Transport of selenium species in Caco-2 cells: Analytical approach employing the Ussing chamber technique and HPLC-ICP-MS

The Bioaccessibility and Bioavailability of Pentachlorophenol in Five Animal-Derived Foods Measured by Simulated Gastrointestinal Digestion

Pentachlorophenol (PCP) is a ubiquitous emerging persistent organic pollutant detected in the environment and foodstuffs. Despite the dietary intake of PCP being performed using surveillance data, the assessment does not consider the bioaccessibility and bioavailability of PCP. Pork, beef, pork liver, chicken and freshwater fish Ctenopharyngodon Idella-fortified by three levels of PCP were processed by RIVM and the Caco-2 cell model after steaming, boiling and pan-frying, and PCP in foods and digestive juices were detected using isotope dilution-UPLC-MS/MS. The culinary treatment and food matrix were significantly influenced (p < 0.05) in terms of the bioaccessibility and bioavailability of PCP. Pan-frying was a significant factor (p < 0.05) influencing the digestion and absorption of PCP in foods, with the following bioaccessibility: pork (81.37-90.36%), beef (72.09-83.63%), pork liver (69.11-78.07%), chicken (63.43-75.52%) and freshwater fish (60.27-72.14%). The bioavailability was as follows: pork (49.39-63.41%), beef (40.32-53.43%), pork liver (33.63-47.11%), chicken (30.63-40.83%) and freshwater fish (17.14-27.09%). Pork and beef with higher fat content were a key factor in facilitating the notable PCP bioaccessibility and bioavailability (p < 0.05). Further, the exposure of PCP to the population was significantly reduced by 42.70-98.46% after the consideration of bioaccessibility and bioavailability, with no potential health risk. It can improve the accuracy of risk assessment for PCP.

Refining health risk assessment of arsenic in wild edible boletus from typical high geochemical background areas: The role of As species, bioavailability, and enterotoxicity

Arsenic (As) is easily accumulated in wild Boletus. However, the accurate health risks and adverse effects of As on humans were largely unknown. In this study, we analyzed the total concentration, bioavailability, and speciation of As in dried wild boletus from some typical high geochemical background areas using an in vitro digestion/Caco-2 model. The health risk assessment, enterotoxicity, and risk prevention strategy after consumption of As-contaminated wild Boletus were further investigated. The results showed that the average concentration of As was 3.41-95.87 mg/kg dw, being 1.29-56.3 folds of the Chinese food safety standard limit. DMA and MMA were the dominant chemical forms in raw and cooked boletus, while their total (3.76-281 mg/kg) and bioaccessible (0.69-153 mg/kg) concentrations decreased to 0.05-9.27 mg/kg and 0.01-2.38 mg/kg after cooking. The EDI value of total As was higher than the WHO/FAO limit value, while the bioaccessible or bioavailable EDI suggested no health risks. However, the intestinal extracts of raw wild boletus triggered cytotoxicity, inflammation, cell apoptosis, and DNA damage in Caco-2 cells, indicating existing health risk assessment models based on total, bioaccessible, or bioavailable As may be not accurate enough. Given that, the bioavailability, species, and cytotoxicity should be systematically considered in accurate risk assessment. In addition, cooking mitigated the enterotoxicity along with decreasing the total and bioavailable DMA and MMA in wild boletus, suggesting that cooking could be a simple and effective way to decrease the health risks of consumption of As-contaminated wild boletus.

Metabolism and Anticancer Mechanisms of Selocompounds: Comprehensive Review

Selenium (Se) is an essential micronutrient with several functions in cellular and molecular anticancer processes. There is evidence that Se depending on its chemical form and the dosage use could act as a modulator in some anticancer mechanisms. However, the metabolism of organic and inorganic forms of dietary selenium converges on the main pathways. Different selenocompounds have been reported to have crucial roles as chemopreventive agents, such as antioxidant activity, activation of apoptotic pathways, selective cytotoxicity, antiangiogenic effect, and cell cycle modulation. Nowadays, great interest has arisen to find therapies that could enhance the antitumor effects of different Se sources. Herein, different studies are reported related to the effects of combinatorial therapies, where Se is used in combination with proteins, polysaccharides, chemotherapeutic agents or as nanoparticles. Another important factor is the presence of single nucleotide polymorphisms in genes related to Se metabolism or selenoprotein synthesis which could prevent cancer. These studies and mechanisms show promising results in cancer therapies. This review aims to compile studies that have demonstrated the anticancer effects of Se at molecular levels and its potential to be used as chemopreventive and in cancer treatment.

Bioaccessibility and bioavailability adjusted dietary exposure of cadmium for local residents from a high-level environmental cadmium region

The critical health risks caused by cadmium (Cd) via dietary exposure are commonly assessed by detecting Cd concentrations in foods. Differently, in this study, the bioaccessibility and bioavailability of Cd in major local harvests were introduced to assess the dietary exposure of local residents from a high-level environmental Cd region. The results indicated that certain Cd was released into the digestive juice after in vitro digestion with a bioaccessibility of 20-63% for rice and 3-32% for leafy vegetables, and the released portion was partially absorbed by Caco-2 cells with a bioavailability of 2-21% for rice and 0.2-13% for leafy vegetables. The results obtained from the toxicokinetic model revealed that the predicted urinary Cd values from the estimated daily intake (EDI) of Cd, which accounted for bioaccessibility and bioavailability, were consistent with the actual measured values, and the EDIs were considerably lower than the acceptable daily intake. This suggests that the bioaccessibility and bioavailability adjusted dietary Cd exposure should be more precise. The key issues addressed in our study implores that a potential health risk cannot be neglected in people with high consumption of rice from high-level zone.

Compilation of selenium metabolite data in selenized yeasts

Selenium-enriched yeast has long been recognized as an important nutritional source of selenium and studies have suggested that supplementation with this material provides chemo-preventative benefits beyond those observed for selenomethionine supplementation, despite the fact that selenomethionine accounts for 60-84% of the total selenium in selenized yeasts. There is much ongoing research into the characterization of the species comprising the remaining 16-40% of the selenium, with nearly 100 unique selenium-containing metabolites identified in aqueous extracts of selenized yeasts (Saccharomyces cerevisiae). Herein, we discuss the analytical approaches involved in the identification and quantification of these metabolites, and present a recently created online database (DOI: 10.4224/40001921) of reported selenium species along with chemical structures and unique mass spectral features.

Intestinal Drug Absorption Enhancement by Aloe vera Gel and Whole Leaf Extract: In Vitro Investigations into the Mechanisms of Action

The co-administration of absorption enhancing agents with macromolecular drugs (e.g., protein and peptide drugs) has been identified as a means to improve the oral bioavailability of these drugs. Absorption-enhancing agents of natural origins have received a great deal of attention due to their sustainable production, in support of green chemistry. In previous studies, certain parts of the Aloe vera leaf (e.g., gel and whole leaf extract) have shown a potential to enhance drug permeation across the intestinal epithelial barrier. The mechanism of the drug-absorption-enhancement action and the capacity for absorption-enhancement of the A. vera gel and whole leaf, were investigated in this study. A clear decrease in transepithelial electrical resistance (TEER) of Caco-2 cell monolayers exposed to A. vera gel and wholeleaf extract, in various concentrations, indicated the opening of tight junctions between the epithelial cells. The transport of Fluorescein isothiocyanate (FITC)-dextran, with a molecular weight of 4 kDa (FD-4), could be enhanced across the Caco-2 cell monolayers, by the A. vera gel and whole-leaf extract, but not the FITC-dextran with larger molecular weights (i.e., 10, 20, and 40 kDa), which indicated a limited drug absorption enhancement capacity, in terms of the molecular size. Accumulation of FD-4 between the Caco-2 cells (and not within the cells), after treatment with the A. vera gel and whole-leaf extract was shown with a confocal laser scanning microscopy (CLSM) imaging, indicating that the paracellular transport of FD-4 occurred after the interaction of the A. vera gel and whole-leaf extract, with the epithelial cell monolayers. Furthermore, changes in the F-actin distribution in the cytoskeleton of the Caco-2 cell monolayers was observed by means of a fluorescence staining, which confirmed tight junction modulation as the mechanism of action for the absorption enhancement effect of the A. vera gel and whole-leaf extract.

Assessment of the effect of cooking on speciation and bioaccessibility/cellular uptake of arsenic in rice, using in vitro digestion and Caco-2 and PSI cells as model

In vitro digestion/Caco-2 or pig small intestinal epithelium cell line (PSI) uptake models were used to study the bioaccessibility and cellular uptake of arsenic (As) in cooked white rice and brown rice. The arsenite(AsIII), was the predominant species in cooked rice and in its bioaccessible fractions. The percentage of total As bioaccessibility in white rice (75%) was slightly higher (p=0.061) than that in brown rice(66%). However, there was no difference in the inorganic As (iAs) bioaccessibility between white rice (95%) and brown rice (96%). In Caco-2 cell monolayer, total As retention was 7-31%, transport was 4-25%, and uptake (sum of retention and transport) was 16-38%. In PSI cell model, the retention, transport, and uptake of tAs were 10-28%, 14-31%, and 29-50%, respectively. In both cells, the cellular uptake of tAs in brown rice was 1.4-1.5 folds lower (p<0.05) than that of white rice. These results indicate that the cellular uptake of As can be affected by nutritional compositions. These in vitro screening methods can serve as preliminary screens to predict the relative impact in rice matrix having different As species and processing conditions, although more research efforts should be applied to validating the existing in vitro methods.