https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Cholesterol and its oxysterol congeners are important constituents of cell membranes and function as intermediates in several crucial biosynthetic pathways. These compounds autoregulate their metabolic fate by end-product repression and activation of downstream catabolism. Although end-product repression by oxysterols is relatively well understood, the mechanism by which these compounds act as positive transcription signalling molecules is unknown. Here we identify a specific group of endogenous oxysterols that activate transcription through the nuclear receptor LXR alpha. Transactivation of LXR alpha by oxysterols occurs at concentrations at which these compounds exist in vivo. The most potent activators also serve as intermediary substrates in the rate-limiting steps of three important metabolic pathways: steroid hormone biosynthesis, bile acid synthesis, and conversion of lanosterol to cholesterol. Our results demonstrate the existence of a nuclear receptor signalling pathway for oxysterols and suggest that LXR alpha may be important as a sensor of cholesterol metabolites.

An oxysterol signalling pathway mediated by the nuclear receptor LXRα

Lipid hydroperoxide generation, turnover, and effector action in biological systems

The primary producs formed from the autoxidation of lipids can be understood based upon a mechanism that involves five different reaction types. These reactions are: reaction of a carbon radical and molecular oxygen, atom transfer of a hydrogen from substrate to the chain carrying peroxyl, fragmentation of the chain carrying peroxyl to give oxygen and a carbon radical, rearrangement of the peroxyl, and cyclization of the peroxyl. The mechanisms of these primary reaction steps has been the focus of extensive research over the past fifty years, and the current level of understanding of these transformations is the subject of this review.

Mechanisms of free radical oxidation of unsaturated lipids

Oxygenated derivatives of cholesterol (oxysterols) present a remarkably diverse profile of biological activities, including effects on sphingolipid metabolism, platelet aggregation, apoptosis, and ...

Oxysterols: modulators of cholesterol metabolism and other processes.

Sterol metabolism. XX. Cholesterol 7.beta.-hydroperoxide

Sterol metabolism. 23. Cholesterol oxidation by radiation-induced processes.

Sterol metabolism--XLVII. Oxidized cholesterol esters in human tissues.

The design and construction of effective delivery vectors for drugs is very important. We have discovered that octadecyl quaternized carboxymethyl chitosan (OQCMC) in combination with cholesterol (Chol) could form stable vesicles with structure similar to that of conventional liposomes prepared from phosphatidylcholine/cholesterol (PC/Chol). Compared to conventional liposomes, our polymeric liposomes formed by OQCMC/Chol have many excellent features, such as good physical and thermal stability, excellent solubility in water, and high effectiveness in drug encapsulation. Trans-activating transcriptional activator protein (TAT peptide) could be connected on the surface of cationic polymeric liposomes by using cross-linking reagent N-hydroxysuccinimidyl-3-(2-pyridyldithio) propionate (SPDP). Also, oil-soluble magnetic nanoparticles were used to verify the bilayer structure of the polymeric liposomes and their ability to solublize hydrophobic materials. Using different preparation methods, OQCMC/Chol could ea...

Characterization of Novel Multifunctional Cationic Polymeric Liposomes Formed from Octadecyl Quaternized Carboxymethyl Chitosan/Cholesterol and Drug Encapsulation

Jon I. Teng

Papers

Sterol metabolism. XX. Cholesterol 7.beta.-hydroperoxide

Sterol metabolism. 23. Cholesterol oxidation by radiation-induced processes.

Sterol metabolism--XLVII. Oxidized cholesterol esters in human tissues.

Characterization of Novel Multifunctional Cationic Polymeric Liposomes Formed from Octadecyl Quaternized Carboxymethyl Chitosan/Cholesterol and Drug Encapsulation

Sterol metabolism. XXIV. On the unlikely participation of singlet molecular oxygen in several enzyme oxygenations.