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Radical Attack (radical + attack)
Selected AbstractsDevelopment of spray- and freeze-dried high-concentration sesamol emulsions and antioxidant evaluation in fibroblasts and UV-exposed rat skin slicesDRUG DEVELOPMENT RESEARCH, Issue 5 2008Juliana Alencar Abstract Dry sesamol emulsions were synthesized from several combinations of saccharose with hydroxypropylmethylcellulose (HPMC) or sodium caseinate (SC) using spray-drying techniques at 120° to 180°C, or freeze-drying. On the basis of physical characteristics such as droplet size distribution, residual moisture, and microscopic structure, the best material was obtained when spray-drying was applied at either 150° or 180°C with SC or HPMC as excipients, respectively. The extent to which the antioxidant properties of free sesamol towards a set of free radicals (galvinoxyl, diphenylpicrylhydrazyl, superoxide, and hydroxyl) were altered in the starting and reconstituted liquid emulsions submitted to normal storage or pre-exposed to a flux hydroxyl radicals was investigated. Emulsions were further evaluated for their antioxidant properties in cultured 3T3 murine fibroblasts and in an ex vivo model of ultraviolet irradiated rat skin. It was found that, in the material having the best physical properties, encapsulation was decisive in: (1) improving the overall antioxidant behavior of reconstituted versus starting liquid emulsions: (2) sparing sesamol consumption due to free radical attack; and (3) significantly protecting cells and skin against free radical- or irradiation-induced enzymatic release and/or lipid peroxidation. Demonstrating a high activity at high dilutions where interactions of excipient become negligible, the new emulsions could be of great interest in sesamol-based pharmacology or topical applications. Drug Dev Res 69:251,266, 2008. © 2008 Wiley-Liss, Inc. [source] Antioxidants, showy males and sperm qualityECOLOGY LETTERS, Issue 5 2001Jonathan D. Blount The fertility of males sometimes correlates with their ornamental display, but we do not have a mechanistic explanation to universally link these traits. We suggest that both sperm quality (fertility; integrity of DNA), and the substrates responsible for male ornamentation, may be vulnerable to free radical attack, which can be mitigated by antioxidants. Support for these ideas is at present weak, and requires validation in ecological contexts. We hypothesize that a link between ornamentation and sperm quality could arise if antioxidants are in limited supply, and the showiest males may be preferred because they are most likely to be fertile, or to provide sperm with undamaged genotypes that could give rise to fit offspring. [source] Production of Off-Odor Volatiles from Liposome-Containing Amino Acid Homopolymers by IrradiationJOURNAL OF FOOD SCIENCE, Issue 7 2002D.U. Ahn ABSTRACT: Irradiation not only generated many new volatiles but also destroyed some volatiles already present in nonirradiated amino acid homopolymer-in-liposome systems. The amounts of some volatiles greatly increased, but others significantly decreased after irradiation. The majority of newly generated and increased volatiles by irradiation were sulfur compounds, indicating that sulfur amino acids are the most susceptible to changes by irradiation. More than one site in amino acid side chains was labile to free radical attack, and many volatiles were produced by the secondary chemical reactions after the primary radiolytic degradation of side chains. Although nonirradiated samples also produced some sulfury notes, irradiated samples produced much a stronger and astringent sulfury odor than nonirradiated samples. [source] EPR study of nitroxides formed from the reaction of nitric oxide with photolyzed amidesMAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2003Fan Wang Abstract Free radicals generated from UV irradiation of simple aliphatic amides in anaerobic and nitric oxide (NO)-saturated liquid mixtures or solutions gave EPR spectra of nitroxides. The application of isotopic effects to EPR spectra and the generation of radicals by transient radical attack on substrate molecules or by photolysing amine or acetoin were used to help identify photochemically produced radicals from the amides. The aliphatic amides used were formamide, acetamide and their N -methyl- or deuterium-substituted derivatives. Transient radicals used to attack the amides via hydrogen-atom abstraction were generated from the initiator AIBN or AAPH. The observation of various nitroxides indicates the reactivity of NO for trapping acyl, carbamoyl and other carbon-centered radicals. Possibly mechanistic pathways diagnosed with this trap are proposed. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||