Comparative gavage subchronic toxicity studies of o-chloroaniline and m-chloroaniline in F344 rats and B6C3F1 mice

Beef, Casein, and Soy Proteins Differentially Affect Lipid Metabolism, Triglycerides Accumulation and Gut Microbiota of High-Fat Diet-Fed C57BL/6J Mice

Consumption of dietary protein at recommended levels is considered a potential strategy to promote satiety and weight management, but how protein from different dietary sources effect the obesity development, lipid metabolism, and gut microbiota is not known. This study focused on the effects of beef, casein, and soy protein diet on lipid metabolism, triglycerides accumulation, and microbial diversity in colon of C57BL/6J mice, which were given either low-fat diets (LFD, 12% Kcal) or high-fat diets (HFD, 60% Kcal) for 12 weeks. Body and liver weight increased significantly in mice fed a beef protein HFD (HFB), whereas reduced cumulative energy intake was seen in a soy protein HFD (HFS) group. HFB-fed mice showed signs of impaired glucose metabolism and insulin resistance along with a significant elevation in the concentration of triglycerides, LDL-cholesterol, total cholesterol, IL1β, TNF-α, IL-6, and leptin in serum. HFB also enhanced lipid accumulation in liver with increased activity of genes important for lipogenesis and hepatic cholesterol metabolism. A 16S rRNA gene sequencing indicated that HFD, regardless of proteins, significantly enhanced the ratio of Firmicutes to Bacteroidetes in colonic microbiota. However, HFB not only reduced the abundance of Akkermansia, compared with LFD independent of proteins, but also decreased the abundance of butyrate-producing bacteria such as Anaerotruncus, Butyricicoccus, and Lactobacillus (P < 0.05) compared with HFS and HFC. In conclusion, consumption of HFB does not only affect the gut microbiota composition but also increases the problems related to metabolic syndromes like dyslipidemia, hypercholesterolemia, and triglycerides accumulation in liver, which lead to systemic inflammation and its associated comorbidities, for example, impaired glucose metabolism and insulin resistance.

A hyaluronic acid nanogel for photo-chemo theranostics of lung cancer with simultaneous light-responsive controlled release of doxorubicin

The combined delivery of photo- and chemo-therapeutic agents is an emerging strategy to overcome drug resistance in treating cancer, and controlled light-responsive drug release is a proven tactic to produce a continuous therapeutic effect for a prolonged duration. Here, a combination of light-responsive graphene, chemo-agent doxorubicin and pH-sensitive disulfide-bond linked hyaluronic acid form a nanogel (called a graphene-doxorubicin conjugate in a hyaluronic acid nanogel) that exerts an activity with multiple effects: thermo and chemotherapeutic, real-time noninvasive imaging, and light-glutathione-responsive controlled drug release. The nanogel is mono-dispersed with an average diameter of 120 nm as observed by using TEM and a hydrodynamic size analyzer. It has excellent photo-luminescence properties and good stability in buffer and serum solutions. Graphene itself, being photoluminescent, can be considered an optical imaging contrast agent as well as a heat source when excited by laser irradiation. Thus the nanogel shows simultaneous thermo-chemotherapeutic effects on noninvasive optical imaging. We have also found that irradiation enhances the release of doxorubicin in a controlled manner. This release synergizes therapeutic activity of the nanogel in killing tumor cells. Our findings demonstrate that the graphene-doxorubicin conjugate in the hyaluronic acid nanogel is very effective in killing the human lung cancer cell line (A549) with limited toxicity in the non-cancerous cell line (MDCK).

Mechanisms of the thermal decay of chlorpropham

DFT calculations were performed on the thermal reactions of chlorpropham 1, a carbamate pesticide and plant growth regulator frequently used in the storage of potatoes. At the conditions normally used in applying 1 (injection of a methanolic solution of 1 into a hot air stream, T ≈ 500°C), both ester pyrolysis of 1 and a methanol-or water-catalysed isocyanate cleavage are expected to proceed rapidly (lifetime of 1 less than a second). In both reactions, the final reaction product will be toxic and carcinogenic m-chloroaniline 2. Matrix-isolation experiments indicate that 1 undergoes thermal decay at temperatures as low as 250°C. Up to temperatures of ca. 500°C, formation of m-chlorophenylisocyanate 4 and isopropanol was the predominant reaction observed, while formation of propene, CO(2), and m-chloroaniline 2 was the most important reaction channel at higher pyrolysis temperatures. m-Chlorophenyl carbamic acid 3 could not be observed. The results indicate that at lower temperatures, 1 decays exclusively via isocyanate cleavage of 1, provided that traces of catalytic water or other protic compounds are present. At higher temperatures, ester cleavage of 1 becomes competitive and outweighs the isocyanate cleavage by a factor of ca. 10:1.

Metabolism studies of a small-molecule tumor necrosis factor-alpha (TNF-α) inhibitor, UTL-5b (GBL-5b)

UTL-5b is an anti-inflammatory and anti-arthritic small-molecule tumor necrosis factor-alpha inhibitor and a structural analogue of the anti-arthritic drug, leflunomide. Leflunomide is known to be metabolized to teriflunomide, but the metabolites of UTL-5b have not been reported. The objective of this study was to investigate whether UTL-5b has a similar metabolic behavior as leflunomide. Preliminary studies showed that when exposed to microsomes in vitro with or without NADPH, UTL-5b disappeared within 30 min. To further investigate the microsomal metabolism, liquid chromatography-ultraviolet (LC-UV) and LC/tandem mass spectrometry (LC-MS/MS) were employed to, respectively, monitor the microsomal metabolites and identify the structure of the metabolites using LC-full scan MS and LC combined with multiple-ion monitoring MS. Fragmentation determination was analyzed by two types of scans: product ion scans and precursor ion scan. The in vitro microsomal treatment of UTL-5b resulted in two major metabolites: 5-methylisoxazole-3-carboxylic acid and 2-chloroaniline. Thus, the in vitro metabolic behavior of UTL-5b appears to be different from that of leflunomide in that the isoxazole ring is cleaved.

Development and evaluation of a harmonized physiologically based pharmacokinetic (PBPK) model for perchloroethylene toxicokinetics in mice, rats, and humans

This article reports on the development of a "harmonized" PBPK model for the toxicokinetics of perchloroethylene (tetrachloroethylene or perc) in mice, rats, and humans that includes both oxidation and glutathione (GSH) conjugation of perc, the internal kinetics of the oxidative metabolite trichloroacetic acid (TCA), and the urinary excretion kinetics of the GSH conjugation metabolites N-Acetylated trichlorovinyl cysteine and dichloroacetic acid. The model utilizes a wider range of in vitro and in vivo data than any previous analysis alone, with in vitro data used for initial, or "baseline," parameter estimates, and in vivo datasets separated into those used for "calibration" and those used for "evaluation." Parameter calibration utilizes a limited Bayesian analysis involving flat priors and making inferences only using posterior modes obtained via Markov chain Monte Carlo (MCMC). As expected, the major route of elimination of absorbed perc is predicted to be exhalation as parent compound, with metabolism accounting for less than 20% of intake except in the case of mice exposed orally, in which metabolism is predicted to be slightly over 50% at lower exposures. In all three species, the concentration of perc in blood, the extent of perc oxidation, and the amount of TCA production is well-estimated, with residual uncertainties of ~2-fold. However, the resulting range of estimates for the amount of GSH conjugation is quite wide in humans (~3000-fold) and mice (~60-fold). While even high-end estimates of GSH conjugation in mice are lower than estimates of oxidation, in humans the estimated rates range from much lower to much higher than rates for perc oxidation. It is unclear to what extent this range reflects uncertainty, variability, or a combination. Importantly, by separating total perc metabolism into separate oxidative and conjugative pathways, an approach also recommended in a recent National Research Council review, this analysis reconciles the disparity between those previously published PBPK models that concluded low perc metabolism in humans and those that predicted high perc metabolism in humans. In essence, both conclusions are consistent with the data if augmented with some additional qualifications: in humans, oxidative metabolism is low, while GSH conjugation metabolism may be high or low, with uncertainty and/or interindividual variability spanning three orders of magnitude. More direct data on the internal kinetics of perc GSH conjugation, such as trichlorovinyl glutathione or tricholorvinyl cysteine in blood and/or tissues, would be needed to better characterize the uncertainty and variability in GSH conjugation in humans.

Methemoglobinemia induced by 1,2-dichloro-4-nitrobenzene in mice with a disrupted glutathione S-transferase Mu 1 gene

A specific substrate to Mu class glutathione S-transferase (GST), 1,2-dichloro-4-nitrobenzene (DCNB), was administered to mice with a disrupted GST Mu 1 gene (Gstm1-null mice) to investigate the in vivo role of murine Gstm1 in toxicological responses to DCNB. A single oral administration of DCNB at doses of 500 and 1000 mg/kg demonstrated a marked increase in blood methemoglobin (MetHB) in Gstm1-null mice but not in wild-type mice. Therefore, Gstm1-null mice were considered to be more predisposed to methemoglobinemia induced by a single dosing of DCNB. In contrast, 14-day repeated-dose studies of DCNB at doses up to 600 mg/kg demonstrated a marked increase in blood MetHB in both wild-type and Gstm1-null mice. However, marked increases in the blood reticulocyte count, relative spleen weight, and extramedullary hematopoiesis in the spleen were observed in Gstm1-null mice compared with wild-type mice. In addition, microarray and quantitative reverse transcription-polymerase chain reaction analyses in the spleen showed exclusive up-regulation of hematopoiesis-related genes in Gstm1-null mice. These changes were considered to be adaptive responses to methemoglobinemia and attenuated the higher predisposition to methemoglobinemia observed in Gstm1-null mice in the single-dose study. In toxicokinetics monitoring, DCNB concentrations in plasma and blood cells were higher in Gstm1-null mice than those in wild-type mice, resulting from the Gstm1 disruption. In conclusion, it is suggested that the higher exposure to DCNB due to Gstm1 disruption was reflected in methemoglobinemia in the single-dose study and in adaptive responses in the 14-day repeated-dose study.

Genotoxic Activities of Aniline and its Metabolites and Their Relationship to the Carcinogenicity of Aniline in the Spleen of Rats

Aniline (in the form of its hydrochloride) has been shown to induce a rather rare spectrum of tumors in the spleen of Fischer 344 rats. The dose levels necessary for this carcinogenic activity were in a range where also massive effects on the blood and non-neoplastic splenotoxicity as a consequence of methemoglobinemia were to be observed. This review aimed at clarifying if aniline itself or one of its metabolites has a genotoxic potential which would explain the occurrence of the spleen tumors in rats as a result of a primary genetic activity. The database for aniline and its metabolites is extremely heterogeneous. With validated assays it ranges from a few limited Ames tests (o- and m-hydroxyacetanilide, phenylhydroxylamine, nitrosobenzene) to a broad range of studies covering all genetic endpoints partly with several studies of the same or different test systems (aniline, p-aminophenol, p-hydroxyacetanilide). This makes a direct comparison rather difficult. In addition, a varying number of results with as yet not validated systems are available for aniline and its metabolites. Most results, especially those with validated and well performed/documented studies, did not indicate a potential of aniline to induce gene mutations. In five different mouse lymphoma tests, where colony sizing was performed only in one test, aniline was positive. If this indicates a peculiar feature of a point mutagenic potential or does represent a part of the clastogenic activity for which there is evidence in vitro as well as in vivo remains to be investigated. There is little evidence for a DNA damaging potential of aniline. The clastogenic activity in vivo is confined to dose levels, which are close to lethality essentially due to hematotoxic effects. The quantitatively most important metabolites for experimental animals as well as for humans (p-aminophenol, p-hydroxyacetanilide) seem to have a potential for inducing chromosomal damage in vitro and, at relatively high dose levels, also in vivo. This could be the explanation for the clastogenic effects that have been observed after high doses/concentrations with aniline. They do not induce gene mutations and there is little evidence for a DNA damaging potential. None of these metabolites revealed a splenotoxic potential comparable to that of aniline in studies with repeated or long-term administration to rats. The genotoxicity database on those metabolites with a demonstrated and marked splenotoxic potential, i.e. phenylhydroxylamine, nitrosobenzene, is unfortunately very limited and does not allow to exclude with certainty primary genotoxic events in the development of spleen tumors. But quite a number of considerations by analogy from other investigations support the conclusion that the effects in the spleen do not develop on a primary genotoxic basis. The weight of evidences suggests that the carcinogenic effects in the spleen of rats are the endstage of a chronic high-dose damage of the blood leading to a massive overload of the spleen with iron, which causes chronic oxidative stress. This conclusion, based essentially on pathomorphological observations, and analogy considerations thereof by previous authors, is herewith reconfirmed under consideration of the more recently reported studies on the genotoxicity of aniline and its metabolites, on biochemical measurements indicating oxidative stress, and on the metabolism of aniline. It is concluded that there is no relationship between the damage to the chromosomes at high, toxic doses of aniline and its major metabolites p-aminophenol/p-hydroxyacetanilide and the aniline-induced spleen tumors in the rat.

Enhanced removal of p-chloroaniline from aqueous solution by a carboxylated polymeric sorbent

In the present study a carboxylated styrene-divinylbenzene (St-DVB) polymeric sorbent (CSPS) was prepared for enhanced removal of p-chloroaniline from aqueous solution. A commercial styrene-divinylbenzene polymeric sorbent Amberlite XAD-4 was selected as the reference sorbent to evaluate the performance of CSPS. Characterization of CSPS was determined by infrared spectroscopy and pore size distribution. A p-chloroaniline sorption enhancement on CSPS at capacity about twice of Amberlite XAD-4 was observed, which was mainly attributed to the carboxyl group added on the polymeric matrix. Different pH-dependent sorption property of p-chloroaniline onto XAD-4 and CSPS was observed partly due to the role of carboxyl group. Sorption isotherm of p-chloroaniline on CSPS could be represented by Freundlich model reasonably, and that on XAD-4 was more suitable for Langmuir model. Kinetic studies demonstrated that the uptake of p-chloroaniline on CSPS and XAD-4 followed the pseudo-second order model. Moreover, breakthrough curves on CSPS further demonstrated its better performance towards p-chloroaniline removal from aqueous solution. Complete regeneration of the spent sorbent CSPS was achieved by dilute hydrochloric acid for its repeated use, implying its potential application in associated chemical wastewater treatments.

Subacute inhalation toxicity of 2-chloro-4-toluidine in rats

This article addresses results from a 4-wk inhalation exposure study in Wistar rats with the vapor and/or aerosol atmospheres of 2-chloro-4-toluidine. Groups of 10 rats/sex were nose-only exposed to mean analytical concentrations of 19.1, 115.1, and 702.3 mg/m3 using an exposure regimen of 6 h/day and 20-22 exposures within a time period of 4 wk. These concentrations were selected based on results from a repeated 5 x 6 h/day pilot study using concentrations of 27.1, 104.8, 381.6, and 1283.7 mg/m3. In a single 4-h exposure study at the maximum tested concentration of 7620 mg/m3, 1 of 10 female rats succumbed (no mortality in males), while no mortality occurred at 3293 mg/m3. In the 1- and 4-wk studies mortality occurred at 1283.7 and 702.3 mg/m3, respectively. Rats exposed for 4 wk to 702.3 mg/m3 displayed characteristic signs of toxicity that included cyanosis, respiratory distress, and significantly decreased body weights. Rectal temperatures were significantly decreased at 115.1 mg/m3 and above. Dark and enlarged spleens occurred at 702.3 mg/m3. At this concentration, prominent treatment-related effects included methemoglobinemia, reticulocytosis, red blood cells with Heinz bodies, decreased hemoglobin, hematocrit, and red blood cell counts. Borderline evidence of erythrocytotoxicty was noticed at 115.1 mg/m3 (based on a minimal increase in Heinz bodies). Spleen and liver weights were significantly increased at 702.3 mg/m3, whereas the thymus weight was decreased at 115.1 mg/m3 and above. Microscopic changes were found in the spleen (hemosiderosis) at 702.3 mg/m3. An atrophy of the olfactory epithelium in the nasal cavities occurred at 115.1 mg/m3 and above. Clinical pathology revealed changes pathognostic of hepatic effects, although microscopic examinations did not reveal any specific changes. The no-observed-adverse-effect level (NOAEL) of the 4-wk study was 19.1 mg/m3 and is based on the predominant atrophic changes of the olfactory epithelium and the minimal to borderline erythrocytotoxic effects at 115.1 mg/m3.

Experimental and Computational Investigation of the Energetics of the Three Isomers of Monochloroaniline

The standard (p degrees = 0.1 MPa) molar enthalpies of formation of 2-, 3-, and 4-chloroaniline were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by rotating bomb combustion calorimetry. The Calvet high-temperature vacuum sublimation technique was used to measure the enthalpies of vaporization or sublimation of the three isomers. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the three isomers of chloroaniline, in the gaseous phase, at T = 298.15 K, as 53.4 +/- 3.1 kJ.mol(-1) for 2-chloroaniline, 53.0 +/- 2.8 kJ.mol(-1) for 3-chloroaniline, and 59.7 +/- 2.3 kJ.mol(-1) for 4-chloroaniline. These values, which correct previously published data, were used to test the computational methodologies used. Therewith, gas-phase acidities, proton affinities, electron donor capacities, and N-H bond dissociation enthalpies were calculated and found to compare well with available experimental data for these parameters.