Application of gas chromatography-mass spectrometry in analyzing pharmacokinetics and distribution of deltamethrin in miniature pig tissues.

OBJECTIVE: To characterize the pharmacokinetics and distribution profiles of deltamethrin in miniature pig tissues by gas chromatography-mass spectrometry (GC-MS). METHODS: Pharmacokinetics and distribution of deltamethrin in blood and tissues of 30 miniature pigs were studied by GC-MS after oral administration of deltamethrin (5 mg/kg bw). Data were processed by 3P97 software. RESULTS: The serum deltamethrin level was significantly lower in tissues than in blood of miniature pigs. The AUC0-72 h, Cmax, of deltamethrin were 555.330 ± 316.987 ng h/mL and 17.861 ± 11.129 ng/mL, respectively. The Tmax, of deltamethrin was 6.004 ± 3.131 h. CONCLUSION: The metabolism of deltamethrin in miniature pigs is fit for a one-compartment model with a weighting function of 1/C2. Deltamethrin is rapidly hydrolyzed and accumulated in miniature pig tissues.

[Study on the interaction of hesperidin or icariin with lysozyme by fluorescence spectroscopy].

The interaction of hesperidin (HES) or icariin (ICA) and lysozyme (LYS) was studied by fluorescence spectroscopy in physiological buffer solution. It was observed that there was a strong fluorescence quenching effect of hesperidin or icariin on lysozyme. The quenching constants of the drugs with lysozyme were measured at different temperatures, and the quenching mechanism was suggested as dynamic quenching for HES-LYS system and both static and dynamic quenching for ICA-LYS system. The thermodynamic parameters of the interaction of hesperidin or icariin and lysozyme were measured according to the Van's Hoff equation: the enthalpy change (DeltaH) and the entropy change (DeltaS) of HES-LYS system and ICA-LYS system were calculated to be 20.29 kJ x mol(-1) and 146.28 J x mol(-1) x K(-1), and -3.47 kJ x mol(-1) and 81.16 J x mol(-1) x K(-1), respectively, which indicated that the interaction of hesperidin and lysozyme was driven mainly by hydrophobic force, whereas the interaction of icariin and lysozyme was driven mainly by electrostatic force. It was showed that the reaCtion processes of the two systems occurred spontaneously since Gibbs free energy change (DeltaG) values were negative. The binding distances of hesperidin and icariin from the lysozyme tryptophan residue were calculated to be 1.34 nm and 1.24 nm, respectively, based on the Förster's theory of non-radiation energy transfer. The results of synchronous fluorescence spectra showed that the binding of hesperidin or icariin to lysozyme induced conformational changes in lysozyme.

[Study of the recognition between alpinetin and calf thymus DNA].

The recognition between alpinetin and DNA under physiological condition (pH 7.4) was investigated by fluorescence and UV-visible spectrometry. The experiment demonstrated that the fluorescence of alpinetin could be quenched by DNA. A quenching mechanism was proved to be the single static quenching procedure according to the deescalating quenching constants Ksv (3.288 X 10(3) , 2.923 X 10(3) and 2.467 X 10(3) L x mol(-1), respectively) along with the escalating temperatures (25, 32 and 39 degrees C) and the quenching rate constant Kq was greater than the maximum scatter collision quenching rate constant of various quenchers with the biomolecule. From the UV-visible spectra of alpinetin and DNA, the result showed that the UV-visible spectra of alpinetin did not changed in the presence of DNA, i. e. neither the decrease in the maximum absorbance intensity nor the red shift of the maximum absorption wavelength changed. Both the fluorescence intensity and the maximum emission wavelength of ethidium bromide-DNA system remained unchanged in the presence of alpinetin, indicating that there is no direct competition for binding DNA between alpinetin and ethidium bromide. Furthermore, DNA thermal denaturation test indicated that the fluorescence quenching effect of alpinetin with unlinking DNA was stronger than that of alpinetin with natural DNA. It was concluded that there was not intercalation binding mode between alpinetin and DNA. At the same time, fluorescence quenching effect and salt effect on the binding of alpinetin with DNA were investigated. It was shown that the major mode of recognition was groove binding between alpinetin and DNA.

[Studies on the interaction between alpinetin and human serum albumin by fluorescence spectroscopy].

The interaction between alpinetin and human serum albumin (HSA) was studied by fluorescence and UV/Vis absorption spectroscopy. The results revealed that alpinetin caused the fluorescence quenching of HSA through a dynamic quenching procedure. The quenching constant was obtained at various temperatures. The binding locality was found to be an area 4.05 nm away from tryptophan residue in HSA based on Forster's non-radiation energy transfer mechanism. The binding power between alpinetin and HSA is mainly the hydrophobic interaction according to the thermodynamic parameters. The effect of alpinetin on the conformation of HSA was analyzed by three-dimensional fluorescence spectra, contour spectra and synchronous spectra.

[Studies on the interaction between puerarin and bovine serum albumin].

The interaction of puerarin and bovine serum albumin (BSA) under physiological condition was studied by fluorospectrophotometry. The experiment demonstrated that the quenching mechanism of puerarin a BSA was static quenching process. The quenching constant is 7.29 x 10(12) L x mol(-1) x s(-1), and the binding constant is 5.04 x 10(4) L x mol(-1). According to the Forster nonradiative energy transfer theory, the binding distance between donor (BSA) and acceptor (puerarin) was calculated to be 3.35 nm. The influence of the presence of puerarin on structure of BSA was studied by synochronous fluorescence method, the binding distance between BSA and puerarin was also measured, and the binding mechanism was discussed. In addition, the effect of some ions on the binding constant of puerarin with BSA was also studied.

Phytochemical profiles and antioxidant activity of brown rice varieties.

The phytochemical content and antioxidant activity of eight varieties of brown rice (BR) are reported. The total phenolic contents of BR ranged from 72.45 to 120.13mg of gallic acid equiv./100g. The phenolics from bound fraction contributed 40.6-50.2% of the total phenolic content. The total flavonoid contents of BR ranged from 75.90 to 112.03mg catechin equiv./100g. The flavonoids from the bound fraction contributed 26.9-48.2% of total flavonoids. Trans-ferulic acid was the predominant phenolic acid in BR. Total trans-ferulic acid content ranged from 161.42 to 374.81µg/100g. The percentage of trans-ferulic acid in bound fraction ranged from 96.4% to 99.2%. Only α- and γ-tocopherols and -tocotrienols were detected in BR with α-tocopherol and γ-tocotrienol being the predominant. The total peroxyl radical scavenging capacity (PSC) of BR ranged from 18.29 to 40.33mg vitamin C equiv./100g. The bound fraction contributed 67.2-77.2% of total PSC.

[Synchronous fluorimetric determination of the residues of three quinolones in Eel by partial least squares].

In the present paper, the synchronous fluorimetric spectra of norfloxacin, lomefloxacin chlorhydric acid, and levofloxacin lactate with deltalambda = 190 nm in a B-R buffer medium of pH 2.87 were measured, and the partial least squares (PLS) method was applied to the quantitative resolution of the seriously overlapped fluorimetric spectra of these compounds. The linear ranges for norfloxacin, lomefloxacin chlorhydric acid, and levofloxacin lactate are 0.016-0.40 microg x mL(-1), 0.01-0.336 microg x mL(-1) and 0.01-0.336 microg x mL(-1), respectively. The limits of detection are 0.012 6 microg x mL(-1) for norfloxacin, 0.006 microg x mL(-1) for lomefloxacin chlorhydric acid, and 0.007 2 microg x mL(-1) for levofloxacin lactate. The analytical results by PLS were compared with principal components regression (PCR) and classical least squares (CLS), and this method was applied to the determination of these three compounds in eel samples with satisfactory results.

[Resolution of synchronous fluorimetric spectrum for carbaryl and coumaphos and its application study].

The synchronous fluorimetric method for the simultaneous determination of carbaryl and coumaphos is described. In the Britton-Robinson buffer at pH 3.0, synchronous scanning with deltalambda= 60 nm was carried out, and the overlapped fluorimetric spectra were better separated. The two synchronous fluorimetric peaks are located at 280 and 322 nm respectively, and can be used for the determination of these two pesticides. No preliminary separation is needed. The method is simple, rapid and successfully applied to the analysis of food samples. The linear ranges of the calibration curves for carbaryl and coumaphos are 0.016-0.384 microg x mL(-1) and 0.016-0.320 microg x mL(-1), respectively. The limits of detection are 0.015 microg x mL(-1) for carbaryl, and 0.010 microg x mL(-1) for coumaphos.

Organochlorine pesticides and pyrethroids in Chinese tea by screening and confirmatory detection using GC-NCI-MS and GC-MS/MS.

One hundred and one tea samples including green tea, dark tea, scented tea, black tea, and oolong tea were screened and confirmed for the contamination of 31 organochlorine pesticides (OCPs) and 19 pyrethroids (PYs) by gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). 50 pesticides, 3 deuterium-labeled PYs, and 24 (13)C-labeled OCPs were separated well with the limits of detection (LODs) ranging from 0.02 to 4.5 µg/kg for GC-NCI-MS, and the positive samples were verified by GC-MS/MS with LODs of 0.1-5.0 µg/kg. High detection rates for some PYs, such as 63.4% for bifenthrin (not detected (ND)-3.848 mg/kg), 55.4% for λ-cyhalothrin (ND-3.244 mg/kg), 46.5% for cypermethrin (ND-0.499 mg/kg), and 24.8% for fenvalerate (ND-0.217 mg/kg), were found in the 101 tea samples. Endosulfan, DDTs, HCHs, and heptachlor, the persistent OCPs, were frequently detected with rates of 63.4% (ND-1.802 mg/kg), 56.4% (ND-0.411 mg/kg), 24.8% (ND-0.377 mg/kg), and 15.8% (ND-0.100 mg/kg), respectively.