[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

https://staff.blog.ui.ac.id/hsuryadi/files/2012/02/ROS_RNS.pdf

Free radicals and antioxidants in normal physiological functions and human disease

Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970–1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010–2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

/pdf/lipid-peroxidation-production-metabolism-and-signaling-234bwmyps5.pdf

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal.

Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach that has seen widespread success involves the use of a proximal heteroatom that serves as a directing group for the selective functionalization of a specific C-H bond. In a survey of examples of heteroatom-directed Rh catalysis, two mechanistically distinct reaction pathways are revealed. In one case, the heteroatom acts as a chelator to bind the Rh catalyst, facilitating reactivity at a proximal site. In this case, the formation of a five-membered metallacycle provides a favorable driving force in inducing reactivity at the desired location. In the other case, the heteroatom initially coordinates the Rh catalyst and then acts to stabilize the formation of a metal-carbon bond at a proximal site. A true test of the utility of a synthetic method is in its application to the synthesis of natural products or complex molecules. Several groups have demonstrated the applicability of C-H bond functionalization reactions towards complex molecule synthesis. Target-oriented synthesis provides a platform to test the effectiveness of a method in unique chemical and steric environments. In this respect, Rh-catalyzed methods for C-H bond functionalization stand out, with several syntheses being described in the literature that utilize C-H bond functionalization in a key step. These syntheses are highlighted following the discussion of the method they employ.

/pdf/rhodium-catalyzed-c-c-bond-formation-via-heteroatom-directed-1wd3dm1jdi.pdf

Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

The organoselenium and organotellurium compounds have been described as promising pharmacological agents in view of their unique biological properties. Glutathione peroxidase mimic, antioxidant activity and thioredoxin reductase inhibition are some of the properties reviewed here. On the other hand, little is known about the molecular toxicological effects of organoselenium and organotellurium compounds. Most of our knowledge arose from research on inorganic selenium and tellurium. However, the ability to oxidize sulfhydryl groups from biological molecules can be involved both in their pharmacological properties and in their toxicological effects. In fact, exposition to high doses of organoselenium or to low doses of organotellurium causes the depletion of endogenous reduced glutathione in a variety of tissues. Thus, the design of compounds that cause low depletion of glutathione and react with specific targeted proteins, controlling specific metabolic pathways, will represent an important progress in understanding the field of organochalcogen compounds. Furthermore, the development of new organochalcogens with higher thiol-peroxidase activity that can use other non-toxic thiol reducing agents, such as N-acetylcysteine instead of glutathione, will permit the investigation of the co-administration of organochalcogens and thiols as a formulation for antioxidant therapy.

Organoselenium and Organotellurium Compounds: Toxicology and Pharmacology

Synthesis of Heterocycles via Palladium π-Olefin and π-Alkyne Chemistry

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Heck-Larock%202006.pdf

Synthesis of heterocycles via palladium-catalyzed oxidative addition.

Synthesis of heterocycles via electrophilic cyclization of alkynes containing heteroatom.

Objective and design: Ebselen, an organoselenium compound is able to modulate the inflammatory response in rodents. In the present study, the anti-inflammatory and antinociceptive activity of diaryl diselenides and ebselen was studied.¶Materials: Adult male Wistar rats and albino mice were treated with diaryl diselenides and ebselen in different doses.¶Methods: Carrageenin-induced paw edema, tail-flick, formalin, acetic acid-induced abdominal writhing and capsaicin models of pain were carried out. Data were analyzed by ANOVA followed by Duncan's multiple range when appropriate.¶Results: In all models, the most promising profile was displayed by diphenyl diselenide, which produced anti-inflammatory and antinociceptive activity significantly higher than ebselen. Diphenyl diselenide also produced dose-dependent antinociception when assessed in acetic acid-induced abdominal constriction, tail-flick test or formalin and capsaicin-induced nociception.¶Conclusion: The data presented here provide evidence that administration of diphenyl diselenide produced anti-inflammatory and antinociceptive activity.

Gilson Zeni

Papers

Organoselenium and Organotellurium Compounds: Toxicology and Pharmacology

Synthesis of Heterocycles via Palladium π-Olefin and π-Alkyne Chemistry

Synthesis of heterocycles via palladium-catalyzed oxidative addition.

Synthesis of heterocycles via electrophilic cyclization of alkynes containing heteroatom.

Anti-inflammatory and antinociceptive activity of diphenyl diselenide.