Search

Design of a new drug entity is usually preceded by analysis of quantitative structure activity (properties) relationships, QSA(P)R. Six newly synthesized succinimide derivatives have been determined for (i) in silico physico-chemical descriptors, pharmacokinetic and toxicity predictors, (ii) in vitro biological activity on four different carcinoma cell lines and on normal fetal lung cells and (iii) lipophilicity on liquid chromatography. All compounds observed were predicted for good permeability and solubility, good oral absorption rate and moderate volume of distribution as well as for modest blood brain permeation, followed by acceptable observed toxicity. In silico determined lipophilicity, permeability through jejunum and aqueous solubility were correlated with experimentally obtained lipophilic constants (by use of high pressure liquid chromatography) and linear correlations were obtained. Absorption rate and volume of distribution were predicted by chromatographic lipophilicity measurements while permeation through blood bran barrier was predicted dominantly by molecular size defined with molecular weight. Five compounds have demonstrated antiproliferative activity toward cervix carcinoma HeLa cell lines; three were cytotoxic against breast carcinoma MCF-7 cells, while one inhibited proliferation of colon carcinoma HT 29 cell lines. Only one compound was cytotoxic toward normal cell lines, while other compounds were proven as safe. Antiproliferative potential against HeLa cells was described as exponential function of lipophilicity. Based on obtained results, lead compounds were selected.

Arterial stiffening is a hallmark of early vascular aging (EVA) syndrome and an independent predictor of cardiovascular morbidity and mortality. In this case-control study we sought to identify plasma metabolites associated with EVA syndrome in the setting of hypertension. An untargeted metabolomic approach was used to identify plasma metabolites in an age-, BMI-, and sex-matched groups of EVA (n = 79) and non-EVA (n = 73) individuals with hypertension. After raw data processing and filtration, 497 putative compounds were characterized, out of which 4 were identified as lysophosphaditylcholines (LPCs) [LPC (18:2), LPC (16:0), LPC (18:0), and LPC (18:1)]. A main finding of this study shows that identified LPCs were independently associated with EVA status. Although LPCs have been shown previously to be positively associated with inflammation and atherosclerosis, we observed that hypertensive individuals characterized by 4 down-regulated LPCs had 3.8 times higher risk of EVA compared to those with higher LPC levels (OR = 3.8, 95% CI 1.7–8.5, P < 0.001). Our results provide new insights into a metabolomic phenotype of vascular aging and warrants further investigation of negative association of LPCs with EVA status. This study suggests that LPCs are potential candidates to be considered for further evaluation and validation as predictors of EVA in patients with hypertension.

Aim: The purpose of this work was to develop and validate a rapid and robust LC–MS/MS method for the determination of dexmedetomidine (DEX) in plasma, suitable for analysis of a large number of samples. Method: Systematic approach, Design of Experiments, was applied to optimize ESI source parameters and to evaluate method robustness, therefore, a rapid, stable and cost-effective assay was developed. The method was validated according to US FDA guidelines. LLOQ was determined at 5 pg/ml. The assay was linear over the examined concentration range (5–2500 pg/ml), Results: Experimental design approach was applied for optimization of ESI source parameters and evaluation of method robustness. The method was validated according to the US FDA guidelines. LLOQ was determined at 5 pg/ml. The assay was linear over the examined concentration range (R2 > 0.98). The accuracies, intra- and interday precisions were less than 15%. The stability data confirmed reliable behavior of DEX under tested conditions. Conclusion: Application of Design of Experiments approach allowed for fast and efficient analytical method development and validation as well as for reduced usage of chemicals necessary for regular method optimization. The proposed technique was applied to determination of DEX pharmacokinetics in pediatric patients undergoing long-term sedation in the intensive care unit.

The present paper reports a comparison study of two data processing procedures in GC–MS metabolome components investigation based on two modern softwares: Automated Mass Spectral Deconvolution and Identification System (AMDIS) and GC–MS Solution Postrun Analysis (GC–MS SPA). GC–MS SPA is intended for manual integration and identification, while AMDIS is proposed as a fast, and automatic data analysis tool. Both methods are based on the same free-access library. In the present study, 12 compounds previously detected in a metabolomic fingerprint of grasshopper abdominal secretion, were tested at three concentration levels: 2.5, 5 and 10 μg/mL. The processing procedures were evaluated by comparison of peak area ratio for each tested concentration. The obtained results proved that processing with the use of AMDIS was more sensitive and enabled the identification of all compounds at the lowest selected concentration. Additionally, the differentiation of structurally similar compounds was possible with the use of AMDIS software.

The purpose of this study was to assess the pharmacokinetics of dexmedetomidine in the ICU settings during the prolonged infusion and to compare it with the existing literature data using the Bayesian population modeling with literature-based informative priors. Thirty-eight patients were included in the analysis with concentration measurements obtained at two occasions: first from 0 to 24 h after infusion initiation and second from 0 to 8 h after infusion end. Data analysis was conducted using WinBUGS software. The prior information on dexmedetomidine pharmacokinetics was elicited from the literature study pooling results from a relatively large group of 95 children. A two compartment PK model, with allometrically scaled parameters, maturation of clearance and t-student residual distribution on a log-scale was used to describe the data. The incorporation of time-dependent (different between two occasions) PK parameters improved the model. It was observed that volume of distribution is 1.5-fold higher during the second occasion. There was also an evidence of increased (1.3-fold) clearance for the second occasion with posterior probability equal to 62 %. This work demonstrated the usefulness of Bayesian modeling with informative priors in analyzing pharmacokinetic data and comparing it with existing literature knowledge. Electronic supplementary material The online version of this article (doi:10.1007/s10928-016-9474-0) contains supplementary material, which is available to authorized users.

Wound healing is still a serious medical problem due to process complexity and lack of effective medicaments. This is particularly true in the treatment of wounds arising in the course of such diseases as AIDS or diabetes. Therefore, scientific efforts are focused on the search for new compounds of natural origin, which could be used as medicines or evaluated for subsequent drug design. In folk medicine, grasshopper (Chorthippus spp.) abdominal secretion has been used to accelerate the wound healing process. In this context, the knowledge of the composition of grasshopper abdominal secretion is crucial. The aim of this study was to determine the main water-soluble components of grasshopper abdominal secretion with the use of GC/MS/MS. Liquid–liquid extraction was used as a pretreatment method to clean up, concentrate and fractionate compounds from the complex insect matrix. To obtain more stable and volatile compounds, necessary for GC/MS/MS analysis, a double-step derivatization process was carried out with the use of methoxyamine hydrochloride and a mixture of bis-N,O-trimethylsilyl trifluoroacetamide and chlorotrimethylsilane. As a result, 2,108 compounds were identified, mainly as amino acids, carbohydrates and organic acids. Some of the identified compounds are emphasized due to antimicrobial, antifungal or antioxidant activities reported in the literature. Moreover, a set of compounds characteristic for Chorthippus spp. samples has been selected. In the last part of the study, a statistical analysis was performed to demonstrate differences in composition of aqueous fractions of abdominal secretions from grasshoppers collected at two distant locations: Starogard Gdanski and Łubianka meadows.

This study evaluates possible circadian rhythms during prolonged midazolam infusion in 27 pediatric intensive care unit (PICU) children under mechanical ventilation.Blood samples for midazolam and 1-OH-midazolam assay were collected throughout the infusion at different times of the day. The blood pressure, heart rate and body temperature were recorded every hour for the rhythms analysis. Population nonlinear mixed-effect modeling with NONMEM was used for data analysis.A two-compartment model for midazolam pharmacokinetics and a one-compartment model for midazolam metabolite adequately described the data. The 24 h profiles of all monitored physiological parameters were greatly disturbed/abolished in comparison with the well-known 24 h rhythmic patterns in healthy subjects. There was no significant circadian rhythm detected with respect to midazolam pharmacokinetics, its active metabolite pharmacokinetics and all monitored parameters.We concluded that the light-dark cycle did not influence midazolam pharmacokinetics in intensive care units children. Also, endogenous rhythms in critically ill and sedated children are severely disturbed and desynchronized. Our results confirmed that it is necessary to adjust the dose of midazolam to the patient's body weight. The low value of midazolam clearances observed in our study was probably caused by mechanical ventilation, which was shown to decrease the cardiac output.

Introduction Multilevel modeling is a quantitative statistical method to investigate variability and relationships between variables of interest, taking into account population structure and dependencies. It can be used for prediction, data reduction and causal inference from experiments and observational studies allowing for more efficient elucidation of knowledge. Objectives In this study we introduced the concept of multilevel pharmacokinetics (PK)-driven modelling for large-sample, unbalanced and unadjusted metabolomics data comprising nucleoside and creatinine concentration measurements in urine of healthy and cancer patients. Methods A Bayesian multilevel model was proposed to describe the nucleoside and creatinine concentration ratio considering age, sex and health status as covariates. The predictive performance of the proposed model was summarized via area under the ROC, sensitivity and specificity using external validation. Results Cancer was associated with an increase in methylthioadenosine/creatinine excretion rate by a factor of 1.42 (1.09–2.03) which constituted the highest increase among all nucleosides. Age influenced nucleosides/creatinine excretion rates for all nucleosides in the same direction which was likely caused by a decrease in creatinine clearance with age. There was a small evidence of sex-related differences for methylthioadenosine. The individual a posteriori prediction of patient classification as area under the ROC with 5th and 95th percentile was 0.57(0.5–0.67) with sensitivity and specificity of 0.59(0.42–0.76) and 0.57(0.45–0.7), respectively suggesting limited usefulness of 13 nucleosides/creatinine urine concentration measurements in predicting disease in this population. Conclusion Bayesian multilevel pharmacokinetics-driven modeling in metabolomics may be useful in understanding the data and may constitute a new tool for searching towards potential candidates of disease indicators. Electronic supplementary material The online version of this article (doi:10.1007/s11306-017-1164-4) contains supplementary material, which is available to authorized users.

Convenient drug candidates testing methods for lipophilicity and acidity are highly requested in modern pharmaceutical research and development strategy. Reversed-phase high-performance liquid chromatography (RP HPLC) might be particularly useful for the determination of both pKa and the apparent (pH-dependent) octanol–water partition coefficient, applicable in high-throughput analysis of multi-component mixtures. In this report the pH/organic modifier gradient RP HPLC is presented as a means of simultaneous determination of acidity and lipophilicity of a series of 26 imidazoline-like drugs. The previously theoretically elaborated approach has been applied consisting in retention measurements in a series of methanol gradient runs differing in pH range and duration of the gradient. The simultaneously determined lipophilicity and dissociation constants have been demonstrated to correlate to the respective parameters form calculation chemistry. The proposed approach can be applied to compound mixtures, it requires only minute amounts of substances, and pKa values can be determined in the range 3–10 units and lipophilicity log P parameter in the range 0–7 units.

Available propofol pharmacokinetic protocols for target-controlled infusion (TCI) were obtained from healthy individuals. However, the disposition as well as the response to a given drug may be altered in clinical conditions. The aim of the study was to examine population pharmacokinetics (PK) and pharmacodynamics (PD) of propofol during total intravenous anesthesia (propofol/fentanyl) monitored by bispectral index (BIS) in patients scheduled for abdominal aortic surgery. Population nonlinear mixed-effect modeling was done with Nonmem. Data were obtained from ten male patients. The TCI system (Diprifusor) was used to administer propofol. The BIS index served to monitor the depth of anesthesia. The propofol dosing was adjusted to keep BIS level between 40 and 60. A two-compartment model was used to describe propofol PK. The typical values of the central and peripheral volume of distribution, and the metabolic and inter-compartmental clearance were V C = 24.7 1, V T = 112 1, Cl = 2.64 1/min and Q = 0.989 1/min. Delay of the anesthetic effect, with respect to plasma concentrations, was described by the effect compartment with the rate constant for the distribution to the effector compartment equal to 0.240 min –1 . The BIS index was linked to the effect site concentrations through a sigmoidal E max model with EC 50 = 2.19 mg/1. The body weight, age, blood pressure and gender were not identified as statistically significant covariates for all PK/PD parameters. The population PK/PD model was successfully developed to describe the time course and variability of propofol concentration and BIS index in patients undergoing surgery.

The predictive capability of the retention time prediction model based on quantitative structure-retention relationships (QSRR) was tested. QSRR model was derived with the use of set of peptides identified with the highest scores and originated from 8 known proteins annotated as model ones. The predictive ability of the QSRR model was verified with the use of aBacillus subtilisproteome digest after separation and identification of the peptides by LC-ESI-MS/MS. That ability was tested with three sets of testing peptides assigned to the proteins identified with different levels of confidence. First, the set of peptides identified with the highest scores achieved in the search were considered. Hence, proteins identified on the basis of more than one peptide were taken into account. Furthermore, proteins identified on the basis of just one peptide were also considered and, depending on the possessed scores, both above and below the assumed threshold, were analyzed in two separated sets. The QSRR approach was applied as the additional constraint in proteomic research verifying results of MS/MS ion search and confirming the correctness of the peptides identifications along with the indication of the potential false positives.

Immobilization of amyloid beta (Abeta) (1-40) peptide on Au-colloid modified gold electrodes has been studied. Colloidal Au was self-assembled onto gold electrodes through the thiol groups of 1,6-hexanedithiol monolayer. Next, buffered aqueous solution of Abeta (1-40) peptide existing in the beta-sheet structure in the acidic media was dropped on the electrode surface. Each step of electrode modification has been confirmed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The changes of the resistance of the layer with deposited Abeta (1-40) peptide, occurred under stimulation by different concentration of (-) nicotine ditartrate and (-) cotinine were measured with EIS and were used for the calculation of association constants. The gentle measuring conditions applied in electrochemical impedance spectroscopy, together with suitable environment for biomolecules immobilization created by Au-colloid, might be recommended as the analytical tool for assessing the effectiveness of potential drugs used in Alzheimer's disease (AD) therapy.

The authors have conducted a systematic study in pigs to verify the models of post-mortem body temperature decrease currently employed in forensic medicine. Twenty-four hour automatic temperature recordings were performed in four body sites starting 1.25 h after pig killing in an industrial slaughterhouse under typical environmental conditions (19.5-22.5 degrees C). The animals had been randomly selected under a regular manufacturing process. The temperature decrease time plots drawn starting 75 min after death for the eyeball, the orbit soft tissues, the rectum and muscle tissue were found to fit the single-exponential thermodynamic model originally proposed by H. Rainy in 1868. In view of the actual intersubject variability, the addition of a second exponential term to the model was demonstrated to be statistically insignificant. Therefore, the two-exponential model for death time estimation frequently recommended in the forensic medicine literature, even if theoretically substantiated for individual test cases, provides no advantage as regards the reliability of estimation in an actual case. The improvement of the precision of time of death estimation by the reconstruction of an individual curve on the basis of two dead body temperature measurements taken 1 h apart or taken continuously for a longer time (about 4 h), has also been proved incorrect. It was demonstrated that the reported increase of precision of time of death estimation due to use of a multiexponential model, with individual exponential terms to account for the cooling rate of the specific body sites separately, is artifactual. The results of this study support the use of the eyeball and/or the orbit soft tissues as temperature measuring sites at times shortly after death. A single-exponential model applied to the eyeball cooling has been shown to provide a very precise estimation of the time of death up to approximately 13 h after death. For the period thereafter, a better estimation of the time of death is obtained from temperature data collected from the muscles or the rectum.

Liquid chromatography and capillary electrophoresis are unique tools for fast and efficient modeling of pharmacokinetic properties of drug candidates. Therefore numerous new separation methods and procedures have very recently been introduced to facilitate the high-throughput screening of biopartitioning features of xenobiotics. This report is a concise, up-to-date review of progress in the chromatographic assessments of data of importance for medicinal chemistry and molecular pharmacology.

Aims/hypothesis. Vascular complications observed in diabetes are often related to altered platelet functions. The most widely used hypoglycaemic drugs for treating Type II (non-insulin-dependent) diabetes mellitus are sulphonylurea derivatives. The purposes of this study were to evaluate the inhibitory effects of hypoglycaemic agents on platelet aggregation, to measure their lipophilicity and identify their structural parameters which assess their antiaggregatory activity. Methods. An antiaggregatory test in vitro was carried out for 13 sulphonylurea derivatives. Aggregation of platelets, incubated with the agents at concentrations varying from 7.5 to 480 μmol/l, was induced by 10 μmol/l ADP. Drug lipophilicity parameter, log kw, was measured by gradient HPLC and the agents were subjected to molecular modelling. Results. The most pronounced inhibition of platelet aggregation was by glimepiride, gliclazide, gliquidone, glibenclamide and compound 2A. The IC25 values were 15.9, 18.6, 20.4, 28.5 and 34.7 μmol/l, respectively. Quantitative structure-activity relationships indicate that antiaggregatory activity is mainly affected by electronic and not by lipophilic properties of the agents. Conclusion/interpretation. Glimepiride appeared to be a more potent ADP-induced platelet aggregation inhibitor in vitro than gliclazide. Antiaggregatory activity was shown for gliquidone and confirmed for glibenclamide. The QSAR analysis supports the hypothesis of a free radical mechanism of action of sulphonylurea derivatives previously suggested for gliclazide.

The extrapyramidal side effect parameters of typical and atypical antypsychotics were correlated with affinity chromatographic data determined on the melanin-based column. The chromatographic study was performed according to the hypothesis that extrapyramidal symptoms (EPS) as side effects of the use of antipsychotic drugs at clinically effective doses are correlated to the affinity of these drugs to neuromelanin. For that aim the polymerization product of L-DOPA (melanin) was immobilized onto aminopropyl silica and the binding efficiency of melanin towards antipsychotics has been determined. The results indicate that melanin based-column can be used to evaluate the risk of EPS of drug candi- dates to antipsychotic drug therapy.

Despite the growing number of cancer cases and cancer surgeries around the world, the pharmacokinetics (PK) and pharmacodynamics (PD) of anesthetics used in this population are poorly understood. Patients operated due to cancer are usually in severe state and often require chemotherapy. It might affect the PK/PD of drugs used in this population. Therefore, in this study we explored the PK/PD of propofol in cancer patients having a major lung surgery. 23 patients that underwent a propofol–fentanyl total intravenous anesthesia were included in the analysis. A large set of demographic, biochemical and hemodynamic parameters was collected for the purpose of covariate analysis. Nonlinear mixed effect modeling in NONMEM was used to analyze the collected data. A three-compartment model was sufficient to describe PK of propofol. The anesthetic effect (AAI index) was linked to the propofol effect site concentrations through a sigmoidal Emax model. A slightly higher value of clearance, a lower value of distribution clearance, and a decreased volume of peripheral compartment were observed in our patients, as compared with the literature values reported for healthy volunteers by Schnider et al. and by Eleveld et al. Despite these differences, both models led to a clinically insignificant bias of −8 and −1 % in concentration predictions, as reflected by the median performance error. The Ce50 and propofol biophase concentration at the time of postoperative orientation were low and equaled 1.40 and 1.13 mg/L. The population PK/PD model was proposed for cancer patients undergoing a major lung surgery. The large body of studied covariates did not affect PK/PD of propofol significantly. The modification of propofol dosage in the group of patients under study is not necessary when TCI-guided administration of propofol by means of the Schnider model is used. Electronic supplementary material The online version of this article (doi:10.1007/s10928-015-9404-6) contains supplementary material, which is available to authorized users.

The performance of several previously designed model series of test analytes has been tested to characterize in an objective, quantitative manner modern stationary phases for reversed-phase high-performance liquid chromatography (RP-HPLC) using quantitative structure-retention relationships (QSRRs). Three QSRR approaches and three respective series of test analytes recommended for studies of the molecular mechanism of chromatographic retention are employed: the reduced linear solvation energy relationship (LSER)-based model of Abraham, a model employing structural descriptors from molecular modeling, and a model relating retention to the n-octanol-water partition coefficient log P. All of the models and test analytes proposed provide reliable QSRR equations. Those equations discriminate in quantitative terms individual columns and chromatographic systems and can be interpreted in straightforward rational chemical categories. In view of QSRRs, the differences in the intermolecular interactions between a given stationary phase and a structurally defined analyte rationalize the observed differences in retention. The QSRR models (previously derived retrospectively) are demonstrated to work well on new sets of RP-HPLC data. At the same time, it has been confirmed that the three test series of analytes have properly been designed and can be recommended for comparative studies of analytical columns. QSRRs once derived on a given column for model analytes can be used to predict the retention of other analytes of a defined structure. That in turn can facilitate the procedure of the rational optimization of chromatographic separations.

Computer software that allows the simulation of any chromatographic separation as a function of simultaneous changes in any one or two variables that can affect sample separation order (selectivity) is described. For one example, an application is described for the simultaneous variation of the mobile phase pH and gradient time in reversed-phase liquid chromatography. The accuracy of such predictions is examined for a sample mixture of 17 substituted benzoic acids and anilines, and requirements for an acceptable predictive accuracy are summarized. In a second example, the separation of three peptides by capillary electrophoresis is optimized.

The interaction of 23 ring-substituted aniline and 22 ring-substituted phenol derivatives with gliadin is studied by reversed-phase high-performance liquid chromatography. The relationship between the strength of interaction and the physicochemical parameters of the solutes is elucidated by principal component analysis followed by traditional and modified nonlinear mapping. It is established that the sterical parameters of solutes exert the highest influence on the interaction. The impact of polarity parameters is of secondary importance. Nonlinear mapping using the absolute values of principal component loadings explains the interaction more precisely than the traditional nonlinear mapping does.

A series of environmental chemicals, mainly nitroaromatics and their transformation products, contaminating soil around former ammunition plants, was analyzed by high-performance liquid chromatography (HPLC) employing 2 reference and 5 recently synthesized new stationary phase materials. The new phases were demonstrated to possess unique separation properties. Quantitative structure-retention relationships (QSRR) were derived relating retention parameters to hydrophobicity parameters, hydrogen-bond descriptors and structural parameters from molecular modeling. Multivariate chemometric analysis of HPLC retention data determined on the seven stationary phases by the principal component analysis (PCA) method allowed for assignment of individual pollutants to defined chemical classes (e.g. metabolic routes).

Endothelial dysfunction is characterized by reduced nitric oxide (NO) bioavailability, resulting in elevated vascular resistance and hypertension.1 Endothelial NO is mainly generated from the conversion of l-arginine to l-citrulline by endothelial nitric oxide synthase (eNOS), a process that involves multiple cofactors. In spontaneously hypertensive rats (SHRs), a pronounced loss of NO in both arterial and glomerular endothelial cells has been observed despite an increase in levels of eNOS.2–4 The basis for the paradoxical loss of NO despite increased enzyme levels is the production of O2 – by uncoupled eNOS and other oxidases. In particular, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase represents major sources of O2 – in animal models of hypertension and other models of cardiovascular risk.5 Even in rats that were made hypertensive by aortic banding, changes in eNOS uncoupling were observed with an associated loss of NO bioavailability.6 Superoxide produced by eNOS or NADPH oxidase can be scavenged by NO to form peroxynitrite (ONOO–).7 Peroxynitrite is a main component of nitroxidative stress. The ratio of NO concentration to ONOO– concentration is a good indicator of the status of the redox environment: cytoprotective vs. cytotoxic in dysfunctional endothelial cells.8 Amlodipine has been shown to increase the release of NO in intact human arteries, cardiac tissue, and isolated cells through eNOS-dependent pathways.9 The ability of amlodipine to stimulate eNOS was not reproduced by other calcium channel blockers (CCBs) in human arteries but related to a novel kinin-dependent pathway.9,10 Indeed, the inactive enantiomer of amlodipine was also able to stimulate eNOS despite little activity as an l-type CCB.10,11 In addition to activation of eNOS, amlodipine enhances vasodilation through modulation of excitation-contraction mechanisms in smooth muscle cells while reducing oxidative stress.9 In a clinical study, it was shown that both amlodipine and S(-)-amlodipine can improve endothelial function in hypertensive patients.12 Also, an amlodipine-based regimen reduced cardiovascular events compared with other antihypertensive regimens in a manner that correlated with reduced central aortic pressures and enhanced vasodilation.13 This study was conducted to evaluate the effects of amlodipine on endothelial NO release and simultaneous release of ONOO– in a well-established model of hypertension using direct measurements with amperometric nanosensors. It was hypothesized that amlodipine may stimulate NO release and reduce ONOO–-related nitroxidative stress in SHRs before changes in blood pressure (BP). To test this hypothesis, we measured NO and ONOO– release in aortic and glomerular endothelium from SHRs after amlodipine vs. vehicle treatments.

Reversed-phase thin-layer chromatographic (RP TLC) retention coefficients for a newly designed series of N-phenyl-3-methyl succinimide derivatives, of a rationally expected anticonvusant activity, were determined as parameters of their lipophilicity. Basic pharmacokinetic descriptors of the agents were calculated in silico with the use of the established medicinal chemistry/drug design software. Highly significant, predictive relationships were found between the chromatographic retention constants and the bioactivity descriptors, which are assumed to account for drug absorption, distribution, elimination and toxicity (ADMETox) in humans. Among the agents investigated, the compounds with halogen substituent (Compounds nos. 9-13 in Fig. 1), were identified as the best drug candidates, because of their predicted proper pharmacokinetics, and have been selected for further research and development studies on new antiepileptic drugs. At the same time, among the congeners studied these can be indicated, which should not be rationally subjected to bioactivity tests.

A specific and reliable high-performance thin layer chromatography method with densitometry detection has been developed for the de- termination of naphazoline nitrate in nasal drops. The best separ- ation of the basic analyte, without spot tailing, was achieved by using a mobile phase composed of acetonitrile -water (60:40, v/v), adding 1.5 % (v/v) imidazolium-class ionic liquid and covering the plates with a stationary phase based on RP-18 with F254S (10 3 20 cm). The presented results confirm that imidazolium tetrafluoro- borate ionic liquids are efficient suppressors of free silanols, which are considered to be responsible for troublesome and irreproducible chromatographic determinations of basic compounds. The devel- oped chromatographic system was found to be convenient in use and to provide a repeatable assay of naphazoline nitrate in nasal drops, which could not be obtained with the use of standard silanol suppressing mobile phase additives such as triethylamine or dimethyloctylamine. the ILs based on the BF4 ,C l 2 and MeSO4 anions are water- stable compounds, which dissolve in typical chromatographic mobile phases. Recently, ILs have been proposed as silanol suppressing agents (15, 16). The significant effects of imidazolium-based ILs as mobile phase modifiers in thinlayer chromatography (TLC) and high-performance liquid chromatography (HPLC) on the retention of basic compounds have been studied and described elsewhere (13). The addition of 0.5 -2.5% (v/v) of some types of ILs composed of 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-octyl-3-methylimidazolium or 1-butyl-4-methylpyridinium cations and bromide chlorate, hexafluorophosphate, methyl sulphate, tetrafluoroborate or tosylate anions more markedly

Imidazol(in)e compounds show the diversity of pharmacological effects including mydriasis, hypotension, sedation, bradycardia and hypothermia. At first it was postulated that these effects are mediated via α2-adrenoceptors exclusively. Clonidine is well known as a model agent to produce pupillary dilation in rats. However, it became obvious later that clonidine-like imidazol(in)e adrenoceptor agonists which produced mydriasis in rats, exhibit also a high affinity for imidazoline I1-receptors. That short report attempts to review the present status of studies to confirm that the mydriasis model in rats can be a selective system to evaluate the α2-adrenergic activity of potential pharmacologically active compounds of imidazol(in)e structure.

The primary aim of this work was to determine the interactions of an oxindole alkaloid (mitraphylline) isolated from Uncaria tomentosa with β-amyloid 1-40 (Aβ1-40 protein) apply­ing the capillary electrophoresis (CE) method. Specifically the Hummel-Dreyer method and Scatchard analysis were performed to study the binding of oxindole alkaloids with Aβ1-40 protein. Prior to these studies extraction of the alkaloid of interest was carried out. Identifica­tion of the isolated alkaloid was performed by the use of thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI-MS). The proposed approach was proved to be an efficient and accurate method for specific compound isolation and identification purposes. Moreover, ana­lytical information from the CE approach can be considered as the valuable tool for binding constant determination. The binding constant of mitraphylline with Aβ1-40 protein deter­mined by the Hummel-Dreyer method and Scatchard analysis equals K = 9.95 x 105 m-1. The results obtained showed the significant binding of the tested compound with Aβ1-40 protein. These results are discussed and interpreted in the view of developing a strategy for identifica­tion of novel compounds of great importance in Alzheimer disease therapy.

Since 20 years the concept of specific imidazoline receptors has remained controversial. The problem with imidazoline receptors is mostly due to their functional similarity to alpha-adrenoceptors. In this work, a pharmacodynamic model of isolated rat jejunum longitudinal muscle strips constricted with acetylcholine (Ach) was applied to separate functional properties of the two types of receptors. Relaxation of the preparation was measured as a function of concentration of 2-(benzofuranyl)-2-imidazoline (2-BFI), a specific imidazoline I2 receptor ligand, cirazoline, a potent I2 receptor ligand and alpha1-adrenoceptor agonist, phenylephrine, an agonist of alpha1-adrenoceptor, moxonidine, a ligand of I1 receptor, efaroxan, a ligand of I3 receptor and 5-bromo-6-(imidazoline-2-yl-amino)quinoxaline (UK14304), an agonist of alpha2-adrenoceptor. Next, the effects of a series of imidazoline-and/or alpha-adrenoceptor-binding drugs (prazosin, yohimbine, RS79948, RX821002, idazoxan and efaroxan) on the relaxation of the Ach-constricted rat jejunum strips, induced by 2-BFI, cirazoline or phenylephrine, were studied. The obtained results demonstrate the involvement of the postsynaptic imidazoline receptors in rat jejunum motility. These receptors are of I2 subtype and are linked to alpha-adrenoceptors of the predominantly alpha1 subtype. The alpha1 receptors dominate functionally over the I2 in the isolated rat jejnum. The proposed model might be useful in search for more specific new drugs.

The authors have conducted a systematic study in pigs to verify the models of post-mortem body temperature decrease currently employed in forensic medicine. Twenty-four hour automatic temperature recordings were performed in four body sites starting 1.25 h after pig killing in an industrial slaughterhouse under typical environmental conditions (19.5-22.5 degrees C). The animals had been randomly selected under a regular manufacturing process. The temperature decrease time plots drawn starting 75 min after death for the eyeball, the orbit soft tissues, the rectum and muscle tissue were found to fit the single-exponential thermodynamic model originally proposed by H. Rainy in 1868. In view of the actual intersubject variability, the addition of a second exponential term to the model was demonstrated to be statistically insignificant. Therefore, the two-exponential model for death time estimation frequently recommended in the forensic medicine literature, even if theoretically substantiated for individual test cases, provides no advantage as regards the reliability of estimation in an actual case. The improvement of the precision of time of death estimation by the reconstruction of an individual curve on the basis of two dead body temperature measurements taken 1 h apart or taken continuously for a longer time (about 4 h), has also been proved incorrect. It was demonstrated that the reported increase of precision of time of death estimation due to use of a multiexponential model, with individual exponential terms to account for the cooling rate of the specific body sites separately, is artifactual. The results of this study support the use of the eyeball and/or the orbit soft tissues as temperature measuring sites at times shortly after death. A single-exponential model applied to the eyeball cooling has been shown to provide a very precise estimation of the time of death up to approximately 13 h after death. For the period thereafter, a better estimation of the time of death is obtained from temperature data collected from the muscles or the rectum.

In a series of reports published recently by our laboratory comprehensive theory and experimental conditions were established for reversed-phase high-performance liquid chromatography (RP HPLC) employing the programmed pH gradient of mobile phase. A procedure was developed providing, rapidly and conveniently, the acidity (pK(a)) of weak acids and bases and their lipophilicity (hydrophobicity) log k(w). The basis of the double-gradient RP HPLC, employing simultaneous gradients of organic modifier content and mobile phase pH, was also elaborated. The fundamentals of the approach are presented briefly and systematically and its advantages and limitations are discussed. It is demonstrated that the newly introduced pH gradient method increases the analytical versatility of RP HPLC and our understanding of its physicochemical basis.

The Quantitative Structure-Activity Relationships (QSAR) has been developed to relate antifungal activity against Candida albicans and Rhodotorula glutinis of new imidazole derivatives with their physico-chemical and structural properties. For 265 imidazole derivatives the most significant statistically equations has been obtained with correlation coefficients R=0.800 and R=0.820 in case of activity against Ca. and Rh.g., respectively. The overall antifungal activity has been described by means of size and bulkiness related parameters as well as polar and lipophilic interactions. The significance of lipophilicity in terms of n-octanol/water partition coefficient, ClogP, on antifungal potency against both fungi has been investigated. QSAR equations for different classes of antifungal activity have been obtained. With a very high probability level (92% and 96%) the weak or very weak antifungal potency against C.a. can be determined and thus the number of required experiments can be reduced.

Over the last decade metabolomics has gained increasing popularity and significance in life sciences. Together with genomics, transcriptomics and proteomics, metabolomics provides additional information on specific reactions occurring in humans, allowing us to understand some of the metabolic pathways in pathological processes. Abnormal levels of such metabolites as nucleosides in the urine of cancer patients (abnormal in relation to the levels observed in healthy volunteers) seem to be an original potential diagnostic marker of carcinogenesis. However, the expectations regarding the diagnostic value of nucleosides may only be justified once an appropriate analytical procedure has been applied for their determination. The achievement of good specificity, sensitivity and reproducibility of the analysis depends on the right choice of the phases (e.g. sample pretreatment procedure), the analytical technique and the bioinformatic approach. Improving the techniques and methods applied implies greater interest in exploration of reliable diagnostic markers. This review covers the last 11 years of determination of urinary nucleosides conducted with the use of high-performance liquid chromatography in conjunction with various types of detection, sample pretreatment methods as well as bioinformatic data processing procedures. Electronic supplementary material The online version of this article (doi:10.1007/s00216-011-4789-6) contains supplementary material, which is available to authorized users.

The linear-solvent strength (LSS) model of gradient elution in high-performance liquid chromatography (HPLC) has been demonstrated to provide parameters of lipophilicity and acidity of analytes. pKa and log kw values are determined in three gradient runs. The first two experiments use an aqueous buffered eluent with a wide-range organic modifier gradient at pH of buffer, providing suppression of ionization of the analyte. That experiment allows an estimate of contents of the organic modifier in the mobile phase (%B), producing requested retention coefficient, k, for the nonionized form of the analyte. The next experiment is carried out with the latter %B and a pH-gradient of the aqueous component of the eluent that is sufficient to overlap possible pKa value of the analyte. The initial pH of the buffer used to make the mobile phase is selected to insure that the analyte is in nonionized form. The resulting retention time allows an estimate of pKa in a solvent of the given %B. The log kw parameter obtained correlated well with the corresponding value obtained by the standard procedure of extrapolation of retention data determined in a series of isocratic measurements. The correlation between log kw and the reference parameter of lipophilicity, log P, was very good for a series of test analytes. The values of pKa were found to correlate with the literature pKa data determined in water for a set of aniline derivatives studied.