Iron-Induced Oxidative Stress in Erythrocyte Membranes of Non-Insulin-Dependent Diabetic Nigerians

The presence of higher level of endogenous free radical reaction products in the erythrocyte ghost membrane (EGM) of Non-insulin-dependent diabetes mellitus (NIDDM) subjects compared with that of normal healthy controls has been demonstrated. The EGMs of NIDDM subjects were also shown to be more susceptible to exogenously generated oxidative stress than those of normal healthy individuals. The decreased level of reactive thiol groups in the EGM of NIDDM individuals supported this observation. We propose that the presence of significant levels of non-heme iron in the EGM of NIDDM subjects is an indication of the potential for iron-catalysed production of hydroxy and other toxic radicals which could cause continuous oxidative stress and tissue damage. Oxygen free radicals could therefore be responsible for most of the erythrocyte abnormalities associated with non-insulin-dependent diabetes and could indeed be intimately involved in the mechanism of tissue damage in diabetic complications

Evidence That Free Fatty Acid-Iron Complexes Directly Initiate Lipid Peroxidation in Vitro and in Vivo: A New Mechanism of Oxidative Stress

Through a series of biochemical and histochemical experiments we explored the novel hypothesis that iron and free fatty acids, liberated after tissue injury, combine to form liposoluble complexes that directly initiate lipid peroxidation. The addition of 100 M ferric iron to 30 mM linoleate suspensions at pH 7.4 produced time dependent lipid peroxidation, measured as conjugated diene formation. Complexes of 100 M ferric iron and 600 M pentanoate also initiated formation of conjugated dienes in linoleate suspensions and formation of malondialdehyde-like materials in rat liver slices. A histochemical stain for free fatty acids revealed positive reactions within cell membranes in traumatized regions of rat liver tissue that underwent compression injury followed by thirty minutes of blood perfusion, but not in nontraumatized control regions. The diaminobenzidine-H2O2 histochemical reaction for iron, revealed increased levels of redox cyclable iron in the membranes and the cytoplasm of traumatized hepatocytes. We propose that traumatic injury initiates cascades leading to liberation of iron from storage proteins and free fatty acids from membranes, which combine, distribute to the lipid domains of cell membranes, and directly initiate lipid peroxidation

Interaction of Liposomal Drug Delivery Systems with Cells and Tissues: Microscopic Studies

Liposomes , as drug carriers, can be administered into the body by several routes e.g. intravenously, intraperitoneally, intramuscularly, intratracheally and topically among others. Radiolabelled markers are suitable to monitor the distribution and elimination of liposomes, but the tissue deposition of intact liposomes, the mode and sites of drug release from the liposomes and liposome-cell interactions cannot be investigated morphologically. Microscopic techniques could provide information regarding the intact state of liposomes and possibly the dynamics of liposomes in tissues provided that they can be identified with certainty in vivo. This is a formidable problem and in spite of several attempts, there is still a lot of work and new ideas needed to overcome this problem. This paper gives a detailed review of liposome markers used in light and electron microscopy. The use of markers or the technique involved in the identification of liposomes in cells or t issues is discussed. The feasibility of using colloidal iron, a new electron dense marker, as a marker for intravenously injected liposomes was investigated in mice. Intact multilamellar vesicles containing colloidal iron were identified in the liver, spleen and lung of mice injected with liposomes. The liver and the spleen are organs for the storage of iron containing proteins (ferritin, hemosiderin), therefore studying the disposition of colloidal iron from the liposomes was not possible. However, in organs not containing iron, e.g. lung, the presence of colloidal iron can easily be recognized. The colloidal iron marker may be suitable to label liposomes targeted to the brain , heart or certain tumors

Lipid peroxidation in tissues and neural fractions during experimental vitamin e deficiency and in patients with friedreich's ataxia.

A severe deficiency of vitamin E in man results in a characteristic neurological syndrome which is very similar to that seen in patients with Friedreich’s ataxia (FA). The mechanism(s) of action of vitamin E in neurological tissues is unknown although it is generally accepted to act as a lipid soluble antioxidant. The purposes of this study were to examine lipid peroxidation in (a) the vitamin E deficient rat and (b) autopsy material from patients with FA. A fractionation procedure using brainstem was validated to isolate myelin, an axolemma-enriched fraction (AEF) and a fraction containing the axoplasmic membranes and organelles (M/O). Endogenous lipid peroxidation was assessed by measuring thiobarbituric acid reactive substances (TBARS), free, bound and total malondialdehyde (MDA) and aliphatic aldehydes. Susceptibility to in-vitro free radical stress was also investigated using the copper sulphate / hydrogen peroxide generating system and measuring free MDA. Endogenous lipid peroxidation was investigated in vitamin E deficient and control rats after 21 and 56 weeks. After 56 weeks concentrations of TBARS in the deficient animals were increased in all tissues except for peripheral nerve. Increases were less in neural than non-neural tissues ( 6-fold). Lesser changes in lipid peroxidation were seen after 21 weeks of deficiency. These results, therefore, provide evidence of increased lipid peroxidation during vitamin E deficiency. When tissues and fractions from 20 and 60 week old rats were stressed in-vitro using copper sulphate / hydrogen peroxide the following observations were made (a) the deficient samples in contrast to control material did not exhibit a lag phase and (b) the following order of susceptibility to peroxidation was noted: brain > > spinal cord > nerve; M/O > > AEF > myelin. The latter result is consistent with the neuropathology seen in vitamin E deficiency where a primary axonopathy leads to secondary demyelination. In studies of autopsy material from patients with FA, vitamin E concentrations in neural tissues were not significantly different from control values. Studies of lipid peroxidation failed to show any significant differences between patients and controls. The results would, therefore, seem to rule out an antioxidant defect in the aetiology of this disease

The role of EPR spectroscopy in studies of the oxidative status of biological systems and the antioxidative properties of various compounds

In this era of intense study of free radicals and antioxidants, electron paramagnetic resonance (EPR) is arguably the best-suited technique for such research, particularly when considering biochemical and biological systems. No attempt was made to cover all the topics of EPR application but instead attention was restricted to two areas that are both novel and received less attention in previous reviews. In the first section, the application of EPR in assessing the oxidative status of various biological systems, using endogenous stabile paramagnetic species, such as the ascorbyl radical, semiquinone, melanin, and oxidized pigments, is addressed. The second section covers the use of EPR in the emerging field of antioxidant development, using EPR spin-trapping and spin-probing techniques. In both sections, in addition to giving an overview of the available literature, examples (mostly from the authors' recent work) are also presented in sufficient detail to illustrate how to explore the full potential of EPR. This review aims at encouraging biologists, chemists and pharmacologists interested in the redox metabolism of living systems, free radical chemistry or antioxidative properties of new drugs and natural products to take advantage of this technique for their investigations

Protective effect of guarana-loaded liposomes on hemolytic activity

Paullinia cupana var. sorbilis (Mart.) Ducke, popularly known as guarana, is one of the most promising plants in Brazilian flora and has attracted considerable interest from the scientific community owing to its numerous therapeutic activities and less side effects. Hence, using nanotechnology is a viable alternative to primarily improve the physicochemical characteristics and bioavailability of guarana. The objective of the present study was to develop, characterize, and evaluate the stability of liposomes containing guarana powder and to evaluate their antioxidant and hemolytic activity in vitro. Three different concentrations of guarana powder and two methods of liposome preparation were tested. Liposomes were developed and characterized, and their stability was analyzed by evaluating physicochemical parameters. Hemolytic activity of guarana liposomal formulation (G-Lip) was compared with that of guarana in its free form (FG) and of liposome without guarana (W-Lip). Red blood cells from rats were exposed to these different formulations dissolved in phosphate buffer solution (PBS; pH 7.4). The best stability was achieved for the formulation containing 1 mg.mL−1 guarana powder produced by the reverse phase evaporation method. FG showed dose-dependent antioxidant activity, which was maintained in G-Lip. W-Lip showed high hemolytic activity in PBS at pH 7.4 possibly because of the presence of polysorbate 80, and on addition of guarana to these structures, the hemolytic process was reversed. The same protective effect was observed for FG. It is believed that the complex structure of guarana, primarily the presence of polyphenols, exerts a powerful antioxidant action, helping to protect erythrocytes

Electrical Properties of Model Lipid Membranes

Biological membranes are essential components of the living systems and processes occurring with their participation are related mainly to electric phenomena, such as signal transduction, the existence of membrane potentials, and transport through the membrane. It is well known that the universal model of the cell membrane structure is the lipid bilayer, which constitutes the environment for integral and surface membrane proteins. Thus, much attention has been given to the study of the organization and properties of these structures concerning both experimental and theoretical aspects. As systematic examinations are impeded by the complexity of the natural membranes, the best approach to conducting detailed physical and chemical studies of biological membranes is to use simplified well-defined model lipid membranes. Among the most commonly used are liposomes, planar lipid membranes, membranes on solid substrates, and lipid monolayers on the free surface.Studies of the electrical properties of model lipid membranes have been carried out for many years. However, there are still many issues that have not been verified experimentally and for which the existing results are incomplete or inconsistent. Therefore, the main objective of this book was to collect recent scientific and review articles on the electrical properties of model lipid membranes. This objective has been successfully achieved, for which I express heartfelt appreciation to all authors and reviewers for their excellent contributions

Vitamin E and iron status in hemodialysis patients

The present study investigated whether vitamin E supplementation reduced oxidative stress in erythrocytes and improved vitamin E status in patients undergoing hemodialysis (HD). Plasma and erythrocyte α-tocopherol, plasma ascorbic acid, and iron status were determined in 11 regular HD patients prior to and post-dialysis, before and during oral supplementation of vitamin E, 400 IU daily for two months. HD patients were categorized into two groups according to their plasma ascorbic acid levels. We found that only the vitamin C sufficient group (>40 μM, Group I) had reliable measurements of erythrocyte α-tocopherol concentrations before vitamin E supplementation. In Group I prior to dialysis, erythrocyte α-tocopherol concentrations increased in response to vitamin E supplementation from 6.7 ± 0.7 μmol/L packed cells to 9.8 ± 0.6 (μmol/L packed cells (p<0.04). Moreover, there was a positive correlation (p<O.001) between plasma and erythrocyte α-tocopherol levels in Group I subjects. Additionally, vitamin E supplementation significantly increased hematocrits (39.9% ± 1.9% to 42.3% ±1.6%, p<0.004) post-dialysis only in Group I subjects. On the contrary, there was no change in hematocrits during vitamin E supplementation in the vitamin C deficient group (<40 μM, Group II). With respect to measures of iron status and recombinant human erythropoietin (rHuEPO) dose, no differences between before and during vitamin E supplementation were observed in two groups ofpatients. In summary, our data suggest that oral vitamin E supplementation protected erythrocytes from oxidative stress and improved vitamin E status in HD patients, but only in patients with adequate vitamin C status

Evaluation of the In vitro cytotoxic activity of caffeic acid derivatives and liposomal formulation against pancreatic cancer cell lines

Pancreatic cancer belongs to the most aggressive group of cancers, with very poor prognosis. Therefore, there is an important need to find more potent drugs that could deliver an improved therapeutic approach. In the current study we searched for selective and effective caffeic acid derivatives. For this purpose, we analyzed twelve compounds and evaluated their in vitro cytotoxic activity against two human pancreatic cancer cell lines, along with a control, normal fibroblast cell line, by the classic MTT assay. Six out of twelve tested caffeic acid derivatives showed a desirable effect. To improve the therapeutic efficacy of such active compounds, we developed a formulation where caffeic acid derivative (7) was encapsulated into liposomes composed of soybean phosphatidylcholine and DSPE-PEG2000. Subsequently, we analyzed the properties of this formulation in terms of basic physical parameters (such as size, zeta potential, stability at 4 &deg;C and morphology), hemolytic and cytotoxic activity and cellular uptake. Overall, the liposomal formulation was found to be stable, non-hemolytic and had activity against pancreatic cancer cells (IC50 19.44 &micro;M and 24.3 &micro;M, towards AsPC1 and BxPC3 cells, respectively) with less toxicity against normal fibroblasts. This could represent a promising alternative to currently available treatment options