Biological reactive intermediates that mediate dacarbazine cytotoxicity

Caffeine reduces viability, induces apoptosis, inhibits migration and modulates the CD39/CD73 axis in metastatic cutaneous melanoma cells

We aimed to evaluate the effect of caffeine on viability, apoptosis, migration, redox profile and modulatory effect of the purinergic system of cutaneous melanoma cells. The melanoma cells SK-MEL-28 and non-tumoural CCD-1059sk cells were treated for 24 h with different concentrations of caffeine. Cell viability was evaluated by a biochemical assay and fluorescence microscopy, and flow cytometry assessed apoptosis induction. A wound-healing assay assessed cell migration. The redox profile was evaluated by the levels of markers of reactive oxygen species (ROS), nitric oxide (NOx), total thiols (PSH) and non-protein thiols (NPSH). RT-qPCR and flow cytometry assessed the expression of CD39 and CD73. ATPase/ADPase and AMPase enzyme activities were evaluated by hydrolysis of ATP, ADP and AMP nucleotides. A bioluminescent assay assessed extracellular ATP levels. Caffeine significantly reduced melanoma cell viability and migration and did not affect non-tumoural cells. Caffeine increased ROS levels and improved PSH levels in melanoma cells. Furthermore, caffeine reduced CD39 and CD73 expression, decreased ATP, ADP and AMP nucleotide hydrolysis and increased extracellular ATP levels. We have shown that caffeine reduces metastatic cutaneous melanoma cell viability and migration, induces ROS generation and improves PSH levels. In an unprecedented manner, we also showed that caffeine reduces the expression of CD39 and CD73 and, consequently, ATPase/ADPase/AMPase hydrolytic activity of ectonucleotidases, thus displacing the CD39/CD73 axis and increasing extracellular ATP levels. Therefore, caffeine may be an interesting compound for clinical trials with the CD39/CD73 axis as a therapeutic target.

Three-Dimensional Hepatocyte Spheroids: Model for Assessing Chemotherapy in Hepatocellular Carcinoma

BACKGROUND

Three-dimensional cellular models provide a more comprehensive representation of in vivo cell properties, encompassing physiological characteristics and drug susceptibility.

METHODS

Primary hepatocytes were seeded in ultra-low attachment plates to form spheroids, with or without tumoral cells. Spheroid structure, cell proliferation, and apoptosis were analyzed using histological staining techniques. In addition, extracellular vesicles were isolated from conditioned media by differential ultracentrifugation. Spheroids were exposed to cytotoxic drugs, and both spheroid growth and cell death were measured by microscopic imaging and flow cytometry with vital staining, respectively.

RESULTS

Concerning spheroid structure, an active outer layer forms a boundary with the media, while the inner core comprises a mass of cell debris. Hepatocyte-formed spheroids release vesicles into the extracellular media, and a decrease in the concentration of vesicles in the culture media can be observed over time. When co-cultured with tumoral cells, a distinct distribution pattern emerges over the primary hepatocytes, resulting in different spheroid conformations. Tumoral cell growth was compromised upon antitumoral drug challenges.

CONCLUSIONS

Treatment of mixed spheroids with different cytotoxic drugs enables the characterization of drug effects on both hepatocytes and tumoral cells, determining drug specificity effects on these cell types.

Curcumin promotes apoptosis of human melanoma cells by caspase 3

Cutaneous melanoma (CM) is a malignant neoplasm with a high metastatic rate that shows poor response to systemic treatments in patients with advanced stages. Recently, studies have highlighted the antineoplastic potential of natural compounds, such as polyphenols, in the adjuvant therapy context to treat CM. The objective of the present study was to evaluate the effect of different concentrations of curcumin (0.1-100 µM) on the metastatic CM cell line SK-MEL-28. The cells were treated for 6 and 24 h with different concentrations of curcumin. Cell viability was assessed by 3-(4,5-dimethyl-2thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and fluorescence microscopy. The apoptotic-inducing potential was detected by annexin V flow cytometry. The wound healing assay was used to verify cell migration after the curcumin exposition. The redox profile was evaluated by levels of the pro-oxidant markers reactive oxygen species (ROS) and Nitric oxide (NOx) and antioxidants of total thiols (PSH) and nonprotein thiols. The gene expression and enzymatic activity of caspase 3 were evaluated by reverse transcription-quantitative polymerase chain reaction and a sensitive fluorescence assay, respectively. Curcumin significantly decreased the cell viability of SK-MEL-28 cells at both exposure times. It also induced apoptosis at the highest concentration tested (p < .0001). SK-MEL-28 cell migration was inhibited by curcumin after treatment with 10 µM (p < .0001) and 100 µM (p < .0001) for 6 and 24 h (p = .0006 and p < .0001, respectively). Furthermore, curcumin significantly increased levels of ROS and NOx. Finally, curcumin was capable of increasing the gene expression at 10 µM (p = .0344) and 100 µM (p = .0067) and enzymatic activity at 10 µM (p = .0086) and 100 µM (p < .0001) of caspase 3 after 24 h. For the first time, we elucidated in our study that curcumin increases ROS levels, promoting oxidative stress that activates the caspase pathway and culminates in SK-MEL-28 metastatic CM cell death.

Preparation of chitosan nanoparticles for simultaneous drug delivery of dacarbazine and enoxaparin in melanoma

The aim of this study was to investigate the anti-melanoma and anti-angiogenic effects of enoxaparin surface-coated dacarbazine-loaded chitosan nanoparticles (Enox-Dac-Chi NPs). The prepared Enox-Dac-Chi NPs had a particle size of 367.95 ± 1.84 nm, zeta potential of -7.12 ± 0.25 mV, efficiency of drug loading (DL%) of 73.90 ± 3.84 %, and attached enoxaparin percentage of 98.53 ± 0.96 %. Both drugs had extended-release profiles and approximately 96 % of enoxaparin and 67 % dacarbazine were released within 8 h. The Enox-Dac-Chi NPs with IC₅₀ of 59.60 ± 1.25 μg/ml were the most cytotoxic against melanoma cancer cells compared with chitosan nanoparticles containing only dacarbazine (Dac-Chi NPs) and free dacarbazine. There was no significant difference between the cellular uptake of Chi NPs and enoxaparin coated Chi NPs (Enox-Chi NPs) in B16F10 cells. Enox-Chi NPs with an average anti-angiogenic score of 1.75 ± 0.125 had more anti-angiogenic effect than enoxaparin. The results showed that simultaneous delivery of dacarbazine and enoxaparin by chitosan nanoparticles can enhance the anti-melanoma effect of dacarbazine. Additionally, enoxaparin can prevent the melanoma metastasis by its anti-angiogenic activity. Thus, the designed nanoparticles can be introduced as effective drug delivery vehicles for the treatment and prevention of metastatic melanoma.

Rosmarinic acid decreases viability, inhibits migration and modulates expression of apoptosis-related CASP8/CASP3/NLRP3 genes in human metastatic melanoma cells

Cutaneous melanoma is the most aggressive type of skin cancer; it is difficult to treat, and has been highlighted in recent years due to increasing numbers of cases worldwide. The use of antitumoral therapeutics for this neoplasm has been associated with severe side effects, low quality of life, and resistance. We aimed in this study to explore the effect of the phenolic compound rosmarinic acid (RA) on human metastatic melanoma cells. SK-MEL-28 melanoma cells were treated for 24 h with different concentrations of RA. In parallel, peripheral blood mononuclear cells (PBMCs) also were treated with RA under the same experimental conditions to verify the cytotoxic effect on non-tumoral cells. Then, we assessed cell viability and migration, levels of intracellular and extracellular reactive oxygen species (ROS), as well as nitric oxide (NOx), non-protein thiols (NPSH), and total thiol (PSH). Gene expression of the caspase 8, caspase 3 and NLRP3 inflammasome was evaluated by RT-qPCR. The enzymatic activity of the caspase 3 protein was assessed by a sensitive fluorescent assay. Fluorescence microscopy was employed to corroborate the effects of RA on melanoma cell viability, mitochondria transmembrane potential and apoptotic bodies formation. We found that RA potently reduces melanoma cell viability and migration after 24 h of treatment. On the other hand, it has no cytotoxic effect on non-tumoral cells. The fluorescence micrographics indicated that RA reduces transmembrane potential of mitochondria and induces apoptotic bodies formation. Moreover, RA significantly decreases intracellular and extracellular ROS levels, and increases the antioxidant defenders NPSH and PSH. A remarkable feature found in our study was that RA strongly upregulates the gene expression of the caspase 8 and caspase 3, and downregulates NLRP3 inflammasome expression. Similar to gene expression, RA greatly increases the enzymatic activity of caspase 3 protein. Taken together, we have shown for the first time that RA reduces cell viability and migration of human metastatic melanoma cells, in addition to modulates apoptosis-related gene expression. We suggest that RA may have the potential to be used in a therapeutic perspective, particularly for CM cell treatment.

Optimizing Dacarbazine Therapy: Design of a Laser-Triggered Delivery System Based on β-Cyclodextrin and Plasmonic Gold Nanoparticles

Dacarbazine (DB) is an antineoplastic drug extensively used in cancer therapy. However, present limitations on its performance are related to its low solubility, instability, and non-specificity. To overcome these drawbacks, DB was included in β-cyclodextrin (βCD), which increased its aqueous solubility and stability. This new βCD@DB complex has been associated with plasmonic gold nanoparticles (AuNPs), and polyethylene glycol (PEG) has been added in the process to increase the colloidal stability and biocompatibility. Different techniques revealed that DB allows for a dynamic inclusion into βCD, with an association constant of 80 M^-1 and a degree of solubilization of 0.023, where βCD showed a loading capacity of 16%. The partial exposure of the NH₂ group in the included DB allows its interaction with AuNPs, with a loading efficiency of 99%. The PEG-AuNPs-βCD@DB nanosystem exhibits an optical plasmonic absorption at 525 nm, a surface charge of -29 mV, and an average size of 12 nm. Finally, laser irradiation assays showed that DB can be released from this platform in a controlled manner over time, reaching a concentration of 56 μg/mL (43% of the initially loaded amount), which, added to the previous data, validates its potential for drug delivery applications. Therefore, the novel nanosystem based on βCD, AuNPs, and PEG is a promising candidate as a new nanocarrier for DB.

Chemotherapy Drugs Act Differently in the Expression and Somatic Mobilization of the mariner Transposable Element in Drosophila simulans

Transposable elements (TEs) are abundant in genomes. Their mobilization can lead to genetic variability that is useful for evolution, but can also have deleterious biological effects. Somatic mobilization (SM) has been linked to degenerative diseases, such as Alzheimer's disease and cancer. We used a Drosophila simulans strain, in which SM can be measured by counting red spots in the eyes, to investigate how chemotherapeutic agents affect expression and SM of the mariner TE. Flies were treated with Cisplatin, Dacarbazine, and Daunorubicin. After acute exposure, relative expression of mariner was quantified by RT-qPCR and oxidative stress was measured by biochemical assays. Exposure to 50 and 100 µg/mL Cisplatin increased mariner expression and ROS levels; catalase activity increased at 100 µg/mL. With chronic exposure, the number of spots also increased, indicating higher mariner SM. Dacarbazine (50 and 100 µg/mL) did not significantly alter mariner expression or mobilization or ROS levels, but decreased catalase activity (100 µg/mL). Daunorubicin (25 and 50 µM) increased mariner expression, but decreased mariner SM. ROS and catalase activity were also reduced. Our data suggest that stress factors may differentially affect the expression and SM of TEs. The increase in mariner transposase gene expression is necessary, but not sufficient for mariner SM.

Attenuation of Hg(II)-induced cellular and DNA damage in human blood cells by uric acid

Mercury (Hg) is a widespread environmental pollutant and toxicant which induces multiple organ damage in humans and animals. Hg toxicity is mediated by the induction of oxidative stress in target cells. We have used uric acid (UA), a potent antioxidant found in biological fluids, to protect human red blood cells (RBC) and lymphocytes against Hg-mediated cell, organelle and genotoxicity. RBC were incubated with HgCl2, an Hg(II) compound, either alone or in presence of UA. Incubation of RBC with only HgCl2 increased production of nitrogen and oxygen radical species, enhanced methemoglobin levels, heme degradation, free ferrous iron, oxidation of proteins and membrane lipids and reduced antioxidant capacity of cells. UA enhanced the antioxidant capacity of RBC and restored metabolic, plasma membrane-bound and antioxidant enzyme activities. Scanning electron microscopy showed that UA prevented HgCl2-mediated morphological changes in RBC. HgCl2 dissipated the mitochondrial membrane potential and increased lysosomal membrane damage in lymphocytes, but UA pre-treatment attenuated these effects. Genotoxicity analysis by comet assay showed that UA protected lymphocyte DNA from HgCl2-induced damage. Importantly, UA itself did not exhibit any deleterious effects in either RBC or lymphocytes. Thus, UA protects human blood cells from Hg(II)-mediated oxidative damage reducing the harmful effects of this extremely toxic metal. We suggest that UA performs a similar protective role in the plasma against heavy metal toxicity.

Antioxidant thymoquinone and eugenol alleviate TiO2 nanoparticle-induced toxicity in human blood cells in vitro

Titanium dioxide (TiO₂) nanoparticles (NPs) are used extensively in a variety of commercial, industrial, and medical products, due to which human exposure is inevitable. This study aimed to explore the potential of eugenol and thymoquinone (TQ), two well-known antioxidants, in counteracting the NP-induced toxicity in human blood cells in vitro. Fresh lymphocytes and erythrocytes were isolated from volunteer human blood donors and incubated with 50 μg/mL of TiO₂ NPs in the presence and absence of 50 μM of TQ and 20 μg/mL of eugenol for 3 h. Results showed that NP-treatment-induced hemolysis, oxidative stress, lactate dehydrogenase (LDH) leakage, and reduced ATPase activity in the erythrocytes. In the lymphocytes treated with NPs alone (50 μg/mL), cytotoxicity in MTT assay and DNA damage in comet assay were observed; in addition, mitochondrial membrane potential collapsed and ADP/ATP ratio increased indicating mitochondrial function impairment. However, in the presence of antioxidants, all these NP-induced changes were mitigated significantly. The results were more significant when both antioxidants eugenol and TQ were given together. Thus, it seems that antioxidants eugenol and TQ can be used as a protective agent against TiO₂ NP-induced toxicity.

Synthesis, Spectroscopic, and Theoretical Study of Copper and Cobalt Complexes with Dacarbazine

Dacarbazine (DAC) 5-(3,3-dimethyl-1-triazenyl)imidazole-4-carboxamide is an imidazole-carboxamide derivative that is structurally related to purines. DAC belongs to the triazene compounds, which are a group of alkylating agents with antitumor and mutagenic properties. DAC is a non-cell cycle specific drug, active in all phases of the cellular cycle. In the frame of this work the 3d metal complexes (cobalt and copper) with dacarbazine were synthesized. Their spectroscopic properties by the use of FT-IR, FT-Raman, and ¹HNMR were studied. The structures of dacarbazine and its complexes with copper(II) and cobalt(II) were calculated using DFT methods. The effect of metals on the electronic charge distribution of dacarbazine was discussed on the basis of calculated NBO atomic charges. The reactivity of metal complexes in relation to ligand alone was estimated on the basis of calculated energy of HOMO and LUMO orbitals. The aromaticity of the imidazole ring in dacarbazine and the complexes were compared (on the basis of calculated geometric indices of aromaticity). Thermal stability of the investigated 3d-metal complexes with dacarbazine and the products of their thermal decomposition were analyzed.

Coenzyme Q10 protects isolated human blood cells from TiO2 nanoparticles induced oxidative/antioxidative imbalance, hemolysis, cytotoxicity, DNA damage and mitochondrial impairment

TiO₂ NPs have been investigated for their toxic potential and studies have reported their toxicity is due to generation of oxidative stress. In the present study, we investigated the toxicity of TiO₂ NPs and explored the potential of well-known antioxidant coenzyme Q10 (CoQ10) in counteracting the NP-induced toxicity in isolated human blood cells. When the isolated blood cells were treated with varying concentrations of TiO₂ NPs (25-100 μg/ml), only 50 μg/ml dose induced statistically significant hemolysis in erythrocytes and cytotoxicity in lymphocytes (p < 0.05). None of the concentrations induced any significant increase in platelet aggregation. To investigate the protective effect of CoQ10, we incubated the isolated blood cells with 50 μg/ml of TiO₂ NPs in the presence and absence of 25 μM of CoQ10 for 3 h. Hemolysis, oxidative stress, LDH leakage and ATPase enzyme activity were studied in erythrocytes; cytotoxic and DNA damaging potential of NPs were determined in lymphocytes, along with mitochondrial membrane potential (MMP) and ADP/ATP ratio. Hemolysis, generation of oxidative stress, LDH leakage and reduced ATPase activity were observed in the erythrocytes treated with NPs alone (50 μg/ml), the results were statistically significant at p < 0.05. Oxidative stress was evident by increased levels of malonaldehyde, indicating lipid peroxidation and generation of reactive oxygen species including hydrogen peroxide, together with statistically significant decrease in the activities of catalase and superoxide dismutase and reduced glutathione levels. In the lymphocytes treated with NPs alone (50 μg/ml), cytotoxicity in MTT assay and DNA damage in comet assay were observed; in addition, mitochondrial membrane potential collapsed and ADP/ATP ratio increased indicating mitochondrial function impairment. However, in the presence of CoQ10, hemolysis, oxidative stress and LDH leakage in the erythrocytes and lymphocyte cytotoxicity and DNA damage were drastically reduced, enzyme activities, MMP and ADP/ATP ratio were restored towards normal levels. TiO₂ NPs induce cytotoxicity, damage DNA in lymphocytes, and induce oxidative/anti-oxidative imbalance in erythrocytes. Antioxidant CoQ10 protects erythrocytes and lymphocytes from toxicity induced by TiO₂ NPs.

Utility of Three-Dimensional Cultures of Primary Human Hepatocytes (Spheroids) as Pharmacokinetic Models

This paper reviews the usefulness, current status, and potential of primary human hepatocytes (PHHs) in three-dimensional (3D) cultures, also known as spheroids, in the field of pharmacokinetics (PK). Predicting PK and toxicity means pharmaceutical research can be conducted more efficiently. Various in vitro test systems using human hepatocytes have been proposed as tools to detect hepatic toxicity at an early stage in the drug development process. However, such evaluation requires long-term, low-level exposure to the test compound, and conventional screening systems such as PHHs in planar (2D) culture, in which the cells can only survive for a few days, are unsuitable for this purpose. In contrast, spheroids consisting of PHH are reported to retain the functional characteristics of human liver for at least 35 days. Here, we introduce a fundamental PK and toxicity assessment model of PHH spheroids and describe their applications for assessing species-specific metabolism, enzyme induction, and toxicity, focusing on our own work in these areas. The studies outlined in this paper may provide important information for pharmaceutical companies to reduce termination of development of drug candidates.

Pre-treatment With PLGA/Silibinin Nanoparticles Mitigates Dacarbazine-Induced Hepatotoxicity

Drug-induced hepatotoxicity is one of the major barriers limiting application of current pharmaceuticals as well as clinical translation of novel and perspective drugs. In this context, numerous hepatoprotective molecules have been proposed to prevent or mitigate drug-induced hepatotoxicity. To date, silibinin (SBN) is a one the most studied hepatoprotective plant-derived agents for prevention/alleviation of drug-induced liver injury. Hepatoprotective mechanisms of SBN include scavenging of free radicals, upregulation of detoxifying enzymes via Nrf2 activation and inhibition of inflammatory activation of resident macrophages. However, low solubility of this phytochemical in water prevents its intravenous administration and constrains its bioavailability and efficacy. Here, we developed SBN-loaded poly(lactic-co-glycolic) acid (PLGA)-based nanoparticles for intravenous administration aiming at mitigation of drug-induced hepatotoxicity. Obtained nanoparticles demonstrated a slow drug release profile in vitro and caused upregulation of antioxidant and phase II enzymes in AML12 hepatocytes including superoxide dismutase 2, glutathione-S-transferase P1, and glutathione-reductase. Intravenous administration of PLGA nanoparticles to mice led to their fast liver accumulation. In vivo analysis of hepatoprotective effects of PLGA/SBN nanoparticles was carried out on melanoma tumor-bearing syngeneic mouse model treated with the antineoplastic drug dacarbazine (DTIC), which often causes severe hepatotoxicity including development of veno-occlusive disease. It was found that PLGA/SBN caused effective induction of detoxifying liver enzymes. Moreover, pre-treatment with PLGA/SBN nanoparticles reduced elevated transaminase and bilirubin levels in blood, caspase 3 activation, and morphological histology changes in liver tissue upon DTIC treatment. Treatment with PLGA/SBN nanoparticles did not interfere with therapeutic efficacy of DTIC.

Structure-activity relationship studies of Longicalcynin A analogues, as anticancer cyclopeptides

Cancer has emerged as the main cause of the highest rate of mortality in the world. Drugs used in cancer, although, show some beneficial effects on cancerous organs, demonstrate side effects on other normal tissues. On the other hand, anticancer peptides, being effective on target tissues, should be safe and less harmful on healthy organs, since peptides have several advantages, i.e., high activity, specificity, affinity, being less immunogenic and not accumulate in the body. In the present work, analogues of Longicalcynin A, a naturally occurring anticancer cyclopeptide, were synthesized and evaluated their cytotoxicity in order to gain information from structure-activity relationships of the such cyclopeptides which may lead to find novel and safer anticancer peptide compound(s) to be used in clinic. Peptides were prepared by the solid-phase peptide synthesis method using trityl-resin. Peptide cyclization was performed in liquid phase. To study anticancer activity of the peptide analogues of Longicalycinin A, several methods including MTT, flow cytometry analysis and Lysosomal membrane integrity assay were employed using two cell lines HepG2 and HT-29. Fibroblast cells were used to control the safety of the synthesized cyclopeptides on normal cells. Two cyclopeptides 11 and 17 with the sequences of cyclo-(Thr-Val-Pro-Phe-Ala) and cyclo-(Phe-Ser-Pro-Phe-Ala), respectively were cytotoxic against the colon as well as hepatic cancer cells with safety profile against fibroblast cells, probably with the mechanism of apoptosis as lysosomal membrane integrity damaged. These cyclopeptides showed to be more favorable compounds better than Longicalycinin A and good candidates to develop cyclopeptides as anticancer agents.

Dacarbazine alone or associated with melanoma-bearing cancer pain model induces painful hypersensitivity by TRPA1 activation in mice

Antineoplastic therapy has been associated with pain syndrome development characterized by acute and chronic pain. The chemotherapeutic agent dacarbazine, used mainly to treat metastatic melanoma, is reported to cause painful symptoms, compromising patient quality of life. Evidence has proposed that transient receptor potential ankyrin 1 (TRPA1) plays a critical role in chemotherapy-induced pain syndrome. Here, we investigated whether dacarbazine causes painful hypersensitivity in naive or melanoma-bearing mice and the involvement of TRPA1 in these models. Mouse dorsal root ganglion (DRG) neurons and human TRPA1-transfected HEK293 (hTRPA1-HEK293) cells were used to evaluate the TRPA1-mediated calcium response evoked by dacarbazine. Mechanical and cold allodynia were evaluated after acute or repeated dacarbazine administration in naive mice or after inoculation of B16-F10 melanoma cells in C57BL/6 mice. TRPA1 involvement was investigated by using pharmacological and genetic tools (selective antagonist or antisense oligonucleotide treatment and Trpa1 knockout mice). Dacarbazine directly activated TRPA1 in hTRPA1-HEK293 cells and mouse DRG neurons and appears to sensitize TRPA1 indirectly by generating oxidative stress products. Moreover, dacarbazine caused mechanical and cold allodynia in naive but not Trpa1 knockout mice. Also, dacarbazine-induced nociception was reduced by the pharmacological TRPA1 blockade (antagonism), antioxidants, and by ablation of TRPA1 expression. TRPA1 pharmacological blockade also reduced dacarbazine-induced nociception in a tumor-associated pain model. Thus, dacarbazine causes nociception by TRPA1 activation, indicating that this receptor may represent a pharmacological target for treating chemotherapy-induced pain syndrome in cancer patients submitted to antineoplastic treatment with dacarbazine.

Vitamin D and its low calcemic analogs modulate the anticancer properties of cisplatin and dacarbazine in the human melanoma A375 cell line

Melanoma represents a significant challenge in cancer treatment due to the high drug resistance of melanomas and the patient mortality rate. This study presents data indicating that nanomolar concentrations of the hormonally active form of vitamin D, 1α,25-dihydroxyvitamin D3 [1α,25(OH)₂D3], its non-calcemic analogues 20S-hydroxyvitamin D3 and 21-hydroxypregnacalciferol, as well as the low-calcemic synthetic analog calcipotriol, modulate the efficacy of the anticancer drugs cisplatin and dacarbazine. It was observed that vitamin D analogs sensitized melanoma A375 cells to hydrogen peroxide used as an inducer of oxidative stress. On the other hand, only 1α,25(OH)₂D3 resulted in a minor, but significant effect on the proliferation of melanoma cells treated simultaneously with dacarbazine, but not cisplatin. Notably, cisplatin (300 µM) exhibited a higher overall antiproliferative activity than dacarbazine. Cisplatin treatment of melanoma cells resulted in an induction of apoptosis as demonstrated by flow cytometry (accumulation of cells at the subG₁ phase of the cell cycle), whereas dacarbazine caused G₁/G₀ cell cycle arrest, with the effects being improved by pre-treatment with vitamin D analogs. Treatment with cisplatin resulted in an initial increase in the level of reactive oxygen species (ROS). Dacarbazine caused transient stimulation of ROS levels and the mitochondrial membrane potential (Δψ_m) (after 1 or 3 h of treatment, respectively), but the effect was not detectable following prolonged (24 h) incubation with the drug. Vitamin D exhibited modulatory effects on the cells treated with dacarbazine, decreasing the half maximal inhibitory concentration (IC₅₀) for the drug, stimulating G₁/G₀ arrest and causing a marked decrease in Δψ_m. Finally, cisplatin, dacarbazine and 1α,25(OH)₂D3 displayed modulatory effects on the expression of ROS and vitamin D-associated genes in the melanoma A375 cells. In conclusion, nanomolar concentrations of 1,25(OH)₂D₃ only had minor effects on the proliferation of melanoma cells treated with dacarbazine, decreasing the relative IC₅₀ value. However, co-treatment with vitamin D analogs resulted in the modulation of cell cycle and ROS responses, and affected gene expression, suggesting possible crosstalk between the signaling pathways of vitamin D and the anticancer drugs used in this study.

The effects of para-phenylenediamine (PPD) on the skin fibroblast cells

1. Para-phenylenediamine (PPD) is the commonest and most well-known component of hair dyes. PPD is found in more than 1000 hair dye formulations and is the most frequently used permanent hair dye component in Europe, North America and East Asia. PPD containing hair dyes have been associated with cancer and mutagenicity. Apart from that, PPD has potential toxicity which includes acute toxicity such as allergic contact dermatitis and subacute toxicity. 2. In this study, we examined the effects of the PPD composition on the skin-isolated fibroblast cells. Fibroblast cells were isolated from the skin and cell viability, reactive oxygen species (ROS) production, the collapse of mitochondrial membrane potential (MMP), lipid peroxidation (LPO), damage to the lysosome release of lactate dehydrogenase (LDH) and finally release of cytochrome c were examined following the exposure to various concentrations of PPD. 3. Our results showed that exposure to PPD increased ROS generation, LPO, the collapse of MMP, LDH release and cytochrome c release. Our results suggest that PPD can induce damage to the lysosomal membrane. 4. These results showed that PPD composition has a selective toxicity on skin fibroblasts cell and mitochondria are considered one of the goals of its toxicity.

Toxicity of Copper Oxide (CuO) Nanoparticles on Human Blood Lymphocytes

CuO nanoparticles (CuO-NPs) serve several important functions in human life, particularly in the fields of medicine, engineering, and technology. These nanoparticles have been utilized as catalysts, semiconductors, sensors, gaseous and solid ceramic pigments, and magnet rotatable devices. Further use for CuO-NPs has been employed in the pharmaceutical industry especially in the production of anti-microbial fabric treatments or prevention of infections caused by Escherichia coli and methicillin-resistant Staphylococcus aureus. Two key potential routes of exposure to CuO-NPs exist through inhalation and skin exposure. Toxicity of these nanoparticles has been reported in various studies; however, no study as of yet has investigated the complete cellular mechanisms involved in CuO-NPs toxicity on human cells. The aim of this study was to determine the cytotoxicity of CuO-NPs on human blood lymphocytes. Blood lymphocytes were obtained from healthy male subjects through the use of Ficoll polysaccharide subsequently by gradient centrifugation. The following parameters were assayed in blood lymphocytes after a 6-h incubation with different concentrations of CuO-NPs: cell viability, reactive oxygen species (ROS) formation, lipid peroxidation, cellular glutathione levels, and mitochondrial and lysosomal damage. Our results demonstrate that CuO-NPs, in particular, decreased cell viability in a concentration-dependent manner and the IC50 determined was 382 μM. CuO-NP cytotoxicity was associated with significant increase at intracellular ROS level and loss of mitochondrial membrane potential and lysosomal membrane leakiness. Hence, CuO-NPs are shown to effectively induce oxidative stress in addition to inflict damage on mitochondria and lysosomes in human blood lymphocytes.

Evaluation of the toxicity effects of silk fibroin on human lymphocytes and monocytes

Silk fibroin nanoparticles (SFNPs) as a natural polymer have been utilized in biomedical applications such as suture, tissue engineering-based scaffolds, and drug delivery carriers. Since there is little data regarding the toxicity effects on different cells and tissues, we aimed to determine the toxicity mechanisms of SFNPs on human lymphocytes and monocytes based on reliable methods. Our results showed that SFNPs (0.5, 1, and 2 mg/mL) induced oxidative stress via increasing reactive oxygen species production, mitochondrial membrane potential (∆Ψ) collapse, which was correlated to cytochrome c release and Adenosine diphosphate (ADP)/Adenosine tri phosphate (ATP) ratio increase as well as lysosomal as another toxicity mechanism, which led to cytosolic release of lysosomal digestive proteases, phosphor lipases, and apoptosis signaling. Taken together, these data suggested that SFNPs toxicity was associated with mutual mitochondrial/lysosomal cross-talk and oxidative stress on human lymphocytes and monocytes with activated apoptosis signaling.

In vitro toxicity of perfluorooctane sulfonate on rat liver hepatocytes: probability of distructive binding to CYP 2E1 and involvement of cellular proteolysis

Perfluorooctanesulfonate (PFOS), an anthropogenic fluorosurfactant, is one of the most common global pollutants. PFOS is used in various consumer products to provide soil, oil, and water resistance to materials used in clothing, upholstery, and food packaging. PFOS is persistent, bioaccumulative, and toxic to mammalian species. In this study, the cellular mechanisms involved in PFOS hepatotoxicity were evaluated. For this purpose, we determined oxidative stress markers including cell lysis, ROS generation, lipid peroxidation, glutathione depletion, mitochondrial membrane potential decrease, lysosomal membrane leakiness, and cellular proteolysis. Our results demonstrated that PFOS liver cytotoxicity was associated with reactive oxygen species (ROS) formation and lipid peroxidation in isolated rat hepatocytes. Incubation of hepatocytes with PFOS caused rapid depletion of hepatocyte glutathione (GSH), an important marker of cellular oxidative stress. Most of the PFOS-induced GSH depletion could be attributed to the expulsion of glutathione disulfide (GSSG). PFOS hepatotoxicity was inhibited by antioxidants and ROS scavengers, mitochondrial permeability transition (MPT) pore sealing agents, and endocytosis inhibitors. Our results suggest that PFOS hepatotoxicity might be the result of oxidative stress-induced lysosomal membrane leakiness and cellular proteolysis in rat hepatocytes.

Hepatoprotective and free radical scavenging actions of quercetin nanoparticles on aflatoxin B1-induced liver damage: in vitro/in vivo studies

The objective of present study was in vitro and in vivo evaluation of hepatoprotective and antioxidant activity of Quercetin nanoparticles (Q NPs) against toxicity induced by aflatoxin B1. The Q NPs were prepared using precipitation method. Hepatocytes were prepared by the method of collagenase enzyme perfusion via portal vein. The NPs were characterized in terms of size and morphology using dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. The level of parameters, such as cell death, ROS formation, lipid peroxidation, mitochondrial membrane potential and cellular glutathione (GSH) content, in the aflatoxin B1-treated and non-treated hepatocytes were determined and the mentioned markers were assessed in the presence of Q NPs. The prepared NPs showed particle size of 52.70 nm with polydispersity index (PDI) of 0.18. In contrast to free Q, the administration of Q NPs more efficiently decreased the rate of ROS formation, lipid peroxidation and improved cell viability, mitochondrial membrane potential and glutathione level and showed a significant hepatoprotective efiect by reducing levels of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase. It is suggested that the Q NPs is a promising candidate for drug delivery, which enhances the hepatoprotective effect of Q against the cytotoxic effects of aflatoxin B1.

Selective toxicity of persian gulf sea cucumber holothuria parva on human chronic lymphocytic leukemia b lymphocytes by direct mitochondrial targeting

Natural products isolated from marine environment are well known for their pharmacodynamic potential in diversity of disease treatments such as cancer or inflammatory conditions. Sea cucumbers are one of the marine animals of the phylum Echinoderm. Many studies have shown that the sea cucumber contains antioxidants and anti-cancer compounds. Chronic lymphocytic leukemia (CLL) is a disease characterized by the relentless accumulation of CD5⁺ B lymphocytes. CLL is the most common leukemia in adults, about 25-30% of all leukemias. In this study B lymphocytes and their mitochondria (cancerous and non-cancerous) were obtained from peripheral blood of human subjects and B lymphocyte cytotoxicity assay, and caspase 3 activation along with mitochondrial upstream events of apoptosis signaling including reactive oxygen species (ROS) production, collapse of mitochondrial membrane potential (MMP) and mitochondrial swelling were determined following the addition of Holothuria parva extract to both cancerous and non-cancerous B lymphocytes and their mitochondria. Our in vitro finding showed that mitochondrial ROS formation, MMP collapse, and mitochondrial swelling and cytochrome c release were significantly (P < 0.05) increased after addition of different concentrations of H. parva only in cancerous BUT NOT normal non-cancerous mitochondria. Consistently, different concentrations of H. parva significantly (P < 0.05) increased cytotoxicity and caspase 3 activation only in cancerous BUT NOT normal non-cancerous B lymphocytes. These results showed that H. parva methanolic extract has a selective mitochondria mediated apoptotic effect on chronic lymphocytic leukemia B lymphocytes hence may be promising in the future anticancer drug development for treatment of CLL. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1158-1169, 2017.

Methotrexate induced mitochondrial injury and cytochrome c release in rat liver hepatocytes

Methotrexate (MTX) is a folic acid antagonist that is widely used to treat a variety of diseases. One of the most serious side effects of MTX therapy is hepatotoxicity. The potential molecular cytotoxic mechanisms of MTX toward isolated rat hepatocytes were investigated using Accelerated Cytotoxicity Mechanism Screening (ACMS) techniques. A concentration and time dependent increase in cytotoxicity and reactive oxygen species (ROS) formation and a decrease in mitochondrial membrane potential (MMP) were observed with MTX. Furthermore, a significant increase in MTX (300 μM)-induced cytotoxicity and ROS formation were observed when glutathione (GSH)-depleted hepatocytes were used whereas addition of N-acetylcysteine (a GSH precursor) decreased cytotoxicity. Catalase inactivation also increased MTX-induced cytotoxicity, while the direct addition of catalase to the hepatocytes decreased cytotoxicity. MTX treatment in isolated rat mitochondria caused swelling and significantly decreased adenosine triphosphate (ATP) and GSH content, and cytochrome c release. Potent antioxidants such as mesna, resveratrol and Trolox decreased MTX-induced cytotoxicity and ROS formation and increased MMP. This study suggests that MTX-induced cytotoxicity caused by ROS formation and GSH oxidation leads to oxidative stress and mitochondrial injury in rat hepatocytes.

Redox Regulating Enzymes and Connected MicroRNA Regulators Have Prognostic Value in Classical Hodgkin Lymphomas

There are no previous studies assessing the microRNAs that regulate antioxidant enzymes in Hodgkin lymphomas (HLs). We determined the mRNA levels of redox regulating enzymes peroxiredoxins (PRDXs) I–III, manganese superoxide dismutase (MnSOD), nuclear factor erythroid-derived 2-like 2 (Nrf2), and Kelch-like ECH-associated protein 1 (Keap1) from a carefully collected set of 41 classical HL patients before receiving any treatments. The levels of redoxmiRs, miRNAs known to regulate the above-mentioned enzymes, were also assessed, along with CD3, CD20, and CD30 protein expression. RNAs were isolated from freshly frozen lymph node samples and the expression levels were analyzed by qPCR. mir23b correlated inversely with CD3 and CD20 expressions (p = 0.00076; r = −0.523 and p = 0.0012; r = −0.507) and miR144 with CD3, CD20, and CD30 (p = 0.030; r = −0.352, p = 0.041; r = −0.333 and p = 0.0032; r = −0.47, resp.). High MnSOD mRNA levels associated with poor HL-specific outcome in the patients with advanced disease (p = 0.045) and high miR-122 levels associated with worse HL-specific survival in the whole patient population (p = 0.015). When standardized according to the CD30 expression, high miR212 and miR510 predicted worse relapse-free survival (p = 0.049 and p = 0.0058, resp.). In conclusion, several redoxmiRs and redox regulating enzyme mRNA levels associate with aggressive disease outcome and may also produce prognostic information in classical HL.

Reduction of Dacarbazine cytogenetic effects on somatic cells in male mice using bee glue (Propolis) to manifest the scientific miracles in the Quran

Objective

This study was carried out to investigate the ability of Propolis to ameliorate the adverse cytogenetic effects of Dacarbazine on bone marrow cells

Methods

In this experimental in vivo study, 18 mice were used, divided into four groups: control group; Propolis-treated group (treated with 50mg/kg Propolis); and Dacarbazine-treated group (treated with 3.5mg/kg Dacarbazine). The fourth, fifth, and sixth were treated with Dacarbazine and Propolis as pre 2h, post 2h, and concomitant treatment. After five days, the Bone Marrow (BM) samples were obtained for cytogenetic investigation.

Results

The in vivo studies revealed that Dacarbazine induced an abnormalities in polychromatic erythrocytes cells (PECs) as increase of cell with micronuclei, while the dual treatment accompanied with improvement of this abnormalities.

Conclusions

It could be concluded that there are protective effects of Propolis against the adverse effects of Dacarbazine. It could be recommended to use Propolis as an adjuvant with chemotherapeutic agents.

Protective effects of Sesamum indicum extract against oxidative stress induced by vanadium on isolated rat hepatocytes

Vanadium toxicity is a challenging problem to human and animal health with no entirely understanding cytotoxic mechanisms. Previous studies in vanadium toxicity showed involvement of oxidative stress in isolated liver hepatocytes and mitochondria via increasing of ROS formation, release of cytochrome c and ATP depletion after incubation with different concentrations (25-200 µM). Therefore, we aimed to investigate the protective effects of Sesamum indicum seed extract (100-300 μg/mL) against oxidative stress induced by vanadium on isolated rat hepatocytes. Our results showed that quite similar to Alpha-tocopherol (100 µM), different concentrations of extract (100-300 μg/mL) protected the isolated hepatocyte against all oxidative stress/cytotoxicity markers induced by vanadium in including cell lysis, ROS generation, mitochondrial membrane potential decrease and lysosomal membrane damage. Besides, vanadium induced mitochondrial/lysosomal toxic interaction and vanadium reductive activation mediated by glutathione in vanadium toxicity was significantly (P < 0.05) ameliorated by Sesamum indicum extracts. These findings suggested a hepato-protective role for extracts against liver injury resulted from vanadium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 979-985, 2016.

Toxicity of methyl tertiary-butyl ether on human blood lymphocytes

Methyl tertiary-butyl ether (MTBE) is a synthetic solvent widely used as oxygenate in unleaded gasoline. Few studies have addressed the cellular toxicity of MTBE on some cell lines, and so far, no comprehensive study has been conducted to investigate the probable immunotoxicity of this compound. In this study, the toxicity of MTBE on human blood lymphocytes was evaluated. Blood lymphocytes were isolated from healthy male volunteers' blood, using Ficoll polysaccharide followed by gradient centrifugation. Cell viability, reactive oxygen species (ROS) formation, lipid peroxidation, glutathione levels, and damage to mitochondria and lysosome were determined in blood lymphocytes after 6-h incubation with different concentrations of MTBE (0.1, 0.5, 1, and 2 mM). Our results showed that MTBE, in particular, decreased cell viability, which was associated with significant increase at intracellular ROS level and toxic alterations in mitochondria and lysosomes in human blood lymphocytes. Moreover, it was shown that MTBE strongly provoked lipid peroxidation and also depleted glutathione level at higher concentrations. Interestingly, MTBE exhibited its cytotoxic effects at low concentrations that may resemble to its concentrations in human blood following occupational and environmental exposure. It is therefore concluded that MTBE was capable of inducing oxidative stress and damage to mitochondria and lysosomes in human lymphocytes at concentrations ranging from 5 to 40 μg/L, which may be present in human blood as a result of environmental exposure.

Putative role of HIF transcriptional activity in melanocytes and melanoma biology

Hypoxia-inducible factor-1α (HIF-1α) is a highly oxygen sensitive bHLH protein that is part of the heterodimeric HIF-1 transcription factor. Under hypoxic stress, HIF-1 activity is induced to control expression of multiple downstream target genes, including vascular endothelial growth factor (VEGF). The normal epidermis exists in a constant mild hypoxic microenvironment and constitutively expresses HIF-1α and HIF-2α. Expression of HIF-1α and/or HIF-2α has been suggested to correlate with the increased malignant potential of melanocytes, therefore, failures of melanoma therapies may be partially linked to high HIF activity. Notably, melanomas that have the V600E BRAF mutation exhibit increased HIF-1α expression. We have utilized a bioinformatics approach to identify putative hypoxia response elements (HREs) in a set of genes known to participate in the process of melanogenesis (includingTRPM1, SLC45A2, HRAS, C-KIT, PMEL and CRH). While some of the mechanistic links between these genes and the HIF pathway have been previously explored, others await further investigation. Although agents targeting HIF activity have been proposed as novel treatment modalities for melanoma, there are currently no clinical trials in progress to test their efficacy in melanoma.

Drosophila modifier screens to identify novel neuropsychiatric drugs including aminergic agents for the possible treatment of Parkinson's disease and depression

Small molecules that increase the presynaptic function of aminergic cells may provide neuroprotection in Parkinson's disease (PD) as well as treatments for attention deficit hyperactivity disorder (ADHD) and depression. Model genetic organisms such as Drosophila melanogaster may enhance the detection of new drugs via modifier or 'enhancer/suppressor' screens, but this technique has not been applied to processes relevant to psychiatry. To identify new aminergic drugs in vivo, we used a mutation in the Drosophila vesicular monoamine transporter (dVMAT) as a sensitized genetic background and performed a suppressor screen. We fed dVMAT mutant larvae ∼ 1000 known drugs and quantitated rescue (suppression) of an amine-dependent locomotor deficit in the larva. To determine which drugs might specifically potentiate neurotransmitter release, we performed an additional secondary screen for drugs that require presynaptic amine storage to rescue larval locomotion. Using additional larval locomotion and adult fertility assays, we validated that at least one compound previously used clinically as an antineoplastic agent potentiates the presynaptic function of aminergic circuits. We suggest that structurally similar agents might be used to development treatments for PD, depression and ADHD, and that modifier screens in Drosophila provide a new strategy to screen for neuropsychiatric drugs. More generally, our findings demonstrate the power of physiologically based screens for identifying bioactive agents for select neurotransmitter systems.

Oxidative mechanisms of fish hepatocyte toxicity by the harmful dinoflagellate Cochlodinium polykrikoides

Harmful Algal Blooms caused by the marine ichthyotoxic dinoflagellate Cochlodinium polykrikoides are responsible for mass mortalities of wild and farmed fish worldwide. In this research, we investigated the cytotoxic mechanisms of aqueous extract of C. polykrikoides on isolated Rainbow trout (Oncorhynchus mykiss) liver hepatocytes. Algal extract exposure with isolated trout hepatocytes caused hepatocyte membrane lysis, reactive oxygen species (ROS) formation, glutathione depletion, lysosomal membrane rupture, collapse of mitochondrial membrane potential, ATP depletion and increase in ADP/ATP ratio, cytochrome C release into the hepatocyte cytosol, and activation of caspases cascade. Anti-oxidants, free radical scavengers, mitochondrial permeability transition (MPT) pore sealing agents, microsomal oxidases inhibitors, ATP generators and lysosomotropic agents protected fish hepatocytes against C. polykrikoides. Fish hepatocyte toxicity was also associated with mitochondrial and lysosomal membrane injury. These events caused cytochrome C release from the mitochondrial intra-membrane space into cytosol. The cytochrome C release could trigger activation of caspase-3 and apoptosis.

Two-step activation prodrugs: transplatin mediated binding of chemotherapeutic agents to vitamin B12

Clinically approved organic chemotherapeutic drugs such as cytarabine, dacarbazine and anastrozole were attached to B12via a {CN-trans-Pt(NH3)2}-bridge to yield [{Co}-CN-{trans-Pt(NH3)2}-{drug}](2+). The active organic drugs are protected by the platinum complex and by B12, which represents at the same time the targeting vector. We refer to these bioconjugates as two-step activation prodrugs since two reactions are finally required to liberate the actual organic drugs. All three prodrugs are soluble and stable in water. The physiological stability and the therapeutic efficiency of [{Co}-CN-{trans-Pt(NH3)2}-{cytarabine}](2+) (2) were studied. Under physiological conditions, 2 is stable for 3 days. Its affinity to the cobalamin transport proteins (haptocorrin, intrinsic factor and transcobalamin) is not substantially affected despite the introduction of a bulky group in the β-axial position. The cleavage of the [trans-CN-Pt(NH3)2-{cytarabine}](+) complex was observed upon chemical reduction of Co(III)→ Co(II) with Zn(0). Cytarabine was subsequently released from the cleaved complex to exhibit its cytotoxicity. 2 displayed a reduced cytotoxicity (IC50 = 230 ± 62 nM) as compared to cytarabine (IC50 = 30 ± 5 nM). However, cytarabine released from 2 showed comparable cytotoxicity (IC50 = 30 ± 11 nM).

Acid ceramidase expression modulates the sensitivity of A375 melanoma cells to dacarbazine

Dacarbazine (DTIC) is the treatment of choice for metastatic melanoma, but its response in patients remains very poor. Ceramide has been shown to be a death effector and to play an important role in regulating cancer cell growth upon chemotherapy. Among ceramidases, the enzymes that catabolize ceramide, acid ceramidase (aCDase) has been implicated in cancer progression. Here we show that DTIC elicits a time- and dose-dependent decrease of aCDase activity and an increase of intracellular ceramide levels in human A375 melanoma cells. The loss of enzyme activity occurred as a consequence of reactive oxygen species-dependent activation of cathepsin B-mediated degradation of aCDase. These events preceded autophagic features and loss of cell viability. Down-regulation of acid but not neutral or alkaline ceramidase 2 resulted in elevated levels of ceramide and sensitization to the toxic effects of DTIC. Conversely, inducible overexpression of acid but not neutral ceramidase reduced ceramide levels and conferred resistance to DTIC. In conclusion, we report that increased levels of ceramide, due to enhanced degradation of aCDase, are in part responsible for the cell death effects of DTIC. These results suggest that down-regulation of aCDase alone or in combination with DTIC may represent a useful tool in the treatment of metastatic melanoma.

A comparison of hepatocyte cytotoxic mechanisms for thallium (I) and thallium (III)

Thallium (Tl) is a highly toxic heavy metal though up to now its mechanisms are poorly understood. In this study, we comparatively investigated the cytotoxic mechanisms of Tl(I) and Tl(III) in isolated rat hepatocytes. Both Tl(I) and Tl(III) cytotoxicities were associated with reactive oxygen species (ROS) formation, lipid peroxidation, collapse of mitochondrial membrane potential, activation of caspases cascade, lysosomal membrane leakiness, and cellular proteolysis. Hepatocyte glutathione (GSH) was also rapidly oxidized. GSH-depleted hepatocytes were more resistant to Tl(I)-induced cytotoxicity, ROS formation and lipid peroxidation. This suggests that Tl(I) is reductively activated by GSH. On the other hand, GSH-depleted hepatocytes were much more sensitive to Tl(III)-induced cytotoxicity, ROS formation, and lipid peroxidation. This suggests that GSH only plays an antioxidant role against Tl(III) cytotoxicity. Our results also showed that CYP2E1 involves in Tl(I) and Tl(III) oxidative stress cytotoxicity mechanism and both cations detoxified via methylation. In conclusion, both Tl(I) and Tl(III) cytotoxicities were associated with mutual mitochondrial/lysosomal injuries (cross-talk) initiated by increased ROS formation resulted from metal-CYP2E1 destructive interaction or metal-induced disruption of mitochondrial electron transfer chain.

Involvement of mitochondrial/lysosomal toxic cross-talk in ecstasy induced liver toxicity under hyperthermic condition

The initial objectives of this study were to evaluate the extent of 3, 4-methylenedioxymethamphetamine (MDMA) induced loss of cell viability (cytotoxicity), induction of reactive oxygen species formation and damage to sub-cellular organelles (e.g. mitochondria/lysosomes) in freshly isolated rat hepatocytes under normothermic conditions (37 degrees C) and to compare the results with the effects obtained under hyperthermic conditions (41 degrees C). MDMA induced cytotoxicity, reactive oxygen species formation, mitochondrial membrane potential decline and lysosomal membrane leakiness in isolated rat hepatocytes at 37 degrees C. A rise in incubation temperature from 37 degrees C to 41 degrees C had an additive/synergic effect on the oxidative stress markers. We observed variations in mitochondrial membrane potential and lysosomal membrane stability that are significantly (P<0.05) higher than those under normothermic conditions. Antioxidants, reactive oxygen species scavengers, lysosomal inactivators, mitochondrial permeability transition (MPT) pore sealing agents, NADPH P450 reductase inhibitor, and inhibitors of reduced CYP2E1 and CYP2D6 prevented all MDMA induced hepatocyte oxidative stress cytotoxicity markers. It is therefore suggested that metabolic reductive activation of MDMA by reduced cytochrome P450s and glutathione could lead to generation of some biological reactive intermediates which could activate reactive oxygen species generation and cause mitochondrial and lysosomal oxidative stress membrane damages. We finally concluded that hyperthermia could potentiate MDMA induced liver toxicity probably through a mitochondrial/lysosomal toxic cross-talk in freshly isolated rat hepatocytes.

A search for hepatoprotective activity of fruit extract of Mangifera indica L. against oxidative stress cytotoxicity

Mango (Mangifera indica L.) and their components are commonly used in folk medicine for many curative effects. The protective effects of different concentrations of aqueous extract of Mangifera indica L. fruit (Mango Extract) (20, 50 and 100 microg/ml) and also gallic acid (100 microM) as a pure compound in the extract were examined against oxidative stress toxicity induced by cumene hydroperoxide (CHP) in isolated rat hepatocytes. The extracts and gallic acid (100 microM) protected the hepatocyte against all oxidative stress markers including cell lysis, ROS generation, lipid peroxidation, glutathione depletion, mitochondrial membrane potential decrease, lysosomal membrane oxidative damage and cellular proteolysis. Mango Extracts (20, 50 and 100 microg/ml) were more effective than gallic acid (100 microM) in protecting hepatocytes against CHP induced lipid peroxidation. On the other hand gallic acid (100 microM) acted more effective than Mango Extracts (20, 50 and 100 microg/ml) at preventing lysosomal membrane damage. In addition H(2)O(2) scavenging effect of all extracts were determined in hepatocytes and compared with gallic acid (100 microM). There were no significance differences (P<0.05) between all plant extracts and gallic acid (100 microM) in H(2)O(2) scavenging activity. These results suggest a hepatoprotective role for Mango Extract against liver injury associated with oxidative stress.