Determination of Carbadox and Olaquindox Residues in Chicken Muscles, Chicken Liver, Bovine Meat, Liver and Milk by MLC with UV Detection: Application to Baby Formulae

A reliable upconversion nanoparticle-based immunochromatographic assay for the highly sensitive determination of olaquindox in fish muscle and water samples

Olaquindox residues in food from its illegal use has received great attention. Here, an immunoassay strategy integrating an upconversion nanoparticle (UCNP)-based immunochromatographic strip with a fluorescence reader was proposed for the highly selective and sensitive detection of olaquindox. Polyacrylic acid-functionalized UCNPs were synthesized using a simple ligand exchange process and combined with an olaquindox polyclonal antibody to form a fluorescent probe. This approach achieved a sensitive response and specific recognition of olaquindox. A convenient upconversion fluorescence reader was introduced to implement accurate and sensitive quantitative analysis of olaquindox based on the fluorescence intensity of control and test lines on a strip. Under optimal conditions, the method demonstrated a favorable linear range (0-50 ng/mL) and sensitive detection (1.42 ng/mL, S/N = 3). This method was applied successfully to determine olaquindox in fish muscle and water samples, and results were consistent with an HPLC approach, and considered a promising strategy for monitoring olaquindox residuals.

Analytical capabilities of micellar liquid chromatography and application to residue and contaminant analysis: A review

Green chemistry is the use of chemistry to reduce or eliminate the use of generation of feedstocks, products, by-products, solvents, reagents, etc. that are hazardous to human health or the environment. One of the branches of green chemistry is micellar liquid chromatography. Micellar liquid chromatography is a reversed-phase liquid chromatographic mode with mobile phases containing a surfactant above its critical micellar concentration. The applications of micellar liquid chromatography for the determination of numerous compounds in pharmaceutical formulation, biological samples, food, environmental samples, and feeds have been growing rapidly. Micellar liquid chromatography technique has several advantages over other chromatographic techniques. Its main advantage is the small amount of organic modifiers used such as acetonitrile and methanol and the safety and recyclability of the mobile phase. In our work, we discuss the development of "green chemistry" and present what micellar liquid chromatography is. This article presents application methods with the use of micellar liquid chromatography for analysis on antibacterial substances, melamine, biogenic amines, plant protection products, flavonoids, as well as peptides in biological matrices such as milk, eggs, tissues, honey, and feed.

Molecularly imprinted electrochemical sensor based on polypyrrole/dopamine@graphene incorporated with surface molecularly imprinted polymers thin film for recognition of olaquindox

In this paper, an advanced molecularly imprinted electrochemical sensor (MIECS) based on electropolymerized olaquindox (OLA) surface molecularly imprinted polymer thin film on a modified glassy carbon electrode (GCE) was developed for the detection of OLA. It was fabricated by coating dopamine@graphene (DGr) on GCE, then electropolymerizing pyrrole (Py) and molecularly imprinted polymers (MIPs). Graphene (Gr) was introduced for improving conductivity and sensitivity. Dopamine (DA) was used for dispersion and adhesion of Gr. Polypyrrole (PPy) could fix DGr and enhance the current response evidently. The established sensor could selectively recognize OLA but not the analogs of OLA. Some essential parameters controlling the performance of the developed sensor were investigated and optimized. Under optimal conditions, the linear relationship between the current intensity and OLA concentration was obtained from 50 nmol L^-1 to 500 nmol L^-1 with a limit of detection (LOD) of 7.5 nmol L^-1. Analytical results of OLA based on the developed MIECS for fish and feedstuffs showed a good agreement with the results based on high performance liquid chromatography (HPLC).

N-O Reduction and ROS-Mediated AKT/FOXO1 and AKT/P53 Pathways Are Involved in Growth Promotion and Cytotoxicity of Cyadox

Cyadox is a novel derivative of quinoxaline-1,4-dioxides (QdNOs) with the potential to be developed as a feed additive. However, the pharmacological and toxicological bioactive molecules of cyadox and the molecular mechanism of its pharmacological and toxic actions remain unclear. In the present study, cyadox and its main metabolites of cy1, cy4, cy6, and cy12 were selected; the growth promotion characteristic was indicated by the mRNA level of EGF; and the cytotoxicity of cyadox was determined by methylthiazol tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release, and Annexin V-FITC/PI apoptosis detection kit with flow cytometry. The intracellular ROS, cyclin D1, and Akt/P53/FOXO1 signaling pathway were also investigated. Our data suggested that cyadox showed relatively higher activity than its metabolites, and the ROS was generated from N-O reduction of cyadox. Moreover, cyadox (2 μM) activated the Akt and increased the EGF, cyclin D1, and FOXO1 expression levels. Cyadox (100 μM) induced cytotoxicity in L02 cells in a concentration- and time-dependent manner. Additionally, the activated P53 pathway, hyperactivated Akt, and apoptosis were found in L02 cells after incubation with 100 μM cyadox. Our data demonstrated that Akt promoted cell survival when it was mildly activated by cyadox at 2 μM, and Akt leads to apoptosis when it was severely activated by cyadox at 100 μM. Thus, the present study revealed that N-O reduction of cyadox and ROS-mediated AKT/FOXO1 and AKT/P53 pathways were involved in growth promotion and cytotoxicity of cyadox.

The Reproductive Toxicity of Mequindox in a Two-Generation Study in Wistar Rats

Mequindox (MEQ), belonging to quinoxaline-di-N-oxides (QdNOs), has been extensively used as a synthetic antibacterial agent. To evaluate the reproductive toxicity of MEQ, different concentrations of MEQ were administered to Wistar rats by feeding diets containing 0, 25, 55, 110, and 275 mg/kg, respectively. Each group consisting of 25 males and 25 females (F₀) was treated with different concentrations of MEQ for 12-week period time, prior to mating and during mating, gestation, parturition and lactation. At weaning, 25 males and 25 females of F₁ generation weanlings per group were randomly selected as parents for the F₂ generation. Selected F₁ weanlings were exposed to the same diet and treatment as their parents. The number of live litter and indexes of mating and fertility were significantly decreased in the F1 and F2 generation at 110 and 275 mg/kg groups. Significant decrease in pup vitality during lactation was observed in F1 litter at 275 mg/kg group, in F2 litter at 55, 110, and 275 mg/kg groups. A downward trend in the body weights was observed in F₁ pups at 55, 110, and 275 mg/kg MEQ groups, and in F₂ pups at 110 and 275 mg/kg MEQ groups. The changed levels of ALT, AST, CREA, BUN, UA, Na, and K were noted in the serum of rats. The histopathologic examination showed that MEQ induced toxicity in the liver, kidney, adrenal, uterus and testis. The no-observed-adverse-effect level (NOAEL) for reproduction toxicity of MEQ was 25 mg/kg diet. The malformations and severe maternal toxicity of MEQ caused adverse effects on the conceptus and embryo, which result in fetal malformations and fetal deaths. In summary, the present study showed that MEQ induced maternal, embryo and reproductive toxicities as well as teratogenicity in rats.

Molecularly imprinted electrochemical sensor based on Au nanoparticles in carboxylated multi-walled carbon nanotubes for sensitive determination of olaquindox in food and feedstuffs

A novel molecularly imprinted electrochemical sensor (MIECS) was proposed to determine olaquindox (OLA) using gold nanoparticles in molecularly imprinted polymer (AuNPs@MIP) and carboxylated multi-walled carbon nanotubes (cMWCNTs). Glassy carbon electrode (GCE) was modified with cMWCNTs (cMWCNTs/GCE), and AuNPs/cMWCNT/GCE was obtained by electrodeposition on cMWCNTs/GCE using chronoamperometry in HAuCl₄. Then, the obtained MIP/AuNPs/cMWCNTs/GCE was electropolymerized using OLA as template and o-PD as monomer to determine OLA. Important experimental parameters, namely, scan cycles, mole ratio of template molecules to functional monomers, pH value, and incubation time were optimized. The novel MIP sensor can offer a 2.7nM of detection limit for OLA. In addition, a series of food and feedstuffs were analyzed to demonstrate the feasibility of MIECS.

In vivo studies to highlight possible illegal treatments of rabbits with carbadox and olaquindox

For the treatment of rabbit dysentery and bacterial enteritis, veterinary practitioners often adopt veterinary medicinal products authorised for other food-producing species, but in some cases non-authorised drugs frequently used in the past, such as carbadox and olaquindox, might be illegally adopted. To verify the carbadox and olaquindox distribution and persistence in rabbit tissues, two independent in vivo studies were carried out. In the first study, 24 healthy rabbits received water medicated with carbadox at 100 mg l(-1) over a period 28 days, whereas in the second one, 24 healthy rabbits were administered water containing olaquindox at 100 mg l(-1). In each study rabbits were randomly assigned to four groups to be sacrificed respectively at 0, 5, 10 and 20 days from treatment withdrawal, for depletion studies. A control group of six animals was adopted for control and as a reservoir of blank tissues. Muscle and liver samples collected from each treated animal were stored at -20°C pending the analysis. Sensitive and robust liquid chromatography-tandem mass spectrometry analytical methods were set up for the parent compounds and their main metabolites quinoxaline-2-carboxylic acid, desoxycarbadox and 3-methylquinoxaline-2-carboxylic acid to verify their residual. Data collected demonstrate that the combination of liver as target matrix, quinoxaline-2-carboxylic acid and 3-methylquinoxaline-2-carboxylic acid as marker residue and enzymatic digestion is strategic to evidence carbadox and/or olaquindox illegal treatments in rabbits, even 20 days after treatment withdrawal at concentration levels higher than 0.5 µg kg(-1). This findings suggests that liver should be proposed as target matrix for official control in national monitoring plan.

Micellar Liquid Chromatography from Green Analysis Perspective

Micellar liquid chromatography (MLC) is a simple well-established branch of high-performance liquid chromatography. The applications of MLC for the determination of numerous compounds in pharmaceutical formulations, biological samples, food, and environmental samples have been growing very rapidly. MLC technique has several advantages over other techniques, such as simultaneous separation of charged and uncharged solutes, rapid gradient capability, direct on-column injection of physiological fluids, unique separation selectivity, high reproducibility, robustness, enhanced luminescence detection, low cost, and safety. This review is devoted to the evaluation of the agreement of MLC with the principles of green chemistry which recently represents a universal trend. Also, it provides an overview on the basics of MLC, in addition to a survey of MLC methods published in the past five years for the assay of various compounds in different matrices.