Ionophoric Properties Research Articles

Cation Dependence of Enniatin B/Membrane-Interactions Assessed Using Surface-Enhanced Infrared Absorption (SEIRA) Spectroscopy.

Enniatins are mycotoxins with well-known antibacterial, antifungal, antihelmintic and antiviral activity, which have recently come to attention as potential mitochondriotoxic anticancer agents. The cytotoxicity of enniatins is traced back to ionophoric properties, in which the cyclodepsipeptidic structure results in enniatin:cation-complexes of various stoichiometries proposed as membrane-active species. In this work, we employed a combination of surface-enhanced infrared absorption (SEIRA) spectroscopy, tethered bilayer lipid membranes (tBLMs) and density functional theory (DFT)-based computational spectroscopy to monitor the cation-dependence (Mz+=Na+, K+, Cs+, Li+, Mg2+, Ca2+) on the mechanism of enniatin B (EB) incorporation into membranes and identify the functionally relevant EBn : Mz+ complexes formed. We find that Na+ promotes a cooperative incorporation, modelled via an autocatalytic mechanism and mediated by a distorted 2 : 1-EB2 : Na+ complex. K+ (and Cs+) leads to a direct but less efficient insertion into membranes due to the adoption of "ideal" EB2 : K+ sandwich complexes. In contrast, the presence of Li+, Mg2+, and Ca2+ causes a (partial) extraction of EB from the membrane via the formation of "belted" 1 : 1-EB : Mz+ complexes, which screen the cationic charge less efficiently. Our results point to a relevance of the cation dependence for the transport into the malignant cells where the mitochondriotoxic anticancer activity is exerted.

Identification and characterization of organic and glycosidic acids in the crude resin glycoside fraction of Ipomoea alba seeds

Resin glycosides act as laxatives in crude drugs derived from plants of the Convolvulaceae family. These compounds have exhibited antibacterial, ionophoric, anti-inflammatory, antiviral, and multidrug resistance-modulating properties, as well as cytotoxicity against cancer cells. This study investigated the organic acid, hydroxyl fatty acid, monosaccharide, and glycosidic acid components of the crude resin glycoside fraction obtained from the methanol extract of Ipomoea alba L. (Convolvulaceae) seeds, which was subjected to alkaline and acidic hydrolysis. The alkaline hydrolysis yielded acetic, isobutyric, (E)-2-methylbut-2-enoic, and 2S-methyl-3S-hydroxybutyric acids as organic acid components, along with a glycosidic acid fraction. The acidic hydrolysis of the glycosidic acid fraction resulted in the isolation of 11S-hydroxytetradecanoic and 11S-hydroxyhexadecanoic acids as hydroxyl fatty acid components, as well as d-glucose, d-quinovose, d-fucose, d-xylose, and l-rhamnose as monosaccharide components. In addition, 10 new glycosidic acid methyl esters were isolated from the glycosidic acid fraction treated with trimethylsilyldiazomethane–hexane, along with one known glycosidic acid methyl ester. Of these, eight compounds contained new glycans. Four of these compounds were unusual natural glycosides with four glycosidic linkages to one monosaccharide. Their structures were determined using MS and NMR spectral analyses, which provided valuable insights into the unique glycosidic composition of I. alba seeds.

Oxovanadium(IV) heteromacrocyclic complexes as ionophores for iodide-selective electrodes

Abstract Highly selective poly(vinyl chloride) (PVC) membrane electrodes, based on oxovanadium(IV) complexes of heteromacrocyclic compounds as new iodide-selective ionophores for ion-selective electrodes (ISEs), were fabricated with a composition of PVC (28.1 wt%), plasticizers (69.3 wt%), ionophores (2.6 wt%), and cation excluders (15 mol% relative to the ionophore). The electrode prepared from oxovanadium(IV) tetraphenyl porphyrin with 2-nitrophenyl octyl ether (o-NPOE) as the membrane solvent and tetradodecylammonium chloride (TDDACl) as the cation excluder was found to exhibit the best sensitivity over a wide concentration range from 5.0 × 10–7 to 2.1 × 10–2 M with a Nernstian response of −59.02 mV per decade and the highest ion-selectivity toward I− ions over perchlorate ions (I−/ClO4− = 91).

Toxicity of the emerging mycotoxins beauvericin and enniatins: A mini-review

Beauvericin and enniatins, emerging mycotoxins produced mainly by Fusarium species, are natural contaminants of cereals and cereal products. These mycotoxins are cyclic hexadepsipeptides with ionophore properties and their toxicity mechanism is related to their ability to transport cations across the cell membrane. Beauvericin and enniatins are cytotoxic, as they decrease cell viability, promote cell cycle arrest, and increase apoptosis and the generation of reactive oxygen species in several cell lines. They also cause changes at the transcriptomic level and have immunomodulatory effects in vitro and in vivo. Toxicokinetic results are scarce, and, despite its proven toxic effects in vitro, no regulation or risk assessment has yet been performed due to a lack of in vivo data. This mini-review aims to report the information available in the literature on studies of in vitro and in vivo toxic effects with beauvericin and enniatins, which are mycotoxins of increasing interest to animal and human health.

Photoinduced Cuproptosis with Tumor-Specific for Metastasis-Inhibited Cancer Therapy.

Cuproptosis is a novel form of regulated cell death which guarantees to increase the efficacy of existing anticancer treatments that employ traditional apoptotic therapeutics. However, reducing the amount of undesirable Cu ions released in normal tissue and maximizing Cu-induced cuproptosis therapeutic effects at tumor sites are the major challenges. In this study, exploiting the chemical properties of copper ionophores and the tumor microenvironment, a novel method is developed for controlling the valence of copper ions that cause photoinduced cuproptosis in tumor cells. CJS-Cu nanoparticles (NPs) can selectively induce cuproptosis after cascade reactions through H2 O2 -triggered Cu2+ release, photoirradiation-induced superoxide radical (∙O2 - ) generation, and reduction of Cu2+ to Cu+ by ∙O2 - . The generated reactive oxygen species can result in glutathione depletion and iron-sulfur cluster protein damage and further augmented cuproptosis. CJS-Cu NPs effectively suppressed tumor growth and downregulated the expression of metastasis-related proteins, contributing to the complete inhibition of lung metastasis. Ultimately, this study suggests novel avenues for the manipulation of cellular cuproptosis through photochemical reactions.

Bispidine as a Versatile Scaffold: From Topological Hosts to Transmembrane Transporters.

The development of designer topological structures is a synthetically challenging endeavor. We present herein bispidine as a platform for the design of molecules with various topologies and functions. The bispidine-based acyclic molecule, which shows intriguing S-shape topology, is discussed. Single-crystal X-ray diffraction studies revealed that this molecule exists in the solid state as two conformational enantiomers. In addition, bispidine-based designer macrocycles were synthesized and investigated for ionophoric properties. Patch clamp experiments revealed that these macrocycles transport both anions and cations non-specifically with at least tenfold higher chloride conductance over the cations under the given experimental conditions. Ultramicroscopy and single-crystal X-ray crystallographic studies indicated that the self-assembling macrocycle forms a tubular assembly. Our design highlights the use of unconventional dihydrogen interactions in nanotube fabrication.

Ion Recognition beyond Size Matching: Cooperative Hydration Effect on the K+ Selectivity of Valinomycin over Na+ Revealed by Cryogenic Double Ion Trap Infrared Spectroscopy.

The naturally occurring ionophore valinomycin (VM) selectively transports K+ across the biological membrane, which makes VM a plausible antivirus and antibacterial candidate. The K+ selectivity of VM was rationalized based on a size-matching model despite structural inconsistency between experiments and computations. In this study, we investigated the conformations of the Na+VM complex with 1-10 water molecules using cryogenic ion trap infrared spectroscopy with computational calculations. It shows that the water molecule penetrates the cavity of VM deeply enough to distort the C3-symmetric structure of gas-phase Na+VM, in stark contrast to hydrated clusters of K+VM with C3-symmetric structure, where H2O is located outside the cavity. The high affinity to K+ would be ascribed to minimal hydration-induced structural deformation of K+VM compared to Na+VM. This study highlights a novel cooperative hydration effect on the K+ selectivity and will provide an updated understanding of its ionophoric properties beyond the traditional size-matching model.

The use of bis–thiadiazole and bis–oxadiazol derivatives as ionophores: A novel copper(II)–selective potentiometric electrodes

In this study, bis–thiadiazole and bis–oxadiazol derivative molecules were synthesized and their ionophore properties were investigated. The synthesized bis–thiadiazole and bis–oxadiazol derivative molecules exhibited selectivity towards copper(II) ions. Electrodes prepared with 5,5′-(1,4-phenylene)bis(1,3,4-thiadiazol-2-amine) (4) exhibited more ideal potentiometric behavior than electrodes prepared with 5,5′-(1,4-phenylene)bis(1,3,4-oxadiazol-2-amine) (7). The copper(II)–selective electrode prepared with bis–thiadiazole derivative molecule (4) have near–Nernstian behavior (32.3 ± 3.3 mV/decade) over a wide linear working range of 1.0 × 10−6– 1.0 × 10−1 mol L−1 (R2 = 09967). The electrode exhibited a low detection limit of 9.02 × 10−7 mol L−1. These novel copper(II)–selective potentiometric electrodes were not only economical because the electroactive material was produced in the laboratory, but also had a fast response time, good selectivity and repeatability. The potential response of the electrode remained unaffected of pH in the range of 4.0 – 9.0. Finally, the developed electrode performed the determination of copper(II) ions in various water samples with very high recoveries.

Highly Selective Potentiometric Sensing of Biologically Relevant Pyrophosphate and Lysophosphatidic Acid Using N-Alkyl/Aryl Ammonium Resorcinarenes/Extended-Resorcinarenes as Ionophores.

The ionophore properties of four kinds of N-alkyl/aryl ammonium resorcinarenes and extended-resorcinarenes were inspected for the first time to fabricate polymeric membrane electrodes for determination of biologically relevant pyrophosphate (PPi) and lysophosphatidic acid (LPA). The proposed ion selective electrodes (ISEs) showed significant preference for PPi and LPA with significant selectivity pattern differences from the Hofmeister series. To gain further insight into the performances of the developed ISEs, the binding constants of ionophore-anion complexes in the plasticized membrane phase were investigated, along with the optimized geometries and calculated electrostatic potential. Nernstian potential responses with good reversibility to target anions can be observed when shifting the optimized membranes in aqueous solutions in the concentration range from 10-6.5 to 10-2.3/10-2.2 M. Moreover, potentiometric sensings of PPi and LPA in mineral water and artificial serum were achieved in low μM concentration range, demonstrating their promising real-world applications. These results provide a promising avenue for the development of polymeric membrane electrodes for biological relevant anions and will broaden the scope of potentiometric sensing.

Anchoring H-Bond Donating/Accepting Pyrrolic Derivatives on Preorganized Scaffolds: Conformationally Switchable Bipedal/Tripodal and Locked Molecular Cage Ionophores for Potentiometric Sensing of Phosphate and Fluoride.

The ionophore properties of a myriad of conformationally switchable bipedal/tripodal receptors and locked molecular cages were evaluated here for the first time to fabricate potentiometric sensors for the determination of environmentally important phosphate and fluoride. Owing to the competent ionophore properties such as high binding selectivity and affinity, the developed ion-selective electrodes displayed response preference for phosphate and fluoride with a selectivity pattern that differs distinctly from traditional Hofmeister series. Binding constants of the ionophore-anion complexes are determined to underscore how modifications in the preorganization and H-bond donating/accepting ability of a given series of ionophores can be exploited to improve the performance for potentiometric sensing. While conformationally switchable bipedal/tripodal ionophores prefer tetrahedral oxyanions, locked molecular cages shift their preference to spherical halides gradually. Nernstian potential responses with good reversibility to target anions can be observed when shifting the optimized membrane electrodes in aqueous solutions within the concentration range of 10-6.5-10-2.0 M. Moreover, potentiometric determination of phosphate and fluoride in mineral water, soil, and tap water samples was achieved in a low μM concentration range with high accuracy, confirming their promising utility in real world applications.

A review on beauvericin production from Fusarium, its biosynthesis, mode of action and bioactivities

This review provides comprehensive information on beauvercin, a cyclic hexadepsipeptide, produced by selected fungi like Beauveria, Paecilomyces, Polyporus, Isaria and Fusarium. The biosynthetic pathway of beauvericin production is elaborated. Numerous bioactivities like anticancer, antiviral, cytotoxic, antiplatelet aggregation, antimicrobial, antiprotozoal, insecticidal properties are reviewed. The potential of beauvericin to diminish the growth of gram-positive or gram-negative pathogenic bacteria and inhibition of melanin production are well documented. It has been noted that beauvericin possesses ionophoric property which renders it these bioactivities. Being genotoxic, beauvericin has been proved to cause apoptosis by DNA fragmentation, chromosomal aberrations and micronucleus formation. In this review, the production yield reported from the different strains of Fusarium spp. is also compiled. This documentation will be of great help to the researchers working on optimization and productivity enhancement studies of beauvericin. Beauvericin needs to be studied in detail as there are many gaps which need to be fulfilled.

Beauvericin (BEA) and enniatin B (ENNB)-induced impairment of mitochondria and lysosomes - Potential sources of intracellular reactive iron triggering ferroptosis in Atlantic salmon primary hepatocytes

Beauvericin (BEA) and enniatin B (ENNB) are emerging mycotoxins frequently detected in plant-based fish feed. With ionophoric properties, they have shown cytotoxic potential in mammalian models. Sensitivity in fish is still largely unknown. Primary hepatocytes isolated from Atlantic salmon (Salmo salar) were used as a model and exposed to BEA and ENNB (0.05–10 μM) for 48 h. Microscopy, evaluation of cell viability, total ATP, total H2O2, total iron content, total Gpx enzyme activity, and RNA sequencing were used to characterize the toxicodynamics of BEA and ENNB. Both mycotoxins became cytotoxic at ≥ 5 μM, causing condensation of the hepatocytes followed by formation of blister-like protrusions on the cell's membrane. RNA sequencing analysis at sub-cytotoxic levels indicated BEA and ENNB exposed hepatocytes to experience increased energy expenditure, elevated oxidative stress, and iron homeostasis disturbances sensitizing the hepatocytes to ferroptosis. The present study provides valuable knowledge disclosing the toxic action of these mycotoxins in Atlantic salmon primary hepatocytes.

Highly efficient potentiometric sensing device for gadolinium based on Tetraazacyclododecane-1, 4, 7, 10 -tetraaceticacid crown ether and multiwalled carbon nanotube composite

A hydrophilic cavity presents in tetraazacyclododecane-1, 4, 7, 10-tetraaceticacid crown ether (DOTA) provides the opportunity for Gadolinium (Gd3+) transfer from an aqueous medium to a lipophilic phase and mimic the ionophoric properties due to strong coordinating link. Therefore, we have developed Gd3+ ion selective electrode (ISE) incorporating synthesized nanocomposite of DOTA as an ionophore and multiwalled carbon nanotube (MWCNT) as signal enhancer in poly vinyl chloride (PVC) membrane sensor employing potentiometry. The composite DOTA-MWCNT was characterized by scanning electron microscopy (SEM). The Nernstian slope of 20.05 ± 0.18 mV per decade with linear range 1 × 10-2 to 1 × 10-8 M and the detection limit was found to be 7.2 ± 0.16 × 10-9 M. This electrode has an excellent selectivity over mono, bi, tri and tetravalent interferent metal species. The proposed sensor was favourably applied as an indicator electrode in the titration of Gd3+ ions with EDTA and recovery of gadolinium (III) from diverse synthetic samples. The presence of four ionizable carboxylic acids groups imparts advantages to DOTA-MWCNT composite in the formation of strong complexes and enhanced solubility of Gd3+ which became the basis for in-vivo analysis of Gd3+ in pharmaceutical and soil samples. DOTA-MWCNT as host forms 1:1 chelate complex with guest Gd3+ employing square wave voltammetry. The stability constant (Log K = 25.41) and Gibbs free energy (DG) of DOTA-MWCNT - Gd3+ complex was calculated which established exothermic and spontaneous inclusion mechanism. The higher stability constant obtained for DOTA-MWCNT chelate complex can provide the opportunity to researchers of biomedical science to minimize/control the amount of free Gd3+ release in the human body through the process of drug delivery.

Ion-Pairing Mechanism for the Valinomycin-Mediated Transport of Potassium Ions across Phospholipid Bilayers.

The role of the anion on the ionophore properties of valinomycin was studied in a model floating bilayer lipid membrane (fBLM) using supporting electrolytes containing K+ with four different counter anion species (ClO4-, H2PO4-, Cl-, and F-). The electrochemical impedance spectra indicate that the membrane resistance of the bilayer decreases with the decrease of Gibbs free energy of anion solvation. The IR spectra demonstrate that valinomycin does not readily bind to K+ in the KH2PO4, KCl, and KF electrolyte solutions, but in the presence of KClO4, valinomycin readily binds to K+, forming a valinomycin-K+ complex. The results in the present paper reveal the role of the counter anion on the transport of cations by valinomycin across the lipid bilayer. The valinomycin-cation complex creates an ion pair with the anion, and this ion pair can enter the hydrophobic region of the bilayer transporting the cation across the membrane. Anions with low solvation energies facilitate the formation of the ion pair improving the ion conductivity of valinomycin-incorporated bilayers. This paper sheds new light on the transport mechanism of valinomycin ionophores and provides new information about the bioactivity of this molecule.

Proteomics evaluation of enniatins acute toxicity in rat liver

Enniatins (ENs) are emerging mycotoxins produced by Fusarium fungi which are cytotoxic also at low concentrations due to its ionophoric properties. The aim of this study was to evaluate the hepatic toxicity of ENs exposure at different concentrations in Wistar rats through a proteomic approach. Animals were intoxicated by oral gavage with medium (EN A 256, ENA1 353, ENB 540, ENB1 296 μg/mL) and high concentrations (ENA 513, ENA1 706, ENB 1021, ENB1 593 μg/mL) of an ENs mixture and sacrificed after 8 h. Protein extraction was performed using powdered liver. Peptides were analyzed using a liquid chromatography coupled with a quadrupole time-of-flight mass spectrometer. Proteins were filtered by abundance using Mass Professional Profiler software (Agilent Technologies) and 57 were differentially expressed when compared to the control. In terms of abundance, the liver biomarker Carboamoyl-phosphate synthase showed the highest levels in all conditions employed while actin-1 had the lowest. Bioinformatic analysis using DAVID platform reported acetylation, nucleotide phosphate-binding region:NAD and catalytic activity as the most represented terms. Furthermore, metabolism was the most significant and enriched pathway in Reactome overrepresentation. In conclusion, ENs acute exposure caused protein expression changes related to major cellular processes in rats, hinting its involvement in liver disturbance.

Potassium Ion Fluorescence Probes: Structures, Properties and Bioimaging

AbstractAs one of the most important minerals in the body, potassium is vital for the heart and neurons. Methods that can non‐invasively and accurately monitor changes in potassium balances would benefit disease diagnoses as well as offer insight into pathologies. Among the sensing approaches, fluorescent probes serve as a unique detection method for its simplicity, tunable detection range, and bioimaging ability. The design of new probes with highly selective K+ receptors and transduction functionality remains a challenge that is motivated by numerous sensing and detection applications. In this minireview, fluoroionophores are summarized that undergo transduction, producing fluorescence signals when interacting with, e. g., potassium ions. The properties of ionophores (afford selective interaction with potassium) and fluorophores (generate signal read‐out) are discussed. Molecular structure design and sensing mechanisms are included along with cell imaging applications. The selectivity towards K+ and the absorption/emission characteristics of the probes are of particular interest.

Ferula L. Plant Extracts and Dose-Dependent Activity of Natural Sesquiterpene Ferutinin: From Antioxidant Potential to Cytotoxic Effects.

The employment studies of natural extracts in the prevention and treatment of several diseases highlighted the role of different species of genus Ferula L., belonging to the Apiaceae family, dicotyledonous plants present in many temperate zones of our planet. Ferula communis L. is the main source of sesquiterpene ferutinin, a bioactive compound studied both in vitro and in vivo, because of different effects, such as phytoestrogenic, antioxidant, anti-inflammatory, but also antiproliferative and cytotoxic activity, performed in a dose-dependent and cell-dependent way. The present review will focus on the molecular mechanisms involved in the different activities of Ferutinin, starting from its antioxidant potential at low doses until its ionophoric property and the subsequent mitochondrial dysfunction induced through administration of high doses, which represent the key point of its anticancer action. Furthermore, we will summarize the data acquired from some experimental studies on different cell types and on several diseases. The results obtained showed an important antioxidant and phytoestrogenic regulation with lack of typical side effects related to estrogenic therapy. The preferential cell death induction for tumor cell lines suggests that ferutinin may have anti-neoplastic properties, and may be used as an antiproliferative and cytotoxic agent in an estrogen dependent and independent manner. Nevertheless, more data are needed to clearly understand the effect of ferutinin in animals before using it as a phytoestrogen or anticancer drug.

A copper(II)-binding triazole derivative with ionophore properties is active against Candida spp.

Invasive fungal infections (IFIs) are life threatening and existing antifungal drugs are not completely effective due to undesirable side effects and resistance emergence. Azoles are often the treatment of choice for IFIs and growing evidence suggests that copper can act synergistically with these drugs. In this work, we designed a compound bringing together azole and copper(II)-binding groups and studied the molecular mechanisms underlying its biological toxicity. Our results show that both the compound, 4, and its copper(II) complex, Cu.4, are active against Candida spp. We found that Cu.4 acts as a copper(II) ionophore, which results in the intracellular accumulation of reactive oxygen species (ROS), whereas compound 4 is an iron chelator and exerts its toxicity by decreasing iron bioavailability. Interestingly, while 4 is not very toxic to macrophages or HeLa cells, Cu.4 significantly affects their viability. Overall, this work provides evidence of how copper can be combined with azoles to deregulate copper homeostasis, opening new horizons for the development of bifunctional antifungals.

Ionophore- Nafion™ modified gold-coated electrospun polymeric fibers electrodes for determination of electrolytes

The present work describes the electrochemical properties of ionophores immobilized at the surface of electrodes obtained from electrospun polymeric fibers, in order to develop sensors for the analysis of electrolytes. Poly(methyl methacrylate) submicrometer fibers were prepared by electrospinning, coated with a gold layer by magnetron sputtering and then transferred on polyethylene terephthalate (PET) in order to obtained flexible electrodes. The ionophores were immobilized at the surface of these electrodes by drop-casting a ionophore-Nafion mixed solution. The sensor surface was investigated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy in order to understand the morphology and distribution of a model Ca2+ ionophore over the electrode surface. Also, Fourier-transformed infrared spectroscopy was performed and demonstrated that the model Ca2+ ionophore can be immobilized in the nafion matrix maintaining its conformation, while cyclic voltammetry and electrochemical impedance spectroscopy demonstrated that the Ca2+ ionophore allows the diffusion of target ions through this this type of membrane. In order to prove the concept of ionophore-based sensors for the analysis of some electrolytes, Ca2+, NH4+, Cl− and H+ ionophore immobilized in a nafion matrix at the surface of these flexible electrodes were tested and the determination of the target ions performed by potentiometry in different media including artificial sweat. Finally, sensitivities, limits of detection, selectivity coefficients were determined.

Beauvericin alters the expression of genes coding for key proteins of the mitochondrial chain in ovine cumulus-oocyte complexes.

Beauvericin (BEA) is a member of the enniatin family of mycotoxins which has received increasing interest because of frequent occurrence in food and feed. By its ionophoric properties, BEA is able to alter membrane ion permeability uncoupling oxidative phosphorylation. It was also shown to alter oocyte mitochondrial function. In this study, the effects of BEA at 0.5, 1, ,3 and 5 μmol/L on expression of genes coding for key proteins of the mitochondrial chain in ovine oocytes and cumulus cells were evaluated at different time points of in vitro maturation (IVM), germinal vesicle (GV; t = 0), metaphase I (MI; t = 7 h), and metaphase II (MII; t = 24 h). The expression of nuclear (TFAM, NDUFA12, UQCRH, COX4, ATP5O) and mitochondrial (ND1, COX1, COX2, ATP6, ATP8) genes coding for proteins of Complexes I, III, IV, and V was analyzed by qRT-PCR. After BEA exposure, perturbed expression of all genes was observed in cumulus cells and in oocytes at the MI stage (7 h IVM). Expression of ND1, UQCRH, COX4 and ATP5O was downregulated in cumulus cells and upregulated in oocytes starting from 0.5 μmol/L BEA. Expression of TFAM, NDUFA12, COX1, COX2, ATP6, and ATP8 was upregulated starting from 1 μmol/L in cumulus cells and from 3 μmol/L in oocytes. Cumulus cells and oocytes displayed different gene expression patterns upon BEA exposure. The downregulation in cumulus cells of four genes coding for proteins of mitochondrial complexes could represent a major toxic event induced by BEA on the cumulus-oocyte complex which may result in mitochondrial functional alteration.