[Determination of seven paraben preservatives in aquatic seasoning using solid-phase extraction coupled with high performance liquid chromatography].

Seven parabens are widely used in soy sauce, vinegar, jam, oyster sauce, stuffing, and other foods. The long-term intake of large amounts of parabens and similar substances may be harmful to the human body. Therefore, the addition of paraben preservatives to food should be strictly controlled. The current detection method is applicable to single target compound and several food categories, and the experimental pretreatment method involves extraction with anhydrous ethyl ether, which is a toxic reagent. Moreover, interferences in the analysis of parabens via gas chromatography limit the versatility and accuracy of the detection method. Herein, a novel method based on solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC) was developed for the determination of seven paraben preservatives (methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, isopropyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate, and heptyl p-hydroxybenzoate) in oyster sauce, shrimp sauce, and fish sauce. Compared with the conventional method, the proposed work enables the determination of more compounds, thereby expanding its scope of application to different food types. This strategy also optimizes the pretreatment method and device parameters. The samples were extracted with methanol and 20% methanol aqueous solution by ultrasonication, respectively, and then centrifuged. The experimental pretreatment method was enriched, and sample clean-up was conducted using a MAX SPE column. The seven parabens were separated using a Chromcore 120 C18 column (150 mm×4.6 mm, 3.0 µm). Gradient elution was performed with acetonitrile-5 mmol/L ammonium acetate aqueous solution as the mobile phase (initial mobile phase volume ratio, 30∶70). The flow rate was 0.7 mL/min, and the column temperature was 35 ℃. A diode array detector with a detection wavelength of 254 nm was also used. The seven paraben preservatives showed good linearity in the range of 0.5-50.0 mg/L, with correlation coefficients greater than 0.9999. The limits of detection (LODs) and quantification (LOQs) for the seven paraben preservatives were 0.2-0.4 mg/kg and 0.5-1.3 mg/kg, respectively. A spiked recovery test was conducted using oyster sauce, shrimp sauce, and fish sauce at three spiked levels of 2, 40, and 200 mg/kg. Good recoveries for the seven paraben preservatives were obtained and the recoveries of the analytes in oyster sauce, shrimp sauce, and fish sauce were 91.0%-102%, 95.5%-106%, and 95.0%-105%, respectively, with relative standard deviations of ≤6.97%. Compared with the liquid-liquid extraction method, the proposed method demonstrated better purification effects. The recoveries of the seven paraben preservatives extracted using this method were also much higher than those obtained from liquid-liquid extraction. We determined the contents of these preservatives in 135 food products using the method established in this study and detected methyl p-hydroxybenzoate and ethyl p-hydroxybenzoate in soy sauce, vinegar, and pickles. Thus, the established method can be used for the effective determination of seven parabens in aquatic seasoning such as oyster sauce, shrimp sauce, and fish sauce.

Mechanism of Robo1 in the pentylenetetrazol-kindled epilepsy mouse model.

The neural network hypothesis is one of the important pathogenesis of drug-resistant epilepsy. Axons guide molecules through synaptic remodeling and brain tissue remodeling, which may result in the formation of abnormal neural networks. Therefore, axon guidance plays a crucial role in disease progression. However, although Robo1 is one of the important components of axon guidance, the role of Robo1 in epilepsy remains unclear. In this study, we aimed to explore the mechanism of Robo1 in epilepsy. Male adult C57BL/6 mice were intraperitoneally injected with pentylenetetrazol to establish an epilepsy model. Lentivirus (LV) was given via intracranial injection 2 weeks before pentylenetetrazol injection. Different expressions of Robo1 between the control group, LV-mediated Robo1 short hairpin RNA group, empty vector control LV group, and normal saline group were analyzed using Western blot, immunofluorescence staining, Golgi staining, and video monitoring. Robo1 was increased in the hippocampus in the pentylenetetrazol-induced epilepsy mouse model; lentiviral Robo1 knockdown prolonged the latency of seizure and reduced the seizure grade in mice and resulted in a decrease in dendritic spine density, while the number of mature dendritic spines was maintained. We speculate that Robo1 has been implicated in the development and progression of epilepsy through its effects on dendritic spine morphology and density. Epileptic mice with Robo1 knockdown virus intervention had lower seizure grade and longer latency. Follow-up findings suggest that Robo1 may modulate seizures by affecting dendritic spine density and morphology. Downregulation of Robo1 may negatively regulate epileptogenesis by decreasing the density of dendritic spines and maintaining a greater number of mature dendritic spines.