New reaction scheme is suggested for the initiated nonbranched-chain addition of free radicals to the multiple bond of the molecular oxygen. The scheme includes the reaction competing with chain propagation reactions through a reactive free radical. The chain evolution stage in this scheme involves a few of free radicals, one of which (tetraoxyl) is relatively low-reactive and inhibits the chai...

radiation damage is to a large extent caused by overproduction of reactive oxygen species (ros). radioprotectors are agents or substances that reduce the effects of radiation in healthy normal tissues while maintaining the sensitivity to radiation damage in tumor cells. radioprotectors are agents or substances that reduce the effects of radiation in healthy normal tissues while maintaining the ...

in this work, the study of various substituted kaempferol derivatives is presented. the bond dissociation energies (bde) have been calculated using b3lyp level and different basis sets in gas-phase. calculated results show that the bde values of substituted kaempferol range from about 77 to100 kcal/mol, demonstrating that kaempferol is an effective chain-breaking antioxidant that prevents lipid...

the present study was designed to explore the flavonoid contents and the radical scavenging activities of 50% ethanol extracts of leaves, stems, rachis and roots of dryopteris erythrosora. the total flavonoid contents in various parts were determined as: stems > roots > rachis > leaves. all extracts from different parts of d. erythrosora showed strong bioactivities. the dpph free radical scaven...

Biological systems that produce or are exposed to nitric oxide (NO radical) exhibit changes in the rate of oxygen free radical production. Considering that mitochondria are the main intracellular source of oxygen radicals, and based on the recently documented production of NO(radical) by intact mitochondria, we investigated whether NO(radical), produced by the mitochondrial nitric-oxide synthas...

abstract introduction: medicinal plants belong to lamiaceae family are potential sources of new drugs to improve the treatment of diseases which its treatment is linked to anti-oxidative agents. in this paper, antioxidant potentials of some lamiaceae species have been evaluated by two methods. methods: phosphomolybdate assay for total antioxidant capacity and ferric reducing antioxidant potenti...

background: one of the new methods for elimination or destruction of estrogen hormones is ultrasound irradiation. the aim of this study was to determine the main mechanism of steroid hormones removal by ultrasound. methods: in this study, estrogen (e1) and 17 beta-estradiol (e2) were irradiated with ultrasound at different frequencies, powers, and exposure times in two cases: with and without b...

For more than a century oxygen has been known to be one of the most powerful radiosensitizers. However, despite decades of preclinical and clinical research aimed at overcoming tumor hypoxia, little clinical progress has been made so far. Ionizing radiation damages DNA through generation of free radicals. In the presence of oxygen these lesions are chemically modified, and thus harder to repair...

Myocardial ischemia causes release of chemotactic factors, migration of neutrophils, peroxidation of lipids, and depletion of free radical scavengers. The invading neutrophils may injure the myocardial vasculature and sarcolemma by generating oxygen free radicals. Several agents that affect neutrophils or oxygen radicals were evaluated in a canine model of regional myocardial ischemia and reper...

Reactive oxygen species have been invoked as a causative agent of cell death in many different developmental and pathological states. The presence of free radicals and their importance of hair cell death due to aminoglycosides is suggested by a number of studies that have demonstrated a protective effect of antioxidants. By using dichlorofluorescin (DCFH) a fluorescent compound that is a report...