ABSTRACT
A method was developed for analyzing the stable carbon isotope ratio of five volatile components ( Ethanol, Glycerol, Acetic acid, Ethyl lactate, 2-methyl-butanol ) in wine using gas chromatography-combustion-isotope ratio mass spectrometer ( GC-C-IRMS ) . The sample injection volume was less than 0. 5 μL, and the analytical time of each run was less than 14 min. The precision of this method was 0. 08‰-0. 25‰ for analyzing standards, while 0. 09‰-0. 36‰ for wine samples. Compared to element analysis-isotope ratio mass spectrometry ( EA-IRMS) results, the deviations were lower than 0. 5‰. Fifty-four wine samples from France, Australia, America and China were considered. The δ13 C of five volatile components were measured using GC-C-IRMS. Discriminant analysis ( DA) was employed for analyzing the geographical origin traceability of selected wine. The result indicated that δ13 C of volatile components could be used to distinguish the origin of wines. The method was shown to be effective in improving detection of the origin traceability of wine.
ABSTRACT
Background and purpose: Multidrug resistance (MDR) is the dominating obstacle to the chemotherapy. There is strong evidence that the phosphoinositide 3-kinases (PI3Ks) signaling pathway is involved in MDR phenotype, however, the mechanism of MDR occurrence is still unknown. This study tended to investigate the regulating effect of PI3K/Akt signaling pathway and its downstream target genes in P-glycoprotein (P-gp) (ABCB1 gene encoding)-mediated MDR in human colon carcinoma HCT-116/L-OHP cells. Methods:Pretreatment with PI3K selective inhibitor LY294002 (20μmol/L) for 2 h, the sensitivity of L-OHP was evaluated by the CCK-8 (cell counting kit-8) assay in HCT-116/L-OHP cells, and the expressions of P-gp, LRP, MRP-2, Akt, p-Akt, IκB and p-IκB were evaluated by Western blot. The activity of ABCB1 promoter was evaluated by chromatin immunoprecipitation analysis (CHIP). Results: After inhibiting the activity of PI3K/Akt signaling pathway, the IC50 value of L-OHP decreased from(157.48±16.73)μg/mL to (53.68±3.18)μg/mL in HCT-116/L-OHP cells, and the reversal index was 2.93 (P<0.01). The expressions of P-gp, p-Akt and p-IκB were down-regulation compared with the concrol group (P<0.01), but the expressions of LRP, MRP-2, Akt and IκB didn't change signiifcantly. CHIP result has conifrmed that NF-κB protein could bind to the region of ABCB1 gene promoter in HCT116/L-OHP cells. Conclusion:Blocking of PI3K/Akt/NF-kB signal pathway could increase the drug sensitivity to MDR cells, inhibit the phosphorylation of p-Akt and p-IκB, and reversing ABCB1/P-glycoprotein-mediated multidrug resistance in colon carcinoma cells.
ABSTRACT
A method for the determination of seven kinds of thiocarbamate herbicides, molinate, pebulate, vernolate, triallate, thibencarb, eradicane and butylate in black tea and green tea has been developed. After homogenization, 2.0 g tea sample was soaked with 6 mL water for 1 h. 2.5 g NaCl was then added, and the sample was extracted twice by 20 mL acetonitrile. After concentration, the extract was put through HLB column and eluted by 3 mL acetonitrile. The eluate was then concentrated and dissolved with 2.0 mL hexane-acetone (7∶ 3, V/V) mixture. The preparation was cleaned by Envi-Carb column and eluted with 5 mL hexane-acetone. After concentration, the residue was dissolved by acetonitrile-water (5∶ 5, V/V) solution. Detection was achieved by electrospray ionization(ESI) in positive mode using multiple reaction monitoring. D_3-carbaryl was used as the internal standard, the linear range for the herbicides was 0-200 μg/L and the limit of detection were from 0.093 to 1.77 μg/L, with the correlation coefficients(r) varying from 0.9954 to 0.9988. The recoveries of all thiocarbamate herbicides were from 77.3% to 91.5% at the spiked levels of 5-20 μg/kg. The RSD of each compound was less than 15%. Black tea and green tea samples were successfully analyzed by the proposed method with satisfactory results.