Lipid Peroxidation: Inhibition, Effects and Mechanisms (original) (raw)

Reactive Oxygen Species, Lipid Peroxidation and Antioxidative Defense Mechanism

Lipid peroxidation can be defined as the oxidative deterioration of lipids containing any number of carbon-carbon double bonds. Lipid peroxidation is a well-established mechanism of cellular injury in both plants and animals, and is used as an indicator of oxidative stress in cells and tissues. Lipid peroxides are unstable and decompose to form a complex series of compounds including reactive carbonyl compounds. The oxidation of linoleates and cholesterol is discussed in some detail. Analytical methods for studying lipid peroxidation were mentioned. Various kinds of antioxidants with different functions inhibit lipid peroxidation and the deleterious effects caused by the lipid peroxidation products.

Lipid peroxidation: Mechanisms, inhibition, and biological effects

Biochemical and Biophysical Research Communications, 2005

In the last 50 years, lipid peroxidation has been the subject of extensive studies from the viewpoints of mechanisms, dynamics, product analysis, involvement in diseases, inhibition, and biological signaling. Lipids are oxidized by three distinct mechanisms; enzymatic oxidation, non-enzymatic, free radical-mediated oxidation, and non-enzymatic, non-radical oxidation. Each oxidation mechanism yields specific products. The oxidation of linoleates and cholesterol is discussed in some detail. The relative susceptibilities of lipids to oxidation depend on the reaction milieu as well as their inherent structure. Lipid hydroperoxides are formed as the major primary products, however they are substrates for various enzymes and they also undergo various secondary reactions. Phospholipid hydroperoxides, for example, are reduced to the corresponding hydroxides by selenoproteins in vivo. Various kinds of antioxidants with different functions inhibit lipid peroxidation and the deleterious effects caused by the lipid peroxidation products. Furthermore, the biological role of lipid peroxidation products has recently received a great deal of attention, but its physiological significance must be demonstrated in future studies.

Chemistry and biochemistry of lipid peroxidation products

Free Radical Research, 2010

Oxidative stress and resulting lipid peroxidation is involved in various and numerous pathological states including infl ammation, atherosclerosis, neurodegenerative diseases and cancer. This review is focused on recent advances concerning the formation, metabolism and reactivity towards macromolecules of lipid peroxidation breakdown products, some of which being considered as ' second messengers ' of oxidative stress. This review relates also new advances regarding apoptosis induction, survival/proliferation processes and autophagy regulated by 4-hydroxynonenal, a major product of omega-6 fatty acid peroxidation, in relationship with detoxication mechanisms. The use of these lipid peroxidation products as oxidative stress/ lipid peroxidation biomarkers is also addressed.

Lipid Peroxidation: Chemical Mechanism, Biological Implications and Analytical Determination

Lipid Peroxidation, 2012

Reduced iron complexes (Fe 2+) react with lipid peroxides (ROOH) to give alkoxy radicals, whereas oxidized iron complexes (Fe 3+) react more slowly to produce peroxyl radicals. Both radicals can take part in the propagation of the chain reaction. The end products of these complex metal ion-catalyzed breakdowns of lipid hydroperoxides include the cytotoxic aldehydes and hydrocarbon gases such as ethane.

Lipid peroxidation and antioxidant enzyme activities of

A large number of micropropagated Euphorbia millii shoots from temporary immersion bioreactor showed thick broad leaves that were translucent, wrinkled and/or curled and brittle, symptoms of hyperhydricity. The environment inside bioreactor normally used in plant micropropagation is characterised by high relative humidity, poor gaseous exchange between the internal atmosphere of the bioreactor and its surrounding environment, and the accumulation of ethylene, conditions that may induce physiological disorders. A comparison of hyperhydric shoots (HS) with normal plants shows marked increase in malondialdehyde (MDA) content in HS plants. MDA, a decomposition product of polyunsaturated fatty acids hydroperoxides, has been utilized very often as a suitable biomarker for lipid peroxidation, which is an effect of oxidative damage. This hypothesis is also confirmed by the higher lipoxygenase (LOX) activity in HS plants. The potential role of antioxidant enzymes in protecting hyperhydric shoots from oxidative injury was examined by analyzing enzyme activities and isozyme profiles of hyperhydric and non-hyperhydric leaves of E. millii. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity were significantly higher in hyperhydric tissue as compared to non-hyperhydric normal leaf tissue. After native polyacrylamide gel electrophoresis (PAGE) analysis, seven SOD isoenzymes were detected and the increase in SOD activity observed in hyperhydric tissue seemed to be mainly due to Mn-SOD and Cu/Zn-SOD. The activity of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) was proportionally increased in HS tissue compared to normal leaves indicating a crucial role in eliminating toxic H 2 O 2 from plant cells. The depletion of GSH and total glutathione in spite of higher GR activities observed in HS tissue indicates that mechanism of antioxidant defense was by enhanced oxidation of GSH to GSSG by DHAR yielding ascorbate (AA). The antioxidant metabolism has been shown to be important in determining the ability of plants to survive in hyperhydric stress and the up regulation of these enzymes would help to reduce the build up of ROS.

Activity of Natural Antioxidants on Lipids

The kinetic behaviour of derivatives of benzoic and cinnamic acids, D-tocopherol, ascorbyl palmitate, flavonoids, coumarins, carnosol, thymol, carvacrol, resveratrol and carotenoids in lipid oxidation were studied. Most of the experiments were carried out with kinetically pure triacylglycerols or methyl esters of fatty acids. Some of the investigations were performed with fats and oils without purification in view to get information for the practice concerning the possibility for stabilization of real lipid systems. A new general parameter, activity A, for complex estimation of the effect of the antioxidants in lipids is proposed. It unifies the effectiveness of an inhibitor in termination of the autoxidation chain, on the one hand, and its ability to change the oxidation rate during the induction period, on the other. The analysis of the kinetic data obtained allowed the participation of the antioxidants in the side reactions of inhibited oxidation to be discussed. The extracts of different Bulgarian plant materials with solvents of various polarity were studied: leaves from Rosemary officinalis L., bark from Fraxinus ornus L., selected spieces of the family Lamiaceae, used as spices in Bulgaria, e.g. Melissa officinalis L., Mentha piperita L., Mentha spicata L., Ocimum basilicum L., Origanum vulgare L., and Saturejae hortensis L. Propolis, algae Scenedesmus acu-tus, Silibum marianum seed oil, Capsicum annum L. were also examined. The participation of carotenoids in the oxidation process differs from that of phenolic antioxidants. Our study on sunflower oil oxidation showed that in an antioxidant-free lipid system, the presence of carotenoids did not show any antioxidative protection, whereas in the presence of tocopherols and under light a synergism occurred.