Pyruvate remediation of cell stress and genotoxicity induced by haloacetic acid drinking water disinfection by‐products

Monohaloacetic acids (monoHAAs) are a major class of drinking water disinfection by‐products (DBPs) and are cytotoxic, genotoxic, mutagenic, and teratogenic. We propose a model of toxic action based on monoHAA‐mediated inhibition of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) as a target cytosolic enzyme. This model predicts that GAPDH inhibition by the monoHAAs will lead to a severe reduction of cellular ATP levels and repress the generation of pyruvate. A loss of pyruvate will lead to mitochondrial stress and genomic DNA damage. We found a concentration‐dependent reduction of ATP in Chinese hamster ovary cells after monoHAA treatment. ATP reduction per pmol monoHAA followed the pattern of iodoacetic acid (IAA) > bromoacetic acid (BAA) >> chloroacetic acid (CAA), which is the pattern of potency observed with many toxicological endpoints. Exogenous supplementation with pyruvate enhanced ATP levels and attenuated monoHAA‐induced genomic DNA damage as measured with single cell gel electrophoresis. These data were highly correlated with the S_N2 alkylating potentials of the monoHAAs and with the induction of toxicity. The results from this study strongly support the hypothesis that GAPDH inhibition and the possible subsequent generation of reactive oxygen species is linked with the cytotoxicity, genotoxicity, teratogenicity, and neurotoxicity of these DBPs. Environ. Mol. Mutagen. 54:629–637, 2013. © 2013 Wiley Periodicals, Inc.     

Blood-Brain Barrier Permeability of Asiaticoside,Madecassoside and Asiatic Acid in Porcine Brain Endothelial Cell Model

Neurotherapeutic potentials of Centella asiatica and its reputation to boost memory, prevent cognitive deficits and improve brain functions are widely acknowledged. The plant's bioactive compounds, i.e. asiaticoside, madecassoside and asiatic acid were reported to have central nervous system (CNS) actions, particularly in protecting the brain against neurodegenerative disorders. Hence, it is important for these compounds to cross the blood-brain barrier (BBB) to be clinically effective therapeutics. This study aimed to explore the capability of asiaticoside, madecassoside and asiatic acid to cross the BBB using in vitro BBB model from primary porcine brain endothelial cells (PBECs). Our findings showed that asiaticoside, madecassoside and asiatic acid are highly BBB permeable with apparent permeability (P_app) of 70.61 ± 6.60, 53.31 ± 12.55 and 50.94 ± 10.91 × 10^?6 cm/s respectively. No evidence of cytotoxicity and tight junction disruption of the PBECs were observed in the presence of these compounds. Asiatic acid showed cytoprotective effect towards the PBECs against oxidative stress. This study reported for the first time that Centella asiatica compounds demonstrated high capability to cross the BBB, comparable to central nervous system drugs, and therefore warrant further development as therapeutics for the treatment of neurodegenerative diseases.     

Protective effect of curcumin against arsenic-induced apoptosis in murine splenocytes in vitro

Arsenic is a potent environmental pollutant and immunotoxic agent. Curcumin is a natural anti-oxidant used to treat a broad variety of diseases. Here, the effects were investigated of curcumin on sodium arsenite-induced apoptosis in murine splenocytes in vitro. Cells were exposed to sodium arsenite (NaAsO₂, 5 µM) with and without curcumin (5 and 10 µg/ml) and incubated at 37°C for 12?h. NaAsO₂ caused a decrease in cell viability and induction of apoptosis. These outcomes were concurrent with increases in the numbers of cells with reactive oxygen species generation, loss of mitochondrial transmembrane potential, an increase in the frequency of cells with sub-G₁ DNA content, and DNA fragmentation. Co-administration of curcumin with the NaAsO₂ caused significant recoveries in cell viability values and mitigation of the induced apoptosis-related molecular changes. A significant protection against apoptosis parameters in murine splenocytes simultaneously treated with NaAsO₂ and curcumin suggested a protective efficacy of curcumin. From the results it is concluded that the immuno-modulation exerted by curcumin might be attributed to its multifaceted effects including its anti-oxidative and anti-apoptotic properties. These findings have implications not only for the under-standing of the toxicity of arsenic to murine splenocytes in vitro but are also potentially important for developing preventive and/or corrective strategies against/during chronic arsenicosis.     

Cardiac oxidative stress and dysfunction by fine concentrated ambient particles (CAPs) are mediated by angiotensin-II

Inhalation exposure to fine concentrated ambient particles (CAPs) increases cardiac oxidants by mechanisms involving modulation of the sympathovagal tone on the heart. Angiotensin-II is a potent vasoconstrictor and a sympatho-excitatory peptide involved in the regulation of blood pressure. We hypothesized that increases in angiotensin-II after fine particulate matter (PM) exposure could be involved in the development of cardiac oxidative stress. Adult rats were treated with an angiotensin-converting enzyme (ACE) inhibitor (benazepril^®), or an angiotensin receptor blocker (ARB; valsartan^®) before exposure to fine PM aerosols or filtered air. Exposures were carried out for 5 hours in the chamber of the Harvard fine particle concentrator (fine PM mass concentration: 440 ± 80 μg/m³). At the end of the exposure the animals were tested for in situ chemiluminescence (CL) of the heart, thiobarbituric acid reactive substances (TBARS) and for plasma levels of angiotensin-II. Also, continuous electrocardiogram (ECG) measurements were collected on a subgroup of exposed animals. PM exposure was associated with statistically significant increases in plasma angiotensin concentrations. Pre-treatment with the ACE inhibitor effectively lowered angiotensin concentration, whereas ARB treatment led to increases in angiotensin above the PM-only level. PM exposure also led to significant increases in heart oxidative stress (CL, TBARS), and a shortening of the T-end to T-peak interval on the ECG that were prevented by treatment with both the ACE inhibitor and ARB. These results show that ambient fine particles can increase plasma levels of angiotensin-II and suggest a role of the renin–angiotensin system in the development of particle-related acute cardiac events.     

Protective effect of polypeptides from larva of housefly (Musca domestica) on hydrogen peroxide-induced oxidative damage in HepG2 cells

Housefly (Musca domestica) is an important medical insect and its larva is an ideal high protein food source. We isolated from housefly larvae the polypeptides hydrolyzed by neutral protease (PHNP), and investigated the protective effect of PHNP on hydrogen peroxide (H₂O₂)-induced oxidative damage in HepG2 cells. Cells exposed to H₂O₂ showed a marked decrease in proliferation and intracellular superoxide dismutase (SOD) activity, and a significant increase in reactive oxygen species (ROS) level and malondialdehyde (MDA) content. H₂O₂ also caused apoptosis and mitochondrial dysfunction including mitochondrial fragmentation and the loss of mitochondrial membrane potential. Pretreatment with PHNP at concentrations of 2.5, 5, 10 μg/mL blocked these H₂O₂-induced cellular events in a dose-dependent manner. The effect of PHNP at 10 μg/mL is equal to that of ascorbic acid at 10 μM. In summary, PHNP has a protective effect against H₂O₂-induced oxidative injury in cells due to its ability to decrease intracellular ROS and elevate antioxidant enzyme activities.     

Insecticidal Activities of the Leaf Oils of Eight Cinnamomum. species Against Aedes aegypti. and Aedes albopictus.

Abstract

The leaf oils of eight Cinnamomum. species (C. rhyncophyllum. Miq., C. microphyllum. Ridl., C. pubescens. Kochummen, C. mollissimum. Hook. f., C. impressicostatum. Kosterm, C. scortechinii. Gamb., C. sintoc. Bl., and C. cordatum. Kosterm) were investigated for their larvicidal and adulticidal activities against Aedes aegypti. (Aedes aegypti Lynn) and Aedes albopictus. (Aedes albopictus Skuse). Acute mortalities of the fourth instar larvae and the adult mosquitoes were determined according to the standard WHO methods. Among the essential oils studied, the leaf oils of C. rhyncophyllum., C. microphyllum., C. pubescens., C. mollissimum., and C. impressicostatum. showed significant effects against the larvae of Ae. aegypti. and Ae. albopictus. with concentrations that caused 50% mortality (LC₅₀) values of less than 12.8 and 11.8 µg ml^?1, respectively. The essential oils that showed strong larvicidal effects also demonstrated relatively strong adulticidal effects on the mosquitoes after 3 h exposure with LC₅₀ values ranging from 133.0 to 243.0 µg ml^?1 against Ae. aegypti. and from 118.0 to 194.0 µg ml^?1 against Ae. albopictus.. The efficacy of the oils toward the larvae and adult mosquitoes of both species was nonselective as the LC₅₀ values showed little variation. The chemical composition of the oils was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). This study suggested that the essential oils containing high levels of benzyl benzoate and benzyl salicylate exhibited strong insecticidal activities against the larvae and adult mosquitoes.     

Melatonin mediates protective effects on inflammatory response induced by interleukin‐1 beta in human mesenchymal stem cells

Joint diseases like osteoarthritis usually are accompanied with inflammatory processes, in which pro‐inflammatory cytokines mediate the generation of intracellular reactive oxygen species (ROS) and compromise survival of subchondral osteoblasts. Melatonin is capable of manipulating bone formation and osteogenic differentiation of mesenchymal stem cells (MSCs). The aim of this work was to investigate the anti‐inflammatory effect of melatonin on MSC proliferation and osteogenic differentiation in the absence or presence of interleukin‐1 beta (IL‐1β), which was used to induce inflammation. Our data showed that melatonin improved cell viability and reduced ROS generation in MSCs in a dose‐dependent manner. When exposed to 10 ng/mL IL‐1β, various concentrations of melatonin resulted in significant reduction of ROS by 34.9% averagely. Luzindole as a melatonin receptor antagonist reversed the anti‐oxidant effect of melatonin in MSCs with co‐exposure to IL‐1β. Real‐time RT‐PCR data suggested that melatonin treatment up‐regulated the expression of CuZnSOD and MnSOD, while down‐regulated the expression of Bax. To investigate the effect of melatonin on osteogenesis, MSCs were cultured in osteogenic differentiation medium supplemented with IL‐1β, melatonin, or luzindole. After exposed to IL‐1β for 21 days, 1 μm melatonin treatment significantly increased the levels of type I collagen, ALP, and osteocalcin, and 100 μm melatonin treatment yielded the highest level of osteopontin. Our study demonstrated that melatonin maintained MSC survival and promoted osteogenic differentiation in inflammatory environment induced by IL‐1β, suggesting melatonin treatment could be a promising method for bone regenerative engineering in future studies.     

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.