Recent advances in reactions of active oxygen species are presented with attention to formation and reactivity. The nature of triplet and singlet oxygen oxygen is briefly described and it is pointed out that the oxidation of various substrates with triplet oxygen slows down in accordance with the spin reservation rule. Reactivities of superoxide ion, hydrogen peroxide, hydroxy and hydroperoxy radicals are compared, and for hydrogen peroxide and hydroperoxy radical are shown to significantly increase with the introduction of electron-attracting groups. The structures and reactivity of adducts of X with oxygen, where X=carbon, sulfur and nitrogen, are discussed. The nucleophilic reactivity of carbonyl oxides (X=R₂C) is considered in relation to the electrophilic nature of dioxiranes. Perepoxides and persulfoxides (X=R₂S), adducts of singlet oxygen with olefins and sulfides, is discussed in relation to nucleophilic reactivity. Nitroso oxides (X=RN) were found to react as electrophilic diradicals in contrast to carbonyl oxides and persulfoxides. Important aspects of the chemistry of nitrogen monoxide and peroxynitrite are summarized briefly.

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This article reviews recent studies on i) electrophilic, nucleophilic and radical oxygenations of C₆₀ and C₇₀ and ii) formation and quenching of singlet oxygen and related active oxygen species by C₆₀.

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Since its discovery a 100 years ago, Baeyer-Villiger oxidation has been widely used to transform carbonyl compounds to the corresponding esters or lactones. Until recently, however, only a few papers have appeared on asymmetric Baeyer-Villiger oxidation, while enzymatic catalytic transformation has been extensively studied and reported. Recent developments in asymmetric Baeyer-Villiger oxidation are discussed in the following such as a catalytic system of chiral Ni or Cu catalysts/O₂/ RCHO and chiral Pt catalysts/H₂O₂ and a stoichiometric process using chiral acetals/MCPBA/SnCl₄, Katsuki/Sharpless reagent and Et₂Zn/O₂/chiral aminoalcohols. The scope and limitations of these methods are also described.

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Ligand-exchange reactions of manganese (III) acetate with 1, 3-dicarbonyl compounds were found to occur in situ in acetic acid with consequent formation of new manganese (III) -enolate complexes. Manganese (III) -enolate complexes were reacted with alkenes in acetic acid at over 100°C to produce the corresponding carbon radicals which were then oxidized with manganese (III) followed by intramolecular cyclization to produce 4, 5-dihydrofurans. Reactions of α, ω-alkadienes with malonic acid or malonamide resulted in inter- and intra-molecular cyclization to afford bicyclic and/or tricyclic lactones and/or lactams. Manganese (III) -based oxidation of oligomethylene di (3-oxobutanoate) s with α, ω-alkadienes gave macrodiolides, each possessing two fused dihydrofuran rings, in good yields. The macrocyclic compounds were shown to have the capacity to incorporate alkali metal ions. Similar reactions of manganese (III) -enolate complexes with alkenes at 23°C in air slowly produced similar carbon radicals. Molecular oxygen was trapped in the reaction mixture with carbon radicals to produce peroxyl radicals which subsequently underwent reduction by manganese (II) and cyclization to quantitatively yield 1, 2-dioxan-3-ols. Using pyrrolidinedione and piperidone derivatives in reaction at 23°C provided azabicyclic peroxides. Acid-catalyzed decomposition of 1, 2-dioxan-3-ols yielded the corresponding functionalized furans, while palladium-catalyzed hydrogenolysis of azabicyclic peroxides led to extrusion of one peroxide oxygen to give tetrahydrofuran derivatives. Manganese (III) -based oxidation of alkenes with 1, 3-dicarbonyl compounds may thus be concluded an effective means for organic synthesis

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New developments in lipid peroxidation are presented. Amongst many biological components lipids are the most susceptible to oxidation since they contain polyunsaturated fatty acids (PUFA). PUFA is oxidized by a free radical chain mechanism in which one radical results in the formation of hundreds of lipid hydroperoxides. Oxidation of arachidonic acid gives polyoxygenated products including isoprostanes, useful as markers of a nonenzymatic oxidation in vivo. The oxidizability of PUFA in homogeneous solution depends on the number of bisallylic positions available for oxidation. In contrast, the oxidizability of PUFA in aqueous micelles decreases with an increasing number of bisallylic sites. Peroxyl radicals derived from docosahexaenoate are considered to be more polar than those from linoleate because the ratio of oxygen uptake to substrate consumption increased from 1 to 3.4 with an increasing number of unsaturation. The rate of disappearance of butyl hydroxytoluene situated in the core of micelles decreased with an increasing number of unsaturation during the oxidation of PUFA. Polar peroxyl radicals from highly unsaturated fatty acid methyl ester would thus appear to migrate from the core to micelle surface with consequent reduction in rate of oxidation by enhancing the rate of termination and reducing the rate of propagation. The authors have established a reliable method for evaluating the regioisomeric composition of Ch 18 : 2-O (O) H in human plasma, with no affect on artifactual oxidation during sample treatment and analysis. All four regioisomers of Ch 18 : 2-O (O) H were detected in blood plasma from healthy young subjects. The 13 ZE-Ch 18 : 2-O (O) H isomer was not a major product produced through the enzymatic oxidation of Ch 18 : 2. Free radical-mediated oxidation of polyunsaturated lipids appears from the present findings to be an ongoing process within normal healthy individuals.

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Today, we are always exposed to stress. Versatile chemical, biological, physical and social stress attack us. On the other hand, stress is a double-edged sword and some of the stress exert beneficial effect. In order to protect us from the stress to maintain good health and high quality of life, it is essential to clarify and understand the mechanisms of biological responses to the stress, to assess the extent of stress, and to establish ways to cope with such stress. The life science of stress including the role of oleoscience will be one of the most important future subjects.

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