In this study, pumpkin (Cucurbita moschata) skin polysaccharide–zinc(II) (PSP−Zn) complex was successfully prepared. The structure and physicochemical properties of PSP and PSP−Zn were analyzed. The anti-inflammatory activity of PSP and PSP−Zn was investigated in zebrafish larvae induced by copper sulphate. PSP and PSP−Zn consisted of rhamnose, arabinose, galactose, glucose, and galacturonic acid. The molecular weight (Mw) of PSP and PSP−Zn were 3.034 × 106 and 3.222 × 106 Da, respectively. Fourier transform infrared spectrum (FT-IR) and circular dichroism (CD) analysis results suggested that the chemical modification of zinc might occur through hydroxyl groups of PSP. The PSP−Zn complex had lamellar texture, smooth surface morphology, and larger particle size. X-ray Diffraction (XRD) analysis revealed that both PSP and PSP−Zn were semi-crystalline substances. PSP−Zn solution showed superior stability in a weak acid and alkaline environment, especially at pH = 6.0. Moreover, PSP and PSP−Zn showed a good inhibitory effect on inflammation cells in zebrafish. Real-time quantitative polymerase chain reaction (RT-PCR) result suggested that the anti-inflammatory mechanism of PSP and PSP−Zn were through downregulation of the expression of nitric oxide synthase 2b (nos2b), inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), and nuclear factor-kappa B2 (NF-κB2). The present study indicated that PSP−Zn is expected to be a safe and efficient novel zinc supplement with anti-inflammatory activity.
A modified-QuEChERS method to determine kresoxim-methyl in banana and soil was developed and validated via high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). The dissipation behavior, residue distribution, and risk assessment of kresoxim-methyl in banana were further investigated based on this method. The dissipation behavior of kresoxim-methyl in banana and soil was described by using first-order kinetics and its half-life, 4.8–5.7 days and 5.5–6.5 days, respectively. The concentrations of kresoxim-methyl were 0.03–0.08 mg kg−1, 0.06–0.17 mg kg−1, and <0.01 mg kg−1 for a whole banana, peel, and pulp, respectively, on the basis of spraying three times the recommended dosage and pre-harvest interval (PHI, 42 days). The results showed that the risk quotient of kresoxim-methyl in banana to people exhibited an acceptable low dietary risk. This current study could help in guiding the scientific and proper usage of this formulation.
A derivatization method combined with high-performance liquid chromatography–fluorescence detection (HPLC–FLD) was used to evaluate the dissipation, residue distribution and risk assessment of emamectin benzoate in whole longan and pulp. The average recoveries were 82–111% with relative standard deviation (RSD) less than 11%. The limit of quantification (LOQ) was 0.001 mg/kg in longan and pulp. The half-lives were 3.3–4.2 days. The terminal residues in whole longan were <0.001–0.025 mg/kg applied two and three times at two levels of dosage with PHIs of 10, 14, and 21 days. The residues in whole longan had a higher quantity than those in the pulp, and the terminal residues of pulp were all lower than LOQ (0.001 mg/kg). The chronic risk of emamectin benzoate was not negligible to humans depending on ADI% value, which was higher than 1; and the acute risk was acceptable to the consumer. This study could provide guidance for the safe use of emamectin benzoate in longan and serve as a reference for the establishment of maximum residue limits (MRLs) in China.
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