The uncoupler desaspidin is labile in the presence of oxidants at alkaline pH values. It also undergoes chlorophyll-sensitized photooxidation at a more acid pH. The products of the oxidation appear to have negligible activity in inhibiting electron transfer and photophosphorylation.Failure of desaspidin to uncouple in the presence of oxidants used as cofactors of noncyclic electron flow is pres...

Chronic exposure to oxidants is associated with an increased incidence of malignancy; however, the mechanism(s) by which oxidants contribute to carcinogenesis is unknown. Since oncogene activation plays an important role in carcinogenesis, we hypothesized that hydroxyl radical-induced DNA damage might contribute to carcinogenesis by causing oncogene activation. The studies reported herein demon...

There is considerable interest in the role that mammalian heme peroxidase enzymes, primarily myeloperoxidase, eosinophil peroxidase and lactoperoxidase, may play in a wide range of human pathologies. This has been sparked by rapid developments in our understanding of the basic biochemistry of these enzymes, a greater understanding of the basic chemistry and biochemistry of the oxidants formed b...

Leakage of mitochondrial oxidants contributes to a variety of harmful conditions ranging from neurodegenerative diseases to cellular senescence. We describe here, however, a physiological and heretofore unrecognized role for mitochondrial oxidant release. Mitochondrial metabolism of pyruvate is demonstrated to activate the c-Jun N-terminal kinase (JNK). This metabolite-induced rise in cytosolic...

Reactive oxygen species (ROS) can damage proteins, cause lipid peroxidation, and react with DNA, ultimately resulting in harmful effects. Antioxidants constitute one of the defense systems used to neutralize pro-oxidants. Since pro-oxidants and antioxidants are found ubiquitously in nature, pro-and antioxidant effects of individual compounds and of mixtures receive much attention in scientific ...

Oxidative stress is an imbalance between pro-oxidants and antioxidants in favor of the pro-oxidants, leading to different responses depending on the level of pro-oxidants achieved and the duration of exposure. In this article, we discuss the cytoprotective or suicidal signaling mechanisms associated with oxidative stress by addressing: (i) the development of an acute and mild pro-oxidant state ...

The concept of oxidative stress (OS) was originally used by Professor Helmut Sies who described it as “an imbalance between oxidants and antioxidants in favor of the oxidants, potentially leading to damage” with the ratio of oxidants to antioxidants as >1 (Sies, 1997). Oxidative/nitrosative stress represents the bodies’ imbalance in the production and the elimination of reactive oxygen and nitr...

Reactive oxygen species are involved in many diseases where the radical species OH, peroxynitrite and the non-radical, hypochlorous acid, play an outstanding role. The formation of OH-type oxidants is essentially confined to a few types of reactions. The most prominent ones are the one-electron reduction of hydrogen peroxide by F2+ or Cu+ -ions (Fenton-type reactions), reaction of hypochlorite ...

Oxidants are ubiquitous in our aerobic environment. While they are always toxic, they can also exert pathophysiological effects at low concentrations and play an etiological role in human disease. For example, oxidants can stimulate cell growth and act as tumor promoters. The cellular antioxidant defense system attenuates the effect of oxidants and consists of low molecular weight components an...

The transcription factor nuclear factor (NF)k B is activated by oxidative stress or cytokines and is critical to the activation of inflammatory genes. Here, we report that hydrogen peroxide or 3-morpholinosydnonimine, which simultaneously releases nitric oxide and superoxide, synergize with the cytokine tumor necrosis factor (TNF)a to activate NFk B in rat lung epithelial cells, suggesting that...