Changhao Sun

Effect of quercetin against dichlorvos induced nephrotoxicity in rats.

This study was carried out to determine the effect of quercetin against renal injury induced by dichlorvos (DDVP) in rats. Rats were randomly assigned to control, DDVP-treated (7.2mg/kg bw), three different doses of quercetin-treated (2mg/kg bw, 10mg/kg bw, 50mg/kg bw) and different doses of quercetin plus DDVP-treated groups. DDVP was administered daily to rats through their drinking water, and quercetin was administered by intragastric gavage for 90 days. By the end of the 90th day in the DDVP-treated group, the following indices significantly increased compared with the control (P<0.01): activities of catalase, glutathione peroxidase and superoxide dismutase; level of malondialdehyde in kidney tissues; serum levels of creatinine and urea nitrogen; and level of β2-microglobulin, level of retinol-conjugated protein, and activity of N-acetyl-β-d-glucosaminidase in urine; by contrast, urine uric acid levels significantly decreased. However, in the quercetin (50mg/kg bw) plus DDVP group, the aforementioned indices were significantly decreased compared with the DDVP-treated group (P<0.05), except the urine uric acid levels were significantly increased (P<0.05). Thus, rat exposure to DDVP caused renal injury, including renal tubular, glomerular filtration, and oxidative stress. These toxic effects were also regulated by high-dose quercetin. Histopathological examination revealed that exposure to DDVP induced extensive cell vacuolar denaturation, but milder histopathological alterations in the kidney tissues of rats co-treated with DDVP and quercetin (50mg/kg bw) were observed. These results indicated that quercetin at 50mg/kg bw can partly prevent the kidney injury induced by DDVP.

Application of Ultraperformance Liquid Chromatography/Mass Spectrometry–Based Metabonomic Techniques to Analyze the Joint Toxic Action of Long-term Low-Level Exposure to a Mixture of Organophosphate Pesticides on Rat Urine Profile

In previously published articles, we evaluated the toxicity of four organophosphate (OP) pesticides (dichlorvos, dimethoate, acephate, and phorate) to rats using metabonomic technology at their corresponding no observed adverse effect level (NOAEL). Results show that a single pesticide elicits no toxic response. This study aimed to determine whether chronic exposure to a mixture of the above four pesticides (at their corresponding NOAEL) can lead to joint toxic action in rats using the same technology. Pesticides were administered daily to rats through drinking water for 24 weeks. The above mixture of the four pesticides showed joint toxic action at the NOAEL of each pesticide. The metabonomic profiles of rats urine were analyzed by ultraperformance liquid chromatography/mass spectrometry. The 16 metabolites statistically significantly changed in all treated groups compared with the control group. Dimethylphosphate and dimethyldithiophosphate exclusively detected in all treated groups can be used as early, sensitive biomarkers for exposure to a mixture of the OP pesticides. Moreover, exposure to the OP pesticides resulted in increased 7-methylguanine, ribothymidine, cholic acid, 4-pyridoxic acid, kynurenine, and indoxyl sulfate levels, as well as decreased hippuric acid, creatinine, uric acid, gentisic acid, C18-dihydrosphingosine, phytosphingosine, suberic acid, and citric acid. The results indicated that a mixture of OP pesticides induced DNA damage and oxidative stress, disturbed the metabolism of lipids, and interfered with the tricarboxylic acid cycle. Ensuring food safety requires not only the toxicology test data of each pesticide for the calculation of the acceptable daily intake but also the joint toxic action.

Metabonomics analysis of urine and plasma from rats given long-term and low-dose dimethoate by ultra-performance liquid chromatography–mass spectrometry

This study assessed the effects of long-term, low-dose dimethoate administration to rats by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Dimethoate (0.04, 0.12, and 0.36 mg/kg body weight/day) was administered daily to male Wistar rats through their drinking water for 24 weeks. Significant changes in serum clinical chemistry were observed in the middle- and high-dose groups. UPLC-MS revealed evident separate clustering among the different dose groups using global metabolic profiling by supervised partial least squares-discriminant analysis. Metabonomic analysis showed alterations in a number of metabolites (12 from urine and 13 from plasma), such as L-tyrosine, dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), citric acid, uric acid, suberic acid, glycylproline, allantoin, isovalerylglutamic acid and kinds of lipids. The results suggest that long-term, low-dose exposure to dimethoate can cause disturbances in liver function, antioxidant and nervous systems, as well as the metabolisms of lipids, glucose, fatty acids, amino acids, and collagen in rats. DMTP and DMDTP, which had the most significant changes among all other studied biomarkers, were considered as early, sensitive biomarkers of exposure to dimethoate. The other aforementioned proposed toxicity biomarkers in metabonomic analysis may be useful in the risk assessment of the toxic effects of dimethoate. Metabonomics as a systems toxicology approach was able to provide comprehensive information on the dynamic process of dimethoate induced toxicity. In addition, the results indicate that metabonomic approach could detect systemic toxic effects at an earlier stage compared to clinical chemistry. The combination of metabonomics and clinical chemistry made the toxicity of dimethoate on rats more comprehensive.

Metabolomic analysis of the toxic effects of chronic exposure to low-level dichlorvos on rats using ultra-performance liquid chromatography–mass spectrometry

The purpose of the current study was to assess the effects of long-term exposure to low levels of DDVP on the biochemical parameters and metabolic profiles of rats. Three different doses (2.4, 7.2, and 21.6 mg/kg body weight/day) of DDVP were administered to rats through their drinking water over 24 weeks. Significant changes in blood cholinesterase, creatinine, urea nitrogen, aspartate aminotransferase, alanine aminotransferase, and albumin concentrations were observed in the middle and high dose groups. Changes in the concentration of some urine metabolites were detected via ultra performance liquid chromatography-mass spectrometry (UPLC-MS). Dimethyl phosphate (DMP), which was exclusively detected in the treated groups, can be an early, sensitive biomarker for DDVP exposure. Moreover, DDVP treatment resulted in an increase in the lactobionic acid, estrone sulfate, and indoxyl sulfic concentrations, and a decrease in citric acid, suberic acid, gulonic acid, urea, creatinine, and uric acid. These results suggest that chronic exposure to low-level DDVP can cause a disturbance in carbohydrate and fatty acid metabolism, the antioxidant system, etc. Therefore, an analysis of the metabolic profiles can contribute to the understanding of the adverse effects of long-term exposure to low doses of DDVP.

Metabolomic analysis of the toxic effect of chronic low-dose exposure to acephate on rats using ultra-performance liquid chromatography/mass spectrometry

To study the toxic effect of chronic exposure to acephate at low-dose levels, a metabolomics approach based on ultra-performance liquid chromatography/mass spectrometry (UPLC-MS) was applied. Three different doses of 0.5 mg/kg/day, 1.5 mg/kg/day, and 4.5 mg/kg/day acephate were administered to Wistar rats for 24 weeks. Endogenous metabolite profiles were obtained with UPLC-MS for all rats at six time points after treatment. Some metabolites like dimethylthiophosphate and uric acid in urine were detected at week 4. Dimethylthiophosphate, which had the most significant elevations compared with other biomarkers, was considered as an early, sensitive biomarker of exposure to acephate. Moreover, there were some endogenous metabolite changes, which demonstrated that the doses of 1.5 mg/kg/day and 4.5 mg/kg/day of acephate led to renal injury and perturbed the normal metabolic processes of rats, including glucose, nucleic acid, and protein metabolism. A connection between exposure to acephate and the metabolic disturbance has been found and interpreted. Our study indicates that the metabolomics approach based on UPLC-MS of urine provides more information on toxicity than the conventional toxicological evaluation methods in measuring changes and can be considered as a promising technique for the study of the toxic effect of acephate.

Effects of long‐term exposure to low levels of organophosphorous pesticides and their mixture on altered antioxidative defense mechanisms and lipid peroxidation in rat liver

Organophosphorous pesticides, commonly used in agriculture for achieving better quality products, are toxic substances that have harmful effects on human health. Recent research on pesticides, especially pesticide mixtures, has shown that they are one of the key environmental health issues. The aim of the present study was to investigate whether dichlorvos, acephate, dimethoate and phorate, either used separately or in combination, can induce oxidative damage in rat livers. The levels of superoxide dismutase, glutathione peroxidase, catalase and lipid peroxidation products (malondialdehyde) were used as criteria. Low, middle and high doses of pesticides in drinking water were continuously administered orally to rats ad libitum for 24 weeks. Results show that the antioxidative defense mechanisms and lipid peroxidation in the rat livers display different responses, depending on the pesticide treatments and doses. The parameters for acephate, dichlorvos, phorate and dimethoate in the low‐dose group, and the corresponding low‐dose co‐treated group were not altered. The oxidative damage in rat livers showed different responses with increasing pesticide dose according to the different pesticide treatments. The combination group of dichlorvos, acephate, dimethoate and phorate displayed different responses compared with the single pesticide‐treated group. However, these responses did not constitute the sum of the response produced by each pesticide in the liver. Copyright

The toxicity of 3-chloropropane-1,2-dipalmitate in Wistar rats and a metabonomics analysis of rat urine by ultra-performance liquid chromatography–mass spectrometry

3-Monochloropropane-1,2-diol(3-MCPD) fatty acid esters can release free 3-MCPD in a certain condition. Free 3-MCPD is a well-known food contaminant and is toxicological well characterized, however, in contrast to free 3-MCPD, the toxicological characterization of 3-MCPD fatty acid esters is puzzling. In this study, toxicological and metabonomics studies of 3-chloropropane-1,2-dipalmitate(3-MCPD dipalmitate) were carried out based on an acute oral toxicity test, a 90-day feeding test and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. The LD50 value of 3-MCPD dipalmitate was determined to be 1780 mg/kg body weight (bw) for Wistar rats. The results of the 90-day feeding test in male Wistar rats showed that 3-MCPD dipalmitate caused a significant increase in blood urea nitrogen and creatinine in the high-dose group (267 mg/kg bw/day) compared to control rats. Renal tubular epithelium cell degeneration and renal tubular hyaline cast accumulation were the major histopathological changes in rats administered 3-MCPD dipalmitate. Urine samples obtained after the 90-day feeding test and analyzed by UPLC-MS showed that the differences in metabolic profiles between control and treated rats were clearly distinguished by partial least squares-discriminant analysis (PLS-DA) of the chromatographic data. Five metabolite biomarkers which had earlier and significant variations had been identified, they were first considered to be the early, sensitive biomarkers in evaluating the effect of 3-MCPD dipalmitate exposure, and the possible mechanism of these biomarkers variation was elucidated. The combination of histopathological examination, clinical chemistry and metabolomics analyses in rats resulted in a systematic and comprehensive assessment of the long-term toxicity of 3-MCPD dipalmitate.

Metabonomic analysis of quercetin against the toxicity of chronic exposure to low-level dichlorvos in rats via ultra-performance liquid chromatography–mass spectrometry

This study aims to determine whether quercetin elicits a protective effect against the toxicity of chronic exposure to low-level DDVP using metabonomic technology. Rats were randomly assigned into the control, DDVP-treated, quercetin-treated, and quercetin plus DDVP-treated groups. DDVP and quercetin were given to rats daily via drinking water and gavage respectively for 90 days. Eighteen metabolites, including the biomarkers of DDVP exposure (dimethyl phosphate, DMP) and quercetin exposure (quercetin and isorhamnetina), were identified from the metabonomic profiles of rat urine using ultra-performance liquid chromatography-mass spectrometry. Compared with the control group, the DDVP-treated group showed statistically significantly increased intensities of indoxyl sulfate, estrone sulfate, cholic acid, deoxycholic acid, p-cresol, p-cresol sulfate, and orotic acid but decreased intensities of suberic acid, citric acid, sebacic acid, hippuric acid, taurine, phosphocreatine, 3-hydroxyanthranilic acid, and kynurenic acid. The tendency of the aforesaid metabolites to change was significantly ameliorated in the quercetin (50mg/kg·bw) plus DDVP (7.2mg/kg·bw)-treated group compared with the DDVP-treated group. However, the levels of these metabolites in the quercetin plus DDVP-treated groups were still significantly different from those of the control group. These results indicate that quercetin has a partial protective effect on DDVP-induced toxicity.

Metabonomics evaluation of urine from rats administered with phorate under long-term and low-level exposure by ultra-performance liquid chromatography-mass spectrometry

The purpose of this study was to investigate the toxic effect of long‐term and low‐level exposure to phorate using a metabonomics approach based on ultra‐performance liquid chromatography‐mass spectrometry (UPLC‐MS). Male Wistar rats were given phorate daily in drinking water at low doses of 0.05, 0.15 or 0.45 mg kg–1 body weight (BW) for 24 weeks consecutively. Rats in the control group were given an equivalent volume of drinking water. Compared with the control group, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBIL), urea nitrogen (BUN) and creatinine (CR) were increased in the middle‐ and high‐dose groups whereas albumin (ALB) and cholinesterase (CHE) were decreased. Urine metabonomics profiles were analyzed by UPLC‐MS. Compared with the control group, 12 metabolites were significantly changed in phorate‐treated groups. In the negative mode, metabolite intensities of uric acid, suberic acid and citric acid were significantly decreased in the middle‐ and high‐dose groups, whereas indoxyl sulfic acid (indican) and cholic acid were increased. In the positive mode, uric acid, creatinine, kynurenic acid and xanthurenic acid were significantly decreased in the middle‐ and high‐dose groups, but 7‐methylguanine (N7G) was increased. In both negative and positive modes, diethylthiophosphate (DETP) was significantly increased, which was considered as a biomarker of exposure to phorate. In conclusion, long‐term and low‐level exposure to phorate can cause disturbances in energy‐related metabolism, liver and kidney function, the antioxidant system, and DNA damage. Moreover, more information can be provided on the evaluation of toxicity of phorate using metabonomics combined with clinical chemistry. Copyright

Effect of quercetin against mixture of four organophosphate pesticides induced nephrotoxicity in rats

Abstract 1. It has been demonstrated that the ingestion of foods containing quercetin protects against the toxicity of single pesticides. The aim of this study is to make a comprehensive elaboration about the protective effect of quercetin against multi-organophosphorous pesticides induced nephrotoxicity by measuring indices in rat kidney, urine and serum. Rats were divided into six groups (n = 10/group): control, two different doses of quercetin, pesticide mixture (PM), and different doses of quercetin plus PM-treated groups. 2. The following parameters were significantly changed in PM-treated groups compared with the control (p < 0.01). In kidney, malondialdehyde level raised; catalase, superoxide dismutase activities and glutathione levels were decreased. Comet assay of nephrocytes showed that the proportion of DNA in the tail and tail length increased. In urine, β2-microglobulin, retinol-conjugated protein levels and N-acetyl-β-d-glucosaminidase activity showed increasing response; meanwhile uric acid level was decreased. In serum, creatinine and urea nitrogen levels were increased. However, the anomaly changes of indexes mentioned above in PM-treated group were alleviated when simultaneously administrated with 50 mg/kg body weight/day quercetin (p < 0.05). 3. From the present findings, it can be evaluated that quercetin may protect against adverse effects resulted from multi-organophosphorous pesticides with significant high levels of uptake in man provided.