Synthesis, Crystal Structures, Lipophilic Properties and Antimicrobial Activity of 5-Pyridylmethylidene-3-rhodanine-carboxyalkyl Acids Derivatives.

The constant increase in the resistance of pathogenic bacteria to the commonly used drugs so far makes it necessary to search for new substances with antibacterial activity. Taking up this challenge, we obtained a series of rhodanine-3-carboxyalkyl acid derivatives containing 2- or 3- or 4-pyridinyl moiety at the C-5 position. These compounds were tested for their antibacterial and antifungal activities. They showed activity against Gram-positive bacteria while they were inactive against Gram-negative bacteria and yeast. In order to explain the relationship between the activity of the compounds and their structure, for selected derivatives crystal structures were determined using the X-ray diffraction method. Modeling of the isosurface of electron density was also performed. For all tested compounds their lipophilicity was determined by the RP-TLC method and by calculation methods. On the basis of the carried-out research, it was found that the derivatives with 1.5 N···S electrostatics interactions between the nitrogen atom in the pyridine moiety and the sulfur atom in the rhodanine system showed the highest biological activity.

Determination of nikethamide by micellar electrokinetic chromatography.

A simple, fast, sensitive and reproducible micellar electrokinetic chromatography (MEKC)-UV method for the determination of nikethamide (NKD) in human urine and pharmaceutical formulation has been developed and validated. The method exhibits high trueness, good precision, short analysis time and low reagent consumption. NKD is an organic compound belonging to the psychoactive stimulants used as an analeptic drugs. The proposed analytical procedure consists of few steps: dilution of urine or drug in distilled water, centrifugation for 2 min (12,000g), separation by MEKC and ultraviolet-absorbance detection of NKD at 260 nm. The background electrolyte used was 0.035 mol/L pH 9 borate buffer with the addition of 0.05 mol/L sodium dodecyl sulfate and 6.5% ACN. Effective separation was achieved within 5.5 min under a voltage of 21 kV (~90 µA) using a standard fused-silica capillary (effective length 51 cm, 75 µm i.d.). The determined limit of detection for NKD in urine was 1 µmol/L (0.18 µg/mL). The calibration curve obtained for NKD in urine showed linearity in the range 4-280 µmol/L (0.71-49.90 µg/mL), with R2 0.9998. The RSD of the points of the calibration curve varied from 5.4 to 9.5%. The analytical procedure was successfully applied to analysis of pharmaceutical formulation and spiked urine samples from healthy volunteers.

The use of a new, modified Dittmer-Lester spray reagent for phospholipid determination by the TLC image analysis technique.

A new phospholipid-specific spray reagent is described. A new phospholipid-specific spray reagent, which is a modification of the Dittmer-Lester reagent, is described in authors' studies. The difference between these two reagents is in the addition of tin (II) chloride to the proposed spray reagent. The use of the described spray reagent together with an image analysis technique allows not only for qualitative, but also for quantitative, determination of major phospholipid classes. Separation of phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC) was conducted on an HPTLC plate with a mixture of chloroform, methanol and 25% ammonia solution in a volume ratio of 65:25:4 as mobile phase. The calibration curves were linear in the ranges of 5.0-25.0, 1.5-15.0 and 1.0-20.0 µg/spot for PC, PS and PE, respectively. The use of the new spray reagent resulted also in lower limits of detection than the standard molybdenum method for the investigated phospholipids. The proposed method was used to determine the amount of PS in the dietary supplement 'Session', and of PS, PE and PC in biological samples, with good results.

Application of Purpald® for determination of 3-cyclohexene-1-carboxaldehyde and hydroxyisohexyl 3-cyclohexene carboxaldehyde.

A spectrophotometric method for determination of 3-cyclohexene-1-carboxaldehyde and hydroxyisohexyl 3-cyclohexene carboxaldehyde was developed. This procedure is based on the reaction of carbonyl compounds with the selective derivatization reagent Purpald® in alkaline solution. The product of reaction is a colored compound with maximum absorption at 538 nm. The linear relationship is in the range of (2.5-30) × 10-5 mol·l-1 for 3-cyclohexene-1-carboxaldehyde and (2.0-20) × 10-5 mol·l-1 for hydroxyisohexyl 3-cyclohexene carboxaldehyde. The proposed method was successfully used for determination of hydroxyisohexyl 3-cyclohexene carboxaldehyde in a cosmetic product.

Evaluation of the effectiveness of iodine prophylaxis in Poland based on over 20 years of observations of iodine supply in school-aged children in the central region of the country.

INTRODUCTION: Due to the mild-to-moderate iodine deficiency in Poland, in 1997 iodine prophylaxis based on obligatory salt iodization was introduced. We attempted to evaluate the effectiveness of such prophylaxis, based on over 20 years of observations of iodine supply in school-aged children in Opoczno district (Central Poland). MATERIAL AND METHODS: A group of 603 children (316 girls and 287 boys), aged 6-14, was examined at 4 time points: in the years 1994, 1999, 2010 and 2016. The children were tested for urine iodine concentration (UIC) and in each child the thyroid volume was measured ultrasonographically. RESULTS: The median UIC in 1994 (45.5 µg/l) indicated moderate iodine deficiency, while after introducing prophylaxis it corresponded to adequate values (1999 - 101.1 µg/l, 2010 - 100.6 µg/l, 2016 - 288.3 µg/l); however, the last value was higher than the previous two. The thyroid size, assessed by ultrasonography and presented as volume/body surface area (V/BSA), in 1994 was 6.55 × 10-6 m; this value was higher than at other time points (2.73 × 10-6 m in 1999, 2.73 × 10-6 m in 2010, and 2.70 × 10-6 m in 2016). CONCLUSIONS: Iodine prophylaxis has proved effective in eliminating iodine deficiency. In recent years, the diversification of iodine sources, despite the reduction of salt consumption, has led to an increase in median UIC to values close to the upper limit of UIC, accepted as normal. Further increase in iodine supply may be unfavourable for health; therefore constant monitoring of iodine prophylaxis is required.

Determination of methimazole in urine with the iodine-azide detection system following its separation by reversed-phase high-performance liquid chromatography.

The iodine-azide detection system to determine methimazole following its separation by RP-HPLC is described in this paper. The reaction between iodine and azide ions induced by methimazole was applied as a post-column reaction detection system. Neither extraction nor preconcentration of the sample was necessary. The methimazole standards added to normal urine show that the response of the detector, set at 350 nm (corresponding to unreacted iodine in the post-column iodine-azide reaction), was linear within the concentration range 2-10 nmol/mL of urine. The relative standard deviation values for precision and recovery within the calibration range were from 0.3 to 3.2% and from 97 to 102%, respectively. Limits of detection (LOD) and quantitation (LOQ) were 1 and 2 nmol/mL of urine, respectively. The method was applied to the separation and determination of patient urine samples and the analytical results were satisfactory.

Application of the iodine-azide postcolumn reaction in RP-HPLC for the determination of thioguanine in urine.

The study focuses on the analysis of a sensitive, selective, and simple postcolumn detection method for thioguanine determination, based on the sensitizing induction of thioguanine on iodine-azide reaction and the combination technique of HPLC. The analysis was accomplished in the optimum conditions for iodine-azide detection system and HPLC separation. The values for the linear range, the LOD, and DOQ amounted to 0.8-1.7, 0.4, and 0.5 nmol/mL urine, respectively.

High-performance liquid chromatographic determination of propylthiouracil in human urine by post-column iodine-azide reaction.

A sensitive, selective and simple post-column detection method for the determination of propylthiouracil (PTU) based on its sensitizing induction on iodine-azide reaction and the combination technique of high-performance liquid chromatography has been presented. The analysis was conducted in the optimum conditions for iodine-azide detection system and HPLC separation. The linear range, the lower limit of detection and quantification for PTU in urine were established at the levels of 0.4-1.0 nmol/ml urine, 0.3 nmol/ml urine and 0.4 nmol/ml urine, respectively.

Determination of propylthiouracil in pharmaceutical formulation by high-performance liquid-chromatography with a post-column iodine-azide reaction as a detection system.

A high-performance liquid chromatographic method with a post-column iodine-azide reaction has been chosen and tested for validity in quantitative determination of propylthiouracil in tablets. A mobile phase with a flow rate of 1.4 ml/min was conducted in the form of isocratic chromatography on a C18 column with acetonitrile-water-sodium azide solution (2.5%; pH 5.5) 24:26:50 (v/v/v). Unreacted iodine from post-column iodine-azide induced by reaction was monitored with visible detection at lambda=350 nm. The method proved both its linearity within the range of 8-100 nM (r2>0.9988) and satisfactory results of inter-day precision (RSD<4.2%) and accuracy (recovery>91%). The limits of detection (DDL) and quantification (DQL) reached the levels of 5 and 8 nM, respectively. The validation of the method comprised also its specificity. The results obtained proved the suitability and appropriateness of the suggested method for intended use.

Chromatographic and Computational Studies of Molecular Lipophilicity and Drug-likeness for few 2-Thioxo-1,3-Thiazolidin-4-one Derivatives and their Analogs.

Hydrophobicity of the eight 2-thioxo-1,3-thiazolidin-4-one derivatives was determined experimentally by thin-layer chromatography and predicted by means of commercially available programmers. RM values were determined by reversed-phase thin-layer chromatography with using acetonitrile-water, methanol-water, acetone-water, propan-2-ol-water or 1,4-dioxane-water and compared with logP values calculated by using computer programs: HyperChem 8.0.10, Virtual Chemical Calculation Laboratory, ACD/LogP. The drug-likeness has been calculated using Molinspiration. All the heterocycles were found to obey Lipinski's rule of 5 for an orally active drug.

Direct determination of metformin in urine by adsorptive catalytic square-wave voltammetry.

A new adsorptive catalytic voltammetric method for voltammetric determination of metformin based on the catalytic hydrogen evolution reaction at a hanging mercury drop electrode was developed. The electrode reaction was analyzed under conditions of linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and Osteryoung-type square-wave voltammetry (SWV). The peak current depends on pH of the medium, concentration and chemical composition of the buffer solution, and instrumental parameters. The optimal conditions for quantitative determination were obtained in an acetate buffer at pH 4.7. The voltammetric procedure was characterized with respect to the repeatability, precision and the recovery. The detection and quantification limits were found to be 1.8 x 10(-8) and 5.9 x 10(-8) mol l(-1) for SWV, 3.2 x 10(-8) and 1.0 x 10(-7) mol l(-1) for DPV, and 7.7 x 10(-8) and 2.5 x 10(-7) mol l(-1) for LSV, respectively. The SW voltammetric method, as the most sensitive one, was applied for determination of metformin in human urine. The voltammetric method has been validated by using HPLC with UV detection.

Detection of mercaptopyridines and mercaptopyrimidines in planar chromatography with iodine-azide reaction as a detection system.

Reaction between iodine and azide ion induced by mercaptopyridines and mercaptopyrimidines was utilized as a detection system in TLC and HPTLC. The developed plates were sprayed with a freshly prepared mixtures of sodium azide and starch solution adjusted to pH 5.5, and exposed to iodine vapour. The spots became visible as white spots on violet-grey background. The iodine-azide detection system has been proved to be the most favourable and enabled to detect quantities per spot in the range of 1-20 pmol (HPTLC) and 1-60 pmol (TLC). The iodine-azide tests were compared with other visualizing techniques commonly used in planar chromatography (iodine vapour and UV254). The developed method was applied to detection of thiopental in biological samples.

Determination of thiopental in urine sample with high-performance liquid chromatography using iodine-azide reaction as a postcolumn detection system.

The reaction between iodine and azide ions induced by thiopental was utilized as a postcolumn reaction for chromatographic determination of thiopental. The method is based on the separation of thiopental on an Nova-Pak CN HP column with an acetonitrile-aqueous solution of sodium azide as a mobile phase, followed by spectrophotometric measurement of the residual iodine (lambda=350 nm) from the postcolumn iodine-azide reaction induced by thiopental after mixing an iodine solution containing iodide ions with the column effluent containing azide ions and thiopental. Chromatograms obtained for thiopental showed negative peaks as a result of the decrease in background absorbance. The detection limit (defined as S/N=3) was 20 nM (0.4 pmol injected amount) for thiopental. Calibration graphs, plotted as peak area versus concentrations, were linear from 40 nM. The elaborated method was applied to determine thiopental in urine samples. The detection limit (defined as S/N=3) was 0.025 nmol/ml urine. Calibration graphs, plotted as peak area versus concentrations, were linear from 0.05 nmol/ml urine. Authentic urine samples were analyzed, thiopental was determined at nmol/ml urine level.

A derivatization approach using pyrylium salts for the sensitive and simple determination of sulfide in spring water by high performance liquid chromatography.

A high-performance liquid chromatography method based on pre-column derivatization with the pyrylium salts (4-[p-(N,N-dimethylamino)phenyl]-2,6-diphenylpyrylium perchlorate (LN1) and 2,4,6-triphenylpyrylium tetrafluoroborate (L1)) has been developed for the determination of sulfide. After the reaction of sulfide ions with LN1 or L1 aiming at the formation of the corresponding thiopyrylium derivatives LN3 or L3, they were separated on a C18 column using phosphate buffer and acetonitrile as eluent, and afterwards detected with a UV/vis detector. By using the described method, sulfide ions can be determined in the range of 5.12-486.4 µg·L(-1) or 1.024-20.48 µg·L(-1) by means of L1 or LN1, respectively. In our experiments, the relative standard deviation was not higher than 2% and the recovery coefficient was in the range of 88-102%. The proposed method was applied to the determination of sulfide in spring water samples from Busko Zdrój and Uniejów health resorts located in Poland.

Application of iodine-azide reaction for detection of amino acids in thin-layer chromatography.

The iodine-azide reaction was employed to TLC detection of sulphur-containing derivatives of protein and some non-protein amino acids. The derivatization reaction with phenyl isothiocyanate (PITC) took place directly on the plate before the developing step. Subsequently, the plates were sprayed with a mixture of sodium azide and starch solution in NP-TLC and in the case of RP-TLC sodium azide solution with starch incorporated into mobile phase and then exposed to iodine vapour. The spots became visible as white spots on violet-grey background. The obtained detection limits of PTC-derivatives have been compared with other visualizing techniques commonly used in TLC practice (UV254 and iodine vapour). The iodine-azide system has been proved to be the most favourable and enabled to detect quantities per spot in the range of 1-60 pmol (HPTLC) and 3-100 pmol (TLC).

Application of improved iodine-azide procedure for the detection of thiouracils in blood serum and urine with planar chromatography.

The application of iodine-azide reaction for the determination of thiouracils in thin-layer chromatography and high-performance thin-layer chromatography is described. The developed plates were sprayed with a freshly prepared mixture of sodium azide, adjusted to a proper pH, and starch solution, and exposed to iodine vapour for 5 s. The detection limits were established at pmol level. The factors depending on the detection limits were described. A comparison of iodine-azide tests reaction with other procedures is presented. The developed method was applied to detection of thiouracils in blood serum and urine. The possibility of detection of a thiouracils mixture was demonstrated.

Determination of urinary 6-mercaptopurine and three of its metabolites by HPLC-UV coupled with the iodine-azide reaction.

BACKGROUND: The presented method is able to determine 6-mercaptopurine (6-MP), 6-thioguanine, 6-mercaptopurine riboside and 6-thioguanine riboside in urine, and is thereby dedicated to control of thiopurine therapy of children with acute lymphoblastic leukemia. Good separation of the mentioned compounds was achieved on a C18 stationary phase with a sodium azide and sodium heptane sulfonate solution, acetonitrile and water at ratio of 50:1:49 (v/v/v). RESULTS: Coefficient of regression is >0.99 for all linearity ranges. LOD and LOQ are 0.3, 0.4, 0.3, 0.8 and 0.4, 0.6, 0.5 and 0.9 nmol/ml of urine for 6-MP, 6-thioguanine, 6-mercaptopurine riboside and 6-thioguanine riboside, respectively. Intra- and inter-day recovery and RSD are close to 100% and less than 10%, respectively, for all investigated thiopurines. CONCLUSION: The elaborated method was successfully applied for detection and quantitation of 6-MP and its selected metabolites in patients' urine samples.

RP-HPLC-UV method coupled with post-column iodine-azide reaction for determination of free captopril in urine samples.

BACKGROUND: A free urinary captopril is measured indirectly employing the iodine-azide reaction in post-column mode. The pre-clean-up and/or derivatization step is needless, so that the method is adequate for rapid captopril determination in the urine samples and its monitoring at clinical trial. Captopril is separated on a C4 column by the eluate composed of sodium azide solution (4% [w/v], pH 5.8), acetonitrile and water at a ratio of 50:5:45 (v/v/v). The linearity exists in the range from 0.06 to 2.25 µmol/ml of urine. LOD and LOQ receive 0.03 and 0.06 µmol/ml of urine, respectively. RESULTS: Inter-day precision and accuracy of measurements of the captopril-spiked urine samples were 9, 8 and 5%, and 104, 107 and 105%, respectively, for 0.060 (low level), 0.50 (medium level) and 1.25 (high level) µmol/ml of urine. CONCLUSION: Captopril content was determined in real urine samples delivered from patients treated with this drug.

The lived experiences of alcohol addiction: men of alcoholics anonymous.

Alcohol addiction is one of the most prevalent and debilitating psychiatric disorders among the general population. Yet, little has been published on what it is like for men to actually experience this disorder. The purpose of this study was to identify commonalities in the experience of alcohol addiction among seven male members of Alcoholics Anonymous. Using a phenomenological approach, the participants completed an audio taped, unstructured, nondirective interview in which they were asked to describe their experience of alcohol addiction. The interviews were then transcribed and read by a phenomenological research team. Four themes were discovered: Emotions, Control, Awareness of Others, and The Turning Point, as well as a temporal ground. The authors conclude that mental health professionals should encourage alcohol addicted persons to talk about their experiences and to help them identify feelings and develop new coping skills.