Cr (VI) induced oxidative stress and toxicity in cultured cerebellar granule neurons at different stages of development and protective effect of Rosmarinic acid

Intrauterine chromium exposure and cognitive developmental delay: The modifying effect of genetic predisposition

There is limited evidence on the effects of intrauterine chromium (Cr) exposure on children's cognitive developmental delay (CDD). Further, little is known about the genetic factors in modifying the association between intrauterine Cr exposure and CDD. The present study involved 2361 mother-child pairs, in which maternal plasma Cr concentrations were assessed, a polygenic risk score for the child was constructed, and the child's cognitive development was evaluated using the Bayley Scales of Infant Development. The risks of CDD conferred by intrauterine Cr exposure in children with different genetic backgrounds were evaluated by logistic regression. The additive interaction between intrauterine Cr exposure and genetic factors was evaluated by calculating the relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI). According to present study, higher intrauterine Cr exposure was significantly associated with increased CDD risk [each unit increase in ln-transformed maternal plasma Cr concentration (ln-Cr): adjusted OR (95 % CI), 1.18 (1.04-1.35); highest vs lowest quartile: adjusted OR (95 % CI), 1.57 (1.10-2.23)]. The dose-response relationship of intrauterine Cr exposure and CDD for children with high genetic risk was more prominent [each unit increased ln-Cr: adjusted OR (95 % CI), 1.36 (1.09-1.70)]. Joint effects between intrauterine Cr exposure and genetic factors were found. Specifically, for high genetic risk carriers, the association between intrauterine Cr exposure and CDD was more evident [highest vs lowest quartile: adjusted OR (95 % CI), 2.33 (1.43-3.80)]. For those children with high intrauterine Cr exposure and high genetic risk, the adjusted AP was 0.39 (95 % CI, 0.07-0.72). Conclusively, intrauterine Cr exposure was a high-risk factor for CDD in children, particularly for those with high genetic risk. Intrauterine Cr exposure and one's adverse genetic background jointly contribute to an increased risk of CDD in children.

An Update Overview on Mechanistic Data and Biomarker Levels in Cobalt and Chromium-Induced Neurodegenerative Diseases

There is increasing evidence that the imbalance of metals as cobalt (Co) and chromium (Cr) may increase the risk of development and progression of neurodegenerative diseases (NDDs). The human exposure to Co and Cr is derived mostly from industry, orthopedic implants, and polluted environments. Neurological effects of Co and Cr include memory deficit, olfactory dysfunction, spatial disorientation, motor neuron disease, and brain cancer. Mechanisms of Co and Cr neurotoxicity included DNA damage and genomic instability, epigenetic changes, mitochondrial disturbance, lipid peroxidation, oxidative stress, inflammation, and apoptosis. This paper seeks to overview the Co and Cr sources, the mechanisms by which these metals induce NDDs, and their levels in fluids of the general population and patients affected by NDDs. To this end, evidence of Co and Cr unbalance in the human body, mechanistic data, and neurological symptoms were collected using in vivo mammalian studies and human samples.

Insights into the effects of chronic combined chromium-nickel exposure on colon damage in mice through transcriptomic analysis and in vitro gastrointestinal digestion assay

Heavy metals interact with each other in a coexisting manner to produce complex combined toxicity to organisms. At present, the toxic effects of chronic co-exposure to heavy metals hexavalent chromium [Cr(VI)] and divalent nickel [Ni(II)] on organisms are seldom studied and the related mechanisms are poorly understood. In this study, we explored the mechanism of the colon injury in mice caused by chronic exposure to Cr or/and Ni. The results showed that, compared with the control group, Cr or/and Ni chronic exposure affected the body weight of mice, and led to infiltration of inflammatory cells in the colon, decreased the number of goblet cells, fusion of intracellular mucus particles and damaged cell structure of intestinal epithelial. In the Cr or/and Ni exposure group, the activity of nitric oxide synthase (iNOS) increased, the expression levels of MUC2 were significantly down-regulated, and those of ZO-1 and Occludin were significantly up-regulated. Interestingly, factorial analysis revealed an interaction between Cr and Ni, which was manifested as antagonistic effects on iNOS activity, ZO-1 and MUC2 mRNA expression levels. Transcriptome sequencing further revealed that the expression of genes-related to inflammation, intestinal mucus and tight junctions changed obviously. Moreover, the relative contents of Cr(VI) and Ni(II) in the Cr, Ni and Cr+Ni groups all changed with in-vitro gastrointestinal （IVG）digestion, especially in the Cr+Ni group. Our results indicated that the chronic exposure to Cr or/and Ni can lead to damage to the mice colon, and the relative content changes of Cr(VI) and Ni(II) might be the main reason for the antagonistic effect of Cr+Ni exposure on the colon damage.

Compositionally engineered Cd-Mo-Se alloyed QDs toward photocatalytic H2O2 production and Cr(VI) reduction with a detailed mechanism and influencing parameters

With the exceptional advantages of safety, greenness, and low cost, photocatalytic H2O2 generation has kindled a wonderful spark, although being severely hampered by the terrible photoinduced exciton recombination, migration, and surface decomposition. Here, employing reflux method, the Cd-Mo-Se quantum dots of varying molar ratios of Cd and Mo were synthesized using thioglycolic acid as the capping ligand to regulate their growth. This type of metal alloying promotes rapid charge migration, improves light harvesting, and reduces the rate of charge recombination. The improved optoelectronic properties and boosted activity of Cd-rich ternary CMSe-1 QDs led to the observed exceptional photocatalytic H2O2 yield of 1403.5 μmol g-1 h-1 (solar to chemical conversion efficiency, 0.27%) under visible light, outperforming the other ternary and Se-based QD photocatalysts. Additionally, CMSe-1 shows 93.6% (2 h) hazardous Cr(VI) photoreduction. The enhanced catalytic performance of CMSe-1 corresponds to effective charge carrier separation and transfer efficiency, well supported by PL, TRPL, and electrochemical measurements. Photocatalytic H2O2 production was also studied under varying experimental conditions and the scavenger test suggests a superoxide radical intermediate 2-step single electron reduction pathway. The catalyst-assisted Cr(VI) reduction is substantiated by the zero-order kinetics as well as the determination of the pHPZC value. The catalyst can be employed for a maximum of four times while retaining its activity, according to the photostability and reusability test outcomes. This research presents interesting approaches for producing ternary QDs and modified systems for efficient photocatalytic H2O2 production and Cr(VI) reduction.

Mitochondrial Oxidative Stress Is the General Reason for Apoptosis Induced by Different-Valence Heavy Metals in Cells and Mitochondria

This review analyzes the causes and consequences of apoptosis resulting from oxidative stress that occurs in mitochondria and cells exposed to the toxic effects of different-valence heavy metals (Ag+, Tl+, Hg2+, Cd2+, Pb2+, Al3+, Ga3+, In3+, As3+, Sb3+, Cr6+, and U6+). The problems of the relationship between the integration of these toxic metals into molecular mechanisms with the subsequent development of pathophysiological processes and the appearance of diseases caused by the accumulation of these metals in the body are also addressed in this review. Such apoptosis is characterized by a reduction in cell viability, the activation of caspase-3 and caspase-9, the expression of pro-apoptotic genes (Bax and Bcl-2), and the activation of protein kinases (ERK, JNK, p53, and p38) by mitogens. Moreover, the oxidative stress manifests as the mitochondrial permeability transition pore (MPTP) opening, mitochondrial swelling, an increase in the production of reactive oxygen species (ROS) and H2O2, lipid peroxidation, cytochrome c release, a decline in the inner mitochondrial membrane potential (ΔΨmito), a decrease in ATP synthesis, and reduced glutathione and oxygen consumption as well as cytoplasm and matrix calcium overload due to Ca2+ release from the endoplasmic reticulum (ER). The apoptosis and respiratory dysfunction induced by these metals are discussed regarding their interaction with cellular and mitochondrial thiol groups and Fe2+ metabolism disturbance. Similarities and differences in the toxic effects of Tl+ from those of other heavy metals under review are discussed. Similarities may be due to the increase in the cytoplasmic calcium concentration induced by Tl+ and these metals. One difference discussed is the failure to decrease Tl+ toxicity through metallothionein-dependent mechanisms. Another difference could be the decrease in reduced glutathione in the matrix due to the reversible oxidation of Tl+ to Tl3+ near the centers of ROS generation in the respiratory chain. The latter may explain why thallium toxicity to humans turned out to be higher than the toxicity of mercury, lead, cadmium, copper, and zinc.

Coenzyme Q10, Biochanin A and Phloretin Attenuate Cr(VI)-Induced Oxidative Stress and DNA Damage by Stimulating Nrf2/HO-1 Pathway in the Experimental Model

Hexavalent chromium [Cr(VI)] has emerged as a prevailing environmental and occupational contaminant over the past few decades. However, the knowledge is sparse regarding Cr(VI)-induced neurological aberrations, and its remediation through natural bioactive compounds has not been fully explored. This study intended to probe the possible invigorative effects of nutraceuticals such as coenzyme Q10 (CoQ10), biochanin A (BCA), and phloretin (PHL) on Cr(VI) intoxicated Swiss albino mice with special emphasis on Nrf2/HO-1/NQO1 gene expressions. Mice received potassium dichromate (75 ppm) through drinking water and were simultaneously co-treated intraperitoneally with CoQ10 (10 mg/kg), BCA, and PHL (50 mg/kg) each for 30-day treatment period. The statistics highlight the elevated levels of lipid peroxidation (LPO) and protein carbonyl content (PCC) with a concomitant reduction in the superoxide dismutase (SOD), glutathione-S-transferase (GST), reduced glutathione (GSH), total thiols (TT), catalase (CAT), and cholinesterase activities in the Cr(VI)-exposed mice. The collateral assessment of DNA fragmentation, DNA breakages, and induced histological alterations was in conformity with the above findings in conjugation with the dysregulation in the Nrf2 and associated downstream HO-1 and NQO1 gene expressions. Co-treatment with the selected natural compounds reversed the above-altered parameters significantly, thereby bringing cellular homeostasis in alleviating the Cr(VI)-induced conciliated impairments. Our study demonstrated that the combination of different bioactive compounds shields the brain better against Cr(VI)-induced neurotoxicity by revoking the oxidative stress-associated manifestations. These compounds may represent a new potential combination therapy due to their ability to modulate the cellular antioxidant responses by upregulating the Nrf2/HO-1/NQO1 signaling pathway against Cr(VI)-exposed population. HIGHLIGHTS: Cr(VI)-associated heavy metal exposure poses a significant threat to the environment, especially to living organisms. Cr(VI) exposure for 30 days resulted in the free radical's generation that caused neurotoxicity in the Swiss albino mice. Natural compounds such as coenzyme Q10, biochanin A, and phloretin counteracted the neurotoxic effect due to Cr(VI) exposure in scavenging of free radicals by enhancing Nrf2/HO-1/NQO1 gene expressions in maintaining the cellular homeostasis.

Therapeutic effects of CoenzymeQ10, Biochanin A and Phloretin against arsenic and chromium induced oxidative stress in mouse (Mus musculus) brain

Arsenic and chromium are the most common environmental toxicants prevailing in nature. Hence, the present study endeavors to investigate the salutary effects of Coenzyme Q10 (CoQ10), Biochanin A (BCA), and Phloretin (PHL) on the combined neurotoxic impact of arsenic and chromium in the Swiss albino mice (Mus musculus). Sodium meta-arsenite (100 ppm) and potassium dichromate (75 ppm) were given orally in conjugation with CoQ10 (10 mg/kg), BCA & PHL (50 mg/kg each) in accordance with body weight per day for the 2 weeks experimental duration. Weight reduction was figured out in the exposed toxic group of arsenic and chromium in contrast with the comparison group (control), and with the selected anti-oxidants treatment, it rose significantly to the basal status (p < 0.05). The concentration of arsenic and chromium was reduced significantly (p < 0.001) amidst all the natural compounds co-medicated groups. Anti-oxidant indicators, viz. lipid peroxidation (LPO) and protein carbonyl content (PCC), were found elevated, with reduction observed in the levels of superoxide dismutase (SOD), reduced glutathione (GSH), glutathione s-transferase (GST), and total thiols (TT) in the arsenic and chromium, co-exposed mice. The alterations in redox homeostasis were well corroborated with the estimations of cholinesterase's enzymes (p < 0.05) along with DNA fragmentation assay and altered Nrf2 signaling. The administration of CoQ10, BCA, and PHL ameliorated the effects of arsenic and chromium induced oxidative stress in the exposed mice. Our research unfolds the remedial outcome of these natural compounds contrary to the combined arsenic and chromium associated-neurotoxicity in the experimental model.

Hair, serum and urine chromium levels in children with cognitive defects: A systematic review and meta-analysis of case control studies

Environmental chromium exposure may cause impaired development of children. We conducted a systematic review and meta-analysis. Electronic databases including PubMed, Embase, Web of Science and CINAHL were searched to identify case-control studies that reported childhood Cr exposure and cognitive development. The Newcastle-Ottawa Scale (NOS) was used to ensure the quality of the included studies. Cr levels were compared in cases and controls, and a random effect meta-analysis was performed using Stata version 16. Twelve of 61 studies identified in the literature search were eligible for this analysis. Hair, serum and urine Cr measurements were reported by seven, two and one studies, respectively. In addition, one study reported both serum and hair Cr exposure and another reported urine and hair Cr exposure. The pooled standard mean differences (SMD) showed that hair Cr levels were non-significantly lower among children with cognitive defects (-0.01 μg/g, 95% CI: -0.04, 00, p = 0.27). In serum and urine, the pooled SMD was higher in children with cognitive deficits compared with healthy control children (0.32 μg/g, 95% CI: -0.78, 1.42, p = 0.56 and 0.64 μg/g, CI: -0.07,1.36, p = 0.08; respectively). In summary, this systematic review found no significant differences in hair, serum and urine Cr levels between children with cognitive deficits and healthy control children when all study data were pooled in the meta-analysis. Larger studies using standardized criteria and longitudinal assessment of cognitive development are needed to determine whether there is a dose response effect of childhood Cr exposure on cognitive development of children.

Current understanding of hexavalent chromium [Cr(VI)] neurotoxicity and new perspectives

Hexavalent chromium [Cr(VI)] is a global environmental pollutant that increases risk for several types of cancers and is increasingly being recognized as a neurotoxicant. Traditionally, the brain has been viewed as a largely post-mitotic organ due to its specialized composition of neurons, and consequently, clastogenic effects were not considered in neurotoxicology. Today, we understand the brain is composed of at least eight distinct cell types - most of which continue mitotic activity throughout lifespan. We have learned these dividing cells play essential roles in brain and body health. This review focuses on Cr(VI), a potent clastogen and known human carcinogen, as a potentially neurotoxic agent targeting mitotic cells of the brain. Despite its well-established role as a human carcinogen, Cr(VI) neurotoxicity studies have failed to find a significant link to brain cancers. In the few studies that did find a link, Cr(VI) was identified as a risk for gliomas. Instead, in the human brain, Cr(VI) appears to have more subtle deleterious effects that can impair childhood learning and attention development, olfactory function, social memory, and may contribute to motor neuron diseases. Studies of Cr(VI) neurotoxicity with animal and cell culture models have demonstrated elevated markers of oxidative damage and redox stress, with widespread neurodegeneration. One study showed mice exposed to Cr(VI)-laden tannery effluent exhibited longer periods of aggressive behavior toward an "intruder" mouse and took longer to recognize mice previously encountered, recapitulating the social memory deficits observed in humans. Here we conducted a critical review of the available literature on Cr(VI) neurotoxicity and synthesize the collective observations to thoroughly evaluate Cr(VI) neurotoxicity - much remains to be understood and recognized.

Inflammatory injury and mitophagy of the brain in chicken exposed to Cr(VI)

The aim of this study is to determine whether Cr(VI) can induce inflammatory injury in chicken brain and influence mitophagy and related mechanisms. A total of 120 hyline brown chickens (1 day old, 20±3g) were selected and randomly divided into four groups and given different doses of Cr(VI) (0, 10, 30, and 50 mg/kg) every day at 45 days. Results showed that excessive intake of Cr(VI) led to increased tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) levels and decreased interferon-gamma (IF-γ) level. Cr(VI) increased the production of mitochondrial reactive oxygen species (ROS) in chicken brain cells, causing the decline of mitochondrial membrane potential (MMP) and formation of autophagosomes for mitophagy. In addition, Cr(VI) promoted the translocation of Parkin to the mitochondrial outer membrane, increased LC3-II protein level, and inhibited p62 and TOM20 protein expression. In conclusion, excessive Cr(VI) intake can induce inflammatory injury and mitophagy in chicken brain.

Shinorine ameliorates chromium induced toxicity in zebrafish hepatocytes through the facultative activation of Nrf2-Keap1-ARE pathway

Hexavalent chromium, a heavy metal toxicant, abundantly found in the environment showed hepatotoxic potential in zebrafish liver and instigated the Nrf2-Keap1-ARE pathway as a cellular stress response as reported in our previous studies. In the present study we have evaluated the ameliorating effect of shinorine, a mycosporine like amino acid (MAAs) and a mammalian Keap1 antagonist against chromium induced stress in zebrafish hepatocytes. Shinorine was found to be effective in increasing the cell viability of chromium treated hepatocytes through curtailing the cellular ROS content. Trigonelline, an Nrf2 inhibitor was found to reduce the viability of hepatocyte cultures co-exposed to shinorine and chromium. In other words, trigonelline being an Nrf2 blocker neutralised the alleviating effect of shinorine. This indicated that shinorine mediated cyto-protection in Cr [VI]-intoxicated cells is Nrf2 dependent. Further, qRT-PCR analysis revealed comparatively higher expression of nfe2l2 and nqo1 in shinorine + chromium treated hepatocytes than cells exposed to chromium alone indicating a better functioning of Nrf2-Keap1-Nqo1 axis. To further confirm if shinorine can lead to disruption of Nrf2-Keap1 interaction in zebrafish hepatocytes and render cytoprotection to chromium exposure, our in silico analysis through molecular docking revealed that shinorine could bind to the active amino acid residues of the DGR domain, responsible for Nrf2-Keap1 interaction of all the three Keap1s evaluated. This is the first report about shinorine that ameliorates chromium induced toxicity through acting as an Nrf2-Keap1 interaction disruptor. We additionally carried out in-silico pharmacokinetic and ADMET studies to evaluate druglikeness of shinorine whose promising results indicated its potential to be developed as an ideal therapeutic candidate against toxicant induced pathological conditions.

Rosmarinic acid attenuates chromium-induced hepatic and renal oxidative damage and DNA damage in rats

Hexavelant chromium (Cr (V1)) is a widely distributed environmental pollutant inducing damage in different organs of human and animals. The current study was designed to investigate the mechanistic role of rosmarinic acid (RA) to diminish chromium-induced hepatorenal oxidative damage and preneoplastic lesions in rats. Plant material was collected, identified, and extracted. The isolated RA was elucidated relying on the nuclear magnetic resonance spectroscopic data. Twenty-eight male Wistar rats received the following materials daily via oral gavage for 60 days; (Gp1): normal saline, (Gp2) 25 mg/kg.bwt RA, (Gp3) 10 mg/kg.bwt potassium dichromate (K2 Cr2 O7 ), (Gp4) K2 Cr2 O7  + RA. All rats were euthanized at the end of the experiment by cervical dislocation and the liver and kidney were collected. Prolonged continuous exposure of rats to chromium-induced oxidant/antioxidant imbalance manifested by significant elevation of malondialdehyde with reduction in reduced glutathione levels. Remarkable histopathological alterations in the liver and kidney tissue sections were recorded and confirmed by overexpression of the immunohistochemical staining of caspase-3, placental glutathione-S transferase, proliferating cell nuclear antigen together with a significant downregulation of nuclear factor erythroid-2 related factor 2 (Nrf2) gene and upregulation of nibrin gene. Observable improvements in the entire toxicopathological parameters were recorded in group cotreated with RA. Our findings revealed that Cr-induced preneoplastic lesions on the liver and kidney tissues of rats when exposed daily for long period of time, as well as confirmed the ability of RA to alleviate this toxicity through upregulation of Nrf2 pathway and its powerful antioxidant effects.

Long-term hexavalent chromium exposure facilitates colorectal cancer in mice associated with changes in gut microbiota composition

Colorectal cancer (CRC) is among the leading causes of cancer-related mortality worldwide. Hexavalent chromium [Cr(VI)] is often present in groundwater. Chronic Cr(VI) exposure is suggested to be one of the main factors inducing cancer. However, the correlation between Cr(VI) and CRC remains unclear. In this study, we investigated the role of Cr(VI) in CRC by establishing a mouse CRC model induced by 1, 2-dimethylhydrazine (DMH). The results showed that Cr(VI) increased weight loss in DMH-induced mice and promoted the formation of tumors. Cr(VI) also increased DMH-induced proliferating cell nuclear antigen (PCNA) levels. Investigation of the underlying mechanisms found that Cr(VI) significantly decreased DMH-induced SOD, GSH and CAT levels, while, the MDA level increased. Metagenomic analyses found that the abundance of Firmicutes and Bacteroidetes in the DMH + Cr group was down-regulated. Interestingly, the combination of Cr(VI) and DMH significantly increased the abundance of Verrucomicrobia. At the family and genus levels, families Akkermansiaceae and Saccharimonadaceae and genus Akkermansia were more abundant in the DMH + Cr group, whereas the abundance of short-chain fatty acid (SCFA)-producing bacteria (family Muribaculaceae, family Lachnosipiraceae, genus Lachnospiraceae_NK4A136_group, and genus Roseburia) decreased. These results indicate that Cr(VI) might aggravate CRC by altering the composition of the gut microflora.

Cr(VI) induces ROS-mediated mitochondrial-dependent apoptosis in neuronal cells via the activation of Akt/ERK/AMPK signaling pathway

Hexavalent chromium (Cr(VI)), a well-known toxic industrial and environmental pollutant, has been shown to cause serious toxic and health effects. However, limited information is available on Cr(VI)-induced neurotoxic potential, with the underlying toxicological mechanisms remain mostly unclear. The present study demonstrated that the mitochondria-dependent apoptosis pathway was involved in Cr(VI)-induced SH-SY5Y cell (the human neuroblastoma cell line) death, which was accompanied by the appearance of cell shrinkage, increased mitochondrial membrane potential (MMP) depolarization and cytochrome c release, and the activation of caspase cascades and poly (ADP-ribose) polymerase (PARP). Cr(VI) treatment also increased the generation of intracellular reactive oxygen species (ROS). Pretreatment of SH-SY5Y cells with antioxidant N-acetylcysteine (NAC) effectively attenuated ROS production and reversed these Cr(VI)-induced cytotoxicity and apoptotic responses. Furthermore, exposure to Cr(VI) significantly increased the phosphorylation levels of Akt, extracellular regulated kinase (ERK)1/2, and AMP-activated protein kinase (AMPK)α. NAC and the pharmacological inhibitor of Akt (LY294002), ERK1/2 (PD980590), and AMPKα (Compound C) markedly abrogated the Cr(VI)-induced activation of Akt, ERK1/2, and AMPKα signal, respectively, with the concomitant inhibition of mitochondrial dysfunction and caspase activation. Additionally, all these inhibitors suppressed Cr(VI)-induced phosphorylation of Akt, ERK1/2, and AMPKα and of each other. Collectively, these results suggest that Cr(VI) exerts its cytotoxicity on neuronal cells by inducing mitochondria-dependent apoptosis through the interdependent activation of Akt, ERK1/2, and AMPKα, which are mainly mediated by ROS generation.

Identification of lead-produced lipid hydroperoxides in human HepG2 cells and protection using rosmarinic and ascorbic acids with a reference to their regulatory roles on Nrf2-Keap1 antioxidant pathway

Lead (Pb) is one of the toxic heavy metals that have several toxicological implications including cytotoxicities and oxidative stress. The release of reactive oxygen species (ROS) usually initiates lipid peroxidation and resulting in inflammation and tissue injury. However, the detailed identification of the Pb-produced lipid hydroperoxides has received little attention. Furthermore, the mechanisms behind such effects are less informed. Therefore, this study firstly investigated Pb-produced lipid hydroperoxides in human HepG2 cells using LC/MS. The effects of Pb on the antioxidant enzymes were additionally examined using qPCR and their dependent activities. As a protection trial, the ameliorative effects of rosmarinic (RMA) and ascorbic (ASA) acids on Pb-induced cytotoxicity and oxidative stress and their regulatory effects on Nrf2/Keap1 pathway were investigated. The achieved results confirmed cytotoxicity and oxidative damage of Pb on HepG2 cells. In addition, 20 lipid hydroperoxides (LOOH) were identified including 11 phosphatidylcholine hydroperoxides (PCOOH), 5 triacylglycerol hydroperoxides (TGOOH) and 4 cholesteryl ester hydroperoxides (CEOOH). The most dominant LOOH species were PCOOH 34:2, PCOOH 34:3, PCOOH 38:7, TGOOH 60:14, TGOOH 60:15, CEOOH 18:3 and CEOOH 20:4. Pb significantly downregulated Nrf2-regulated antioxidant enzymes at both the pretranscriptional and functional levels. Co-exposure of HepG2 cells to RMA and ASA significantly reduced Pb-produced adverse outcomes. This protection occurred via activation Nrf2-Keap1 antioxidant pathway.

Childhood chromium exposure and neuropsychological development in children living in two polluted areas in southern Spain

This study aimed to assess the association between exposure to chromium and neuropsychological development among children. A cross-sectional study was conducted with 393 children aged 6-11 years old randomly selected from State-funded schools in two provinces in Southern Spain (Almeria and Huelva), in 2010 and 2012. Chromium levels in urine and hair samples were analyzed by inductively coupled plasma mass spectrometry with an octopole reaction system. Neuropsychological development was evaluated using the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and three computerized tests from the Behavioural Assessment and Research System (BARS): Reaction Time Test (RTT), Continuous Performance Test (CPT) and Selective Attention Test (SAT). Multivariable linear regression models adjusted for potential confounders, including heavy metals, were applied to examine the association between chromium levels and neuropsychological outcomes. A 10-fold increase in urine chromium levels was associated with a decrease of 5.99 points on the WISC-IV Full-Scale IQ (95% CI: 11.98 to -0.02). Likewise, a 10-fold increase in urine chromium levels in boys was associated with a decrease of 0.03 points in the percentage of omissions (95% CI: 0.0 to 0.05) in the SAT, with an increase of 68.35 points in latency (95% CI: 6.60 to 130.12) in the RTT, and with an increase in the number of trials with latencies > 1000 ms (β = 37.92; 95% CI: 2.73 to 73.12) in the RTT. An inverse significant association was detected between chromium levels in hair and latency in the SAT in boys (β = -50.53; 95% CI: 86.86 to -14.22) and girls (β = -55.95; 95% CI: 78.93 to -32.97). Excluding trials with latencies >1000 ms in the RTT increased latency scores by 29.36 points in boys (95% CI: 0.17 to 58.57), and 39.91 points in girls (95% CI: 21.25 to 58.59). This study is the first to show the detrimental effects of postnatal chromium exposure on neuropsychological development in school-aged children.

Therapeutic Potential of Rosmarinic Acid: A Comprehensive Review

Naturally occurring food-derived active ingredients have received huge attention for their chemopreventive and chemotherapy capabilities in several diseases. Rosmarinic acid (RA) is a caffeic acid ester and a naturally-occurring phenolic compound in a number of plants belonging to the Lamiaceae family, such as Rosmarinus officinalis (rosemary) from which it was formerly isolated. RA intervenes in carcinogenesis through different ways, including in tumor cell proliferation, apoptosis, metastasis, and inflammation. On the other hand, it also exerts powerful antimicrobial, anti-inflammatory, antioxidant and even antidepressant, anti-aging effects. The present review aims to provide an overview on anticancer activities of RA and to deliberate its therapeutic potential against a wide variety of diseases. Given the current evidence, RA may be considered as part of the daily diet in the treatment of several diseases, with pre-determined doses avoiding cytotoxicity.

Ascorbic acid protects male rat brain from oral potassium dichromate-induced oxdative DNA damage and apoptotic changes: the expression patterns of caspase-3, P 53, Bax, and Bcl-2 genes

Our study designed to study the potential of potassium dichromate (K₂Cr₂O₇) oral exposure to induce damage in male rat brain and to compare the possible protective role of vitamin C (VC) either pre and/or concurrent supply against (K₂Cr₂O₇) induced changes. Thirty male rats were divided into five groups. First control group received distilled water (C), second received 120 mg/kg b.wt (VC), third received 25 mg/kg b.wt K₂Cr₂O₇ (Cr), fourth group received VC together with K₂Cr₂O₇ by the same former doses (VC + Cr), and the fifth group received the same oral doses of VC 2 weeks prior to and along with K₂Cr₂O₇ for 6 weeks (VC + Cr pro/co treated). The obtained results revealed that K₂Cr₂O₇ induced a significant decrease in cholinergic activity, glutathione reductase GR activity, reduced glutathione content GSH and ATP levels. Furthermore, K₂Cr₂O₇ induced a significant increase in oxidative DNA damage indicated by 8-hydroxy 2'-deoxyguanosine (8OH2'dG) and formation of apoptotic DNA ladders, significant increase in malondialdehyde (MDA), protein carbonyl, and lactate dehydrogenase enzyme. Increased mRNA expression of pro-apoptotic genes, including caspase-3, p53, and Bax, unlike Bcl-2 expression, was decreased. K₂Cr₂O₇ increased caspase-3 and decreased Bcl-2 immuno-labeling. VC supply noticeably ameliorates K₂Cr₂O₇-induced changes which were more significantly in VC pro and concurrent supplement rather than VC concurrent supply only. Finally, it is concluded that K₂Cr₂O₇ oral administration induced oxidative apoptotic changes in rat brain and confirms the usefulness of VC pre and concurrent supply for the amelioration of K₂Cr₂O₇-induced events more significantly than VC concurrent supply only.

Selenium-Chromium(VI) Interaction Regulates the Contents and Correlations of Trace Elements in Chicken Brain and Serum

This study aims to investigate the contents of trace elements in the brain and serum of male chickens and the effect of selenium-chromium(VI) interaction. A chronic experimental model was established by supplementing 22.14 mg/kg K₂Cr₂O₇ with 0.00, 0.31, 0.63, 1.25, 2.50, and 5.00 mg/kg Na₂SeO₃ mg/kg B.W. to water for chicken daily. After 14, 28, and 42 days of exposure to the solution, the brain and serum of chickens from each group were collected to detect the levels of Ca, Cu, Mn, Fe, Zn, and Mg by inductively coupled plasma mass spectrometer (ICP-MS). Cr(VI) time-dependently accumulated in the brain and serum. The contents of Cr increased both in the brain and serum with prolonged exposure. Cr contents in the brain and serum decreased in all Se groups compared with those in only Cr-treated groups. Ca contents decreased with prolonged exposure and increasing Se dosage. The contents of Cu and Mn increased on the 28th day but decreased on the 42nd day in the brain and serum. Fe and Zn contents decreased in the serum under prolonged exposure and increased on the 28th day but decreased on the 42nd day in the brain. Cr exposure did not significantly affect Mg contents in the brain but slightly decreased those in the serum. Therefore, appropriate doses of Se affected Cr accumulation, leading to adjustments in the contents and correlations of trace elements.

Influence of co-existed tetrabromobisphenol A (TBBPA) and hexavalent chromium on the cellular characteristics of Pycnoporus sanguineus during their removal and reduction

Simultaneous TBBPA removal and Cr(VI) reduction by Pycnoporus sanguineus together with the effect of these co-existed pollutants on the fungal cellular characteristics were investigated in this study, aiming at illuminating the mechanism involved in the interactions between contaminants and microbial cells. The results revealed that Cr(VI) reduction and TBBPA removal declined from 92.5%, 75.4-30.6%, 44.8% when Cr(VI) concentration increased from 5 to 40mg/L, respectively. The removal efficiencies for Cr(VI) and TBBPA reached 61.4% and 94% separately under the optimum concentration of TBBPA at 10mg/L. Subsequent analyses indicated that the negative effect of Cr(VI) of high concentrations on Cr(VI) reduction and TBBPA removal was mainly attributed to the inhibition of fungal growth, intracellular proteins synthesis, cell viability and ATP enzyme activity. Compared with the moderate impact of TBBPA, the cell membrane of P. sanguineus was impaired severely and the surface morphology and intracellular structure changed dramatically in the presence of high concentration of Cr(VI) (above 10mg/L). This study also suggested that high level of TBBPA (15 and 20mg/L) promoted the synthesis of intracellular proteins and improved ATP enzyme activity within the first 48h of the reaction for enhancing the transportation and transformation of TBBPA.

Interaction of single-walled carbon nanotubes and saxitoxin: Ab initio simulations and biological responses in hippocampal cell line HT-22

Saxitoxins (STXs) are potent neurotoxins that also induce cytotoxicity through the generation of reactive oxygen species. Carbon nanotubes (CNTs) are nanomaterials that can promote a Trojan horse effect, facilitating the entry of toxic molecules to cells when adsorbed to nanomaterials. The interaction of pristine single-walled (SW)CNTs and carboxylated (SWCNT-COOH) nanotubes with STX was evaluated by ab initio simulation and bioassays using the cell line HT-22. Cells (5 × 10⁴  cells/mL) were exposed to SWCNT and SWCNT-COOH (5 μg mL^-1 ), STX (200 μg L^-1 ), SWCNT+STX, and SWCNT-COOH+STX for 30 min or 24 h. Results of ab initio simulation showed that the interaction between SWCNT and SWCNT-COOH with STX occurs in a physisorption. The interaction of SWCNT+STX induced a decrease in cell viability. Cell proliferation was not affected in any treatment after 30 min or 24 h of exposure (p > 0.05). Treatment with SWCNT-COOH induced high reactive oxygen species levels, an effect attenuated in SWCNT-COOH+STX treatment. In terms of cellular oxygen consumption, both CNTs when coexposed with STX antagonize the toxin effect. Based on these results, it can be concluded that the results obtained in vitro corroborate the semiempirical evidence found using density functional theory ab initio simulation. Environ Toxicol Chem 2017;36:1728-1737. © 2016 SETAC.

Transcriptomic analyses reveal biosynthetic genes related to rosmarinic acid in Dracocephalum tanguticum

Dracocephalum tanguticum Maxim, a Lamiaceae species endemic to the Qinghai-Tibetan Plateau and adjacent regions, is an important ornamental, medicinal and aromatic herb. In this study, a comprehensive transcriptome of 18 libraries from six organs namely, roots, stems, leaves, sepals, flowers and seeds of D. tanguticum were generated. More than 100 Gb of sequence data were obtained and assembled de novo into 187,447 transcripts, including 151,463 unigenes, among which the six organs shared 17.7% (26,841). In addition, all unigenes were assigned to 362 pathways, in which 'biosynthesis of secondary metabolites' is the second enriched pathway. Furthermore, rosmarinic acid (RA) is one of the multifunctional phenolic bioactive compounds produced in some Lamiaceae species. The six organs of D. tanguticum were confirmed to produce RA. A total of 22 predicted biosynthetic genes related to RA from the transcriptome were further isolated. Two of these genes were identified as candidates by evaluating the correlation coefficient between the RA contents and the expression of the predicted biosynthetic genes in the six organs. The new sequence information will improve the knowledge of D. tanguticum, as well as provide a reference tool for future studies of biosynthetic genes related to RA in this species.