Simultaneous determination of diaveridine, trimethoprim and ormetoprim in feed using high performance liquid chromatography tandem mass spectrometry

Metabolism and Tissue Elimination of Diaveridine in Swine, Chickens, and Rats Using Radioactive Tracing Coupled with LC-ESI-IT-TOF/MS

Diaveridine (DVD) has widespread use in food animals due to its antibacterial synergistic effects. This study revealed the metabolism, excretion, and tissue elimination of DVD in swine, chickens, and rats following oral gavage of 10 mg/kg b.w. tritium-labeled DVD using radioactive tracing coupled with liquid chromatography-electron spray ionization-ion trap-time-of-flight-mass spectrometry (LC-ESI-IT-TOF/MS). The metabolic pathways involved demethylation, α-hydroxylation, glucuronidation, and sulfonylation and produced four metabolites in swine (M0, DVD; M1, 3'/4'-demethyl-DVD; M2, 3'/4'-demethyl-DVD-O-glucuronide; M4, 2/4-glucuronidated-DVD) and five in chickens (M0∼M2; M3, α-hydroxy-DVD; M4) and rats (M0∼M3; M5, 3'/4'-demethyl-DVD-O-sulfation). M0 was dominant in the excreta of chicken and female and male rats, while M2 was mainly excreted in swine. Among the three species studied, M0 was the most persistent in the kidneys (t_1/2 3.15-3.89 d); therefore, M0 kidney levels are residue monitoring targets. This study enabled a thorough comprehension of the metabolism and pharmacokinetic characteristics of DVD in animals.

Nanostructured ZnO-Based Electrochemical Sensor with Anionic Surfactant for the Electroanalysis of Trimethoprim

In this research, detection of trimethoprim (TMP) was carried out using a nanostructured zinc oxide nanoparticle-modified carbon paste electrode (ZnO/CPE) with an anionic surfactant and sodium dodecyl sulphate (SDS) with the help of voltametric techniques. The electrochemical nature of TMP was studied in 0.2 M pH 3.0 phosphate-buffer solution (PBS). The developed electrode displayed the highest peak current compared to nascent CPE. Effects of variation in different parameters, such as pH, immersion time, scan rate, and concentration, were investigated. The electrode process of TMP was irreversible and diffusion controlled with two electrons transferred. The effective concentration range (8.0 × 10^-7 M-1.0 × 10^-5 M) of TMP was obtained by varying the concentration with a lower limit of detection obtained to be 2.58 × 10^-8 M. In addition, this approach was effectively employed in the detection of TMP in pharmaceutical dosages and samples of urine with the excellent recovery data, suggesting the potency of the developed electrode in clinical and pharmaceutical sample analysis.

Rapid determination of 2,4-diaminopyrimidine residues through sample pretreatment using immunomagnetic bead purification along with HPLC-UV

To reduce matrix interference and realize simultaneous detection of multiple homologous compounds (trimethoprim (TMP), diaveridine (DVD), ormetoprim (OMP), baquiloprim (BQP), and aditoprim (ADP) in pig, cattle, chicken, and fish muscles), an immunomagnetic bead (IMB)-based sample purification pretreatment with HPLC-UV was developed. A broad-spectrum monoclonal antibody (mAb, named 14C6) was prepared and conjugated with carboxylic-acid-functionalized magnetic nanoparticles using the active ester method to obtain IMBs for sample purification. The extraction solvent was optimized based on the extraction efficiency. Good linearity was observed for all the five analytes (10-200 μg/kg) with the LOD and LOQ of 5 and 10 μg/kg, respectively. The mean recoveries ranged from 62.5% to 76.9%, while the coefficient of variation was <12.2%. The IMB method afforded greater sample purification and enrichment than those achieved with the SPE column-based conventional method. Hence, the IMB-based sample purification is a useful tool to determine 2,4-diaminopyrimidine residues in edible animal tissues.

Metabolite Identification and Pharmacokinetic Behavior of Diaveridine in the Plasma of Pigs and Chickens Based on Radioactive Tracing Coupled With LC/MS-IT-TOF Assay

Diaveridine (DVD) is widely used for the prevention and treatment of coccidiosis and leucocytozoonosis infections in food-producing animals. To gain a better understanding of DVD metabolism and pharmacokinetics in healthy Landrace/Doric Cross castrated male pigs and both female and male Cobb 500 broiler chickens, a method involving radioactive tracing coupled with LC/MS-IT-TOF was developed for the identification and quantitation of DVD and its metabolites in pig and chicken plasma, and then was applied to investigate DVD pharmacokinetics. A simple MCX solid phase extraction procedure was adopted for sample preparation. After a single oral administration of 3H-DVD (10 mg/kg BW), three radioactive compounds (D0: DVD; D1: 3'-desmethyl-DVD; and D2: monoglucuronide of 3'-desmethyl-DVD) were identified in pig plasma, while only two radioactive compounds (D0 and D2) were identified in chicken plasma. In both species, the C max values for all detected compounds were reached at 2 h after dosing. The C max order was D2 (1.38 μg/ml) > D0 (0.49 μg/ml) > D1 (0.24 μg/ml) in pigs and D0 (1.55 μg/ml) > D2 (0.27 μg/ml) in chickens. The longer t 1/2 (elimination half-life) of D0 contributed to the slow elimination of DVD-related compounds. The t 1/2β of D0 in pigs (66.41 h) was significantly longer than that in chickens (48.30 h), but the t 1/2 of total DVD-related metabolites in pigs (42.86 h) was lower than that in chickens (56.11 h). These findings suggested that the metabolism and pharmacokinetics of DVD in pigs and chickens were significantly different, and that this would affect its effectiveness, toxicology, and food safety in these animals.

Trace analysis and identification of 33 sulfonamides and sulfonamide potentiators in eggs by ultrahigh-performance liquid chromatography coupled with quadrupole-high-field orbitrap high-resolution mass spectrometry

A method was established for the simultaneous trace analysis and identification of 27 sulfonamides and 6 sulfonamide potentiators in eggs by ultrahigh-performance liquid chromatography coupled with quadrupole-high-field orbitrap high-resolution mass spectrometry and multifunction impurity adsorption cleaning. The appropriate extraction, purification, and instrument conditions were optimized. The drugs were extracted by acetonitrile with 1% formic acid and purified with optimized adsorption material based on multifunction impurity adsorption cleaning. The elution was evaporated by nitrogen blowing, dissolved, and then assayed. The limits of detection were 0.01-0.28 μg kg^-1 for all drugs, while the recoveries were 82.4-110.6%, the relative standard deviations were 2.5-14.9%, and the linearity of the drugs in the corresponding concentration range was greater than 0.995. The proposed method was successfully applied for the monitoring of sulfonamides and their potentiators in egg samples, whereby 4 sulfonamides and 3 sulfonamide potentiators were detected in 200 egg samples.

Development of radioactive tracing coupled with LC/MS-IT-TOF methodology for the discovery and identification of diaveridine metabolites in pigs

We developed a sensitive and reliable method by coupling radiotracing with LC/MS-IT-TOF to identify diaveridine metabolites. Tritium-labeled diaveridine was orally administered to pigs and their organs, blood, bile, and excreta were collected. Under optimized conditions, radioactive recovery was >90% and the highest numbers of metabolites were detected. MCX-based solid-phase extraction was conducted for urine, plasma, and bile purification. Methanol-chloroform 1:1 (v/v), methanol-chloroform 6:1 (v/v), methanol, methanol-chloroform 1:1 (v/v), and methanol were used as solvents to extract feces, liver, kidney, fat and muscle, respectively. The method validation confirmed satisfactory ³H-H exchange efficiency (<5%), chromatographic column efficiency (≥97.5%), LOQ (10.73 μg/kg), and analytical accuracy (97.6-107.8%) and precision (RSD < 5%). Moreover, novel in vivo metabolites were detected in the pigs, including D2 (3'-desmethyl-diaveridine monoglucuronide), D3 (diaveridine monoglucuronide). Hence, the analytical method developed herein lays an empirical foundation for further systematic studies of the diaveridine metabolism.

Development and comparison of two nanomaterial label-based lateral flow immunoassays for the detection of five antibacterial synergists

Label is a significant factor when analyzing the performance of lateral flow immunoassays (LFIAs). Thus, this study developed two nanomaterial label-based LFIA and compared their analytical performance in practical applications.

Generic Hapten Synthesis, Broad-Specificity Monoclonal Antibodies Preparation, and Ultrasensitive ELISA for Five Antibacterial Synergists in Chicken and Milk

An antibody with broad specificity and principally depending on hapten structure and size is a key reagent for developing a class-selective immunoassay. In the present study, three new generic haptens of antibacterial synergists (ASGs) were proposed using trimethoprim as the starting molecule. These haptens contained carboxyl groups on the meta position of trimethoxybenzene for conjugating to protein, while, the common moiety of ASGs, i.e., diaminopyrimidine, was intentionally and maximally exposed to the immune system in animals in order to induce antibodies with broad specificity against ASGs. Five monoclonal antibodies (mAbs) were finally obtained, and 5C4 from the hapten with a short spacer arm, named Hapten A, showed not only uniform broad specificity but also high affinity to all five ASGs. We further determined the possible recognition mechanism of mAbs in terms of conformational and electronic aspects. An indirect competitive ELISA (icELISA)-based 5C4 was established and exhibited IC₅₀ values of 0.067-0.139 μg L^-1 with cross-reactivity of 48.2%-418.7% for the five ASGs in buffer under optimal conditions. The calculated limits of detection of the icELISA for chicken and milk were 0.06-0.8 μg kg^-1 and 0.05-0.6 μg L^-1, respectively. The recoveries in spiked chicken and milk samples were 75.2%-101.4% with a coefficient of variation less than 14.3%. In summary, we have developed, for the first time, a rapid and reliable icELISA for ASGs with significantly improved sensitivity and class selectivity.

Pharmacodynamics and Medicinal Chemistry of an External Chinese Herbal Formula for Mammary Precancerous Lesions

Ruyan Neixiao Cream (RYNXC) is a traditional Chinese herbal formula for treating mammary precancerous disease. This study was carried out to investigate in vivo anticancer effect of RYNXC and multiple constituents. 32 virginal Sprague-Dawley rats were randomly divided into blank control group (BC), mammary precancer models group (MODEL), tamoxifen group (TAM), and Ruyan Neixiao Cream group (RYNXC). TAM was intervened by tamoxifen; RYNXC was intervened by Ruyan Neixiao Cream. The chromatographic separation was performed by high performance liquid chromatography (HPLC) coupled with mass spectrometry (MS). RYNXC showed significant improvement in erythrocyte aggregation index (EAI), hematocrit (HCT), fibrinogen (FIB), spleen coefficient, and uterus coefficient compared with MODEL. In RYNXC and TAM groups, atypical hyperplasia was observed in pathological mammary tissues; meanwhile in MODEL group, ductal carcinoma was observed in situ. Moreover, fifteen compounds were characterized according to HPLC-MS data, including organic acids, tannin, alkaloid, volatile oil, anthraquinones, and flavonoids. The study suggests that RYNXC was an effective Chinese herbal formula for mammary precancerous lesions and provides a scientific basis for the quality standard and the pharmacology of RYNXC. It will be beneficial to the future clinical application of RYNXC.

Comparative pharmacokinetics of diaveridine in pigs and chickens following single intravenous and oral administration

Comparative pharmacokinetic profiles of diaveridine following single intravenous and oral dose of 10 mg/kg body weight in healthy pigs and chickens were investigated, respectively. Concentrations of diaveridine in plasma samples were determined using a validated high-performance liquid chromatography-ultraviolet (HPLC-UV) method. The concentration-time data were subjected to noncompartmental kinetic analysis by WinNonlin program. The corresponding pharmacokinetic parameters in pigs or chickens after single intravenous administration were as follows, respectively: t_1/2β (elimination half-life) 0.74 ± 0.28 and 3.44 ± 1.07 h; V_d (apparent volume of distribution) 2.70 ± 0.99 and 3.86 ± 0.92 L/kg; Cl_B (body clearance) 2.59 ± 0.62 and 0.80 ± 0.14 L/h/kg; and AUC_0-∞ (area under the blood concentration vs. time curve) 4.11 ± 1.13 and 12.87 ± 2.60 μg∙h/mL. The corresponding pharmacokinetic parameters in pigs or chickens after oral administration were as follows, respectively: t_1/2β 1.78 ± 0.41 and 2.91 ± 0.57 h; C_max (maximum concentration) 0.43 ± 0.24 and 1.45 ± 0.57 μg/mL; T_max (time to reach C_max ) 1.04 ± 0.67 and 3.25 ± 0.71 h; and AUC_0-∞ 1.33 ± 0.55 and 9.28 ± 2.69 μg∙h/mL. The oral bioavailability (F) of diaveridine in pigs or chickens was determined to be 34.6% and 72.2%, respectively. There were significant differences between the pharmacokinetics profiles in these two species.