Liposomal Antioxidants for Protection against Oxidant-Induced Damage

Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress

Role Of Metallothionein In Chemical Toxicity Mediated By Reactive Intermediates Generated From Xenobiotic And Oxygen Metabolism

This research was concerned with the role of metallothionein (MT) in chemical toxicity mediated by reactive intermediates generated from xenobiotic and oxygen metabolism. Metallothionein(s) are ubiquitous, low molecular weight, cysteine-rich (30% of total amino acids), metal binding proteins. These proteins have been shown to be important in the regulation of essential metal metabolism and in the detoxication of toxic metals. In the present research it was hypothesized that (i) because of its high cysteinyl thiolate concentration, MT is reactive towards intermediates generated from xenobiotic metabolism; and (ii) the metal (Zn, Cu) released from MT concomitant with the inactivation of metal binding sites would influence the modulating role of MT in chemical toxicity.;To determine the role of MT thiolate groups in scavenging free radicals generated from xenobiotic metabolism, experiments were carried out to characterize the reaction between CCl{dollar}\sb4{dollar} and purified Cd,Zn-MT, focusing on MT thiols as potential sites of interaction. Incubation of MT with CCl{dollar}\sb4{dollar} resulted in time-dependent depletion of MT thiols with concurrent reduction in the metal binding sites of the protein; this was due to CCl{dollar}\sb4{dollar}-linked oxidation of MT, rather than the covalent binding of {dollar}\sp{lcub}14{rcub}{dollar}CCl{dollar}\sb4{dollar} metabolites, indicating an antioxidative property of MT thiol groups.;Because Zn and Cu ions by themselves have antioxidant or prooxidant properties, respectively, the influence of Zn-MT or Cu-MT in oxidative stress was examined to determine the role of metal complement of MT in chemical toxicity. For this, Ehrlich cells with different concentrations of Zn-MT or Cu-MT were exposed to H{dollar}\sb2{dollar}O{dollar}\sb2{dollar}. In vitro toxicity testing revealed that the H{dollar}\sb2{dollar}O{dollar}\sb2{dollar} toxicity was negatively correlated with cellular Zn-MT concentrations but directly related to cellular Cu-MT concentrations. H{dollar}\sb2{dollar}O{dollar}\sb2{dollar} treatment resulted in oxidation of MT thiolate groups, loss of its metal-binding capacity, and translocation of MT-bound Zn or Cu to other cellular sites. Study with Cu and Fe chelating agents as well as antioxidant showed that Cu-MT enhanced sensitivity to H{dollar}\sb2{dollar}O{dollar}\sb2{dollar} by a Cu-dependent Fenton chemistry. The direct effect of Zn or Cu in H{dollar}\sb2{dollar}O{dollar}\sb2{dollar} was also examined in control cells. Zn and Cu produced inhibition and enhancement of H{dollar}\sb2{dollar}O{dollar}\sb2{dollar} toxicity, respectively, indicating the inherent antioxidative and prooxidative properties of Zn and Cu, respectively.;To investigate the toxicological significance of the prooxidative property of Cu-MT, the influence of Cu-MT in vivo was also investigated. Neonatal guinea pigs were used as the biological model because copper and Cu-MT are known to exist in high concentrations in the liver of 3-day-old guinea pigs but declined to low adult levels by day 7 of life. Comparison of the hepatotoxic responses to iron nitrilotriacetate (FeNTA) in the three age groups revealed heightened sensitivity in the 3-day-old guinea pigs but not in 7-day-old and adult animals. FeNTA treatment resulted in oxidation of MT thiolate groups, loss of its metal binding capacity and translocation of MT-bound Cu to other cellular sites. Results of in vitro studies confirmed the prooxidative function of Cu-MT and indicated involvement of Cu released from MT.;In conclusion, the data of these studies showed that MT thiolate groups possess antioxidative property and that MT can act either as an antioxidant or a prooxidant, a property related to the metal complement of the metalloprotein

Protective Effects of Liposomal N-Acetylcysteine against Paraquat-Induced Cytotoxicity and Gene Expression

Paraquat (PQ) is a herbicide that preferentially accumulates in the lung and exerts its cytotoxicity via the generation of reactive oxygen species (ROS). There is no specific treatment for paraquat poisoning. Attempts have been made to increase the antioxidant status in the lung using antioxidants (e.g., superoxide dismutase, vitamin E, N-acetylcysteine) but the outcome from such treatments is limited. Encapsulation of antioxidants in liposomes improves their therapeutic potential against oxidant-induced lung damage because liposomes facilitate intracellular delivery and prolong the retention of entrapped agents inside the cell. In the present study, we compared the effectiveness of conventional N-acetylcysteine (NAC) and liposomal-NAC (L-NAC) against PQ-induced cytotoxicity and examined the mechanism(s) by which these antioxidant formulations conferred cytoprotection. The effects of NAC or L-NAC against PQ-induced cytotoxicity in A549 cells were assessed by measuring cellular PQ uptake, intracellular glutathione content, ROS levels, mitochondrial membrane potential, cellular gene expression, inflammatory cytokine release and cell viability. Pretreatment of cells with L-NAC was significantly more effective than pretreatment with the conventional drug in reducing PQ-induced cytotoxicity, as indicated by the biomarkers used in this study. Our results suggested that the delivery of NAC as a liposomal formulation improves its effectiveness in counteracting PQ-induced cytotoxicity

Sulfur Mustard Toxicity Following Dermal Exposure: Role of Oxidative Stress, and Antioxidant Therapy

Objective: Sulfur mustard (bis-2-(chloroethyl) sulfide) is a chemical warfare agent (military code: HD) causing extensive skin injury. The mechanisms underlying HD-induced skin damage are not fully elucidated. This review will critically evaluate the evidence showing that oxidative stress is an important factor in HD skin toxicity. Oxidative stress results when the production of reactive oxygen (ROS) and/or reactive nitrogen oxide species (RNOS) exceeds the capacity of antioxidant defense mechanisms. Methods: This review will discuss the role of oxidative stress in the pathophysiology of HD skin toxicity in both in vivo and in vitro model systems with emphasis on the limitations of the various model systems. Evidence supporting the therapeutic potential of antioxidants and antioxidant liposomes will be evaluated. Antioxidant liposomes are effective vehicles for delivering both lipophilic (incorporated into the lipid bilayers) and water-soluble (encapsulated in the aqueous inner-spaces) antioxidants to skin. The molecular mechanisms interconnecting oxidative stress to HD skin toxicity are also detailed. Results: DNA repair and inflammation, in association with oxidative stress, induce intracellular events leading to apoptosis or to a programmable form of necrosis. The free radical, nitric oxide (NO), is of considerable interest with respect to the mechanisms of HD toxicity. NO signaling pathways are important in modulating inflammation, cell death, and wound healing in skin cells. Conclusions: Potential future directions are summarized with emphasis on a systems biology approach to studying sulfur mustard toxicity to skin as well as the newly emerging area of redox proteomics

Solitary chemosensory cells throughout the life cycle of the sea lamprey, Petromyzon marinus

The sea lamprey is a basal lineage vertebrate and an invasive species in the Great Lakes. It possess a diffuse chemosensory system with microvillous solitary chemosensory cells (SCCs) located on papillae along the gill pore, oral disc and tail. The objectives of this study were to assess the abundance of SCCs across life stages, and to characterize the innervation and biochemical properties. At all three locations, SCCs were most abundant in the spawning stage compared to earlier life stages, suggesting a role during reproduction. Prominent calretinin and 5-HT labeling show homology to previously identified taste cells and to SCCs in other vertebrates. Labeling for phospholipase C (also seen in mammalian SCCs) suggests that chemosensory signal transduction occurs by an IP3 mediated cascade. This study suggests that SCC function is important during the end of the sea lamprey life cycle and shows homology between lamprey SCCs and more derived vertebrates

Organization of glomerular territories in the olfactory bulb of post-embryonic wild chinook salmon Oncorhynchus tshawytscha

The post-embryonic odor imprinting paradigm suggests Chinook salmon (Oncorhynchus tshawytscha) acquire memory to stream-specific amino acid olfactory odors prior to emergence as fry. Because effects of olfactory experience on development can be examined by mapping olfactory sensory neurons extending into distinct territories of glomerular neuropil in the olfactory bulb, glomerular patterning from early yolk-sac larva to fry was documented in wild salmonids, a temporal scale not yet thoroughly explored. Labeling olfactory sensory neurons with anti-keyhole limpet hemocyanin (anti-KLH) revealed seven spatially conserved glomerular territories visible at hatch and well established by the late yolk-sac larva developmental stage. Because of the responsiveness of microvillous olfactory sensory neurons to amino acids, corresponding glomeruli in the lateral bulbar region were mapped using anti-calretinin. The dorsolateral territory, distinct glomeruli of the lateral glomerular territory and the ventromedial glomeruli were immunoreactive to both KLH and calretinin. This study offers a morphological description of glomerular patterning in post-embryonic stages in wild Chinook salmon, a temporal window previously shown to be significant for olfactory imprinting. J. Morphol. 278:464–474, 2017. © 2017 Wiley Periodicals, Inc

Attenuation of half sulfur mustard gas-induced acute lung injury in rats

Airway instillation into rats of 2-chloroethyl ethyl sulfide (CEES), the half molecule of sulfur mustard compound, results in acute lung injury, as measured by the leak of plasma albumin into the lung. Morphologically, early changes in the lung include alveolar hemorrhage and fibrin deposition and the influx of neutrophils. Following lung contact with CEES, progressive accumulation of collagen occurred in the lung, followed by parenchymal collapse. The co-instillation with CEES of liposomes containing pegylated (PEG)-catalase (CAT), PEG-superoxide dismutase (SOD), or the combination, greatly attenuated the development of lung injury. Likewise, the co-instillation of liposomes containing the reducing agents, N-acetylcysteine (NAC), glutathione (GSH), or resveratrol (RES), significantly reduced acute lung injury. The combination of complement depletion and airway instillation of liposomes containing anti-oxidant compounds maximally attenuated CEES-induced lung injury by nearly 80%. Delayed airway instillation of anti-oxidant-containing liposomes (containing NAC or GSH, or the combination) significantly diminished lung injury even when instillation was delayed as long as 1 h after lung exposure to CEES. These data indicate that CEES-induced injury of rat lungs can be substantially diminished by the presence of reducing agents or anti-oxidant enzymes delivered via liposomes. Copyright © 2005 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49522/1/1115_ftp.pd

Antioxidant, Antibacterial, and Cytotoxic Activities of the Ethanolic Origanum vulgare

Oregano is a perennial shrub that grows in the mountains of the Mediterranean and Euro/Irano-Siberian regions. This study was conducted to identify the major constituents of the ethanolic Origanum vulgare extract and examine the cytotoxic, antioxidant, and antibacterial properties of the extract but more importantly the contribution of its specific major constituent(s) or their combination to the overall extract biological activity. Gas chromatography/mass spectroscopy analysis showed that the extract contained monoterpene hydrocarbons and phenolic compounds, the major ones being carvacrol and thymol and to a lesser extent p-cymene, 1-octacosanol, creosol, and phytol. A549 epithelial cells challenged with the extract showed a concentration-dependent increase in cytotoxicity. A combination of thymol and carvacrol at equimolar concentrations to those present in the extract was less cytotoxic. The A549 cells pretreated with nonlethal extract concentrations protected against hydrogen-peroxide-induced cytotoxicity, an antioxidant effect more effective than the combination of equimolar concentrations of thymol/carvacrol. Inclusion of p-cymene and/or 1-octacosanol did not alter the synergistic antioxidant effects of the carvacrol/thymol mixture. The extract also exhibited antimicrobial properties against Gram-positive and Gram-negative bacterial strains including clinical isolates. In conclusion, the oregano extract has cytotoxic, antioxidant, and antibacterial activities mostly attributed to carvacrol and thymol

Concomitant pulmonary and hepatic toxicity secondary to nitrofurantoin: a case report

<p>Abstract</p> <p>Background</p> <p>Concomitant pulmonary and hepatic toxicity secondary to nitrofurantoin is a rare but serious complication of the use of Nitrofurantoin.</p> <p>Case presentation</p> <p>A 72 year old woman taking Nitrofurantoin for recurrent urinary sepsis presenting with breathlessness abdominal discomfort and abnormal liver function tests is described. Drug toxicity secondary to Nitrofurantoin was diagnosed. Cessation of the drug and a course of steroids markedly improved her condition.</p> <p>Discussion</p> <p>We review the drug reactions associated with Nitrofurantoin and suggest an alternative treatment strategy for recurrent urinary sepsis.</p> <p>Conclusion</p> <p>Adverse drug reactions are an important cause of concomitant lung and liver toxicity and the mainstay of treatment is drug withdrawal.</p