Peroxides biosynthesis

S-adenosylmethionine 406 biosynthesis of epoxide 349 bis(trimethylsilyl) peroxide (BTSP) 448, 450 bis(trimethylsilyl)urea 449 bis-oxepane ring 281... 

Ryd6n A-M, Kayser O (2007) Chemistry, biosynthesis and biological activity of artemisinin and related natm-al peroxides. 9 1-31... 

Chemistry, Biosynthesis and Biological Activity of Artemisinin and Related Natural Peroxides A.-M. Ryden O. Kayser... 

Hemler, M.E. and Lands, W.E.M. (1980). Evidence for a peroxide-initiated free radical mechanism of prostaglandin biosynthesis. J. Biol. Chem. 255, 6253-6261. 

The stimulus for the recent surge of activity in this previously dormant area of organic chemistry can be traced to the prostaglandin connection . That is to the discovery that saturated bicyclic peroxides are key intermediates in the biosynthesis of prostaglandins and other physiologically active substances by the enzymatic oxygenation of polyunsaturated fatty acids. 

Studies on the biosynthesis of prostaglandins revealed that a strained bicyclic bis(secondary-alkyl) peroxide was not only a key intermediate, but could survive the biological conditions long enough to be isolated, albeit in minute amounts. This was a startling discovery in that no simple bicyclic peroxides of the same type were known, clearly for reasons of preparative difficulty. The prostaglandin connection focused attention upon this missing class of peroxides and stimulated... 

In the Gram-positive bacterium Bacillus subtilis (DNA with low G + C content), three Fur-like proteins have been characterized (Bsat et al., 1998). One, called Fur, regulates mainly iron uptake and siderophore biosynthesis. A second one, called PerR, regulates peroxide stress response genes and acts with manganese as corepressor. A third one, Zur, regulates genes for zinc uptake. The Zur protein found in E. coli shows only 25 % identity to the B. subtilis Zur, while the two Fur proteins have 32 % identical amino acids. 

Substituted-l-naphthols are the most potent 5-hpoxygenase inhibitors known. 2-PhenylteUuro-l-naphthol inhibits stimulated LTB4 biosynthesis in human neu-hophiles, and acts as a catalytic peroxide decomposer as well as a catalytic chain-breaking antioxidant. ... 

Riboflavin (vitamin Bj) is chemically specified as a 7,8-dimethyl-10-(T-D-ribityl) isoalloxazine (Eignre 19.22). It is a precnrsor of certain essential coenzymes, such as flavin mononucleotide (FMN) and flavin-adenine dinucleotide (FAD) in these forms vitamin Bj is involved in redox reactions, such as hydroxylations, oxidative carboxylations, dioxygenations, and the reduction of oxygen to hydrogen peroxide. It is also involved in the biosynthesis of niacin-containing coenzymes from tryptophan. 

Lipoxygenases (LOX), cycloxygenases (COXs), and xanthine oxidase (XO) are metalloen-zymes whose catalytic cycle involves ROS such as lipid peroxyl radicals, superoxide, and hydrogen peroxide. LOXs and COXs catalyze important steps in the biosynthesis of leuco-trienes and prostaglandins from arachidonic acid, which is an important cascade in the development of inflammatory responses. XO catalyzes the ultimate step in purine biosynthesis, the conversion of xanthine into uric acid. XO inhibition is an important issue in the... 

Present in foodstuffs and various pharmacological and cosmetics products, organic peroxides are also generated during lipid peroxidation and prostaglandin biosynthesis. They readily undergo one-electron reduction and oxidation reactions, with the formation of alkoxyl and peroxyl radicals, respectively ... 

Malonaldehyde is found in human and animal tissue as an end-product of lipid peroxidation. It is also a side-product of prostaglandin and thromboxane biosynthesis. Malonaldehyde is present in blood platelets and in serum (lARC, 1985). 

An example is adrenodoxin reductase (see chapter banner, p. 764), which passes electrons from NADPH to cytochrome P450 via the small redox protein adrenodoxin. This system functions in steroid biosynthesis as is indicated in Fig. 22-7.209a b Other flavin-dependent reductases have protective functions catalyzing the reduction of ascorbic acid radicals,210 211 toxic quinones,212-214 and peroxides.215-218... 

C) The antioxidant actions of flavonoids appear to participate in their antithrombotic action. Flavonoids bind to platelet membranes and scavenge platelet-generated lipid peroxides and free radicals, restoring the biosynthesis and the action of endothelial prostacyclin and nitric oxide (NO), respectively [49,88]. 

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