Monoisoamyl Dimercaptosuccinic Acid Research Articles

Alpha Lipoic Acid and Monoisoamyl-DMSA Combined Treatment Ameliorates Copper-Induced Neurobehavioral Deficits, Oxidative Stress, and Inflammation.

Copper (Cu), being an essential trace metal, plays several roles in biological processes, though exposure to Cu can be potentially toxic to the brain and a few other soft organs. In the present study, we investigated the effects of the combined administration of monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA), which is a new chelator, and alpha lipoic acid (ALA) and an antioxidant that is made naturally in the body and is also found in foods, against Cu-induced oxidative stress in rats. Rats were exposed to 20 mg/kg copper sulfate for 16 weeks once a day via the oral route. After 16 weeks of exposure, animals were divided into different sub-groups. Group I was divided into three subgroups: Group IA, control; Group IB, MiADMSA (75 mg/kg, oral); Group IC, ALA (75 mg/kg, oral), while Group II was divided into four subgroups: Group IIA, Cu pre-exposed; Group IIB, Cu+ MiADMSA; Group IIC, Cu+ ALA; Group IID, Cu+ ALA+ MiADMSA. Exposure to Cu led to significant neurobehavioral abnormalities; treatment with MiADMSA, and in particular MiADMSA + ALA, significantly ameliorated the neurobehavioral parameters and restored the memory deficits in rats. Oxidative stress variables (ROS, nitrite, TBARS, SOD, catalase) and inflammatory markers (TNF-α, and IL-1β), which were altered on Cu exposed rats, also responded favorably to ALA+ MiADMSA combined treatment. Thus, combined administration of MiADMSA and ALA might be a better treatment strategy than monotherapy with MiADMSA or ALA against Cu-induced neurotoxicity, particularly in reducing oxidative stress, neurobehavioral abnormalities, and inflammatory markers.

Chemoprevention of Arseniasis-Past, Present and Future (Mini Review)

Clinical management of arsenic poisoning has been a major concern especially in countries like Bangladesh., India., Taiwan., Chile, Hungary and Argentina. In recent past, therapeutic efficacy of chelating agents, vitamins, nutrients, antioxidants and hormones has been investigated in many laboratories. Whereas, arsenic can be chelated by several agents viz: British Anti Lewisite (BAL), unithiol (DMPS), succimer (DMSA), monoisoamyl dimercaptosuccinic acid (MiADMSA), monocyclohexyl dimercaptosuccinic acid (MchDMSA), coadministration of quercetin and MiADMSA and taurine and MiADMSA have been found to reduce arsenic burdeon more effectively than their individual treatments. There are convincing reports that non-enzymatic antioxidants i.e. ascorbic acid, alpha tocopherol, B carotene, N-acetyl cysteine, alpha lipoic acid, curcumin, GSH and selenium offer protection against arseniasis by reducing oxidative stress. Melatonin, a product of pineal gland being a strong free radical scavenger possesses immense therapeutic importance against arseniasis. Thyroid hormones too influence arsenic toxicity. All these studies made in experimental animals have been briefly described in this review. However, cohorts made in human population are insignificant. Suitable clinical trials using these therapeutic agents individually or in combination may lead to the discovery of a “magic bullet” against arseniasis.

Protective Effect of Monoisoamyl-2, 3-Dimercaptosuccinic Acid against Manganese-induced Neurotoxicity in Rats.

Apart from being an essential heavy metal, Manganese (Mn) serves as an important component of the antioxidant enzyme system in humans. Overexposure to manganese leads to the development of manganism, which is characterized by motor dysfunction along with neurodegeneration. The management of manganism often utilizes chelation therapy. In this regard, Monoisoamyl-2, 3-Dimercaptosuccinic Acid (MiADMSA) has been reported as a novel arsenic chelator, due to the presence of vicinal sulfhydril group. MiADMSA has been reported to reduce the level in divalent ions (like copper) therefore, it may be hypothesized that MiADMSA would be helpful in Mn-induced neurotoxicity. This study is envisaged to explore the protective effect of MiADMSA on Mn-induced neurotoxicity. Mn exposure was carried out by intraperitoneal administration of Mn (as manganese chloride, 10 mg/kg; i.p.). The animals were treated with MiADMSA (50 mg/kg; p.o.) either alone or in combination with Mn. The effect of different treatments on neurobehavioral functions was observed by assessing spontaneous locomotor activity, motor rotarod test, and depression-like behavior in the forced swim test. After behavioral evaluations, all the animals were sacrificed and the brain and liver were isolated for metal estimations. Mn exposure leads to loss of motor coordination as observed in spontaneous locomotor activity and rotarod test. However, treatment with MiADMSA significantly improved motor impairments as compared to Mn exposed animals. Accumulation of Mn in the liver and brain has been recorded with Mn exposure; however, MiADMSA treatment significantly reduced the Mn content from the liver and brain. The outcome of the study suggests that treatment with MiADMSA reversed Mn-induced neurotoxicity by reducing Mn load. Therefore, the use of MiADMSA may be suggested in manganese toxicity, after careful investigation.

MiADMSA abrogates sodium tungstate-induced oxidative stress in rats

Tungsten (W) and its compounds have emerged as a relatively new area of environmental health concern in the last decade. Tungsten is environmentally benign due to its increasing use in armour-piercing munitions and as a replacement for lead in other ammunition. It has also been identified in various hazardous waste sites and therefore been proposed for inclusion in the Environmental Protection Agency National Priorities List. The major objective of this study was to evaluate the therapeutic efficacy of orally administered monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA) against tungstate induced oxidative injury in blood, liver and kidneys of male Wistar rats. MiADMSA, a thiol chelator has gained wide recognition recently as a future chelating drug of choice specifically for arsenic and was chosen for this study as tungstate ions too have an affinity toward the –SH group thus, being less bioavailable in the body. We determined the effects of MiADMSA (50 mg/kg, p.o.) against sodium tungstate (500 ppm in drinking water, daily for 28 days) induced biochemical changes indicative of oxidative stress in blood, and other soft tissues of of male Wistar rats. Tungsten exposure led to an increased levels of Reactive Oxygen Species (ROS) in liver, kidney, spleen and blood accompanied also by an increase in TBARS levels. The GSH: GSSG ratio also showed a decrease on sodium tungstate intoxication. Treatment with MiADMSA restored most of the sodium tungstate-induced alterations in the biomarkers suggestive of oxidative stress. These preliminary results led us to conclude that sub-acute exposure to tungstate-induced oxidative stress could be effectively reduced by the administration of MiADMSA and thus might be a promising antidote for studying in detail its efficacy in reducing body tungstate burden and its excretion post tungstate exposure.

Interaction study of monoisoamyl dimercaptosuccinic acid with bovine serum albumin using biophysical and molecular docking approaches

Monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA), a lipophilic chelator has been evaluated for its potential use as an antidote in arsenic poisoning. The pharmacokinetics and pharmacodynamics properties of a drug could be understood via study its mechanism of interaction with bovine serum albumin protein (BSA). Therefore, the interaction between MiADMSA with BSA was investigated using various spectroscopic techniques and computational methods. Linear quenching of BSA intrinsic fluorescence intensity with the increasing concentration of MiADMSA was observed in the fluorescence study. Furthermore, synchronous results revealed that MiADMSA slightly changed the conformation of BSA. The binding constant value of the BSA-MiADMSA complex was found 1.60 × 104 M−1 at 298 K. The value of thermodynamic parameters ΔG, ΔH, and ΔS described that the process is spontaneous, endothermic, and hydrophobic forces are involved in the interaction of MiADMSA with BSA. Competitive site marker experiments showed that MiADMSA binds to site-II of BSA. Conformational changes of BSA with the interaction of MiADMSA were apparent by CD, UV–Visible, FT-IR, and 3D fluorescence spectroscopy. To strengthen the experimental findings we have also performed a theoretical study on the BSA-MiADMSA complex. Two sites were identified with docking score of − 6.642 kcal/mol at site IIa and − 3.80 kcal/mol for site IIb via molecular docking study. Molecular dynamics simulation study inferred the stability of the BSA-MiADMSA complex which was analyzed in a long simulation run. The experimental and computational studies have shown the effective binding of MiADMSA with BSA which is essential for the transportation and elimination of a drug from the body.

MiADMSA abrogates chronic copper-induced hepatic and immunological changes in Sprague Dawley rats

Wilson disease (WD) is an autosomal-recessive disorder associated with the impaired copper metabolism, resulting in hepatic and neurologic manifestations. D-Pencillamine (DPA) is a first-line of treatment however, monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA), is gaining recognition recently as a future chelating agent of choice. We evaluated the effects of MiADMSA against copper-induced (20 mg/kg, orally, once, daily for 16 weeks) hepatic and immunological changes in the male Sprague Dawley (SD) rats. Copper overload increased the levels of pro-oxidant and concurrently decreased the levels of antioxidant enzymes in the liver. Increased oxidative stress triggered the up-regulation of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in the liver and down-regulated the anti-inflammatory cytokine IL-4. Altered liver function parameters as well as serum immunoglobulins’ (IgG, IgA, IgE, and IgM) levels, were also noted. MiADMSA treatment restored most of copper altered biochemical and immunological changes. Further, the histopathological changes proved that MiADMSA treatment ameliorated copper induced hepatic injury. Infra red spectra of liver tissue indicated shift in the characteristic –OH peak during copper exposure while the shifting came to normal in MiADMSA administered rat liver. We conclude that MiADMSA could be a promising antidote for the chronic copper toxicity and possibly in the clinical management of WD.

Monoisoamyl DMSA reduced copper-induced neurotoxicity by lowering 8-OHdG level, amyloid beta and Tau protein expressions in Sprague-Dawley rats.

copper dyshomeostasis has long been linked with several neurodegenerative disorders. The binding of Cu with amyloid beta and other neuronal proteins in the brain leads to the generation of oxidative stress, which eventually causes neurotoxicity. the present study was aimed at elucidating the efficacy of monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA) and d-penicillamine (DPA) (0.3 mEq kg-1, oral administration for 2 weeks) against Cu(ii)-induced (20 mg kg-1, oral administration for 16 weeks) neurotoxicity in Sprague-Dawley (SD) rats. we observed that the MiADMSA treatment modulated the altered oxidative and nitrosative stress parameters, antioxidant enzymes, and acetylcholinesterase (AChE) activity. Significant improvements were noticed in the neurobehavioral parameters except for the memory parameter. We also observed moderate improvement of memory impairment in the rats treated with MiADMSA and DPA post Cu(ii) exposure, as assessed by a passive avoidance test. Disease progression involves multiple factors and results in the up-regulation of intra and extracellular proteins such as amyloid beta and tau proteins; the expressions of these proteins were significantly reduced by the treatment proposed in our study, and these results were confirmed by ELISA and qRT-PCR. The expression of caspase-3 was higher in Cu(ii)-exposed rats, whereas it was lower in the MiADMSA-treated group. The proposed treatment reduced the copper-induced histological changes in the cortex and hippocampus regions of the brain. it can be summarised from the present study that MiADMSA is effective in reducing Cu(ii)-induced oxido-nitrosative stress, antioxidant defense enzymes, neurobehavioral changes, neuronal markers, apoptotic markers, and their genetic expressions. We conclude that chelation therapy using MiADMSA might be a promising approach for the treatment of copper-induced neurotoxicity.

MiADMSA ameliorate arsenic induced urinary bladder carcinogenesis in vivo and in vitro

Background and purposeArsenicosis is a major threat to public health and is a major cause of the development of urinary bladder cancer. Oxidative/ nitrosative stress is one of the key factors for these effects but the involvement of other associated factors is less known. There is a lack of data for the efficacy of chelator against urinary bladder carcinogenesis. The present study demonstrates the early signs of arsenic exposed urinary bladder carcinogenesis and its attenuation by Monoisoamyl dimercaptosuccinic acid (MiADMSA). MethodsMale rats were exposed to 50 ppm of sodium arsenite and dimethylarsinic acid (DMA) via drinking water for 18 weeks and treated with MiADMSA (50 mg/kg, orally once daily for 5 days) for 3 weeks with a gap one week between the two courses of treatments. We compared in vivo data with in vitro by co-exposing 100 nM of sodium arsenite and DMA to rat (NBT-II) as well as human transitional epithelial carcinoma (T-24) cells with 100 nM of MiADMSA. ResultsThe data showed that sodium arsenite and DMA exposure significantly increased the tissue arsenic contents, ROS, TBARS levels, catalase, SOD activities and significantly decreased GSH level which might be responsible for an increased 8−OHdG level. These changes might have increased pro-oncogenic biomarkers like MMP-9 and survivin in serum, bladder tissues, NBT-II, and T-24 cells. High cell migration and clonogenic potential in NBT-II and T-24 cells exposed to arsenic suggest pronounced carcinogenic potential. Significant recovery in these biomarkers was noted on treatment with MiADMSA. ConclusionEarly signs of urinary bladder carcinogenesis were observed in arsenic and DMA exposed rats which were linked to metal accumulation, oxidative/ nitrosative stress, 8-OHdG, MMP-9 and survivin which were reduced by MiADMSA possibly via its efficient chelation abilities in vivo and in vitro.

MiADMSA minimizes arsenic induced bone degeneration in Sprague Dawley rats

Arsenic considered as one of the most hazardous chemical while arsenic poisoning is also one of the serious medical issues worldwide. Long term arsenic exposure is associated with bone degeneration. The exact mechanism involving arsenic induced bone degeneration remains unclear but, plentiful literature suggested that oxidative/nitrosative stress caused by generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is one of the leading causes.Various treatment strategies are available for bone degeneration however, the suitable treatment for arsenic induced bone degeneration still lacks. In the current investigation, we evaluated the efficacy of chelation against arsenic induced bone degeneration in experimental rats. Male Sprague Dawley rats were exposed to sodium arsenite and dimethylarsinic acid (DMA) (50 ppm) for 18 weeks. After arsenic exposure, animals were treated with Monoisoamyl dimercaptosuccinic acid (MiADMSA) for three course of treatment (50 mg/kg, p.o., once daily for 5 days) with an interval of one week between two courses of treatment. MiADMSA minimizes the bone degeneration through reduction of oxidative stress (Reactive Oxygen Species, Reactive Nitrogen Species, and thiobarbituric reactive substances), alteration of antioxidant status (rGSH, Superoxide dismutase, Catalase) which led to the depletion in the levels of inflammatory markers like TNFα and IL-1β and alteration in the bone remodelling biomarkers like ALP, RANKL, and Runx2. It can be concluded from this study that MiADMSA could be an effective therapeutic strategy against arsenic induced bone degeneration and the possible mechanism could be the chelation of arsenic accompanied by the reduction in oxidative stress and inflammation.

Oxidative stress and neurobehavioural changes in rats following copper exposure and their response to MiADMSA andd-penicillamine

An increase in copper concentration in body may lead to hepatolenticular degeneration which is considered as one clinical feature of Wilson’s disease. Chelation therapy using d-penicillamine is the preferred medical treatment for reducing the toxic effects of copper. However, a few shortcomings associated with d-penicillamine led us to search of an alternative antidote for copper toxicity. Monoisoamyl-2, 3-dimercaptosuccinic acid (MiADMSA), a potent arsenic chelator under clinical trial, has been reported to reduce system copper level. Thus, the present study was envisaged to explore the ameliorative effect of MiADMSA against copper toxicity. Copper pre-exposed animals (CuSO4.5H2O; 100 mg/kg; p.o., for 6 weeks) were segregated in different groups and were administered equimolar dose (0.3 mEq/kg/day; p.o.) of d-penicillamine and MiADMSA for 5 days. The effect of different treatments on spontaneous locomotor activity, muscle coordination, depression like behaviour and contextual fear memory was analysed using neurobehavioural battery test. Biochemical variables related to oxidative stress, zinc and copper concentration were determined in liver, kidney and brain. The results suggested that copper exposure led to oxidative stress in liver, kidney and blood, along with moderate effects in brain. Treatment with d-penicillamine and MiADMSA reduced liver copper load. MiADMSA produced more pronounced beneficial effect compared to d-penicillamine by increasing brain GPx activity. Our study suggests that MiADMSA might be equally effective as d-penicillamine in depleting body copper load. More detailed studies using different doses are required to suggest whether MiADMSA could be an alternative for d-penicillamine in reducing oxidative injury, neurobehavioural changes and depleting body copper burden.

Effects of combined arsenic and lead exposure on the brain monoaminergic system and behavioral functions in rats: Reversal effect of MiADMSA.

In this study, we evaluated the therapeutic efficacy of monoisoamyldimercaptosuccinic acid (MiADMSA) against individual and combined effects of arsenic (As) and lead (Pb) on the monoaminergic system and behavioral functions in rats. Pregnant rats were exposed to sodium metaarsenite (50 ppm) and lead acetate (0.2%) individually and in combination (As = 25 ppm + Pb = 0.1%) via drinking water from gestation day (GD) 6 to postnatal day (PND) 21. MiADMSA (50 mg/kg body weight) was given orally through gavage for 3 consecutive days to pups from PND 18 to PND 20. The results showed increases in synaptosomal epinephrine, dopamine, and norepinephrine levels with individual metal exposures and decreases with combined exposure to As and Pb in the cortex, cerebellum, and hippocampus in PND 21, PND 28, and 3 months age-group rats. We found decreased activity of mitochondrial monoamine oxidase in the selected brain regions following individual and combined exposures to Pb and As. In addition, rats treated with Pb and As alone or in combination showed significant deficits in open-field behavior, grip strength, locomotor activity, and exploratory behavior at PND 28 and 3 months of age. However, MiADMSA administration showed reversal effects against the As- and/or Pb-induced impairments in the monoaminergic system as well as in behavioral functions of rats. Our data demonstrated that the mixture of Pb and As induced synergistic toxicity to developing brain leading to impairments in neurobehavioral functions and also suggest therapeutic efficacy of MiADMSA against Pb- and/or As-induced developmental neurotoxicity.

Combinatorial drug delivery strategy employing nano-curcumin and nano-MiADMSA for the treatment of arsenic intoxication in mouse

Chelation therapy is the mainstream treatment for heavy metal poisoning. Apart from this, therapy using antioxidant/herbal extracts are the other strategies now commonly being tried for the treatment. We have previously reported individual beneficial efficacy of nanoparticle mediated administration of an antioxidant like ‘curcumin’ and an arsenic chelator ‘monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA)’ for the treatment of arsenic toxicity compared to bulk drugs. The present paper investigates our hypothesis that a combination drug delivery therapy employing two nanosystems, a chelator and a strong antioxidant, may produce more pronounced therapeutic effects compared to individual effects in the treatment of arsenic toxicity.An in-vivo study was conducted wherein arsenic as sodium arsenite (100 ppm) was administered in drinking water for 5 months to Swiss albino mice. This was followed by a treatment protocol comprising of curcumin encapsulated chitosan nanoparticles (nano-curcumin, 15 mg/kg, orally for 1 month) either alone or in combination with MiADMSA encapsulated polymeric nanoparticles (nano-MiADMSA, 50 mg/kg for last 5 days) to evaluate the therapeutic potential of the combination treatment. Our results demonstrated that co-treatment with nano-curcumin and nano-MiADMSA provided beneficial effects in a synergistic way on the adverse changes in oxidative stress parameters and metal status induced by arsenic.

Nanoencapsulation of DMSA monoester for better therapeutic efficacy of the chelating agent against arsenic toxicity.

Exposure to toxic metals remains a widespread occupational and environmental problem in world. Chelation therapy is a mainstream treatment used to treat heavy metal poisoning. This paper describes the synthesis, characterization and therapeutic evaluation of monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA)-encapsulated polymeric nanoparticles as a detoxifying agent for arsenic poisoning. Polymeric nanoparticles entrapping the DMSA monoester, which can evade the reticulo-endothelial system and have a long circulation time in the blood, were prepared. Particle characterization was carried out by transmission electron microscopy and dynamic light scattering. An in vivo study was conducted to investigate the therapeutic efficacy of MiADMSA-encapsulated polymeric nanoparticles (nano- MiADMSA; 50 mg/kg orally for 5 days) and comparison drawn with bulk MiADMSA. Swiss albino mice exposed to sodium arsenite for 4 weeks were treated for 5 days to evaluate alterations in blood, brain, kidney and liver oxidative stress variables. The study also evaluated the histopathological changes in tissues and the chelating potential of the nanoformulation. Our results show that nano-MiADMSA have a narrow size distribution in the 50-nm range. We observed an enhanced chelating potential of nano-MiADMSA compared with bulk MiADMSA as evident in the reversal of biochemical changes indicative of oxidative stress and efficient removal of arsenic from the blood and tissues. Histopathological changes and urinary 8-OHdG levels also prove better therapeutic efficacy of the novel formulation for arsenic toxicity. The results from our study show better therapeutic efficacy of nano-MiADMSA in removing arsenic burden from the brain and liver.

Alterations in apoptotic caspases and antioxidant enzymes in arsenic exposed rat brain regions: Reversal effect of essential metals and a chelating agent

Arsenic (As) widely studied for its effects as a neurotoxicant. The present study was designed to evaluate the protective effect of calcium, zinc or monoisoamyl dimercaptosuccinic acid (MiADMSA), either individually or in combination on As induced oxidative stress and apoptosis in brain regions (cerebral cortex, hippocampus and cerebellum) of postnatal day (PND) 21, 28 and 3 months old rats. Arsenic exposure significantly decreased the activities of superoxide dismutase (SOD) isoforms, catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) with increase in glutathione s transferase (GST) while lipid peroxidation (LPx), arsenic levels, mRNA expression of caspase 3 and 9 were significantly increased in different brain regions. Arsenic induced alterations in these parameters were greater in PND 28 and more pronounced in cerebral cortex. From the results it is evident that combined supplementation of calcium and zinc along with MiADMSA would be most effective compared to individual administration in reducing arsenic induced neurotoxicity.

Reversal effect of monoisoamyl dimercaptosuccinic acid (MiADMSA) for arsenic and lead induced perturbations in apoptosis and antioxidant enzymes in developing rat brain

Oxidative stress (OS) has been implicated in the pathophysiology of many neurodegenerative disorders. Several studies have shown that exposure to arsenic (As) and lead (Pb) produces oxidative stress, one of the most noted molecular mechanisms for the neurotoxicity of these metals. In the present study, we examined the effect of combined exposure to these metals (As and Pb) on the activity levels of antioxidant enzymes and apoptotic marker enzymes in brain regions (cerebral cortex, hippocampus and cerebellum) of rats at postnatal day (PND) 21, 28 and 3 months age and compared the toxicity levels with individual metals (As or Pb). Further, we also evaluated the therapeutic efficacy of a chelating agent, monoisoamyl dimercaptosuccinic acid (MiADMSA) against arsenic and lead induced developmental neurotoxicity. Pregnant rats were exposed to sodium meta-arsenite (50ppm) and lead acetate (0.2%) individually, and in combination (As=25ppm+Pb=0.1%) via drinking water throughout perinatal period (GD 6 to PND 21). MiADMSA (50mg/kg, orally through gavage) was given for three consecutive days to the PND 18 pups (i.e., PND 18 to PND 20). Exposure to metal mixture resulted in a significant decrease in the activity levels of antioxidant enzymes such as manganese-superoxide dismutase (Mn-SOD), Cu/Zn superoxide dismutase (Cu/Zn-SOD), catalase (CAT) and glutathione peroxidase (GPx) while the malondialdehyde (MDA) levels and mRNA expression levels of caspase-3 and caspase-9 were significantly increased in all the three brain regions. The observed alterations were greater with exposure to metal mixture than individual metals (As or Pb) and the changes were more prominent at PND 28 and greater in cerebral cortex than hippocampus and cerebellum. Interestingly, chelation therapy with MiADMSA showed significant recovery in antioxidant enzymes, lipid peroxidation and gene expression levels of caspase-3 and caspase-9. From these findings, it can be concluded that combined exposure to As and Pb showed an additive effect on antioxidant enzymes than individual metal exposure and chelation therapy with MiADMSA significantly reversed the As and Pb induced apoptosis and oxidative stress, a major contributing factor to neurotoxicity.

MiADMSA Protects Arsenic-Induced Oxidative Stress in Human Keratinocyte ‘HaCaT’ Cells

Arsenic toxicity may lead to skin manifestations and arsenic accumulation in keratinised tissue. Thus human keratinocytes has been extensively used to study dermal effects of arsenic exposure. The present study was aimed to investigate time and dose-dependent effects of arsenic using HaCaT cell line. Another major focus of the study was to evaluate if treatment with monoisoamyl dimercaptosuccinic acid (MiADMSA) offers protection against arsenic-induced oxidative stress and apoptotic cell death using HaCaT cells. HaCaT cell lines were incubated to three different concentrations of arsenic (10, 30 and 50μM) for 24h to identify the toxic dose by measuring oxidative stress variables. Later, MiADMSA pre-incubation for an hour preceded arsenic exposure (30μM). We evaluated cell morphology, lactate dehydrogenase, glutathione linked enzyme and antioxidant enzyme activities to measure oxidative stress status, while MTT assay and caspase 9 and 3 levels were determined for cell viability and apoptotic status. The present study suggests arsenic-induced toxicity in a concentration-dependant manner. Arsenic also caused a significant increase in lactate dehydrogenase accompanied by an elevated antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase and caspase activity). Interestingly, pre-treatment of cell with MiADMSA elicited significant protection against arsenic-induced oxidative stress and apoptotic cell death. The present findings are of clinical relevance and suggest MiADMSA to be a promising candidate in protecting skin against arsenic-induced toxic effects, which need further exploration using in vivo experimental models.

MiADMSA reverses impaired mitochondrial energy metabolism and neuronal apoptotic cell death after arsenic exposure in rats

Arsenicosis, due to contaminated drinking water, is a serious health hazard in terms of morbidity and mortality. Arsenic induced free radicals generated are known to cause cellular apoptosis through mitochondrial driven pathway. In the present study, we investigated the effect of arsenic interactions with various complexes of the electron transport chain and attempted to evaluate if there was any complex preference of arsenic that could trigger apoptosis. We also evaluated if chelation with monoisoamyl dimercaptosuccinic acid (MiADMSA) could reverse these detrimental effects. Our results indicate that arsenic exposure induced free radical generation in rat neuronal cells, which diminished mitochondrial potential and enzyme activities of all the complexes of the electron transport chain. Moreover, these complexes showed differential responses towards arsenic. These early events along with diminished ATP levels could be co-related with the later events of cytosolic migration of cytochrome c, altered bax/bcl 2 ratio, and increased caspase 3 activity. Although MiADMSA could reverse most of these arsenic-induced altered variables to various extents, DNA damage remained unaffected. Our study for the first time demonstrates the differential effect of arsenic on the complexes leading to deficits in bioenergetics leading to apoptosis in rat brain. However, more in depth studies are warranted for better understanding of arsenic interactions with the mitochondria.

Monoisoamyl dimercaptosuccinic acid abrogates arsenic-induced developmental toxicity in human embryonic stem cell-derived embryoid bodies: Comparison with in vivo studies

The ability of human embryonic stem (ES) cells to differentiate into the three germ layers has proposed its application in studying human developmental toxicity in vitro. In the current study we investigated if the prompted application could be utilized to evaluate the efficacy of a newly developed arsenic antidote, monoisoamyl dimercaptosuccinic acid (MiADMSA) against arsenic (III) and if the results obtained in vitro were in concordance with the animal model for studying developmental toxicity. On the basis of real time PCR (qRT-PCR) and cytotoxicity analysis of human embryoid bodies (EBs), we observed that arsenic (III) caused a significant down regulation of gene expression in all the three germ layers, which could be correlated with high mortality, visceral and skeletal defects in pups. Reversal of arsenic-induced dysfunctioning could be observed with concomitant treatment of MiADMSA in vitro and in vivo, indicating ES–EB model could provide toxicity information similar to in vivo model. IR spectroscopy further suggested that MiADMSA bind to arsenic to form adduct, which prevents arsenic from exerting its toxic effect in both models. To our knowledge this study provides first experimental evidence suggesting human ES cells could be utilized in studying the efficacy of drugs in a comparable manner with animal models. We conclude that the ES–EB model seems to be an effective, faster, cost effective method for predicting efficacy of a drug.

Co-Administration of Monoisoamyl Dimercaptosuccinic Acid and Moringa Oleifera Seed Powder Protects Arsenic-Induced Oxidative Stress and Metal Distribution in Mice

Arsenic contamination of groundwater in the West Bengal basin in India is unfolding as one of the worst natural geo-environmental disasters to date. Chelation therapy with chelating agents is considered to be the best known treatment against arsenic poisoning; however, they are compromised with certain serious drawbacks/side-effects. Efficacy of combined administration of Moringa oleifera (M. oleifera) (English: Drumstick tree) seed powder, a herbal extract, with a thiol chelator monoisoamyl DMSA (MiADMSA) post-arsenic exposure in mice was studied. Mice were exposed to 100 ppm arsenic in drinking water for 6 months, followed by 10-days treatment with M. oleifera seed powder (500 mg/kg, orally through gastric gavage, once daily), MiADMSA (50 mg/kg, intraperitoneally, once daily) either individually or in combination. Arsenic exposure caused significant decrease in blood glutathione, δ-aminolevulinic acid dehydratase (ALAD), accompanied by increased production of reactive oxygen species in blood and soft tissues. Significant inhibition of superoxide dismutase, catalase, and glutathione peroxidase activities in tissues (liver in particular) along with significant increase in thiobarbituric acid reactive substances and metallothionein levels in arsenic intoxicated mice was also noted. Combined administration of MiADMSA with M. oleifera proved better than all other treatments in the recovery of most of the above parameters accompanied by more pronounced depletion of arsenic. The results suggest that concomitant administration of M. oleifera during chelation treatment with MiADMSA might be a better treatment option than monotherapy with the thiol chelator in chronic arsenic toxicity.

Quercetin Administration During Chelation Therapy Protects Arsenic-Induced Oxidative Stress in Mice

We studied the efficacy of quercetin and a thiol chelating agent, monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA) either individually or in combination against arsenic-induced oxidative stress and mobilization of metal in mouse. Animals were chronically exposed to 25 ppm arsenite as sodium arsenite in drinking water for 12 months followed by treatment with MiADMSA (0.2 mmol/kg, orally), quercetin (0.2 mmol, orally) either alone or in combination, once daily for 5 consecutive days. Arsenic exposure led to a significant depletion of blood delta-aminolevulinic acid dehydratase (ALAD) activity, glutathione, white (WBC) and red blood cell (RBC) counts, and an increase in platelet levels while significantly increasing the level of reactive oxygen species (in RBCs). Hepatic reduced catalase (CAT) and glutathione peroxidase activities showed a depletion, whereas thiobarbituric acid reactive substances (TBARS) levels increased on arsenic exposure indicating arsenite-induced oxidative stress in blood and liver. Kidney CAT activity showed a depletion, whereas TBARS levels increased on arsenic exposure. These biochemical changes were accompanied by an increase in blood, liver, and kidney arsenic concentration. Treatment with MiADMSA was effective in increasing ALAD activity, whereas quercetin was ineffective when given alone. Quercetin when co-administered with MiADMSA also provided no additional beneficial effect on blood ALAD activity but significantly brought altered platelet counts nearer to the normal value. In contrast, administration of quercetin alone provided significant beneficial effects on hepatic oxidative stress and kidney TBARS levels. Renal biochemical variables remained insensitive to arsenic and any of the treatments. Interestingly, combined administration of quercetin with MiADMSA had a remarkable effect in depleting total arsenic concentration from blood and soft tissues. These results lead us to conclude that quercetin administration during chelation treatment had some beneficial effects particularly on the protection of inhibited blood ALAD activity and depletion of arsenic level from target organs. The study supports our earlier conclusion that a co-administration of an antioxidant particularly flavonoids more beneficial than monotherapy with the chelating agents to achieve optimal effects of chelation in arsenite toxicity.