Inhibition of mitochondrial electron transport by hydroxy-substituted 1,4-quinones

Abstract

Mitochondrial electron transport from NADH, succinate, or duroquinol to oxygen is inhibited by 5-omega-cyclohexyl-n-pentyl-6-hydroxy-2,3-dimethoxy-1,4-benzoquinone and 2-omega-cyclohexyl-n-pentyl-3-hydroxy-1,4-napthoquinone. Assays of partial electron transport activities indicate a site of inhibition in the region between the site of duroquinol oxidation and cytochrome c reduction. Effects of the inhibitors on cytochrome spectra indicate the principle site of inhibition is between cytochromes of the b group and cytochrome c1. The quinones do not induce increased reduction of the b566 as does antimycin A. The benzoquinone can induce a partial antimycin insensitive bypass of the cytochromes b-c1 region. Uncoupling agents do not affect the extent of inhibition as has been reported for analogous naphthoquinone inhibitors.

Kinetic Microplate-Based Assays for Inhibitors of Mitochondrial NADH:Ubiquinone Oxidoreductase (Complex I) and Succinate:Cytochrome c Oxidoreductase

“…The smp suspension was added to the assay medium (20 ml) and allowed to stand at room temperature for 30 min before commencing the measurements to obviate the problem of slow activation of the enzyme. This slow activation phenomenon has been reported previously (22). The complete assay mixture (180 l per well) was then transferred to the microplate.…”

The Use of Time-Lapse Optical Coherence Tomography to Image the Effects of Microapplied Toxins on the Retina

“…41 Among its many effects, chloroquine, like cyanide, also is a known inhibitor of the mitochondrial electron transport chain. [65][66][67] Here, we observed a reduction of the PRT reflectance with our accelerated screening procedure. In addition to metabolic effects, prolonged administration of chloroquine corresponded to disappearance of rod and cone outer segments in fish 68 and in rats and cats, 69 which may be related to our findings.…”

Nanostructured CuO Thin-Film-Based Conductometric Sensors for Real-Time Tracking of Sweat Loss

“…However, if the structure has electronegative atoms, as in lawsone, this bonding becomes more complex and coordination occurs due to the charge delocalization involving the anchoring of the carboxylic group. ,− Therefore, this illustrates more stability of the metal center after the coordination of the lawsone ligand. The stability of metals against the corrosion is increased by the donated electron of the phenol group of lawsone and usually revives to explain the corrosion-resistant nature of some lawsone or henna coatings. ,− Similarly, the donor ability of hydroxynaphthoquinones is also used to explain an electron transfer mediator in biochemical fuel cells or other neighbor atoms/molecules. , …”