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

Newly discovered developmental and ovarian toxicity of 3-monochloro-1,2-propanediol in Drosophila melanogaster and cyanidin-3-O-glucoside's protective effect

3-Monochloro-1,2-propanediol (3-MCPD) is a pervasive environmental pollutant that is unintentionally produced during industrial production and food processing. Although some studies reported the carcinogenicity and male reproduction toxicity of 3-MCPD thus far, it remains unexplored whether 3-MCPD hazards to female fertility and long-term development. In this study, the model Drosophila melanogaster was employed to evaluate risk assessment of emerging environmental contaminants 3-MCPD at various levels. We found that flies on dietary exposure to 3-MCPD incurred lethality in a concentration- and time-dependent way and interfered with metamorphosis and ovarian development, resulting in developmental retardance, ovarian deformity and female fecundity disorders. Mechanistically, 3-MCPD caused redox imbalance observed as a drastically increased oxidative status in ovaries, confirmed by increased reactive oxygen species (ROS) and decreased antioxidant activities, which is probably responsible for female reproductive impairments and developmental retardance. Intriguingly, these defects can be substantially prevented by a natural antioxidant, cyanidin-3-O-glucoside (C3G), further confirming a critical role of ovarian oxidative damage in the developmental and reproductive toxicity of 3-MCPD. The present study expanded the findings that 3-MCPD acts as a developmental and female reproductive toxicant, and our work provides a theoretical basis for the exploitation of a natural antioxidant resource as a dietary antidote for the reproductive and developmental hazards of environmental toxicants that act via increasing ROS in the target organ.

Occurrence and risk assessment of 3-monochloropropanediols esters (3-MCPDE), 2-monochloropropanediol esters (2-MCPDE), and glycidyl esters (GE) in commercial infant formula samples from Malaysia

The presence of 3-monochloropropanediol esters (3-MCPDE), 2-monochloropropanediol esters (2-MCPDE) and glycidyl esters (GE) in infant formula products has raised serious concerns. They incorporate vegetable oils, particularly palm-based oils, which are well-known to contain large amounts of these process contaminants. An analysis was conducted on infant formula samples (n = 16) obtained from the Malaysian market to determine the levels of 3-MCPDE, 2-MCPDE and GE using gas chromatography-mass spectrometry (GC-MS). The method was validated, with a limit of quantification (LOQ) on instrument of 0.10 µg/g for all analytes. The median concentrations of 3-MCPDE, 2-MCPDE and GE in infant formula in this study were 0.008 µg/g, 0.003 µg/g and 0.002 µg/g respectively. The estimated dietary intakes calculated from consumption of infant formula show higher exposures to infants within the age group of 0 to 5 months, highest for GE (1.61 µg/kg bw/day), followed by 3-MCPDE (0.68 µg/kg bw/day) and 2-MCPDE (0.41 µg/kg bw/day) compared to the age group of 6 to 12 months. Only one sample, relating to GE exposure is a potential risk for both age groups with MOE value below 25,000.

Bibliometric Analysis of Research Trends on 3-Monochloropropane-1,2-Diol Esters in Foods

3-Monochloropropane-1,2-diol esters (3-MCPDE) are common food contaminants mainly formed in the edible oil refining process. Due to their potential hazards, 3-MCPDE has become a widespread food safety concern. In this study, CiteSpace and VOSviewer were used to conduct a bibliometric analysis on the 3-MCPDE research papers collected in the Web of Science Core Collection from 1998 to 2022. The results showed that the number of research publications on 3-MCPDE has increased rapidly since 2010. Analysis of the hotspots in 3-MCPDE studies showed that more attention has been paid to the exposure assessment, formation mechanism, detection methods, mitigation methods and toxicity, and toxicology of 3-MCPDE. Finally, the future trends of research on 3-MCPDE were analyzed and proposed. The mitigation methods and toxicology studies of 3-MCPDE are still the research hotspots in the future. In addition, nutritional intervention for 3-MCPDE toxicity will be an emerging trend.

Methods, principles, challenges, and perspectives of determining chloropropanols and their esters

Chloropropanols and their esters are a group of food contaminants that have various toxicities to the human body. Research and control to chloropropanols and their esters is important to food safety. Therefore, the sensitive, accurate, precise, and effective determination of chloropropanols and their esters is highly essential to study their concentration, formation, and mitigation. The indirect method, commonly applied in the determination of chloropropanols and their esters, is based on the cleavage of ester bond, extraction, and derivatization. The conventional indirect method will still be the mostly used method in the near future due to its good sensitivity and feasibility, although its parameters need to be chosen and optimized according to sample stuffs and chloropropanol concentrations. Meanwhile, direct method and other quantitative methods should also be developed for special applications, such as studying the profile of chloropropanol esters and rapid screening protocol. The challenges and future perspectives of these methods are discussed in this review. This review can provide a reference on the selection, designation, and modification of methods for determining chloropropanols and their esters.

Associations of 3-monochloropropane-1,2-diol and glycidol with prevalence of metabolic syndrome: Findings from Lanxi Nutrition and Safety Study

In this study, we investigated the association of 2,3-dihydroxypropyl mercapturic acid (DHPMA), a urinary biomarker of environmental and dietary exposure to 3-monochloropropane-1,2-diol and glycidol, with prevalent MetS in a Chinese middle-aged and elderly population. The urinary DHPMA concentrations were determined by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis and further calibrated by the urinary creatinine content. MetS cases were defined by the Adult Treatment Panel III criteria for Asian-Americans of National Cholesterol Education Program (NCEP/ATPIII). Multivariate-adjusted modified Poisson regression models were used to analyze the associations between the urinary DHPMA concentrations and MetS prevalence. Of the 1613 participants aged 45-75 years, we documented 552 (34.2%) MetS cases. After adjustment for potential risk factors, the relative risks (95% confidence intervals) of MetS prevalence across the increasing quartiles of DHPMA concentrations were 1.14 (0.93-1.39), 1.29 (1.06-1.56), and 1.50 (1.25-1.80), respectively, compared with the lowest quartile. We also observed strong positive association between urinary DHPMA concentrations and hypertriglyceridemia prevalence (P < 0.001 for trend). These positive associations remained unchanged in the subgroups stratified by general demographic, dietary and behavioral risk factors. These results suggested that urinary DHPMA was associated with higher prevalence of MetS among Chinese elderly people.

Apoptosis is induced by sub-acute exposure to 3-MCPD and glycidol on Wistar Albino rat brain cells

3-chloropropane-1,2-diol (3-MCPD) and its toxic metabolite glycidol were classified by the International Agency for Research on Cancer (IARC) as belonging to group 2B and 2A for humans. This study aimed to determine the sub-acute toxicity of these agents. Rats were exposed to 3-MCPD at 0.87 and 10 mg/kg/bw and glycidol (2,4 and 37,5 mg/kg/bw) for 90 days. miR-21 gene expression levels significantly decreased in all group's cerebellar tissues compared with control. Exposure to 10 mg/kg/bw 3-MCPD showed significant increases in PTEN in brain as compared to control group. The Akt gen expressions were significantly decreased in 3-MCPD and glycidol groups when compared to control group brains. Additionally, Caspase 3 and AIF immunopositivity significantly increased in 3-MCPD high dose and glycidol high dose groups in cerebellum granular layers compared to control. The results of the present study conclude that 3-MCPD and glycidol can induce apoptosis in rat brain tissue.

Investigation of factors influencing the release of chloropropanols (3-MCPD and 1,3-DCP) from food contact paper

Chloropropanols such as 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) have drawn increasing attention due to their release from food contact paper and their potential carcinogenic effects. In this study, the effects were investigated of water extraction conditions on release of chloropropanols from food contact paper, and the extraction efficiencies of chloropropanols by water extract and migration method were compared. Cold water was found to be more severe than hot water for extraction of chloropropanols, with the highest water extraction value obtained at 23°C. Two hours of extraction was sufficient as the chloropropanols can be fully extracted from food contact paper within a short period of time. Increase of temperature in the range of 10°C-60°C had little impact on release of chloropropanols, however, the extraction of chloropropanols decreased when high temperatures (80°C or above) were applied due to volatilisation losses. Hence, attention should be paid when choosing extract conditions representing the worst-case scenario. The water extraction value using EN 645 method gives higher results compared to migration test described in GB 31604.1 and GB 5009.156, suggesting that the water extract method was probably more severe. For migration test, aqueous-based simulants were found to be more conservative than oil-based simulants, suggesting the conventional experiment conditions applicable for compliance test of chloropropanols migration can be simplified and optimised.

Dietary exposure to fatty acid esters of monochloropropanediols and glycidol of 2- to 3-year-old children attending nursery schools from two areas in China using the duplicate-diet collection method

The dietary exposures to fatty esters of 3- and 2-monochloropropanediol (MCPD) and glycidol were estimated for children aged 2- to 3-year-old from two areas of China using duplicate diet collection method. The 24-h daily duplicate diet samples over three consecutive days were collected from 40 healthy children aged between 26 and 36 months. The analysis of these contaminates in food samples was measured by an indirect method that entails MCPD/glycidol cleavage from their esterified forms for GC-MS analysis. Over 71% of the mixed diet and dairy products samples were found to be contaminated with 3-MCPD and glycidyl esters. The estimated daily exposure to bound 3-MCPD (mean: 0.48-0.49 μg kg^-1 bw day^-1; P95: 1.00-1.11 μg kg^-1 bw day^-1) were well below the health guidance values and were considered of low safety concern. The daily exposure to bound 2-MCPD was estimated to be 0.031-0.038 μg kg^-1 bw day^-1 on average and 0.12-0.14 μg kg^-1 bw day^-1 for the P95 exposure. However, it was not possible to assess its risk due to the lack of health guidance value of 2-MCPD. The margin of exposure (MOE) estimates for the mean exposure to bound glycidol (0.10-0.12 μg kg^-1 bw day^-1) were far above 10000 and were considered of low safety concern. However, the margin of exposure estimates for the P95 bound glycidol exposure (0.41-0.45 μg kg^-1 bw day^-1) were below 10000 and indicated a health concern. Our data indicated that the mixed diet accounted for nearly 76% to 91% of bound MCPD and glycidol exposure. In addition, the follow-on formula was also an important source for the children aged 2-3 years.

Fatty Acid Esters of 3-Monochloropropanediol: A Review

Fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD esters) are a new group of processing-induced chemical toxicants with possible nephrotoxicity and testicular toxicity. 3-MCPD esters have been detected in many food categories, including refined edible oils, bread, coffee, and infant formula. 3-MCPD esters have also been detected in human breast milk, indicating their possible absorption and distribution in human organs and tissues. 3-MCPD esters have become a food safety concern, and in 2013 the European Food Safety Authority estimated a tolerable daily value (TDI) of 2 μg/kg body weight (BW) for the amount of free 3-MCPD. This review summarizes the available information on 3-MCPD ester research, including the analytical methods, exposure biomarkers, absorption and metabolism, toxicities, formation mechanisms, and mitigation strategies as well as the occurrence of 3-MCPD esters in human foods. This review may serve as a scientific foundation for advancing our understanding of 3-MCPD esters and their food safety concerns.

Proteomic effects of repeated-dose oral exposure to 2-monochloropropanediol and its dipalmitate in rat testes

2- and 3-monochloropropanediol (2-MCPD) and their fatty acid esters are food contaminants which are concomitantly formed upon thermal treatment of foodstuff containing fats and salt. Exposure to 2- or 3-MCPD thus results, for example, from refined vegetable oils, in instant meals or infant formula, as well as in cereals or pastries. The molecular mechanisms of 2-MCPD toxicity are poorly understood. Here, we performed a comprehensive proteomic analysis of 2-MCDP-induced alterations in the testes from rats following oral administration of 10 mg/kg body weight per day 2-MCPD, or an equimolar dose of 2-MCPD dipalmitate as a representative 2-MCPD fatty acid ester. In the absence of overt histopathologically detectable toxicity, moderate alterations in cellular proteomic signatures were recorded. The observations are in line with the assumption that the molecular mechanisms of 2-MCPD and 3-MCPD toxicity differ. Observed proteomic alterations point towards effects of 2-MCPD on mitogen-dependent signaling and mitochondrial energy utilization. Presented data for the first time provide insight into proteomic effects of 2-MCPD in testicular tissue.

Update of the risk assessment on 3-monochloropropane diol and its fatty acid esters

The CONTAM Panel updated the assessment of the risks for human health related to the presence of 3-monochloropropane diol (3-MCPD) and its fatty acid esters in food published in 2016 in view of the scientific divergence identified in the establishment of the tolerable daily intake (TDI) in the Joint FAO/WHO Expert Committee on Food Additives and Contaminants (FAO/WHO) report published in 2017. In this update, dose-response analysis was performed following the recent EFSA Scientific Committee guidance on the use of benchmark dose (BMD) approach in risk assessment, and a review of available data on developmental and reproduction toxicity was included. The outcome of this review indicates that in rats short-term exposure to 3-MCPD above 1 mg/kg body weight (bw) per day can induce reduced sperm motility associated with reduced male fecundity. Decreased sperm count and histopathological changes in the testis and epididymis were observed following longer treatment periods at higher doses. Regarding increased incidence kidney tubular hyperplasia, BMD analysis using model averaging resulted in a BMDL 10 of 0.20 mg/kg bw per day in male rats, which was selected as the new Reference Point (RP) for renal effects. For the effects on male fertility, decreased sperm motility was selected as the most sensitive relevant endpoint and a BMDL 05 of 0.44 mg/kg bw per day was calculated. The RP for renal effects was considered to derive an updated group TDI of 2 μg/kg bw per day for 3-MCPD and its fatty acid esters and was considered protective also for effects on male fertility. The established TDI of 2 μg/kg bw per day is not exceeded in the adult population. A slight exceedance of the TDI was observed in the high consumers of the younger age groups and in particular for the scenarios on infants receiving formula only.

Absorption, Distribution, Metabolism and Excretion of 3-MCPD 1-Monopalmitate after Oral Administration in Rats

Fatty acid esters of monochloropropane 1,2-diol (3-MCPD) are processing-induced toxicants and have been detected in several food categories. This study investigated the absorption, distribution, metabolism, and excretion of 3-MCPD esters in Sprague-Dawley (SD) rats using 3-MCPD 1-monopalmitate as the probe compound. The kinetics of 3-MCPD 1-monopalmitate in plasma was investigated using SD rats, and the results indicated that 3-MCPD 1-monopalmitate was absorbed directly in vivo and metabolized. Its primary metabolites in the liver, kidney, testis, brain, plasma, and urine were tentatively identified and measured at 6, 12, 24, and 48 h after oral administration. Structures were proposed for eight metabolites. 3-MCPD 1-monopalmitate was converted to free 3-MCPD, which formed the phase II metabolites. All of the metabolites were chlorine-related chemical components; most of them existed in urine, reflecting the excretion pattern of 3-MCPD esters. Understanding the metabolism of 3-MCPD esters in vivo is critical for assessing their toxicities.

Palm oil and threats to a critically important food source

The oil palm, an ancient tropical tree species that originated in West Africa, has a history of centuries-long use both as a food and a medicine. Based on its higher saturated fatty acid composition, primarily palmitic acid, concerns have been flagged about its nutritional attributes. Elevation of low-density lipoprotein cholesterol effects of the associated palmitic acid is far less profound than animal sources of this fatty acid and is linked with multiple health benefits. Recently, the European Food Safety Authority raised issues about potential health risks of the chloropropanols, heat- or acid-induced food contaminants created during the refining of all edible oils, and some hydrolyzed proteins. Despite the fact that the levels of 3-monochloropropane1,2 diol and its glycidyl esters are generally <800 ppb and without demonstrated toxicological effects in humans, the chloropropanols in palm oil appear to be a lightning rod for global criticism. The toxicological data are reviewed and evaluated, and an approach for mitigation of the emerging challenge is suggested.

Comparative proteomic data of M13SV1 human breast epithelial cells and their tumorigenic variants under treatment with estrogenic compounds

Data from a comparative proteomic analysis of three human breast epithelial cell lines are presented. M13SV1 cells and their tumorigenic derivatives M13SV1-R2-2 and M13SV1-R2-N1 were used. Proteomic data were obtained using 2-dimensional gel electrophoresis and subsequent identification of proteins by MALDI-TOF mass spectrometry. In a second experiment, the three cell lines were treated with different concentrations of the estrogenic compounds β-estradiol or genistein and alterations in protein expression were monitored by 2-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. Presented data provide a comprehensive overview of proteomic differences between the three cell lines and their response to estrogenic stimulation.