1-naphthylisothiocyanate Research Articles

MiR-194 Up-Regulates Cholesterol 7 Alpha-Hydroxylase Expression via β-Catenin Signaling and Aggravates Cholestatic Liver Diseases

miR-194 is abundantly expressed in hepatocytes, and its depletion increases hepatic resistance to acetaminophen-induced acute injuries. In this study, the biological role of miR-194 in cholestatic liver injury was investigated by using miR-194/miR-192 cluster liver-specific knockout (LKO) mice, in which no liver injuries or metabolic disorders were predisposed. Bile duct ligation (BDL) and 1-naphthyl isothiocyanate (ANIT) were applied to LKO and matched control wild-type (WT) mice to induce hepatic cholestasis. Periportal liver damage, mortality rate, and liver injury biomarkers in LKO mice were significantly less than in WT mice after BDL and ANIT injection. Intrahepatic bile acid level was significantly lower in the LKO liver within 48 hours of BDL- and ANIT-induced cholestasis compared with WT. Western blot analysis showed that β-catenin (CTNNB1) signaling and genes involved in cellular proliferation were activated in BDL- and ANIT-treated mice. The expression levels of cholesterol 7 alpha-hydroxylase (CYP7A1), pivotal in bile synthesis, and its upstream regulator hepatocyte nuclear factor 4α were reduced in primary LKO hepatocytes and liver tissues compared with WT. The knockdown of miR-194 using miRNA inhibitors reduced CYP7A1 expression in WT hepatocytes. In contrast, the knockdown of CTNNB1 and overexpression of miR-194, but not miR-192, in LKO hepatocytes and AML12 cells increased CYP7A1 expression. In conclusion, the results suggest that the loss of miR-194 ameliorates cholestatic liver injury and may suppress CYP7A1 expression via activation of CTNNB1 signaling.

High Pressure Liquid Chromatography Identification and Quantification of Morpholine Residual Content in Cobicistat After Derivatization

A derivatization HPLC procedure has been developed to identify and enumerate morpholine (MPE) in cobicistat (CCT) pharmaceutical active substances. MPE react with acetonitrile solution of 1-Naphthyl isothiocyanate to produce stable MPE derivative. The MPE derivative produced was identified and enumerated by HPLC based procedure. The linearity range of MPE was 0.3002675–1.201070 μg/mL with good squared correlation (0.9995), and limits of detection and quantification were 0.1000 μg/mL and 0.3001 μg/mL, respectively. Low (50% of specification quantity), medium (100% of specification quantity), and high (150% of specification quantity) concentrations of MPE were added in CCT samples to evaluate recovery rate. The added recovery rate ranged from 97.9% to 100.4%. The precision value was 0.79% relative standard deviation. The developed procedure also has good selectivity and robustness. This quantitative procedure for MPE can successfully be implemented to analyse the MPE residual quantities in CCT pharmaceutical active substances.

A Comparative Study of Microwave-Assisted and Conventional Heating Methods of the Synthesis of 1-(Naphthalene-1-Yl)-3-(O, M, P-Tolyl)Thioureas, DFT Analysis, Antibacterial Evaluation and Drug-Likeness Assessment

New isomers of naphthalene-monothioureas, 3a-3c, were synthesized and characterized by using infrared (IR), 1H and 13 C nuclear magnetic resonance (NMR) and mass spectroscopies (MS). The compounds were obtained from the reaction ofo-, m-, p- toluidine with naphthyl isothiocyanate using conventional reflux and microwave-assisted irradiation methods. Microwave-assisted reaction gave higher yields with reduces the reaction time compared to the conventional heating method. Density Functional Theory (DFT) calculations with 6-31G(d, p) basic set at the B3LYP level is carried out to optimize the structure of isomers and calculate the IR, 1H and 13 C NMR spectra. The DFTB3LYP calculation of FTIR, 1H and 13C NMR spectra of 3a-3c isomers were in accordance with the experimental data. The calculation of frontier molecular orbitals was also selected to study a relationship as a molecular descriptor in antibacterial activity. The isomers were screened for their in vitro antibacterial activity by using Staphylococcus aureus bacteria. Inhibition activity was displayed for compound 3c with the value of inhibition zone 7 ± 0.34 mm at a concentration of 10 μg/mL. All compounds appeared to be in agreement with Lipinski’s rule of five assessments as they adhered to most of the rules that can be preliminarily classified as active drug-like.

Hepatoprotective Effect of S-ademetionine in the treatment of Intrahepatic Cholestasis through Farnesoid X Receptor Mechanism in Rats

S-ademetionine (AdoMet) had been extensively studied in several clinical studies to treat Intrahepatic Cholestasis (IHC). The exact mechanism of action of AdoMet to regulator bile acid is unknown. Farnesoid X Receptor (FXR), a multifunctional nuclear receptor, plays vital roles in metabolism of bile acid. This study aims to investigate the mechanism of action of S-ademetionine in FXR to treat IHC. The IHC Sprague Dawley (SD) rat model was developed by administering Alpha Naphthyl Isothiocyanate (ANIT, 50 mg/kg). FXR excitant GW4064 (3 mg/kg) was used as a control to observe the impact of AdoMet (60 mg/kg) on the changes in serum direct levels in these rats. The hepatic histology between the HE staining contrast groups was performed using the Q-PCR to test FXR and the in situ hybridization was used to test the changes of bile salt export pump (Bsep), multidrug resistance-associated protein 2 (Mrp2), and Na+-taurocholate cotransporting polypeptide (Ntcp). AdoMet significantly reduced the serum direct levels and the hepatic tissue damage. AdoMet can also increase the expression of FXR, Bsep, Mrp2 and Ntcp. These findings confirm that AdoMet could reduce serum direct levels as well as improving hepatic tissue damage by enhancing the expression of FXR, Bsep, Mrp2 and Ntcp. These findings could also explain the great therapeutically effect of AdoMet in intrahepatic cholestasis.

Rho-kinase/myosin light chain kinase pathway plays a key role in the impairment of bile canaliculi dynamics induced by cholestatic drugs.

Intrahepatic cholestasis represents a frequent manifestation of drug-induced liver injury; however, the mechanisms underlying such injuries are poorly understood. In this study of human HepaRG and primary hepatocytes, we found that bile canaliculi (BC) underwent spontaneous contractions, which are essential for bile acid (BA) efflux and require alternations in myosin light chain (MLC2) phosphorylation/dephosphorylation. Short exposure to 6 cholestatic compounds revealed that BC constriction and dilation were associated with disruptions in the ROCK/MLCK/myosin pathway. At the studied concentrations, cyclosporine A and chlorpromazine induced early ROCK activity, resulting in permanent MLC2 phosphorylation and BC constriction. However, fasudil reduced ROCK activity and caused rapid, substantial and permanent MLC2 dephosphorylation, leading to BC dilation. The remaining compounds (1-naphthyl isothiocyanate, deoxycholic acid and bosentan) caused BC dilation without modulating ROCK activity, although they were associated with a steady decrease in MLC2 phosphorylation via MLCK. These changes were associated with a common loss of BC contractions and failure of BA clearance. These results provide the first demonstration that cholestatic drugs alter BC dynamics by targeting the ROCK/MLCK pathway; in addition, they highlight new insights into the mechanisms underlying bile flow failure and can be used to identify new predictive biomarkers of drug-induced cholestasis.

Effect of Yajieshaba, a preparation of Dai indigenous medicine, on enhanced liver detoxification

ObjectiveTo explore the mechanistic effects of Yajieshaba (YJSB) on enhanced liver detoxification. MethodsThe effects of YJSB on alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were assayed in five acute chemical liver injury models [carbon tetrachloride (CCl4), D-galactosamine (D-Glan), 4-acetamidophenol (AAP), thioacetamide (TAA) and 1-naphthyl isothiocyanate (ANIT)]. Sleep latency and sleep time of pentobarbital sodium were tested in control mice and CCl4 model miceafter oral YJSB administration. The effects of YJSB on drug metabolism enzymes of liver microsomes were tested in control rats and CCl4 model rats. The levels of cytochrome P450 (CYP450) and Cyt b5 in liver microsomes were assayed using the method by Omura and Sato, and activities of erythromycin N-demethylase (ERD) and aminopyrine N-demethyl (ADM) were evaluated by Nash colorimetry. Probe substrate-based high performance liquid chromatography (HPLC) methods were established for CYP3A4 and CYP1A2. ResultsThe level of serum ALT was reduced by YJSB at 3.51 g/kg in the five models as follows: CCl4 > D-Glan, AAP, ANIT > TAA. YJSB treatment did not reduce the level of serum AST. YJSB at 3.51 g/kg prolonged the sleep latency in control mice and shortened the sleep time of control mice and CCl4 model mice. For control rats, YJSB at 2.43 g/kg increased the levels of CYP450 and Cyt b5 and induced the activities of ERD and ADM; for liver injuries induced by CCl4 in rats, YJSB at 2.43 g/kg increasedthe levels of CYP450 and Cyt b5. These results suggest that YJSB at 2.43 g/kg induces CYP3A4 and CYP1A2. ConclusionThese results suggest that YJSB enhanced liver detoxification and the mechanisms may be partially related to CYP3A4 and CYP1A2 induction.

Validation of putative genomic biomarkers of nephrotoxicity in rats

Drug-induced renal injury is a common finding in the early preclinical phase of drug development. But the specific genes responding to renal injury remain poorly defined. Identification of drug-induced gene changes is critical to provide insights into molecular mechanisms and detection of renal damage. To identify genes associated with the development of drug-induced nephrotoxicity, a literature survey was conducted and a panel of 48 genes was selected based on gene expression changes in multiple published studies. Male Sprague–Dawley rats were dosed daily for 1, 3 or 5 days to the known nephrotoxicants gentamicin, bacitracin, vancomycin and cisplatin, or the known hepatotoxicants ketoconazole, 1-naphthyl isothiocyanate and 4,4-diaminodiphenylmethane. Histopathological evaluation and clinical chemistry revealed renal proximal tubular necrosis in rats treated with the nephrotoxicants, but not from those treated with the hepatotoxicants. RNA was extracted from the kidney, and RT-PCR was performed to evaluate expression profiles of the selected genes. Among the genes examined, 24 genes are confirmed to be highly induced or repressed in rats treated with nephrotoxicants; further investigation identified that 5 of the 24 genes were also altered by hepatotoxicants. These data led to the identification of a set of genomic biomarker candidates whose expression in kidney is selectively regulated only by nephrotoxicants. Among those genes displaying the highest expression changes specifically in nephrotoxicant-treated rats were kidney injury molecule 1 (Kim1), lipocalin 2 (Lcn2), and osteopontin (Spp1). The establishment of such a genomic marker set offers a new tool in our ongoing quest to monitor nephrotoxicity.

Determination and Kinetics of Producing Glucosamine Using Fungi

This work used three fungi, Rhizopus oligosorus BCRC 31996, Monascus pilosus BCRC31527, and Aspergillus sp. BCRC31742, to produce glucosamine by using submerged fermentation and flask cultures. The reaction of glucosamine with 1-naphthyl isothiocyanate as derivatizing agent was carried out in pyridine at 50 degrees C for 1 h. The derivative was accurately analyzed and quantified by using high performance liquid chromatography. The relative standard deviation of glucosamine determined between experimental and real values were less than 2%. The kinetic and strategy of producing glucosamine in a flask culture was investigated to achieve an optimum yield of glucosamine under different conditions including three kinds of fungi, medium, and pH values. The descending ability of producing glucosamine for the three fungi was Aspergillus sp. BCRC31742 > Monascus pilosus BCRC31527 > Rhizopus oligosorus BCRC 31996 under the conditions studied. The experimental result shows that the glucosamine concentration had an optimum value and was 3430 mg/L by using Aspergillus sp. BCRC31742 culture in glucose and peptone (GP) medium, the yield of which was the best amount using wild-type microorganisms in the past. The generation culture of fungi and the pH control played important roles in enhancing the yield of glucosamine. The specific growth rate of the microorganism and the biomass, content, yield, and productivity of glucosamine were calculated as well.

Analysis of Glucosamine in Cream Dosage Form and Diffusion Liquid by High Performance Liquid Chromatography

A simple and sensitive high performance liquid chromatography (HPLC) method based on a reaction of 1-naphthyl isothiocyanate (NITC) with glucosamine was developed and validated to determine glucosamine in cream dosage form and diffusion liquid. The derivatisation products were cleaned up using styrene divinylbenzene quaternary ammonium ion exchanger and was then analyzed on a reverse-phase C18 column (150 mm × 4.6 mm, 5 μm) using acetonitrile-water-triethylamine (15: 85: 0.05) as the mobile phase and was detected at wavelength of 254 nm. The detector response was linear in the concentration range of 1-1200 μg/ml. The recovery of glucosamine from cream and diffusion liquid were 95.9-97.4% and 97.6-98.4%, respectively. The intra- and inter-day relative standard deviation (%RSD) was less than 5%.

Analysis of kanamycin A in human plasma and in oral dosage form by derivatization with 1-naphthyl isothiocyanate and high-performance liquid chromatography

A simple and sensitive HPLC method has been developed for trace determination of kanamycin A by derivatization. Plasma proteins are precipitated by acetonitrile and chemical derivatization is performed on the supernatant containing kanamycin A with 1-naphthyl isothiocyanate in pyridine at 70 degrees C. After the derivatization reaction, a methylamine/acetonitrile solution was added to the reaction mixture to eliminate the excess of derivatizing agent and shorten the analysis time. The resulting derivative was separated using a Lichrocart Purospher STAR RP-18e column and water/methanol (33:67, v/v) as a mobile phase (detection at 230 nm). Optimization conditions for the derivatization of kanamycin A were investigated by HPLC. The linear range for the quantitation of kanamycin A in spiked plasma was over 1.2-40 microg/mL; the detection limit (signal to noise ratio = 3; injection volume, 10 microL) was about 0.3 microg/mL. The relative standard deviation was less than 2.9% for intra-day assay (n = 6) and inter-day assay (n = 6) and relative recoveries were found to be greater than 98%. Preliminary application of the method for monitoring kanamycin A in humans upon intramuscular injection of the injection product demonstrated the usefulness of the assay for clinical studies. The proposed method can also be used to analyze the compound in pharmaceutical formulations.

Effects of -naphthyl isothiocyanate and a heterocyclic amine, PhIP, on cytochrome P-450, mutagenic activation of various carcinogens and glucuronidation in rat liver

To elucidate the mechanism underlying suppression by alpha-naphthyl isothiocyanate (ANIT) of mammary carcinogenesis induced by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), we evaluated hepatic levels of cytochrome P-450 (CYP) enzymes, mutagenic activation of environmental carcinogens and UDP-glucuronyltransferase (UDPGT) activities in female Sprague-Dawley rats fed a high fat diet. Immunoblot analyses revealed induction of CYP1A1, newly found 51 and 53 kDa proteins and constitutive CYP1A2 and 2B2 by intragastric treatment with 85 mg/kg PhIP eight times for 11 days. Although the extents of induction were not as high as in the case of PhIP, 3 weeks feeding of 400 p.p.m. ANIT induced CYP1A1 and the 51 and 53 kDa proteins. CP1A2 level was decreased by the feeding of ANIT. The mutagenicity in strain TA98 of PhIP, four other heterocyclic amines (HCAs) and benzo[a]pyrene was greatly enhanced in the presence of liver S9 mix prepared from rats pretreated with PhIP but not with ANIT. The mutagenicities of these five HCAs were significantly decreased in the presence of liver S9 from rats pretreated with a combination of PhIP and ANIT as compared with that pretreated with PhIP alone. The level of hepatic CYP1A2, which is known to be involved in the metabolic activation of PhIP, was consistently decreased in liver microsomes from rats administered PhIP plus ANIT as compared with that from rats administered PhIP alone. On the other hand, UDPGT activity towards 4-nitrophenol (4-NP) was enhanced using liver microsomes prepared from rats pretreated with a combination of PhIP and ANIT as compared with those pretreated with PhIP or ANIT alone. These results show that chemoprevention by ANIT against PhIP-induced rat mammary carcinogenesis can be explained by a dual action mechanism, i.e. a reduction in metabolic activation by hepatic CYP1A2 and an enhancement of detoxification by 4-NP UDPGT. The role of the newly found 51 and 53 kDa proteins in activation of HCAs is also discussed.

Dietary organic isothiocyanates are cytotoxic in human breast cancer MCF-7 and mammary epithelial MCF-12A cell lines.

Organic isothiocyanates (ITCs) are dietary components present in cruciferous vegetables. The purpose of this investigation was to examine the cytotoxicity of 1-naphthyl isothiocyanate (NITC), benzyl isothiocyanate (BITC), beta-phenethyl isothiocyanate (PEITC), and sulforaphane in human breast cancer MCF-7 and human mammary epithelium MCF-12A cell lines, as well as in a second human epithelial cell line, human kidney HK-2 cells. The cytotoxicity of NITC, BITC, PEITC, and sulforaphane, as well as the cytotoxicity of the chemotherapeutic agents daunomycin (DNM) and vinblastine (VBL), were examined in MCF-7/sensitive (wt), MCF-7/Adr (which overexpresses P-glycoprotein), MCF-12A, and HK-2 cells. Cell growth was determined by a sulforhodamine B assay. The IC50 values for DNM and VBL in MCF-7/Adr cells were 7.12 +/- 0.42 microM and 0.106 +/- 0.004 microM (mean +/- SE) following a 48-hr exposure; IC50 values for BITC, PEITC, NITC, and sulforaphane were 5.95 +/- 0.10, 7.32 +/- 0.25, 77.9 +/- 8.03, and 13.7 +/- 0.82 microM, respectively, with similar values obtained in MCF-7/wt cells. Corresponding values for BITC, PEITC, NITC, and sulforaphane in MCF-12A cells were 8.07 +/- 0.29, 7.71 +/- 0.07, 33.6 +/- 1.69, and 40.5 +/- 1.25 microM, respectively. BITC and PEITC can inhibit the growth of human breast cancer cells as well as human mammary epithelium cells at concentrations similar to those of the chemotherapeutic drug DNM. Sulforaphane and NITC exhibited higher IC50 values. The effect of these ITCs on cell growth may contribute to the cancer chemopreventive properties of ITCs by suppressing the growth of preclinical tumors, and may indicate a potential use of these compounds as chemotherapeutic agents in cancer treatment.

Development of a LC-MS/MS method for the analysis of volatile primary and secondary amines as NIT (naphthylisothiocyanate) derivatives.

High-performance liquid chromatography with mass spectrometric detection was used for the structure elucidation of eighteen primary and secondary amines and ammonia derivatised with naphthylisothiocyanate (NIT). A fragmentation scheme was established using reference compounds and the scheme was applied to real air samples from a tyre repair shop and from the air above a bacterial culture. The sampling was performed using a solid sorbent, XAD-2, impregnated with NIT, and the derivatives were extracted with acetonitrile and analysed with LC-MS/MS. A three-step process was developed for screening and identifying of volatile amines. The first step, selected reaction monitoring; SRM was applied in order to screen the samples for NIT derivatives. In the second step, a precursor ion scan gave the [M+H](+) ion, and in the third step a product ion scan gave the fragments needed for identification. The detection limits varied between 0.12 and 0.25 ng microL(-1) when screening for unknown derivatised amines. It was possible to separate and identify all the amines with the structural information obtained and the method proved to be general, sensitive and well suited for sampling and analysis of complex environmental samples.

Trace analysis of tobramycin in human plasma by derivatization and high-performance liquid chromatography with ultraviolet detection

A simple and sensitive high-performance liquid chromatographic (HPLC) method is established for the trace determination of tobramycin in human plasma by derivatization. The method is based on the chemical derivatization of aminoglycoside antibiotic, tobramycin in human plasma, with 1-naphthyl isothiocyanate (NITC) in pyridine at 70 °C. After derivatization reaction, a methylamine/acetonitrile solution was added to the reaction mixture to eliminate the excess derivatizing agent and shorten the analysis time. The resulting derivative was separated using a Purospher ® STAR RP-18e column and a water–acetonitrile (50:50, v/v) mobile phase (detection at 230 nm). Optimization conditions for the derivatization of tobramycin were investigated by HPLC. The linear range for the quantitation of tobramycin in spiked plasma was over 0.93–9.34 mg/l; the detection limit (signal-to-noise ratio=3; injection volume, 10 μl) was about 0.23 mg/l. The relative standard deviation was less than 2.1% for intra-day assay ( n=6) and 5.2% for inter-day assay ( n=6) and relative recoveries were found greater than 99%.

Trace Analysis of Amikacin by Derivatization and High Performance Liquid Chromatography

A simple and sensitive liquid chromatographic method was developed for the determination of amikacin. The method is based on the detection of amikacin derivatized at amino groups with 1-naphthyl isothiocyanate. This reaction was carried out in pyridine at 70°C for 1 h. After derivatization, methylamine acetonitrile solution was added to the reaction mixture to eliminate the excess detribalizing agent. The derivative was analysed by reverse-phase HPLC on a LiChroCART Rp C18 column with water-acetonitrile (57:43, v/v) as the mobile phase, and detected at 230 nm. Several parameters affecting the derivatization of amikacin, including the reaction solvent, reaction temperature, reaction time and the amount of derivatizing agent, were investigated. The linear range of the method for the determination of amikacin was over 20-500 nmol/mL; the detection lime it (signal to noise ratio = 3; injection volume, 10 μl) was 5 nmol/mL. Application of the method to the analysis of amikacin in commercial injections has proven to be satisfactory.

Trace analysis of amikacin in human plasma by high-performance liquid chromatography

A simple and sensitive liquid chromatographic method is described for the determination of amikacin in human plasma. The amikacin is derivatized with 1-naphthyl isothiocyanate (NITC) at 70°C. After derivatization, a methylamine acetonitrile solution is added to the reaction mixture to eliminate excess derivatizing agent. The resulting derivative was analysed by HPLC on a LiChroCART RP-C18 column with water-acetonitrile (57:43,v/v) mobile phase and detection at 230 nm. Parameters affecting derivatization of amikacin, including reaction temperature, reaction time and amount of derivatizing agent, were investigated. The linear range for the determination of amikacin in spiked plasma was over 10–52 nmol mL−1; the detection limit (signal-to-noise ratio=3; injection volume, 10 μL) was ca. 1 nmol mL−1. The relative standard deviation was 91%.

Ruthenium-Assisted Insertion of Isothiocyanates into the Silicon−Sulfur Bond: A Comparative Study on the Reactivity of the S−Si and S−H Bonds in CpRu(PPh3)2SX (X = H, SiiPr3) Complexes

CpRu(PPh3)2SSiiPr3 (1) and CpRu(PPh3)2SH (2) reacted with phenyl, p-tolyl, and 1-naphthyl isothiocyanates, as well as with 1,4-phenylene diisothiocyanate, to give the corresponding κ2S,S-dithiocarbamato complexes, CpRu(PPh3)S2CNR1R2 (R1 = SiiPr3, R2 = Ph (3a), p-Tol (3b), 1-Naphth (3c); R1 = H, R2 = Ph (3d), 1-Naphth (3e)) and 1,4-[CpRu(PPh3)S2CNR]2C6H4 (R = SiiPr3 (4a), H (4b)), the result of insertion of the isothiocyanates into the S−Si and S−H bonds, respectively. The reactions of 1 proceed via precoordination of the isothiocyanates to the ruthenium atom, followed by the formation of N-silyl κ2S,S-dithiocarbamates. The reactions of 2, at least in part, involve direct nucleophilic addition of the S−H bond to the isothiocyanates via κ1S-dithiocarbamato intermediates. Accordingly, CpRu(dppe)SSiiPr3, where ligand exchange does not occur, did not react, but CpRu(dppe)SH reacted with phenyl and 1-naphthyl isothiocyanate to give the corresponding κ1S-dithiocarbamato complexes, CpRu(dppe)SC(S)NHR (R = Ph (9a)...

Cytotoxicity of naphthylisothiocyanates in rat hepatocyte–neutrophil cocultures

1-Naphthylisothiocyanate (ANIT) produces cholangiolitic hepatitis in rats. This injury is characterized by periportal bile duct and hepatic parenchymal cell necrosis with inflammatory cell involvement. In contrast, 2-naphthylisothiocyanate (BNIT) does not induce cholangiolitic hepatitis. The mechanism(s) involved in ANIT-induced hepatic injury remain to be elucidated. To investigate this difference in toxicity further, we examined the cytotoxicity of ANIT and BNIT in primary rat hepatocyte cultures. Since neutrophils (PMNs) are required for the development of ANIT-induced cholangiolitic hepatitis in vivo, we also examined the potential for PMNs to modulate ANIT and BNIT cytotoxicity in rat hepatocyte–PMN cocultures. Both ANIT and BNIT injured rat hepatocytes within the range of concentrations examined (0–100 μM); however, BNIT was more potent. The presence of PMNs did not significantly influence the hepatocellular injury produced by either naphthylisothiocyanate (NIT). In an attempt to clarify the disparity between these results in vitro and observations reported in vivo, we examined, in hepatocyte–PMN cocultures, the cytotoxic potential of bile collected from NIT-treated rats. Bile from BNIT-treated rats was markedly more cytotoxic to hepatocytes than was bile from ANIT-treated rats. As was observed in earlier experiments, the inclusion of PMNs had no effect on the hepatocellular toxicity of bile from NIT- treated rats. These findings prompted evaluation of the effect of NITs on rat PMNs. ANIT (1 and 10 μM) had no effect on phorbal myristate acetate (PMA)-induced superoxide production by PMNs, whereas BNIT (1 and 10 μM) markedly inhibited PMA-induced superoxide production. In contrast, ANIT and BNIT were equally effective at inhibiting f–met–leu–phe (fMLP)-induced PMN degranulation (β-glucuronidase release). Altogether, the relative NIT toxicity observed in hepatocyte primary cultures is contrary to reports of hepatotoxic potential of these NITs in vivo. The PMN-dependence of ANIT hepatotoxicity in vivo was not reproduced in hepatocyte–PMN cocultures exposed to ANIT, suggesting that the PMN dependence in vivo involves factors not present in hepatocyte–PMN cocultures. The greater PMN inhibitory effect of BNIT may, in part, underlie its inability to elicit the PMN-dependent liver injury in vivo that characterizes ANIT-induced cholangiolitic hepatitis.

Enantiomeric separation of amphetamine, methamphetamine and ring substituted amphetamines by means of a β-cyclodextrin-chiral stationary phase

The enantioseparation of amphetamine, methamphetamine and various ring-substituted amphetamines by use of a chiral stationary phase carrying immobilized native β-cyclodextrin (β-CyD) selectors is reported. The system is evaluated for resolving the specified compounds directly without any derivatization and after derivatization with phenyl isothiocyanate (PITC), naphthyl isothiocyanate (NITC) and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). This direct enantioseparation is compared with the features of indirect separation of diasteromeric derivatives after reaction with the optically pure Marfey's reagent employing a simple non-chiral alkyl-silica (RP-8) column. A selection of those methods best suited for each single amphetamine is given.

Diffusive air sampling of reactive compounds. A review

Methods for diffusive sampling of reactive compounds in air are reviewed. Sampler types include sorbent, liquid and filter samplers. The most versatile sampler for reactive compounds is the filter sampler, where reactive compounds are trapped on a reagent-coated filter. Applications are described for the sampling of reactive organics and inorganics. Aldehydes can be sampled using a 2, 4-dinitrophenylhydrazine-coated filter, and amines with a filter coated with 1-naphthyl isothiocyanate. The derivatives formed are determined by high-performance liquid chromatography with ultraviolet detection. Inorganics such as ozone and nitrogen oxides can also be determined with the filter sampler technique.