Analysis of bacitracin and its related substances by liquid chromatography tandem mass spectrometry

A suitable liquid chromatography quadrupole time-of-flight mass spectrometric(LC–Q-TOF–MS) method was developed for separation and characterization of related substances in bacitracin test drug. The separation was performed on Li Chrospher RP-18 column using methanol as mobile phase A and 0.2% ammonium acetate buffer solution as mobile phase B in gradient elution. A total of 12 related substances were detected through high resolution mass spectrometric determination in a positive electrospray ionization mode. They were identified as co-existing active components and degradation products of bacitracin through the analysis and elucidation of both the protonated parents and the product ions of all the related substances and their fragmentation pathways were also proposed.

Automatic analytical approach for the determination of 12 illicit drugs and nicotine metabolites in wastewater using on-line SPE-UHPLC-MS/MS

In this study,we developed a novel on-line solid phase extraction(SPE)-ultra-high-performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS)-based analytical method for simultaneously quantifying 12 illicit drugs and metabolites(methamphetamine,amphetamine,morphine,codeine,6-monoacetylmorphine,benzoylecgonine,3,4-methylenedioxymethamphetamine,3,4-methylenedioxyamphetamine,cocaine,ketamine,norketamine,and methcathinone)and cotinine(COT)in wastewater samples.The analysis was performed by loading 2 m L of the sample onto an Oasis hydrophilic-lipophilic balance cartridge and using a cleanup step(5%methanol)to eliminate interference with a total run time of 13 min.The isotope-labeled internal standard method was used to quantify the target substances and correct for unavoidable losses and matrix effects during the on-line SPE process.Typical analytical characteristics used for method validation were sensitivity,linearity,precision,repeatability,recovery,and matrix effects.The limit of detection(LOD)and limit of quantification(LOQ)of each target were set at 0.20 ng/L and 0.50 ng/L,respectively.The linearity was between 0.5 ng/L and250 ng/L,except for that of COT.The intra-and inter-day precisions were<10.45%and 25.64%,respectively,and the relative recovery ranged from 83.74%to 162.26%.The method was used to analyze various wastewater samples from 33 cities in China,and the results were compared with the experimental results of identical samples analyzed using off-line SPE.The difference rate was between 19.91%and-20.44%,and the error range could be considered acceptable.These findings showed that on-line SPE is a suitable alternative to off-line SPE for the analysis of illicit drugs in samples.

Liposome-based anchoring and core-encapsulation for combinatorial cancer therapy

Downregulated pro-apoptotic protein in cancer cells compromises the chemotherapy by a cytotoxic drug.Here,we report co-delivery of a pro-apoptotic protein,caspase 3(Cas 3),and cytotoxic agent,oridonin(ORD),for synergistic cancer treatment,using a method of liposome-based anchoring and core encapsulation.First,ORD is modified with hyaluronic acid(HA)to improve its solubility.Then,the targeted co-delivery system is prepared by assembling the conjugate HA-ORD onto the Cas 3-loaded liposomes,which the surface HA can target the CD44 receptor on cancer cells.In vitro,the co-loaded liposomes(120 nm)are specifically taken up by 4T1 cells and endow a 1.5-fold increase of Cas 3.After intravenous injection into the tumor-bearing mice,the liposomes accumulate in the tumor with high efficacy and significantly inhibit tumor growth via promoting apoptosis and anti-proliferation of cancer cells.Mechanistically,the co-delivery works synergistically by upregulating the activated Cas form,cleaved-Cas 3.

Hepatic retinaldehyde deficiency is involved in diabetes deterioration by enhancing PCK1-and G6PC-mediated gluconeogenesis

Type 2 diabetes(T2D) is often accompanied with an induction of retinaldehyde dehydrogenase 1(RALDH1 or ALDH1A1) expression and a consequent decrease in hepatic retinaldehyde(Rald)levels. However, the role of hepatic Rald deficiency in T2D progression remains unclear. In this study, we demonstrated that reversing T2D-mediated hepatic Rald deficiency by Rald or citral treatments, or liverspecific Raldh1 silencing substantially lowered fasting glycemia levels, inhibited hepatic glucogenesis,and downregulated phosphoenolpyruvate carboxykinase 1(PCK1) and glucose-6-phosphatase(G6PC)expression in diabetic db/db mice. Fasting glycemia and Pck1/G6pc mRNA expression levels were strongly negatively correlated with hepatic Rald levels, indicating the involvement of hepatic Rald depletion in T2D deterioration. A similar result that liver-specific Raldh1 silencing improved glucose metabolism was also observed in high-fat diet-fed mice. In primary human hepatocytes and oleic acidtreated HepG2 cells, Rald or Rald + RALDH1 silencing resulted in decreased glucose production and downregulated PCK1/G6PC mRNA and protein expression. Mechanistically, Rald downregulated direct repeat 1-mediated PCK1 and G6PC expression by antagonizing retinoid X receptor a, as confirmed by luciferase reporter assays and molecular docking. These results highlight the link between hepatic Rald deficiency, glucose dyshomeostasis, and the progression of T2D, whilst also suggesting RALDH1 as a potential therapeutic target for T2D.

Bile duct ligation differently regulates protein expressions of organic cation transporters in intestine,liver and kidney of rats through activation of farnesoid X receptor by cholate and bilirubin

Body is equipped with organic cation transporters(OCTs).These OCTs mediate drug transport and are also involved in some disease process.We aimed to investigate whether liver failure alters intestinal,hepatic and renal Oct expressions using bile duct ligation(BDL)rats.Pharmacokinetic analysis demonstrates that BDL decreases plasma metformin exposure,associated with decreased intestinal absorption and increased urinary excretion.Western blot shows that BDL significantly downregulates intestinal Oct2 and hepatic Oct1 but upregulates renal and hepatic Oct2.In vitro cell experiments show that chenodeoxycholic acid(CDCA),bilirubin and farnesoid X receptor(FXR)agonist GW4064 increase OCT2/Oct2 but decrease OCT1/Oct1,which are remarkably attenuated by glycine-β-muricholic acid and silencing FXR.Significantly lowered intestinal CDCA and increased plasma bilirubin levels contribute to different Octs regulation by BDL,which are confirmed using CDCA-treated and bilirubin-treated rats.A disease-based physiologically based pharmacokinetic model characterizing intestinal,hepatic and renal Octs was successfully developed to predict metformin pharmacokinetics in rats.In conclusion,BDL remarkably downregulates expressions of intestinal Oct2 and hepatic Oct1 protein while upregulates expressions of renal and hepatic Oct2 protein in rats,finally,decreasing plasma exposure and impairing hypoglycemic effects of metformin.BDL differently regulates Oct expressions via Fxr activation by CDCA and bilirubin.