An analysis of the role of coenzyme Q in free radical generation and as an antioxidant

1992 ◽  
Vol 70 (6) ◽  
pp. 390-403 ◽  
Author(s):  
Robert E. Beyer
Keyword(s):  
Electron Transfer ◽  
Superoxide Dismutase ◽  
Free Radical ◽  
Human Subjects ◽  
Coenzyme Q ◽  
Quinone Reductase ◽  
Vital Role ◽  
Free Radical Damage ◽  
Dt Diaphorase

The vital role of coenzyme Q in mitochondrial electron transfer and its regulation, and in energy conservation, is well established. However, the role of coenzyme Q in free oxyradical formation and as an antioxidant remains controversial. Demonstration of the existence of the semiquinone form of coenzyme Q during electron transport, coupled with recent evidence that hydrogen peroxide (but not molecular oxygen) may act as an oxidant of the semiquinone, suggests that the highly reactive OH∙ radical may be formed from the semiquinone. On the other hand, data exist implicating the Fe–S species as the source of electron transfer chain, free radical production. Additional data exist suggesting instead that the unpaired electron of the coenzyme Q semiquinone most likely dismutates superoxide radicals. These concepts and those arising from observations at several levels of organization including subcellular systems, intact animals, and human subjects in the clinical setting, supporting the concept of reduced coenzyme Q as an antioxidant, will be presented. The results of recent studies on the interaction between the two-electron quinone reductase – DT diaphorase and coenzyme Q10 will be presented. The possibility that superoxide dismutase may interact with reduced coenzyme Q, in conjunction with DT diaphorase inhibiting its autoxidation, will be described. The regulation of cellular coenzyme Q concentrations during oxidative stress accompanying aerobic exercise, resulting in increased protection from free radical damage, will also be presented.Key words: coenzyme Q, ubiquinone, free radicals, lipid peroxidation, antioxidant, DT diaphorase, superoxide dismutase, review.

Study of antioxidant potential in leaves, stems, nuts of Juglans regia L.

2012 ◽  
Vol 1 (10) ◽  
pp. 79 ◽  
Author(s):  
G. Raja* ◽  
Ivvala Anand Shaker ◽  
Inampudi Sailaja ◽  
R. Swaminathan ◽  
S. Saleem Basha ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Juglans Regia ◽  
Radical Scavenging ◽  
Antioxidant Compounds ◽  
Free Radical Damage ◽  
Radical Damage

Natural antioxidants can protect the human body from free radicals and retard the progress of many chronic diseases as well as lipid oxidative rancidity in foods. The role of antioxidants has protected effect against free radical damage that may cause many diseases including cancer. Primary sources of naturally occurring antioxidants are known as whole grains, fruits, and vegetables. Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. The role of antioxidants has attracted much interest with respect to their protective effect against free radical damage that may cause many diseases including cancer. Juglans regia L. (walnut) contains antioxidant compounds, which are thought to contribute to their biological properties. Polyphenols, flavonoids and flavonols concentrations and antioxidant activity of Leaves, Stems and Nuts extract of Juglans regia L. as evaluated using DPPH, ABTS, Nitric acid, hydroxyl and superoxide radical scavenging activity, lipid peroxidation and total oxidation activity were determined. The antioxidant activities of Leaves, Stems and Nuts extract of Juglans regia L. were concentration dependent in different experimental models and it was observed that free radicals were scavenged by the test compounds in all the models.

scholarly journals An approach to the development of new drugs for African trypanosomiasis.

1978 ◽  
Vol 148 (2) ◽  
pp. 569-579 ◽  
Author(s):  
S R Meshnick ◽  
S H Blobstein ◽  
R W Grady ◽  
A Cerami
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radical ◽  
Coenzyme Q ◽  
New Drugs ◽  
H2o2 Production ◽  
Glycerol Phosphate ◽  
Free Radical Damage ◽  
Pharmacological Agents

The inability of the bloodstream form of Trypanosoma brucei brucei to decompose hydrogen peroxide forms the basis of our attempt to develop new pharmacological agents to kill these organisms. Approximately 1-3% of the oxygen consumed by these parasites appears in the form of hydrogen peroxide. Our previous observation that free radical initiators such as heme and hematoporphyrin D proved to be trypanocidal in vitro and in vivo, respectively, prompted this investigation into the mechanism of action of this class of compounds to enhance their therapeutic efficacy. The locus of H2O2 production within the trypanosome was examined using cell-free homogenates. Experiments described herein suggest that H2O2 is formed by the alpha-glycerol phosphate dehydrogenase in an adventitious manner, and that no enzymatic means of disposing of this potentially toxic compound are present with the organisms. Naphthoquinones were found to substantially increase the rate of both oxygen consumption and H2O2 production by trypanosomal mitochondrial preparations. Presumably, the naphthoquinones are acting as coenzyme Q analogues. The addition of sublytic concentrations of both naphthoquinones and heme leads to a synergistic lysis of the organisms in vitro. Another approach to increasing the susceptibility of T. b. brucei to free radical damage involved reduction of the intracellular concentration of glutathione. This was accomplished through the use of trypanocidal arsenicals. Melarsenoxide and heme acted synergistically in vitro, an effect which was further enhanced via addition of a naphthoquinone. Moreover, hematoporphyrin D and tryparsamide were shown to have a synergistic effect in T. b. brucei-infected mice.

scholarly journals Role of superoxide dismutase in survival of Leishmania within the macrophage

2003 ◽  
Vol 369 (3) ◽  
pp. 447-452 ◽  
Author(s):  
Sanjay GHOSH ◽  
Srikanta GOSWAMI ◽  
Samit ADHYA
Keyword(s):  
Superoxide Dismutase ◽  
Antisense Rna ◽  
Axenic Culture ◽  
Free Radical Damage ◽  
Enhanced Sensitivity ◽  
Mouse Macrophages ◽  
Parasite Survival ◽  
Radical Damage ◽  
Genus Leishmania

Intracellular parasitic protozoans of the genus Leishmania depend for their survival on the elaboration of enzymic and other mechanisms for evading toxic free-radical damage inflicted by their phagocytic macrophage host. One such mechanism may involve superoxide dismutase (SOD), which detoxifies reactive superoxide radicals produced by activated macrophages, but the role of this enzyme in parasite survival has not yet been demonstrated. We have cloned a SOD gene from L. tropica and generated SOD-deficient parasites by expressing the corresponding antisense RNA from an episomal vector. Such parasites have enhanced sensitivity to menadione and hydrogen peroxide in axenic culture, and a markedly reduced survival in mouse macrophages. These results indicate that SOD is a major determinant of intracellular survival of Leishmania.

The role of iron in oxygen-free radical damage during kidney storage at hypothermia

Cryobiology ◽  
1985 ◽  
Vol 22 (6) ◽  
pp. 614 ◽  
Author(s):  
B. Fuller ◽  
C. Green ◽  
G. Healing ◽  
S. Marley ◽  
S. Simpkin ◽  
...  
Keyword(s):  
Free Radical ◽  
Oxygen Free Radical ◽  
Free Radical Damage ◽  
Radical Damage

scholarly journals The role of DT-diaphorase in the maintenance of the reduced antioxidant form of coenzyme Q in membrane systems.

1996 ◽  
Vol 93 (6) ◽  
pp. 2528-2532 ◽  
Author(s):  
R. E. Beyer ◽  
J. Segura-Aguilar ◽  
S. Di Bernardo ◽  
M. Cavazzoni ◽  
R. Fato ◽  
...  
Keyword(s):  
Coenzyme Q ◽  
Membrane Systems ◽  
Dt Diaphorase
Sign in / Sign up

Export Citation Format

Share Document