Thermal treatment of bentonite reduces aflatoxin b1 adsorption and affects stem cell death

Brazilian bentonite/MgO composites for adsorption of cationic and anionic dyes

Industrial effluents, especially those containing dyes, have become the main cause of contamination of water resources. In this context, Brazilian bentonite/MgO composites, with excellent adsorptive properties, were prepared and investigated for their effectiveness in removing cationic and anionic dyes from aqueous solutions. The new adsorbents were obtained using Brazilian bentonites and MgO using the mechanochemical method followed by heat treatment (at 700 °C for 4 h). Different characterization techniques were used for the chemical, mineralogical, thermal, surface, and morphological analysis of the raw clays and the composites. The experimental adsorption isotherms were quantified under different conditions of initial concentration, contact time, pH, adsorbent dosage, and temperature variation to interpret the adsorption mechanism of the crystal violet (CV) and Congo red (CR) dyes. The modeling results were obtained from the empirical Sips equation and Pseudo Second Order (PSO) kinetics, indicating that the adsorption of molecules is a heterogeneous phenomenon that occurs in a monolayer on the surface (ns > 1), with the adsorption rate determined by chemisorption. The composites showed the best removal efficiency performance compared to the raw bentonites, with an increase of 12% for the CV dye and 46% for the CR dye. In addition, the qmax values obtained were 423.02 mg/g and 479.86 mg/g (AM01). This research underscores the potential of Brazilian bentonite/MgO composites as a promising solution for the removal of cationic and anionic dyes from water, offering hope for future applications in the field of environmental engineering and materials science.

Cellular and molecular mechanisms of aflatoxin B1-mediated neurotoxicity: The therapeutic role of natural bioactive compounds

Aflatoxin B1 (AFB1), a dietary toxin from the mold Aspergillus species, is well acknowledged to elicit extra-hepatic toxicity in both animals and humans. The neurotoxicity of AFB1 has become a global public health concern. Contemporary research on how AFB1 enters the brain to elicit neuronal dysregulation leading to noxious neurological outcomes has increased greatly in recent years. The current review discusses several neurotoxic outcomes and susceptible targets of AFB1 toxicity at cellular, molecular and genetic levels. Specifically, neurotoxicity studies involving the use of brain homogenates, neuroblastoma cell line IMR-32, human brain microvascular endothelial cells, microglial cells, and astrocytes, as well as mammalian and non-mammalian models to unravel the mechanisms associated with AFB1 exposure are highlighted. Further, some naturally occurring bioactive compounds with compelling therapeutic effects on AFB1-induced neurotoxicity are reviewed. In conclusion, available data from literature highlight AFB1 as a neurotoxin and its possible pathological contribution to neurological disorders. Further mechanistic studies aimed at discovering and developing effective therapeutics for AFB1 neurotoxicity is warranted.

Mesoporous silica nanoparticles adsorb aflatoxin B1 and reduce mycotoxin-induced cell damage

The present study examined the effects of mesoporous silica nanoparticles (MSNs) on its adsorption capacity of aflatoxin B₁ (AFB₁). Moreover, the study evaluated the toxicity of MSNs with AFB₁ using NIH3T3 cells and hemolysis test. The obtained MSNs were spherical, irregular-like in shape, having a mean size of 39.97 ± 7.85 nm and a BET surface area of 1195 m²/g. At 0.1 mg mL^-1 concentration of MSN, the AFB₁ adsorption capacity was 30%, which reached 70% when the MSN concentration increased to 2.0 mg mL^-1. Our findings showed that AFB₁ was adsorbed (∼67%) in the first few minutes on being in contact with MSNs, reaching an adsorption capacity of ∼70% after 15 min. Thereafter, the adsorption capacity remained constant in solution, demonstrating that the MSNs adsorbed toxins even beyond overnight. MSN treatment (0.5-2.0 mg mL^-1) using NIH3T3 cells did not result in any reduction in cell viability. In addition, MSN treatment completely reversed the cytotoxic effect of AFB₁ at all concentrations. Hemolysis test also revealed no hemolysis in MSNs evaluated alone and in those combined with AFB₁. To the best of our knowledge, this study is the first to demonstrate that MSN can reduce cell toxicity produced by AFB₁ due to its potential to adsorb mycotoxins.

Simultaneous Detoxification of Aflatoxin B1, Zearalenone and Deoxynivalenol by Modified Montmorillonites

Raw Ca-based montmorillonite (MMT) was treated by H₂SO₄, calcination and organic compounds (hexadecyltrimethyl ammonium bromide (HTAB), cetylpyridinium chloride (CPC) and chitosan (CTS)), respectively. The modified montmorillonites were characterized by different methods and their adsorption performances for three mycotoxins (Aflatoxin B1 (AFB1), zearalenone (ZEA) and deoxynivalenol (DON)) were evaluated at pH = 2.8 and 8.0, respectively. The results indicate that surfactants (CPC and HTAB) intercalation is the most efficient modification, which obviously improves the adsorption performance of montmorillonite for mycotoxins, with adsorption efficiency of above 90% for AFB1 and ZEA whether under acid or alkaline conditions, due to the increase in basal spacing and the improvement of hydrophobicity. Moreover, the adsorption efficiencies of AFB1 and ZEA over CPC-modified montmorillonite (CPC-AMMT-3) coexisting with vitamin B6 or lysine are still at a high level (all above 94%). All modified montmorillonites, however, have low adsorption efficiency for DON, with somewhat spherical molecular geometry.

Brazilian bentonite and a new modified bentonite material, BAC302, reduce zearalenone-induced cell death

Bentonite clays exhibit high adsorptive capacity for contaminants and is frequently used as a feed additive to reduce the bioavailability and thus the toxicity of several mycotoxins. Zearalenone (ZEN) is a secondary Fusarium toxic metabolite that can contaminate a wide range of food- and feedstuff. Since organophilic treatments is known to increase the adsorption capacity of bentonites, the aim of study was to evaluate and compare the ability of natural bentonite and bentonite treated with BAC302 to protect against ZEN-induced cytotoxicity in the epithelial colorectal adenocarcinoma (Caco-2) and human leukemia monocytic (THP-1) cell lines. The two materials were not toxic to the cell lines at lower concentrations. Furthermore, the results indicate that the two materials protect the Caco-2 and THP-1 cells against ZEN-induced cytotoxicity, probably by extracellular adsorption of ZEN. The tested natural bentonite shows potential for in vivo testing to evaluate if it is suitable for intoxication in ZEN contaminated animal feeds.

Calcination Improves the In Vivo Efficacy of a Montmorillonite Clay to Bind Aflatoxin G1 in Broiler Chickens: A Toxicokinetic Approach

The goal of this study was to investigate the toxicokinetic characteristics of aflatoxin G1 (AFG1) in broiler chickens and the effect of calcination of a Tunisian montmorillonite clay on the in vivo absorption of AFG1. In this study, broiler chickens were randomly distributed into four groups of 10 animals. Group 1 was administered AFG1 (2 mg/kg body weight (BW)) by single intravenous injection (IV), group 2 received an intra-crop bolus (PO) of AFG1 without any clay, group 3 was dosed AFG1 PO together with an oral bolus of purified clay (CP), and group 4 received AFG1 PO with an oral bolus of calcined clay. A significant difference in the area under the curve (AUC_0-t) was observed for group 4 (6.78 ± 4.24 h*ng/mL) in comparison with group 2 (12.83 ± 4.19 h*ng/mL). A significant reduction of the oral bioavailability of AFG1 was observed for group 4 (7.61 ± 4.76%) compared with group 2 (14.40 ± 4.70%), while no significant effect was observed of CP. In this experiment, no phase I nor phase II metabolites of AFG1 were observed. These findings confirm that calcination of the purified montmorillonite clay enhances the adsorption of AFG1 in the gastrointestinal tract after oral administration, thereby reducing its bioavailability, thus reducing its toxic effects.

Calcination Enhances the Aflatoxin and Zearalenone Binding Efficiency of a Tunisian Clay

Clays are known to have promising adsorbing characteristics, and are used as feed additives to overcome the negative effects of mycotoxicosis in livestock farming. Modification of clay minerals by heat treatment, also called calcination, can alter their adsorption characteristics. Little information, however, is available on the effect of calcination with respect to mycotoxin binding. The purpose of this study was to characterize a Tunisian clay before and after calcination (at 550 °C), and to investigate the effectiveness of the thermal treatment of this clay on its aflatoxin B1 (AFB1), G1 (AFG1), B2 (AFB2), G2 (AFG2), and zearalenone (ZEN) adsorption capacity. Firstly, the purified clay (CP) and calcined clay (CC) were characterized with X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-IR), cation exchange capacity (CEC), specific surface area (SBET), and point of zero charge (pHPZC) measurements. Secondly, an in vitro model that simulated the pH conditions of the monogastric gastrointestinal tract was used to evaluate the binding efficiency of the tested clays when artificially mixed with aflatoxins and zearalenone. The tested clay consisted mainly of smectite and illite. Purified and calcined clay had similar chemical compositions. After heat treatment, however, some changes in the mineralogical and textural properties were observed. The calcination decreased the cation exchange capacity and the specific surface, whereas the pore size was increased. Both purified and calcined clay had a binding efficacy of over 90% for AFB1 under simulated poultry GI tract conditions. Heat treatment of the clay increased the adsorption of AFB2, AFG1, and AFG2 related to the increase in pore size of the clay by the calcination process. ZEN adsorption also increased by calcination, albeit to a more stable level at pH 3 rather than at pH 7. In conclusion, calcination of clay minerals enhanced the adsorption of aflatoxins and mostly of AFG1 and AFG2 at neutral pH of the gastrointestinal tract, and thus are associated with protection against the toxic effects of aflatoxins.

Use of bentonite calcined clay as an adsorbent: equilibrium and thermodynamic study of Rhodamine B adsorption in aqueous solution

The Rhodamine B adsorption was realized in batch using calcined bentonite clay. The effects of Rhodamine B initial concentration, pH, and temperature were evaluated and the conditions where the adsorption was favored were in 500 mg L^-1, pH 3, and 35 °C. The equilibrium isotherms studied were from Langmuir and Freundlich. The coefficients of determination (R² > 0.99) were found to confirm the best fitted to Langmuir isotherm, with a monolayer adsorption capacity (q_max) of 552.49 mg g^-1. The kinetic data agreed well with the pseudo-second order model (R² > 0.99). The in natura and calcined clay were characterized by the techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N₂ physisorption (BET), and scanning electron microscopy (SEM). Thermodynamic parameters including Gibbs free energy (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were calculated to estimate the nature of Rhodamine B adsorption in clay. The results suggested that the adsorption was endothermic and spontaneous, with the enthalpy adsorption increasing with the increase of temperature. Therefore, calcined bentonite can be used as an efficient adsorbent for discoloration of large volume of residual water, presenting low-cost and high adsorptive capacity.

Latin American contributions to the neural crest field

The neural crest (NC) is one of the most fascinating structures during embryonic development. Unique to vertebrate embryos, these cells give rise to important components of the craniofacial skeleton, such as the jaws and skull, as well as melanocytes and ganglia of the peripheral nervous system. Worldwide, several groups have been studying NC development and specifically in the Latin America (LA) they have been growing in numbers since the 1990s. It is important for the world to recognize the contributions of LA researchers on the knowledge of NC development, as it can stimulate networking and improvement in the field. We developed a database of LA publications on NC development using ORCID and PUBMED as search engines. We thoroughly describe all of the contributions from LA, collected in five major topics on NC development mechanisms: i) induction and specification; ii) migration; iii) differentiation; iv) adult NC; and, v) neurocristopathies. Further analysis was done to correlate each LA country with topics and animal models, and to access collaboration between LA countries. We observed that some LA countries have made important contributions to the comprehension of NC development. Interestingly, some LA countries have a topic and an animal model as their strength; in addition, collaboration between LA countries is almost inexistent. This review will help LA NC research to be acknowledged, and to facilitate networking between students and researchers worldwide.

Antifungal activities against toxigenic Fusarium specie and deoxynivalenol adsorption capacity of ion-exchanged zeolites

Zeolites are often used as adsorbents materials and their loaded cations can be exchanged with metal ions in order to add antimicrobial properties. The aim of this study was to use the 4A zeolite and its derived ion-exchanged forms with Zn²⁺, Li⁺, Cu²⁺ and Co²⁺ in order to evaluate their antifungal properties against Fusarium graminearum, including their capacity in terms of metal ions release, conidia germination and the deoxynivalenol (DON) adsorption. The zeolites ion-exchanged with Li⁺, Cu²⁺, and Co²⁺ showed an excellent antifungal activity against F. graminearum, using an agar diffusion method, with a zone of inhibition observed around the samples of 45.3 ± 0.6 mm, 25.7 ± 1.5 mm, and 24.7 ± 0.6 mm, respectively. Similar results using agar dilution method were found showing significant growth inhibition of F. graminearum for ion-exchanged zeolites with Zn²⁺, Li⁺, Cu²⁺, and Co²⁺. The fungi growth inhibition decreased as zeolite-Cu²⁺>zeolite-Li⁺>zeolite-Co²⁺>zeolite-Zn²⁺. In addition, the conidia germination was strongly affected by ion-exchanged zeolites. With regard to adsorption capacity, results indicate that only zeolite-Li⁺ were capable of DON adsorption significantly (P < 0.001) with 37% at 2 mg mL^-1 concentration. The antifungal effects of the ion-exchanged zeolites can be ascribed to the interactions of the metal ions released from the zeolite structure, especially for zeolite-Li⁺, which showed to be a promising agent against F. graminearum and its toxin.

Bentonite modified with zinc enhances aflatoxin B1 adsorption and increase survival of fibroblasts (3T3) and epithelial colorectal adenocarcinoma cells (Caco-2)

Bentonites are commonly used as feed additives to reduce the bioavailability and thus the toxicity of aflatoxins by adsorbing the toxins in the gastrointestinal tract. Aflatoxins are particular harmful mycotoxins mainly found in areas with hot and humid climates. They occur in food and feedstuff as a result of fungal contamination before and after harvest. The aim of this study was to modify Brazilian bentonite clay by incorporation of zinc (Zn) ions in order to increase the adsorption capacity and consequently reduce the toxicity of aflatoxins. The significance of Zn intercalating conditions such as concentration, temperature and reaction time were investigated. Our results showed that the Zn treatment of the bentonite increased the aflatoxin B₁ (AFB₁) adsorption and that Zn concentration had a negative effect. Indeed, temperature and time had no significant effect in the binding capacity. The modified bentonite (Zn-Bent1) was not cytotoxic to either fibroblasts (3T3) nor epithelial colorectal adenocarcinoma cells (Caco-2) cell lines. Interestingly, Zn-Bent1 has higher protective effect against AFB₁ induced cytotoxicity than the unmodified bentonite. In conclusion, the Zn modified bentonite, Zn-Bent1, represent an improved tool to prevent aflatoxicosis in animals fed on AFB₁ contaminated feed.

Organophilic treatments of bentonite increase the adsorption of aflatoxin B1 and protect stem cells against cellular damage

Bentonite clays exhibit high adsorptive capacity for contaminants, including aflatoxin B1 (AFB1), a mycotoxin responsible for causing severe toxicity in several species including pigs, poultry and man. Organophilic treatments is known to increase the adsorption capacity of bentonites, and the primary aim of this study was to evaluate the ability of Brazilian bentonite and two organic salts - benzalkonium chloride (BAC) and cetyltrimethylammonium bromide (CTAB) to adsorb AFB1. For this end, 2(2) factorial designs were used in order to analyze if BAC or CTAB was able to increase AFB1 adsorption when submitted in different temperature and concentration. Both BAC and CTAB treatment (at 30°C and 2% of salt concentration) were found to increase the adsorption of AFB1 significantly compared with untreated bentonite. After organophilic bentonite treatments with BAC or CTAB, a vibration of CH stretch (2850 and 2920cm(-1)) were detected. A frequency of the SiO stretch (1020 and 1090cm(-1)) was changed by intercalation of organic cation. Furthermore, the interlayer spacing of bentonite increases to 1.23nm (d001 reflection at 2θ=7.16) and 1.22 (d001 reflection at 2θ=7.22) after the addition of BAC and CTAB, respectively. Another aim of the study was to observe the effects of these two bentonite salts in neural crest stem cell cultures. The two materials that were created by organophilic treatments were not found to be toxic to stem cells. Furthermore the results indicate that the two materials tested may protect the neural crest stem cells against damage caused by AFB1.