Chromium(III)-induced 8-hydroxydeoxyguanosine in DNA and its reduction by antioxidants: comparative effects of melatonin, ascorbate, and vitamin E.

Abstract

Chromium compounds are well documented carcinogens. Cr(III) is more reactive than Cr (VI) toward DNA under in vitro conditions. In the present study, we investigated the ability of Cr (III) to induce oxidative DNA damage by examining the fonnation of 8-hydrorydeoxyguanosine (8-OH-dG) in calf thymus DNA incubated with CrC13 plus H202. We measured 8-OH-dG using HPLC with electrochemical detection. In the presence of H202, we observed that Cr(III)-induced formation of 8-OH-dG in isolated DNA was dose and time dependent. Melatonin, ascorbate, and vitamin E (Trolox), all of which are free radical scavengers, markedly inhibited the formation of 8-OH-dG in a concentration-dependent manner. The concentrtion that reduced DNA damage by 50% was 0.51, 30.4, and 36.2 pM for melatonin, ascorbate, and Trolox, respectively. The results show that melatonin is 60-and 70-fold more effective than ascorbate or vitamin E, respectively, in reducing idatve DNA damage in this in vitro model. These findings also are consis-

Do carotenoid-based sexual traits signal the availability of non-pigmentary antioxidants?

“…In vitro, melatonin scavenges hydroxyl radicals, peroxides, singlet oxygen and nitric oxide Tan et al, 2002), and it has been shown that melatonin is superior to vitamin E as a peroxyl radical scavenger (Pieri et al, 1994). Compared with other major antioxidants (ascorbate and vitamin E), melatonin is also 60-and 70-fold more effective, respectively, in reducing oxidative DNA damage (assessed as the production of 8-hydroxy-29-deoxyguanosine) (Qi et al, 2000). Second, melatonin has an indirect effect on the antioxidant machinery by stimulating antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, glutathione reductase, catalase, and other antioxidant molecules, such as ascorbate, trolox and NADH (Gitto et al, 2001), but also by inhibiting pro-oxidant enzymes such as nitric oxide synthase and lipoxygenase Anisimov, 2003;Rodriguez et al, 2004).…”

The Speciation and Morphology of Chromium Oxide Nanoparticles in a Diffusion Flame

“…Evidence in the toxicological literature (Qi et al 2000) has suggested that bioavailable Cr(III) induces DNA damage. While the most common chromium oxides, e.g., Cr 2 O 3 , have very low solubility in water, toxicological studies have shown evidence of deep translocation of ultrafine particles, as well as leaching of metal that contributes to the toxicity of these particles (Veranth et al 2000).…”

Evaluation of Chromium Composition of Commonly Consumed Leafy Vegetables Juice Selected from South West Nigeria

“…An antidepressant which helps in prevention of obesity and type 2 diabetes mellitus by preventing appetite in insulin resistance and glucose intolerance as well as regulation of body composition [2,3]. While chromium intake is crucial in optimal energy metabolism and regulation excess consumption has been reported to accumulate intracellular Cr3+ ions that may lead to long-term genotoxic effects by formation of covalent bonds to DNA [4]. Taken together, cytotoxic, genotoxic and mutagenic effects as well as activity damaging to the mitochondria and induction of apoptosis have been reported for CrPic using mammalian cell cultures [5,6].…”