Biomaterial Database

A mechanism for epoxidation of cholesterol by hepatic microsomal lipid hydroperoxides. 1984

T Watabe, and A Tsubaki, and M Isobe, and N Ozawa, and A Hiratsuka

Evidence was obtained, using cis-stilbene as a model substrate, for the participation of peroxy and/or oxy radicals in epoxidation of cholesterol by rat liver microsomal phospholipid hydroperoxides and a ferrous ion-ADP complex. Under the conditions used, cholesterol was epoxidised to the alpha- and beta-epoxides in the ratio 1:2-4, and cis-stilbene to trans-stilbene oxide without concomitant formation of the cis-oxide. Microsomal phospholipid hydroperoxides could be replaced with methyllinoleate monohydroperoxide for the epoxidation of both substrates. The hydroperoxide-mediated epoxidations were completely inhibited by alpha-tocopherol and t-butylhydroxyanisole. A GLC study suggested that highly polyunsaturated fatty acyl constituents of the microsomal phospholipids might play an important role in epoxidation of the olefinic substrates.

UI	MeSH Term	Description	Entries
D008054	Lipid Peroxides	Peroxides produced in the presence of a free radical by the oxidation of unsaturated fatty acids in the cell in the presence of molecular oxygen. The formation of lipid peroxides results in the destruction of the original lipid leading to the loss of integrity of the membranes. They therefore cause a variety of toxic effects in vivo and their formation is considered a pathological process in biological systems. Their formation can be inhibited by antioxidants, such as vitamin E, structural separation or low oxygen tension.	Fatty Acid Hydroperoxide,Lipid Peroxide,Lipoperoxide,Fatty Acid Hydroperoxides,Lipid Hydroperoxide,Lipoperoxides,Acid Hydroperoxide, Fatty,Acid Hydroperoxides, Fatty,Hydroperoxide, Fatty Acid,Hydroperoxide, Lipid,Hydroperoxides, Fatty Acid,Peroxide, Lipid,Peroxides, Lipid
D008563	Membrane Lipids	Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.	Cell Membrane Lipid,Cell Membrane Lipids,Membrane Lipid,Lipid, Cell Membrane,Lipid, Membrane,Lipids, Cell Membrane,Lipids, Membrane,Membrane Lipid, Cell,Membrane Lipids, Cell
D008862	Microsomes, Liver	Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.	Liver Microsomes,Liver Microsome,Microsome, Liver
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid
D002784	Cholesterol	The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.	Epicholesterol
D005231	Fatty Acids, Unsaturated	FATTY ACIDS in which the carbon chain contains one or more double or triple carbon-carbon bonds.	Fatty Acids, Polyunsaturated,Polyunsaturated Fatty Acid,Unsaturated Fatty Acid,Polyunsaturated Fatty Acids,Acid, Polyunsaturated Fatty,Acid, Unsaturated Fatty,Acids, Polyunsaturated Fatty,Acids, Unsaturated Fatty,Fatty Acid, Polyunsaturated,Fatty Acid, Unsaturated,Unsaturated Fatty Acids
D005296	Ferrous Compounds	Inorganic or organic compounds that contain divalent iron.	Compounds, Ferrous
D000244	Adenosine Diphosphate	Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.	ADP,Adenosine Pyrophosphate,Magnesium ADP,MgADP,Adenosine 5'-Pyrophosphate,5'-Pyrophosphate, Adenosine,ADP, Magnesium,Adenosine 5' Pyrophosphate,Diphosphate, Adenosine,Pyrophosphate, Adenosine
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia