Comparison of various iron chelators used in clinical practice as protecting agents against catecholamine-induced oxidative injury and cardiotoxicity

Effects of carvacrol on ketamine-induced cardiac injury in rats: an experimental study

AIM

We aimed to investigate the preventive effects of carvacrol against ketamine-induced cardiotoxicity biochemically and histopathologically in an experimental model.

MATERIAL AND METHOD

The rats were divided into three groups; healthy control (HC), ketamine alone (KG), and ketamine + carvacrol (KCG) groups. Serum Creatine Kinase Myocardial Band (CK-MB) and Troponin I (TP I) levels were determined. Malondialdehyde (MDA), Glutathione (GSH), Superoxide Dismutase (SOD), Tumor Necrosis Factor α (TNF-α), Interleukin 1 beta (IL-1beta), and Interleukin 6 (IL-6) levels were measured in the heart tissues of the rats. Heart tissues were also evaluated histopathologically.

RESULTS

In the ketamine-treated group, tissue MDA, TNF-α, IL-1beta, and IL-6 levels increased while tissue GSH and SOD levels decreased significantly compared with the control group. However, in the ketamine plus carvacrol applied group, all those alterations were significantly less pronounced, close to the healthy controls. Severe mononuclear cell infiltrations, degenerated myocytes and hemorrhage were determined in the ketamine alone administered group, and these alterations were at a mild level in the carvacrol + ketamine administered group.

CONCLUSION

Prolonged exposure to ketamine resulted in induced oxidative stress in rat heart tissue; concomitant carvacrol application could counteract the negative effects of ketamine by protecting tissues from lipid peroxidation and decreasing the inflammatory response.

The role of ferroptosis in cell-to-cell propagation of cell death initiated from focal injury in cardiomyocytes

AIMS

Ferroptosis has grown in importance as a key factor in ischemia-reperfusion (I/R) injury. This study explores the mechanism underlying fibrotic scarring extending along myofibers in cardiac ischemic injury and demonstrates the integral role of ferroptosis in causing a unique cell death pattern linked to I/R injury.

MAIN METHODS

Cadaveric hearts from individuals who had ischemic injury were examined by histological assays. We created a novel model of inducing cell death in H9c2 cells, and used it to demonstrate ferroptotic cell death extending in a cell-to-cell manner. Ex vivo Langendorff-perfused hearts were used alongside the model to replicate cell death extension along myofibers while also demonstrating protective effects of a ferroptosis inhibitor, ferrostatin-1 (Fer-1).

KEY FINDINGS

Human hearts from individuals who had I/R injury demonstrated scarring along myofibers that was consistent with mouse models, suggesting that cell death extended from cell-to-cell. Treatment with Ras-selective lethal 3 (RSL3), a ferroptosis inducer, and exposure to excess iron exacerbated cell death propagation in in vitro models, and inhibition of ferroptosis by Fer-1 blunted this effect in both settings. In ex vivo models, Fer-1 was sufficient to reduce cell death along the myofibers caused by external injury.

SIGNIFICANCE

The unique I/R injury-induced pattern of cell death along myofibers requires novel injury models that mimic this phenomenon, thus we established new methods to replicate it. Ferroptosis is important in propagating injury between cells and better understanding this mechanism may lead to therapeutic responses that limit I/R injury.

Cardioprotective potential of the antioxidant-rich bioactive fraction of Garcinia pedunculata Roxb. ex Buch.-Ham. against isoproterenol-induced myocardial infarction in Wistar rats

This Study aimed to characterise the phenolic compounds in Garcinia pedunculata extract and assess their potential antioxidant activity as well as its cardioprotective potential in isoproterenol-induced cardiac hypertrophy in an experimental animal model. In vitro antioxidant properties were determined using DPPH, ABTS, FRAP, PMD assays. In vitro lipid peroxidation experiment was also performed with heart tissues. Cardioprotective and cardiotoxicity effects were determined using the cell line studies. The cardioprotective effect of GP was assessed in a rat model of isoproterenol-(ISO-) induced cardiac hypertrophy by subcutaneous administration. Heart weight/tail length ratio and cardiac hypertrophy indicators were reduced after oral administration of GP. Additionally, GP reduced oxidative stress and heart inflammation brought on by ISO. In H9c2 cells, the antihypertrophic and anti-inflammatory effects of the extract of GP were seen in the presence of ISO, which were further supported by the in vivo observations. This study makes a compelling case for the possibility that supplementing with dried GP fruit can prevent heart hypertrophy by reducing oxidative stress and inflammation.

Post-Partum Depression Lactating Rat Model for Evaluating Ketamine's Safety as a Pharmacotherapeutic Treatment: Roles in Cardiac and Urinary Function

Depression is one of the world's most common and mentally disabling illnesses. Post-partum depression is a subtype of depression that affects one in seven women worldwide. Successful pharmacological treatment must consider the consequences for both, since the mother-child bond is fundamental for the well-being of both mother and infant as well as the general development of the newborn. Changes in maternal physiology and/or behavior can significantly influence the development of breastfed infants. Ketamine has been extensively studied for use as an antidepressant due to its mixed mechanisms of action. Safety and efficacy studies in the cardiovascular and urinary systems of a lactating postpartum depression animal model are essential for contributing toward ketamine's clinical use in the respective patient population. Thus, this project aimed to study the implications of postpartum maternal exposure to ketamine during lactation on the cardiovascular system of female rats submitted to the depression induction model by maternal separation. This model promotes depressive effects through stress caused by the interruption of mother-infant bond early in the offspring's life. To achieve depression, each dam was separated from her offspring for 3 h per day, from post-natal day 2 (PND2) to PND12. Experimental groups received daily treatment with either 5, 10, or 20 mg/kg of ketamine intraperitoneally during the lactation period, from PND2 to PND21. Behavioral tests consisted of the maternal and aggressive maternal behavior tests, the olfactory preference test, and the forced swim test. A technique for the detection of catecholamines and indoleamines in the heart muscle was developed for the experimental model groups. The histopathological evaluation was performed on these animals' cardiac muscles and urinary bladders. Our findings suggest that ketamine is safe for use in postpartum depression and does not induce cardiovascular and/or urinary systems toxicity.

Characteristics and perioperative complications of hip fracture in the elderly with acute ischemic stroke: a cross-sectional study

BACKGROUND

Patients with acute ischemic stroke (AIS) after hip fracture in the elderly have worse prognosis. We aimed to describe the characteristics and complications of hip fracture with AIS in the elderly.

METHODS

This cross-sectional study selected patients with hip fracture (age ≥65 years) from January 2018 to September 2020. The collected data included age, sex, fracture types, comorbidities. In above screened patients, we further collected cerebral infarction related information of AIS patients. The least absolute shrinkage and selection operator (LASSO) logistic regression was performed to identify the strongest predictors of AIS after hip fracture. Multivariate logistic regression analysis was conducted to find independent risk factors for AIS after hip fracture.

RESULTS

Sixty patients (mean age 79.7 years;female 56.7%) occurred AIS after hip fracture in 1577 cases. The most common infarction type was partial anterior circulation infarction (PACI) (70.0%). The majority of these infarction lesions were single (76.7%) and most infarction lesions(65.0%) were located in the left side. 81.7% of AIS patients had mild (Health stroke scale NIHSS <4) AIS. Older patients with AIS after hip fracture were more frequently complicated by hypertension(73.3%), prior stroke (46.7%), diabetes(35.0%) and were more likely to have hypoproteinemia(68.3%), electrolyte disorders ( 66.7%), anemia (65.0%), deep vein thrombosis (51.6%), pneumonia (46.6%),cardiac complications (45.0%). Combined with hypertension (OR 2.827, 95%CI 1.557-5.131) and male sex(OR 1.865, 95%CI 1.095-3.177) were associated with the increased risk of AIS after hip fracture.

CONCLUSIONS

Older patients combined with hypertension are more likely to have AIS after hip fracture. For these patients, early preventions should be administered. AIS patients after hip fracture are prone to have multiple complications under traumatic stress, and we should enhance the management of these patients to reduce the stress and avoid occurrence of complications.

Examination of diverse iron-chelating agents for the protection of differentiated PC12 cells against oxidative injury induced by 6-hydroxydopamine and dopamine

Labile redox-active iron ions have been implicated in various neurodegenerative disorders, including the Parkinson's disease (PD). Iron chelation has been successfully used in clinical practice to manage iron overload in diseases such as thalassemia major; however, the use of conventional iron chelators in pathological states without systemic iron overload remains at the preclinical investigative level and is complicated by the risk of adverse outcomes due to systemic iron depletion. In this study, we examined three clinically-used chelators, namely, desferrioxamine, deferiprone and deferasirox and compared them with experimental agent salicylaldehyde isonicotinoyl hydrazone (SIH) and its boronate-masked prochelator BSIH for protection of differentiated PC12 cells against the toxicity of catecholamines 6-hydroxydopamine and dopamine and their oxidation products. All the assayed chelating agents were able to significantly reduce the catecholamine toxicity in a dose-dependent manner. Whereas hydrophilic chelator desferrioxamine exerted protection only at high and clinically unachievable concentrations, deferiprone and deferasirox significantly reduced the catecholamine neurotoxicity at concentrations that are within their plasma levels following standard dosage. SIH was the most effective iron chelator to protect the cells with the lowest own toxicity of all the assayed conventional chelators. This favorable feature was even more pronounced in prochelator BSIH that does not chelate iron unless its protective group is cleaved in disease-specific oxidative stress conditions. Hence, this study demonstrated that while iron chelation may have general neuroprotective potential against catecholamine auto-oxidation and toxicity, SIH and BSIH represent promising lead molecules and warrant further studies in more complex animal models.

Role of Iron Phthalocyanine Coordination in Catecholamines Detection

Catecholamines are an important class of neurotransmitters responsible for regularizing, controlling, and treating neural diseases. Based on control and diseases treatment, the development of methodology and dives to sensing is a promissory technology area. This work evaluated the role of iron phthalocyanine coordination (FePc) with the specific groups from catecholamine molecules (L-dopa, dopamine, epinephrine, and the amino acid tyrosine) and the effect of this coordination on electrochemical behavior. The in situ coordination analysis was performed through isotherms π-A of FePc Langmuir films in the absence and presence of catecholamines. The π-A isotherm indicates a strong interaction between FePc monolayer and L-Dopa and DA, which present a catechol group and a side chain with a protonated amino group (-NH3+). These strong interactions with catechol and amine groups were confirmed by characterization at the molecular level using the surface-enhanced Raman spectroscopy (SERS) from a Langmuir–Schaefer monolayer deposited onto Ag surfaces. The electrochemical measurements present a similar tendency, with lower oxidation potential observed to DA>L-Dopa>Ep. The results corroborate that the coordination of the analyte on the electron mediator surface plays an essential role in an electrochemical sensing application. The FePc LS film was applied as a sensor in tablet drug samples, showing a uniformity of content of 96% for detecting active compounds present in the L-Dopa drug samples.

Ferrous iron binding to epinephrine promotes the oxidation of iron and impedes activation of adrenergic receptors

Upon release in response to stress, epinephrine (Epi) may interact with labile iron pool in human plasma with potentially important (patho)physiological consequences. We have shown that Epi and Fe³⁺ build stable 1:1 high-spin bidentate complex at physiological pH, and that Epi does not undergo degradation in the presence of iron. However, the interactions of Epi with the more soluble Fe²⁺, and the impact of iron on biological activity of Epi are still not known. Herein we showed that Epi and Fe²⁺ build colorless complex which is stable under anaerobic conditions. In the presence of O₂, Epi promoted the oxidation of Fe²⁺ and the formation of Epi-Fe³⁺ complex. Cyclic voltammetry showed that mid-point potential of Epi-Fe²⁺ complex is very low (-582 mV vs. standard hydrogen electrode), which explains catalyzed oxidation of Fe²⁺. Next, we examined the impact of iron binding on biological performance of Epi using patch clamping in cell culture with constitutive expression of adrenergic receptors. Epi alone evoked an increase of outward currents, whereas Epi in the complex with Fe³⁺ did not. This implies that the binding of Epi to adrenergic receptors and their activation is prevented by the formation of complex with iron. Pro-oxidative activity of Epi-Fe²⁺ complex may represent a link between chronic stress and cardiovascular problems. On the other hand, labile iron could serve as a modulator of biological activity of ligands. Such interactions may be important in human pathologies that are related to iron overload or deficiency.

Role of catecholamines in the pathogenesis of diabetic cardiomyopathy 1

Although the sympathetic nervous system plays an important role in the regulation of cardiac function, the overactivation of the sympathetic nervous system under stressful conditions including diabetes has been shown to result in the excessive production of circulating catecholamines as well as an increase in the myocardial concentration of catecholamines. In this brief review, we provide some evidence to suggest that the oxidation products of catecholamines such as aminochrome and oxyradicals, lead to metabolic derangements, Ca²⁺-handling abnormalities, increase in the availability of intracellular free Ca²⁺, as well as activation of proteases and changes in myocardial gene expression. These alterations due to elevated levels of circulatory catecholamines are associated with oxidative stress, subcellular remodeling, and the development of cardiac dysfunction in chronic diabetes.

Deferoxamine preconditioning ameliorates mechanical ventilation-induced lung injury in rat model via ROS in alveolar macrophages: a randomized controlled study

Background

Mechanical ventilation (MV) can provide effective breathing support; however, ventilatior-induced lung injury (VILI) has also been widely recognized in clinical practice, including in the healthy lung. Unfortunately, the morbidity and mortality of VILI remain unacceptably high, and no satisfactory therapeutic effect can be achieved. The current study aimed to examine the effects of iron chelator preconditioning on the mitochondrial reactive oxygen species (ROS) in alveolar macrophages and pathological lung injury in VILI.

Methods

Twenty four healthy male Sprague–Dawley (SD) rats (250–300 g in weight) were randomly divided into 3 groups, including the control group (NC group, n = 8), the high-volume mechanical ventilation group (HV group, n = 8), and the deferoxamine treatment group (HV + DFO group, n = 8). Rats in the HV and HV + DFO groups were subjected to high-volume MV at a dose of 40 ml/kg. DFO was administered at a dose of 200 mg/kg 15 min prior to over-ventilation. Spontaneously breathing anesthetized rats were used as the controls. The animals were sacrificed after 4 h of high-volume ventilation or under control conditions, the animals were sacrificed. Purified alveolar macrophages from bronchoalveolar lavage fluid (BALF) and lung tissue were collected for further analysis through light microscopy and flow cytometry.

Results

Compared with the controls, the high-volume-ventilated rats had exhibited typical lung edema and histological lung injury, and ROS were markedly increased in alveolar macrophages and mitochondria. Moreover, all indices of VILI were remarkably different in rats treated with DFO preconditioning. DFO could ameliorate lung injury in the mechanically ventilated SD rat model.

Conclusions

DFO preconditioning contributes to mitigating the histological lung damage while reducing ROS levels in alveolar macrophages and mitochondria, suggesting that iron metabolism in alveolar macrophages may participate in VILI.

Comprehensive review of cardiovascular toxicity of drugs and related agents

Cardiovascular diseases are a leading cause of morbidity and mortality in most developed countries of the world. Pharmaceuticals, illicit drugs, and toxins can significantly contribute to the overall cardiovascular burden and thus deserve attention. The present article is a systematic overview of drugs that may induce distinct cardiovascular toxicity. The compounds are classified into agents that have significant effects on the heart, blood vessels, or both. The mechanism(s) of toxic action are discussed and treatment modalities are briefly mentioned in relevant cases. Due to the large number of clinically relevant compounds discussed, this article could be of interest to a broad audience including pharmacologists and toxicologists, pharmacists, physicians, and medicinal chemists. Particular emphasis is given to clinically relevant topics including the cardiovascular toxicity of illicit sympathomimetic drugs (e.g., cocaine, amphetamines, cathinones), drugs that prolong the QT interval, antidysrhythmic drugs, digoxin and other cardioactive steroids, beta-blockers, calcium channel blockers, female hormones, nonsteroidal anti-inflammatory, and anticancer compounds encompassing anthracyclines and novel targeted therapy interfering with the HER2 or the vascular endothelial growth factor pathway.

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Coordinate and redox interactions of epinephrine (Epi) with iron at physiological pH are essential for understanding two very different phenomena – the detrimental effects of chronic stress on the cardiovascular system and the cross-linking of catecholamine-rich biopolymers and frameworks. Here we show that Epi and Fe³⁺ form stable high-spin complexes in the 1:1 or 3:1 stoichiometry, depending on the Epi/Fe³⁺ concentration ratio (low or high). Oxygen atoms on the catechol ring represent the sites of coordinate bond formation within physiologically relevant bidentate 1:1 complex. Redox properties of Epi are slightly impacted by Fe³⁺. On the other hand, Epi and Fe²⁺ form a complex that acts as a strong reducing agent, which leads to the production of hydrogen peroxide via O₂ reduction, and to a facilitated formation of the Epi–Fe³⁺ complexes. Epi is not oxidized in this process, i.e. Fe²⁺ is not an electron shuttle, but the electron donor. Epi-catalyzed oxidation of Fe²⁺ represents a plausible chemical basis of stress-related damage to heart cells. In addition, our results support the previous findings on the interactions of catecholamine moieties in polymers with iron and provide a novel strategy for improving the efficiency of cross-linking.

Mechanistic studies on ketamine-induced mitochondrial toxicity in zebrafish embryos

Ketamine, a phencyclidine derivative, is an antagonist of the Ca²⁺-permeable N-methyl-d-aspartate (NMDA)-type glutamate receptors. It is a pediatric anesthetic and has been implicated in developmental neurotoxicity. Ketamine has also been shown to deplete ATP in mammalian cells. Our previous studies showed that acetyl l-carnitine (ALCAR) prevented ketamine-induced cardiotoxicity and neurotoxicity in zebrafish embryos. Based on our finding that ALCAR's protective effect was blunted by oligomycin A, an inhibitor of ATP synthase, we further investigated the effects of ketamine and ALCAR on ATP levels, mitochondria and ATP synthase in zebrafish embryos. The results demonstrated that ketamine reduced ATP levels in the embryos but not in the presence of ALCAR. Ketamine reduced total mitochondrial protein levels and mitochondrial potential, which were prevented with ALCAR co-treatment. To determine the cause of ketamine-induced ATP deficiency, we explored the status of ATP synthase. The results showed that a subunit of ATP synthase, atp5α1, was transcriptionally down-regulated by ketamine, but not in the presence of ALCAR, although ketamine caused a significant upregulation in another ATP synthase subunit, atp5β and total ATP synthase protein levels. Most of the ATP generated by heart mitochondria are utilized for its contraction and relaxation. Ketamine-treated embryos showed abnormal heart structure, which was abolished with ALCAR co-treatment. This study offers evidence for a potential mechanism by which ketamine could cause ATP deficiency mediated by mitochondrial dysfunction.

The hydrolytic susceptibility of prochelator BSIH in aqueous solutions

The prochelator BSIH ((E)-N'-(2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzylidene)isonicotinohydrazide) contains a boronate group that prevents metal coordination until reaction with peroxide releases the iron chelator SIH ((E)-N'-(2-hydroxybenzylidene)isonicotinohydrazide). BSIH exists in aqueous buffer and cell culture media in equilibrium with its hydrolysis products isoniazid and (2-formylphenyl)boronic acid (FBA). The relative concentrations of these species limit the yield of intact SIH available for targeted iron chelation. While the hydrolysis fragments are nontoxic to retinal pigment epithelial cells, these results suggest that modifications to BSIH that improve its hydrolytic stability yet maintain its low inherent cytotoxicity are desirable for creating more efficient prochelators for protection against cellular oxidative damage.

Comparative Investigation of Protective Effects of Metyrosine and Metoprolol Against Ketamine Cardiotoxicity in Rats

This study investigated the effect of metyrosine against ketamine-induced cardiotoxicity in rats and compared the results with the effect of metoprolol. In this study, rats were divided into groups A, B and C. In group A, we investigated the effects of a single dose of metyrosine (150 mg/kg) and metoprolol (20 mg/kg) on single dose ketamine (60 mg/kg)-induced cardiotoxicity. In group B, we investigated the effect of metyrosine and metoprolol, which were given together with ketamine for 30 days. In group C, we investigated the effect of metyrosine and metoprolol given 15 days before ketamine and 30 days together with ketamine on ketamine cardiotoxicity. By the end of this process, we evaluated the effects of the levels of oxidant-antioxidant parameters such as MDA, MPO, 8-OHGua, tGSH, and SOD in addition to CK-MB and TP I on cardiotoxicity in rat heart tissue. The experimental results show that metyrosine prevented ketamine cardiotoxicity in groups A, B and C and metoprolol prevented it in only group C.

TPEN prevents rapid pacing-induced calcium overload and nitration stress in HL-1 myocytes

INTRODUCTION

Atrial fibrillation (AF) is the most common cardiac arrhythmia. However, the current drug interference of antiarrhythmia has limited efficacy and off-target effects. Accumulating evidence has implicated a potential role of nitration stress in the pathogenesis of AF. The aim of the study was to determine whether TPEN provided antinitration effects on atrial myocytes during AF, especially under circumstances of nitration stress.

METHODS

We utilized a rapid paced HL-1 cells model for AF. The changes of electrophysiological characteristics and structure of paced HL-1 cells were determined by a patch clamp and a TEM method. The effects of TPEN on pacing and ONOO(-) pretreated HL-1 cells were examined using MTT assay, TUNEL technique, confocal microscope experiment, and Western blot analysis.

RESULTS

The results revealed that ONOO(-) reduced the viability of HL-1 cells in a dose-dependent manner, and 1 μmol/L TPEN significantly ameliorated the damage caused by 50 μmol/L ONOO(-) (P < 0.05). Pacing and/or ONOO(-) -induced marked shortening of APD, myolysis, and nuclear condensation. TPEN inhibited the Ca(2+) overload induced by rapid pacing (P < 0.05) and ONOO(-) stimulation (P < 0.05). The application of TPEN significantly prevented the protein nitration caused by pacing or pacing plus ONOO(-) (P < 0.05). Additionally, pacing in combination with ONOO(-) treatment led to increase in apoptosis in HL-1 cells (P < 0.01), which could be reduced by pretreatment with TPEN (P < 0.05).

CONCLUSIONS

TPEN prevents Ca(2+) overload and nitration stress in HL-1 atrial myocytes during rapid pacing and circumstances of nitration stress.

Oxidative stress does not play a primary role in the toxicity induced with clinical doses of doxorubicin in myocardial H9c2 cells

The implication of oxidative stress as primary mechanism inducing doxorubicin (DOX) cardiotoxicity is still questionable as many in vitro studies implied supra-clinical drug doses or unreliable methodologies for reactive oxygen species (ROS) detection. The aim of this study was to clarify whether oxidative stress is involved in compliance with the conditions of clinical use of DOX, and using reliable tools for ROS detection. We examined the cytotoxic mechanisms of 2 μM DOX 1 day after the beginning of the treatment in differentiated H9c2 rat embryonic cardiac cells. Cells were exposed for 2 or 24 h with DOX to mimic a single chronic dosage or to favor accumulation, respectively. We found that apoptosis was prevalent in cells exposed for a short period with DOX: cells showed typical hallmarks as loss of anchorage ability, mitochondrial hyperpolarization followed by the collapse of mitochondrial activity, and nuclear condensation. Increasing the exposure period favored a shift to necrosis as the cells preferentially exhibited early DNA impairment and nuclear swelling. In either case, measuring the fluorescence lifetime of 1-pyrenebutyric acid or the intensities of dihydroethidium or amplex red showed a consistent pattern in ROS production which was a slight increased level far from representative of an oxidative stress. Moreover, pre-treatment with dexrazoxane provided a cytoprotective effect although it failed to detoxify ROS. Our data support that oxidative stress is unlikely to be the primary mechanism of DOX cardiac toxicity in vitro.

Cardiovascular and Hepatic Toxicity of Cocaine: Potential Beneficial Effects of Modulators of Oxidative Stress

Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy.

Serum Levels of Stress Hormones and Oxidative Stress Biomarkers Differ according to Sasang Constitutional Type

Objectives. This study investigated whether Sasang constitutional type is associated with differences in the serum levels of stress hormones and oxidative stress. Methods. A total of 236 participants (77 males and 159 females) were enrolled. The serum levels of cortisol, adrenaline, reactive oxygen species (ROS), and malondialdehyde (MDA) were analyzed. Results. The distribution of Sasang constitutional types was as follows: Taeumin, 35.6%; Soumin, 33.0%; and Soyangin, 31.4%. The serum cortisol levels of Taeumin were significantly lower than Soumin (p < 0.1 in both sexes) and Soyangin (p < 0.05 in males and p < 0.1 in females). The adrenaline levels were also significantly lower in Taeumin than in Soumin (p < 0.05 in males and p < 0.1 in females) and Soyangin (p < 0.1 in males). Serum ROS levels were significantly higher in Soyangin than in Taeumin and Soumin (p < 0.05 in males), whereas MDA levels were significantly lower in Taeumin compared with Soumin and Soyangin (p < 0.05 in males and p < 0.1 in females). Conclusion. Taeumin type may tolerate psychological or oxidative stress better than other types, which suggests a biological mechanism to explain the different pathophysiological features of Sasang constitutional types.

The traditional drug Gongjin-Dan ameliorates chronic fatigue in a forced-stress mouse exercise model

ETHNOPHARMACOLOGICAL RELEVANCE

Gongjin-Dan is a representative traditional Oriental medicine herbal drug that has been used to treat chronic fatigue symptoms for several hundred years. We evaluated the anti-fatigue effects of Gongjin-Dan and the underlying mechanisms in a chronic forced exercise mouse model.

METHODS AND MATERIALS

Balb/C male mice underwent an extreme treadmill-based running stress (1-h, 5 days/week), and daily oral administration of distilled water, Gongjin-Dan (100, 200, or 400 mg/kg), or ascorbic acid (100 mg/kg) for 28 days. The anti-fatigue effects of Gongjin-Dan were evaluated with behavioral tests (exercise tolerance and swimming tests), and the corresponding mechanisms were investigated based on oxidative stress and inflammatory cytokine and stress hormone levels in skeletal muscle, sera, and brain tissue.

RESULTS

Gongjin-Dan significantly increased exercise tolerance and latency times but reduced the number of electric shocks and immobilization time on the treadmill running and swimming tests, compared with the control group. Gongjin-Dan also significantly ameliorated alterations in oxidative stress-related biomarkers (reactive oxygen species and malondialdehyde), inflammatory cytokines (tumor necrosis factor-α, interleukin-1 beta, interleukin-6, and interferon-γ) and glycogen and L-lactate levels in skeletal muscle, compared with those in the control group. Moreover, Gongjin-Dan considerably normalized the forced running stress-induced changes in serum corticosterone and adrenaline levels, as well as brain serotonin level. These antioxidant and anti-stress effects of Gongjin-Dan were supported by the results of Western blotting (4-hydroxynonenal and heme oxygenase-1) and the gene expression levels (serotonin receptor and serotonin transporter).

CONCLUSION

These results support the clinical relevance of Gongjin-Dan regarding anti-chronic fatigue properties. The underlying mechanisms involve attenuation of oxidative and inflammatory reactions in muscle and regulation of the stress response through the hypothalmo-pituitary-adrenal axis.

Comparison of various iron chelators and prochelators as protective agents against cardiomyocyte oxidative injury

Oxidative stress is a common denominator of numerous cardiovascular disorders. Free cellular iron catalyzes the formation of highly toxic hydroxyl radicals, and iron chelation may thus be an effective therapeutic approach. However, using classical iron chelators in diseases without iron overload poses risks that necessitate more advanced approaches, such as prochelators that are activated to chelate iron only under disease-specific oxidative stress conditions. In this study, three cell-membrane-permeable iron chelators (clinically used deferasirox and experimental SIH and HAPI) and five boronate-masked prochelator analogs were evaluated for their ability to protect cardiac cells against oxidative injury induced by hydrogen peroxide. Whereas the deferasirox-derived agents TIP and TRA-IMM displayed negligible protection and even considerable toxicity, the aroylhydrazone prochelators BHAPI and BSIH-PD provided significant cytoprotection and displayed lower toxicity after prolonged cellular exposure compared to their parent chelators HAPI and SIH, respectively. Overall, the most favorable properties in terms of protective efficiency and low inherent cytotoxicity were observed with the aroylhydrazone prochelator BSIH. BSIH efficiently protected both H9c2 rat cardiomyoblast-derived cells and isolated primary rat cardiomyocytes against hydrogen peroxide-induced mitochondrial and lysosomal dysregulation and cell death. At the same time, BSIH was nontoxic at concentrations up to its solubility limit (600 μM) and in 72-h incubation. Hence, BSIH merits further investigation for prevention and/or treatment of cardiovascular disorders associated with a known (or presumed) component of oxidative stress.

The heart as a target for xenobiotic toxicity: the cardiac susceptibility to oxidative stress

The heart is a target organ for oxidative stress-related injuries. Because of its very high energetic metabolic demand, the heart has the highest rate of production of reactive oxygen species, namely, hydrogen peroxide (H2O2), per gram of tissue. Additionally, the heart has lower levels of antioxidants and total activity of antioxidant enzymes when compared to other organs. Furthermore, drugs that have relevant antioxidant activity and that are used in the treatment of oxidative stress related cardiac diseases demonstrate better clinical cardiac outcomes than other drugs with similar receptor affinity but with no antioxidant activity. Several xenobiotics particularly target the heart and promote toxicity. Anticancer drugs, like anthracyclines, cyclophosphamide, mitoxantrone, and more recently tyrosine kinase targeting drugs, are well-known cardiac toxicants whose therapeutic application has been associated to a high prevalence of heart failure. High levels of catecholamines or drugs of abuse, namely, amphetamines, cocaine, and even the consumption of alcohol for long periods of time, are linked to cardiovascular abnormalities. Oxidative stress may be one common link for the cardiac toxicity elicited by these compounds. We aim to revise the mechanisms involved in cardiac lesions caused by the above-mentioned substances specially focusing in oxidative stress related pathways. Oxidative stress biomarkers can be useful in the early recognition of cardiotoxicity in patients treated with these drugs and aid to minimize the setting of cardiac irreversible events.

Myelophil attenuates brain oxidative damage by modulating the hypothalamus-pituitary-adrenal (HPA) axis in a chronic cold-stress mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Myelophil is composed of Astragali Radix and Salviae Miltiorrhizae Radix, according to the long traditional pharmacological practices, and it has been used for patients with chronic fatigue-associated symptoms including concentration problem or memory loss.

AIM OF THE STUDY

This study aimed to evaluate the clinical relevance of Myelophil on brain oxidative damage using a chronic cold stress mice model.

MATERIAL AND METHODS

Balb/c mice were subjected to cold stress (4°C for 4h) six times per week for 2 weeks with or without oral administration of Myelophil (50, 100, or 200mg/kg), or ascorbic acid (50mg/kg).

RESULTS

Chronic cold stress induced histopathological hippocampal apoptosis with drastically increased serum levels of total reactive oxygen species and nitric oxide, as well as brain lipid peroxidation levels, protein carbonyl, and caspase-3/7 activity. These alterations were significantly ameliorated by Myelophil treatment. Myelophil administration significantly recovered the depleted glutathione and its enzymes, superoxide dismutase activity, and catalase protein and gene expression levels. Serum levels of corticosterone, dopamine, and adrenaline were notably altered by chronic cold stress but were significantly ameliorated by Myelophil treatment. Myelophil also normalized alterations in tumor necrosis factor-α, interleukin (IL)-1β, and IL-10 gene expression and protein levels. Chronic cold stress up-regulated gene expression levels of phenylethanolamine N-methyltransferase and monoamine oxidase-B, and glucocorticoid receptors in the hypothalamus and hippocampus, respectively, whereas Myelophil treatment completely normalized these levels.

CONCLUSIONS

These results suggest that Myelophil has potent pharmaceutical effects against chronic cold-stress-induced brain damage by relieving oxidative stress and inflammation and regulating stress hormones in mice.

Oxidative stress, redox signaling, and metal chelation in anthracycline cardiotoxicity and pharmacological cardioprotection

SIGNIFICANCE

Anthracyclines (doxorubicin, daunorubicin, or epirubicin) rank among the most effective anticancer drugs, but their clinical usefulness is hampered by the risk of cardiotoxicity. The most feared are the chronic forms of cardiotoxicity, characterized by irreversible cardiac damage and congestive heart failure. Although the pathogenesis of anthracycline cardiotoxicity seems to be complex, the pivotal role has been traditionally attributed to the iron-mediated formation of reactive oxygen species (ROS). In clinics, the bisdioxopiperazine agent dexrazoxane (ICRF-187) reduces the risk of anthracycline cardiotoxicity without a significant effect on response to chemotherapy. The prevailing concept describes dexrazoxane as a prodrug undergoing bioactivation to an iron-chelating agent ADR-925, which may inhibit anthracycline-induced ROS formation and oxidative damage to cardiomyocytes.

RECENT ADVANCES

A considerable body of evidence points to mitochondria as the key targets for anthracycline cardiotoxicity, and therefore it could be also crucial for effective cardioprotection. Numerous antioxidants and several iron chelators have been tested in vitro and in vivo with variable outcomes. None of these compounds have matched or even surpassed the effectiveness of dexrazoxane in chronic anthracycline cardiotoxicity settings, despite being stronger chelators and/or antioxidants.

CRITICAL ISSUES

The interpretation of many findings is complicated by the heterogeneity of experimental models and frequent employment of acute high-dose treatments with limited translatability to clinical practice.

FUTURE DIRECTIONS

Dexrazoxane may be the key to the enigma of anthracycline cardiotoxicity, and therefore it warrants further investigation, including the search for alternative/complementary modes of cardioprotective action beyond simple iron chelation.

Safety and efficacy of ethylenediaminetetraacetic acid for removing microcapsules

BACKGROUND

Microencapsulated islets are used to prevent immune rejection associated with pancreatic islet transplantation, but cellular overgrowth affects transplantation success, necessitating removal of microcapsules prior to retransplantation. This study aimed to investigate the safety and efficacy of ethylendiaminetetraacetic acid (EDTA) for the removal of microcapsules surrounding islet cells.

METHODS

Microcapsule dissolution was investigated after in vitro exposure to EDTA for 72 h. Dissolution, blood biochemical markers, and pathologic changes in abdominal organs were observed after intraperitoneal administration of different concentrations of EDTA to rats with abdominally transplanted empty microcapsules. The extent of overgrowth and time to adhesion development were recorded after implantation of microencapsulated islets into the abdominal cavity of diabetic rats. EDTA (0-240 mmol/L) was injected to observe the transplantation effect and ability to dissolve microcapsules.

RESULTS

There was a positive correlation between the rate of microcapsule dissolution and EDTA concentration in vitro. Following administration of 60 mmol/L EDTA, the majority of microcapsules within the abdominal cavity were dissolved and the retrieval rate was 2.6%. No adverse effects, abnormal blood biochemical markers, or organ damage were observed in rats 1 mo following intraperitoneal injection with EDTA at doses up to 60 mmol/L. Microcapsule retrieval and blood glucose were significantly higher in cases of grade II cellular overgrowth than in cases of grade 0-I overgrowth.

CONCLUSIONS

EDTA (60 mmol/L) dissolved microcapsules in vivo without affecting islet cell viability or secretion capacity, and without affecting blood biochemical markers. Optimal dissolution was achieved with grade 0-I overgrowth after implantation of microencapsulated islets.

The iron chelator, deferasirox, as a novel strategy for cancer treatment: oral activity against human lung tumor xenografts and molecular mechanism of action

Deferasirox is an orally effective iron (Fe) chelator currently used for the treatment of iron-overload disease and has been implemented as an alternative to the gold standard chelator, desferrioxamine (DFO). Earlier studies demonstrated that DFO exhibits anticancer activity due to its ability to deplete cancer cells of iron. In this investigation, we examined the in vitro and in vivo activity of deferasirox against cells from human solid tumors. To date, there have been no studies to investigate the effect of deferasirox on these types of tumors in vivo. Deferasirox demonstrated similar activity at inhibiting proliferation of DMS-53 lung carcinoma and SK-N-MC neuroepithelioma cell lines compared with DFO. Furthermore, deferasirox was generally similar or slightly more effective than DFO at mobilizing cellular (59)Fe and inhibiting iron uptake from human transferrin depending on the cell type. However, deferasirox potently inhibited DMS-53 xenograft growth in nude mice when given by oral gavage, with no marked alterations in normal tissue histology. To understand the antitumor activity of deferasirox, we investigated its effect on the expression of molecules that play key roles in metastasis, cell cycle control, and apoptosis. We demonstrated that deferasirox increased expression of the metastasis suppressor protein N-myc downstream-regulated gene 1 and upregulated the cyclin-dependent kinase inhibitor p21(CIP1/WAF1) while decreasing cyclin D1 levels. Moreover, this agent increased the expression of apoptosis markers, including cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase 1. Collectively, we demonstrate that deferasirox is an orally effective antitumor agent against solid tumors.

A boronate prochelator built on a triazole framework for peroxide-triggered tridentate metal binding

Iron chelating agents have the potential to minimize damage associated with oxidative stress in a range of diseases; however, this potential is countered by risks of indiscriminant metal binding or iron depletion in conditions not associated with systemic iron overload. Deferasirox is a chelator used clinically for iron overload, but also is cytotoxic to cells in culture. In order to test whether a prodrug version of deferasirox could minimize its cytotoxicity but retain its protective properties against iron-induced oxidative damage, we synthesized a prochelator that contains a self-immolative boronic ester masking group that is removed upon exposure to hydrogen peroxide to release the bis-hydroxyphenyltriazole ligand deferasirox. We present here the synthesis and characterization of this triazole-based, self-immolative prochelator: TIP (4-(5-(2-((4-boronobenzyl)oxy)phenyl)-3-(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl)benzoic acid). TIP does not coordinate to Fe(3+) and shows only weak affinity for Cu(2+) or Zn(2+), in stark contrast to deferasirox, which avidly binds all three metal ions. TIP converts efficiently in vitro upon reaction with hydrogen peroxide to deferasirox. In cell culture, TIP protects retinal pigment epithelial cells from death induced by hydrogen peroxide; however, TIP itself is more cytotoxic than deferasirox in unstressed cells. These results imply that the cytotoxicity of deferasirox may not derive exclusively from its iron withholding properties.

Dexrazoxane provided moderate protection in a catecholamine model of severe cardiotoxicity

Positive effects of dexrazoxane (DEX) in anthracycline cardiotoxicity have been mostly assumed to be associated with its iron-chelating properties. However, this explanation has been recently questioned. Iron plays also an important role in the catecholamine cardiotoxicity. Hence in this study, the influence of DEX on a catecholamine model of acute myocardial infarction (100 mg/kg of isoprenaline by subcutaneous injection) was assessed: (i) the effects of an intravenous dose of 20.4 mg/kg were analyzed after 24 h, (ii) the effects were monitored continuously during the first two hours after drug(s) administration to examine the mechanism(s) of cardioprotection. Additional in vitro experiments on iron chelation/reduction and influence on the Fenton chemistry were performed both with isoprenaline/DEX separately and in their combination. DEX partly decreased the mortality, reduced myocardial calcium overload, histological impairment, and peripheral haemodynamic disturbances 24 h after isoprenaline administration. Continuous 2 h experiments showed that DEX did not influence isoprenaline induced atrioventricular blocks and had little effect on the measured haemodynamic parameters. Its protective effects are probably mediated by inhibition of late myocardial impairment and ventricular fibrillation likely due to inhibition of myocardial calcium overload. Complementary in vitro experiments suggested that iron chelation properties of DEX apparently did not play the major role.