallised from EtOAc with slow cooling, m 168-170o, [] D +214o (CHCl3)], de-brominated with Zn dust to give the acetate (below) which is recrystallised from 3-4 parts of Me2CO/MeOH (4:1) and hydrolysed as for stigmasterol (below). Recrystallise it from anhydrous MeOH. Dry it in vacuo over P2O5 for 3hours at 90o. The purity is checked by proton magnetic resonance. The acetate crystallises from MeOH with m 131-133o and [ ] 25D +62o (c 1,CHCl3). [Block & Urech Biochemical Preparations 6 32 1958. van Tamelen et al. J Am Chem Soc 104 6479, 6480 1982, Beilstein 6 III 2880, 6 IV 4188.]