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

Lipidomics Analysis Explores the Mechanism of Renal Injury in Rat Induced by 3-MCPD

3-monochloropropane-1,2-diol (3-MCPD) is a food-process toxic substance, and its main target organ is the kidney. The present study examined and characterized the nephrotoxicity and the lipidomic mechanisms in a model of kidney injury in Sprague Dawley (SD) rats treated with high (45 mg/kg) and low (30 mg/kg) doses of 3-MCPD. The results showed that the ingestion of 3-MCPD led to a dose-dependent increase in serum creatinine and urea nitrogen levels and histological renal impairment. The oxidative stress indicators (MDA, GSH, T-AOC) in the rat kidney altered in a dose-dependent manner in 3-MCPD groups. The lipidomics analysis revealed that 3-MCPD caused kidney injury by interfering with glycerophospholipid metabolism and sphingolipid metabolism. In addition, 38 lipids were screened as potential biomarkers. This study not only revealed the mechanism of 3-MCPD renal toxicity from the perspective of lipidomics but also provided a new approach to the study of 3-MCPD nephrotoxicity.

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.

Ginsenoside Rb1 alleviates liver injury induced by 3-chloro-1,2-propanediol by stimulating autophagic flux

In recent years, foodborne pollutants have become a hot issue in the field of food safety. 3-chloro-1,2-propanediol (3-MCPD) is a widely existing food contaminant. In our previous study, it was confirmed that 3-MCPD can block autophagic flux by inhibiting lysosomal function, thus causing liver injury. Ginseng is a traditional Chinese herbal medicine that contains a variety of bioactive ingredients, among which ginsenoside Rb1 (Gs-Rb1) is the most abundant. In this study, we aim to use Gs-Rb1 to improve 3-MCPD-induced autophagic flux blockage to alleviate liver injury. First, a nontoxic dose of Gs-Rb1 was identified by screening with the MTT method in which Gs-Rb1was added to HepG2 cells and co-treated with 3-MCPD. We found that Gs-Rb1 effectively enhanced the cell activity inhibited by 3-MCPD. Meanwhile, apoptosis data showed that Gs-Rb1 significantly alleviated the apoptosis of HepG2 cells induced by 3-MCPD. Subsequently, we found that Gs-Rb1 could alleviate autophagic flux blockage caused by 3-MCPD in a dose-dependent manner by detecting autophagy-related protein levels and transfecting mRFP-GFP-LC3 adenovirus. On this basis, we used Western blotting and qPCR to explore whether miR-128 was involved in the alleviation effect of Gs-Rb1 on autophagic flux blockade induced by 3-MCPD. The results showed that Gs-Rb1 inhibited the expression of miR-128 and promoted the nuclear expression and target gene transcription of TFEB. Finally, the findings were confirmed by using a hsa-miR-128 inhibitor and mimic. We found that hsa-miR-128 inhibitor alleviated the autophagic flux blockage and apoptosis caused by 3-MCPD and Gs-Rb1 also had a certain alleviation effect on the autophagic flux blockage and apoptosis caused by hsa-miR-128 mimic. This study elaborated the mechanism by which Gs-Rb1 alleviates hepatotoxicity induced by foodborne 3-MCPD by stimulating autophagic flux via miR-128-targeted TFEB, which provides a reliable theoretical basis and target for the use of natural substances to reduce the harm of food processing pollutants on the human body. PRACTICAL APPLICATION: We found that natural ginsenoside Rb1 can alleviate liver injury induced by 3-MCPD(a toxic substance found in foods such as refined vegetable oil, soy sauce, and baby milk powder), which is conducive to the development and utilization of ginseng and has practical significance for the prevention of foodborne liver injury.

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.

3-Chloro-1, 2-propanediol inhibits autophagic flux by impairment of lysosomal function in HepG2 cells

3-chloro-1, 2-propanediol (3-MCPD) is a well-known contaminant that was produced in the thermal processing of food. Dietary intake represents the greatest source of exposure to 3-MCPD. Autophagy is an important catabolic pathway that plays an important role in liver physiological function. Evidence suggests that 3-MCPD exposure causes toxicity in liver, but the mechanism remains unknown. Here, we explored the effects of 3-MCPD on autophagic flux and traced the molecular mechanism in HepG2 cells. The data showed 3-MCPD exposure promoted the accumulation of autophagosomes in HepG2 cells. Subsequently, by detected te expression of LC3-Ⅱ and P62 and transfection of mRFP-GFP-LC3 adenovirus, we found that the accumulation of autophagosomes was caused by inhibition of autophagic flux. After that, we investigate lysosomal function and found that 3-MCPD induced lysosomal alkalinization. Further, we detected the expression of TFEB, which is a key nuclear transcription factor in control of lysosome biogenesis and function. We found that 3-MCPD inhibited the nuclear expression of TFEB and mRNA levels of some target genes of TFEB. In order to further verify the role of TFEB in autophagic flux blockage in HepG2 cells induced by 3-MCPD, we overexpressed TFEB by transfection with adenovirus and found that both autophagy inhibition and lysosomal alkalization induced by 3-MCPD were alleviated. These results suggested that 3-MCPD could induce the autophagic flux blockage in HepG2 cells. The possible mechanism was due to the destruction of lysosomal function.

Ninety-Day Nephrotoxicity Evaluation of 3-MCPD 1-Monooleate and 1-Monostearate Exposures in Male Sprague Dawley Rats Using Proteomic Analysis

Fatty acid esters of 3-monochloropropane 1,2-diol (3-MCPD esters) are processing-induced food toxicants, with the kidney as their major target organ. For the first time, this study treated Sprague Dawley (SD) rats with 3-MCPD 1-monooleate at 10 and 100 mg/kg BW/day and 1-monostearate at 15 and 150 mg/kg BW/day for 90 days and examined for their potential semi-long-term nephrotoxicity and the associated molecular mechanisms. No bodyweight difference was observed between groups during the study. Both 3-MCPD 1-monooleate and 1-monostearate resulted in a dose-dependent increase of serum urea creatinine, uric acid and urea nitrogen levels, and histological renal impairment. The proteomic analysis of the kidney samples showed that the 3-MCPD esters deregulated proteins involved in the pathways for ion transportation, apoptosis, the metabolism of xenobiotics, and enzymes related to endogenous biological metabolisms of carbohydrates, amino acids, nitrogen, lipids, fatty acids, and the tricarboxylic acid (TCA) cycle, providing partial explanation for the nephrotoxicity of 3-MCPD esters.

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.

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.