3-MCPD Dipalmitate Research Articles

Potential Biomarkers for Early Detection of 3-MCPD Dipalmitate Exposure in Sprague-Dawley Rats.

3-Chloro-1,2-propandiol (3-MCPD) dipalmitate is one of the major 3-MCPD esters formed during food processing. In this single-dose study, the metabonomic profile changes in the 48 h after orally administrated 3-MCPD dipalmitate at 1600 mg/kg BW to Sprague-Dawley (SD) rats were determined with liquid chromatography (LC) coupled with mass spectrometry (MS) system. The chemical structures of 12 potential biomarkers for 3-MCPD dipalmitate exposures early detection were detected and tentatively identified from the plasma of SD rats, including indoxyl sulfate, phenol sulfate, p-cresol sulfate, 2-phenylethanol glucuronide, p-cresol glucuronide, p-cresol, allantoin, phenylacetylglycine, pyrocatechol sulfate, phenyllactic acid, 5-hydroxyindoleacetic acid, and creatinine. Taking into account the metabolites identified from SD rats' kidney, liver, testes, and spleen samples, 3-MCPD dipalmitate might potentially disturb the phenylalanine, tryptophan, tyrosine, glycine, fatty acid, and purine metabolisms. The results suggested that the 12 plasma metabolites could be potentially applied in detecting the early exposures of 3-MCPD esters.

Toxicokinetics and Metabolism of 3-Monochloropropane 1,2-Diol Dipalmitate in Sprague Dawley Rats.

Fatty acid esters of 3-monochloropropane 1,2-diol (3-MCPD) are a group of processing-induced toxicants. To better clarify their possible toxicological effects and mechanisms, it is important to investigate their absorption, distribution, metabolism, and excretion. In this study, the kinetic parameters of 3-MCPD dipalmitate in Sprague Dawley (SD)rat plasma were determined using ultraperformance liquid chromatography-triplequadrupole mass spectrometry. 3-MCPD dipalmitate was absorbed in rats with a Cmax of 135.00 ng/mL, a T1/2 of 3.87 h, a Tmax of 2.5 h, an MRT of 5.08 h, a CL of 3.50 L/h/g, a Vd of 21.34 L/g, and an AUC0-∞ of 458.47 h·ng/mL. A total of 17 metabolites were identified, and 16 of them were reported for the first time. Furthermore, these metabolites were examined for their presences in the liver, kidney, testis, brain, spleen, thymus, intestine, plasma, feces, and urine samples 2, 6, 12, 24, and 48 h after oral administration of 3-MCPD dipalmitate using Metabolynx software.

An investigation of presence of 2- and 3-monochloropropanediol fatty acid esters in Canadian human milk samples

ABSTRACTOccurrence of 2- and 3-monochloropropanediol fatty acid esters (MCPDEs) in 199 human milk samples collected from Canadian women was examined in this study. MCPDEs were determined via indirect analytical approach by using acidic hydrolysis/transesterification and derivatization with cyclohexanone using a fluorinated sulfonic acid resin as a catalyst followed by GC-MS analysis. Analyses were done by a stable isotope dilution assay (SIDA) using 3-monochloropropanediol-d5 dipalmitate and 2-monochloropropanediol-d5 distearate as internal standards. In all samples 2-MCPD esters were not detected, at LOD = 1 ng/g for 2-MCPD equivalent. 3-MCPD esters were not detected, at LOD = 2 ng/g for 3-MCPD equivalent, in 193 samples. Six samples had the apparent concentration of 3-MCPD equivalent in the range of 2.0–5.1 ng/g, which was likely caused by accidental contamination during processing of samples. For selected samples, these findings were confirmed by direct analysis via LC-MS/MS analysis based on SIDA for 3-MCPD dipalmitate and 2-MCPD distearate. To our best knowledge, this is the first study to analyze human milk samples for 2-MCPD esters.

Suppression of T lymphocyte activation by 3-chloro-1,2-propanediol mono- and di-palmitate esters in vitro

This study investigated whether and how 3-chloro-1,2-propanediol (3-MCPD) fatty acid esters, a group of food contaminants formed during processing, might inhibit the immune system through suppressing T lymphocyte activation for the first time. Three 3-MCPD esters including 1-palmitoyl-3-chloropropanediol (1-pal), 2-palmitoyl-3-chloropropanediol (2-pal), and1,2-dipalmitoyl-3-chloropropanediol (dipal) were selected as the probe compounds to test the possible effects of fatty acid structure on their potential immune inhibitory effect. The results showed that 1-pal and 2-pal, but not dipal, significantly suppressed ConA-induced T lymphocyte proliferation, cell cycle activity, Th1 and Th2 cytokine secretion, CD4+ T cell populations, and the ratio of CD4+/CD8+ T cells under the experimental conditions. Moreover, Western blotting and immunofluorescence analyses revealed that 1-pal and 2-pal could inhibit the activation of ConA-stimulated mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. In addition, 1-pal significantly suppressed DNFB-induced delayed-type hyper sensitivity (DTH) reaction characterized by the increased ear thickness and IFN-γ production in mice. These observations indicated that 3-MCPD esters exerted a negative effect on T lymphocyte-mediated immunity, and the immunosuppressive activities of 3-MCPD monopalmitates were stronger than 3-MCPD dipalmitate.

Lanthanum chloride precipitation-based toxicoproteomic analysis of 3-monochloropropane-1,2-diol toxicity in rat kidney reveals involvement of extracellular signal-regulated kinase 2.

The heat-induced food contaminant 3-monochloropropane-1,2-diol (3-MCPD) and its fatty acid esters exert nephrotoxicity in rodents. Previous studies including a non-targeted toxicoproteomics approach using samples from a 28-day oral toxicity study in rats with 10mg/kg body weight (b.w.) of 3-MCPD, an equimolar dose of 53mg/kg b.w. 3-MCPD dipalmitate and a lower dose of 13.3mg/kg b.w. of 3-MCPD dipalmitate, revealed substance-induced alterations in metabolic pathways, especially for glycolysis and energy metabolism. In order to obtain deeper insight into mechanisms of 3-MCPD toxicity, samples from the above-mentioned study were reanalyzed using a lanthanum chloride precipitation-based toxicoproteomics approach in order to increase the yield of phosphorylated proteins, crucial players in cellular signaling. A comparison of standard 2D-gel-based proteomics and lanthanum chloride precipitation was performed, thus providing a comprehensive case study on these two methods using in vivo effects of an important food toxicant in a primary target organ. While resulting in similar 2D-gel electrophoresis pherograms and spot counts, data analysis demonstrated that lanthanum precipitation yielded more significantly deregulated proteins thus considerably improving our knowledge on 3-MCPD-dependent proteomic alterations in the kidney. 3-MCPD-induced deregulation of the phosphorylated, active version of extracellular signal-regulated kinase 2 (ERK2) in rat kidney was demonstrated using mass spectrometry and immunohistochemistry. In summary, this paper for the first time links 3-MCPD effects to deregulation of the ERK/mitogen-activated protein kinase signaling pathway in rat kidney and demonstrates that lanthanum chloride precipitation is suited to support the gain of mechanistic knowledge on organ toxicity using 2D-gel-based proteomics.

Analysis of 3-MCPD- and 3-MCPD dipalmitate-induced proteomic changes in rat liver

3-Monochloropropane-1,2-diol (3-MCPD) and 3-MCPD fatty acid esters are process contaminants in foodstuff which are generated during thermal treatment. Long-term exposure to 3-MCPD or 3-MCPD esters causes toxicity especially in kidney and testis. 3-MCPD esters are efficiently hydrolyzed in the gastrointestinal tract, suggesting that their toxicity is mediated by free 3-MCPD. Combined exposure to free 3-MCPD and 3-MCPD released from 3-MCPD esters might lead to dietary consumption above the tolerable daily intake of 2 μg/kg body weight/day. Suspected mechanisms of 3-MCPD toxicity include the inhibition of glycolysis and oxidative stress. Here, a comparative proteomic approach was followed to analyze the effects of 3-MCPD or 3-MCPD dipalmitate in livers from rats exposed to 10 mg/kg body weight 3-MCPD, an equimolar dose of 3-MCPD dipalmitate, or a 4-fold lower dose of the ester during a 28-day repeated-dose feeding study. Early cellular changes were monitored in the absence of overt toxicity. A comprehensive view of 3-MCPD- or 3-MCPD dipalmitate-triggered proteomic changes in rat liver links to previously proposed mechanisms of toxicity and substantially extends our knowledge on molecular hepatic effects of 3-MCPD. Organ-independent marker proteins altered upon 3-MCPD exposure, for example DJ-1/PARK7, were identified by comparison of the proteomic patterns of kidney, testis and liver.

Orally administered glycidol and its fatty acid esters as well as 3-MCPD fatty acid esters are metabolized to 3-MCPD in the F344 rat

IARC has classified glycidol and 3-monochloropropane-1,2-diol (3-MCPD) as group 2A and 2B, respectively. Their esters are generated in foodstuffs during processing and there are concerns that they may be hydrolyzed to the carcinogenic forms in vivo. Thus, we conducted two studies. In the first, we administered glycidol and 3-MCPD and associated esters (glycidol oleate: GO, glycidol linoleate: GL, 3-MCPD dipalmitate: CDP, 3-MCPD monopalmitate: CMP, 3-MCPD dioleate: CDO) to male F344 rats by single oral gavage. After 30 min, 3-MCPD was detected in serum from all groups. Glycidol was detected in serum from the rats given glycidol or GL and CDP and CDO in serum from rats given these compounds. In the second, we examined if metabolism occurs on simple reaction with rat intestinal contents (gastric, duodenal and cecal contents) from male F344 gpt delta rats. Newly produced 3-MCPD was detected in all gut contents incubated with the three 3-MCPD fatty acid esters and in gastric and duodenal contents incubated with glycidol and in duodenal and cecal contents incubated with GO. Although our observation was performed at 1 time point, the results showed that not only 3-MCPD esters but also glycidol and glycidol esters are metabolized into 3-MCPD in the rat.

Proteomic analysis of 3-MCPD and 3-MCPD dipalmitate-induced toxicity in rat kidney.

3-Chloropropane-1,2-diol (3-MCPD) and its fatty acid esters are formed during thermal treatment of fat-containing foodstuff in the presence of salt. Toxicological studies indicate a carcinogenic potential of 3-MCPD, pointing to the kidney as the main target organ. It is assumed that the toxicological property of 3-MCPD esters is constituted by the release of 3-MCPD during digestion. In a repeated-dose 28-day oral toxicity study using Wistar rats, animals were treated with equimolar doses of either 3-MCPD (10mg/kg body weight) or 3-MCPD dipalmitate (53mg/kg body weight). A lower dose of 3-MCPD dipalmitate (13.3mg/kg body weight) was also applied. No histopathologically visible toxicity was observed in the study. To address molecular mechanisms leading to toxicity of 3-MCPD and its esters, kidney samples were analyzed by a comparative, two-dimensional gel electrophoresis/mass spectrometry proteomic approach. After either 3-MCPD or 3-MCPD dipalmitate treatment, alterations in proteins related to various metabolic pathways, including carbohydrate, amino acid, and fatty acid metabolism, were detected. These findings confirm and complement previous data on the inhibition of glucose metabolism by 3-MCPD. Altogether, broad overlap of 3-MCPD- and 3-MCPD dipalmitate-induced proteomic changes was observed. Further analyses revealed that the observed induction of glutathione S-transferase pi 1 (Gstp1) occurred at the transcriptional level and was not related to nuclear factor (erythroid-derived 2)-like 2 activation. Overall, the results indicate common mechanisms of toxicity for 3-MCPD and its dipalmitate ester. Furthermore, data suggest Gstp1 as a sensitive marker for early 3-MCPD-induced effects in rat kidney.

Proteomic analysis of 3-MCPD and 3-MCPD dipalmitate toxicity in rat testis

Thermal treatment of foodstuff containing fats and salt promotes the formation of 3-chloropropane-1,2-diol (3-MCPD) and its fatty acid esters. 3-MCPD-exposed rats develop testicular lesions and Leydig cell tumors. 3-MCPD and 3-MCPD ester toxicity is thought to be caused by 3-MCPD and its metabolites, since 3-MCPD esters are hydrolyzed in the gut. Inhibition of glycolysis is one of the few known molecular mechanisms of 3-MCPD toxicity. To obtain deeper insight into this process, a comparative proteomic approach was chosen, based on a 28-days repeated-dose feeding study with male Wistar rats. Animals received equimolar doses of 3-MCPD or 3-MCPD dipalmitate. A lower dose of 3-MCPD dipalmitate was also administered. Absence of histopathological changes supported an analysis of early cellular disturbance. Testes were analyzed by two-dimensional gel electrophoresis followed by mass-spectrometric protein identification. Data provide a comprehensive overview of proteomic changes induced by 3-MCPD and 3-MCPD dipalmitate in rat testis in an early phase of organ impairment. Results are compatible with known 3-MCPD effects on reproductive function, substantially extend our knowledge about cellular responses to 3-MCPD and support the hypothesis that toxicity of 3-MCPD and 3-MCPD esters is mediated via common effectors. DJ-1 was identified as a candidate marker for 3-MCPD exposure.

Study on the thermal degradation of 3-MCPD esters in model systems simulating deodorization of vegetable oils

The establishment of effective strategies for the mitigation of 3-MCPD esters in refined vegetable oils is restricted by limited knowledge of their mechanisms of formation and decomposition. In order to gain better understanding on the thermal stability of these compounds, a model system for mimicking oil refining conditions was developed. Pure 3-MCPD esters (3-MCPD dipalmitate and 3-MCPD dilaurate) were subjected to thermal treatment (180–260°C) and the degradation products where monitored over time (0–24h). After 24h of treatment, both 3-MCPD esters showed a significant degradation (ranging from 30% to 70%), correlating with the temperature applied. The degradation pathway, similar for both compounds, was found to involve isomerisation (very rapid, equilibrium was reached within 2h at 260°C), dechlorination and deacylation reactions. The higher relative abundance of non-chlorinated compounds, namely acylglycerols, in the first stages of the treatment suggested that dechlorination is preferred over deacylation with the conditions applied in this study.

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 1780mg/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 (267mg/kgbw/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.

Acute oral toxicity of 3-MCPD mono- and di-palmitic esters in Swiss mice and their cytotoxicity in NRK-52E rat kidney cells

The acute oral toxicity of 1-palmitoyl-3-chloropropanediol (3-MCPD 1-monopalmitate) and 1,2-bis-palmitoyl-3-chloropropanediol (3-MCPD dipalmitate) in Swiss mice were examined, along with their cytotoxicity in NRK-52E rat kidney cells. LD50 (median lethal dose) value of 3-MCPD 1-monopalmitate was determined 2676.81mg/kg body weight (BW). The results showed that 3-MCPD 1-monopalmitate dose-dependently decreased the mean body weight, and caused significant increase of serum urea nitrogen and creatinine in dead mice compared to the control and survived mice. Major histopathological changes in mice fed 3-MCPD 1-monopalmitate were renal tubular necrosis, protein casts and spermatids decrease in the seminiferous tubules. According to the limit test for 3-MCPD dipalmitate, LD50 value of 3-MCPD dipalmitate was presumed to be greater than 5000mg/kg BW. Obvious changes were not observed on mean body weight, absolute and relative organ weight or serum urea nitrogen and creatinine levels in mice fed 3-MCPD dipalmitate. However, renal tubular necrosis, protein casts and spermatids decrease were also observed in the dead mice. In addition, MTT and LDH assay results only showed the cytotoxicity of 3-MCPD 1-monopalmitate in NRK-52E rat kidney cells in a dose-dependent manner. Together, the results indicated a greater toxicity of 3-MCPD 1-monopalmitate compared to 3-MCPD dipalmitate.

Fatty acid esters of 3-chloropropane-1,2-diol in edible oils

A series of 25 virgin and refined edible oils, obtained from retailers, was analyzed for levels of free 3-chloropropane-1,2-diol (3-MCPD) and 3-MCPD released from esters with higher fatty acids (bound 3-MCPD). Oils containing free 3-MCPD ranging from <3 µg kg−1 (LOD) to 24 µg kg−1. Surprisingly, bound 3-MCPD levels were much higher and varied between <100 (LOD) and 2462 µg kg−1. On average, virgin oils had relatively low levels of bound 3-MCPD, ranging from <100 (LOD) to <300 µg kg−1 (LOQ). Higher levels of bound 3-MCPD were found in oils from roasted oilseeds (337 µg kg−1) and in the majority of refined oils (<300–2462 µg kg−1), including refined olive oils. In general, it appears that the formation of bound 3-MCPD in oils is linked to preliminary heat treatment of oilseeds and to the process of oil refining. Analysis of unrefined, de-gummed, bleached, and deodorized rapeseed oil showed that the level of bound MCPD decreased during the refining process. However, additional heating of seed oils for 30 min at temperatures ranging from 100 to 280°C, and heating at 230°C (260°C) for up to 8 h, led to an increase in bound 3-MCPD levels. On the other hand, heating of olive oil resulted in a decrease in bound 3-MCPD levels. For comparison, fat isolated from salami was analyzed for intact fatty acid esters of 3-MCPD. This fat contained bound 3-MCPD at a level of 1670 µg kg−1 and the fatty acid esters of 3-MCPD mainly consisted of 3-MCPD diesters; monoesters of 3-MCPD were present in smaller amounts. The major types of 3-MCPD diesters (about 85%) were mixed diesters of palmitic acid with C18 fatty acids (stearic, oleic, linoleic acids). These diesters were followed by 3-MCPD distearate (11%) and 3-MCPD dipalmitate (4%). Generally, very little 3-MCPD existed as the free compound (31 µg kg−1).