Anna Tsantili-Kakoulidou

Synthesis, lipophilicity and biological evaluation of indole-containing derivatives of 1,3,4-thiadiazole and 1,2,4-triazole

3-[(2-Methyl-1H-3-indolyl) methyl]-4-aryl-4, 5-dihydro-1H-1,2,4-triazole-5-thiones 6a-c and their respective N-¿5-[2-methyl-1H-3-indolyl) methyl]-1,3,4-thiadiazol-2-yl¿-N-arylamines 7a,b have been prepared. The antidepressant profile of 6a,c and 7a was studied on mice with respect to that of the analogous 3-(1H-1-indolylmethyl)-4-aryl-4,5-dihydro-1H-1,2,4-triazole-5-thio nes 1a-c and the respective N-¿5-[(2-methyl-1H-3-indolyl) methyl]-1,3,4-thiadiazole-2-yl¿-N-arylamines 2a-c, the synthesis and antimicrobial potency of which we have recently reported. Behavioral effects, induced by the members of both series, in conjunction with their activity in some specific tests (forced swim, pentetrazole convulsions) on mice, show that these derivatives cross the blood-brain barrier and could develop an antidepressant activity comparable to that of imipramine. Blood-brain barrier penetration is also supported by the lipophilicity data obtained for all analogs.

Alternative Measures of Lipophilicity: From Octanol–Water Partitioning to IAM Retention

This review describes lipophilicity parameters currently used in drug design and QSAR studies. After a short historical overview, the complex nature of lipophilicity as the outcome of polar/nonpolar inter- and intramolecular interactions is analysed and considered as the background for the discussion of the different lipophilicity descriptors. The first part focuses on octanol-water partitioning of neutral and ionisable compounds, evaluates the efficiency of predictions and provides a short description of the experimental methods for the determination of distribution coefficients. A next part is dedicated to reversed-phase chromatographic techniques, HPLC and TLC in lipophilicity assessment. The two methods are evaluated for their efficiency to simulate octanol-water and the progress achieved in the refinement of suitable chromatographic conditions, in particular in the field of HPLC, is outlined. Liposomes as direct models of biological membranes are examined and phospolipophilicity is compared to the traditional lipophilicity concept. Difficulties associated with liposome-water partitioning are discussed. The last part focuses on Immobilised Artificial Membrane (IAM) chromatography as an alternative which combines membrane simulation with rapid measurements. IAM chromatographic retention is compared to octanol-water and liposome-water partitioning as well as to reversed-phase retention and its potential to predict biopartitioning and biological activities is discussed.

Preventive doping control screening analysis of prohibited substances in human urine using rapid‐resolution liquid chromatography/high‐resolution time‐of‐flight mass spectrometry

Unification of the screening protocols for a wide range of doping agents has become an important issue for doping control laboratories. This study presents the development and validation of a generic liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) screening method of 241 small molecule analytes from various categories of prohibited substances (stimulants, narcotics, diuretics, beta(2)-agonists, beta-blockers, hormone antagonists and modulators, glucocorticosteroids and anabolic agents). It is based on a single-step liquid-liquid extraction of hydrolyzed urine and the use of a rapid-resolution liquid chromatography/high-resolution time-of-flight mass spectrometric system acquiring continuous full scan data. Electrospray ionization in the positive mode was used. Validation parameters consisted of identification capability, limit of detection, specificity, ion suppression, extraction recovery, repeatability and mass accuracy. Detection criteria were established on the basis of retention time reproducibility and mass accuracy. The suitability of the methodology for doping control was demonstrated with positive urine samples. The preventive role of the method was proved by the case where full scan acquisition with accurate mass measurement allowed the retrospective reprocessing of acquired data from past doping control samples for the detection of a designer drug, the stimulant 4-methyl-2-hexanamine, which resulted in re-reporting a number of stored samples as positives for this particular substance, when, initially, they had been reported as negatives.

Current State of the Art in HPLC Methodology for Lipophilicity Assessment of Basic Drugs. A Review

Abstract HPLC provides a users friendly, rapid, and compound sparing methodology, which is successfully applied to determine drug lipophilicity. Under suitable chromatographic conditions isocratic and extrapolated retention factors correlate well with octanol‐water partition or distribution coefficients. The present review provides an overview of the stationary and mobile phases, which are preferably used for lipophilicity assessment mainly in the case of basic compounds. Difficulties raised by the interference of silanophilic interactions in the partition mechanism, and the ways proposed to face this problem are discussed. Attention has been given to the extrapolation procedure and the standardization of conditions to obtain 1∶1 correlation between extrapolated retention factors and logP or logD. Other chromatographic indices encoding information on the lipophilic behavior are briefly presented. A separate section refers to recent advances in IAM Chromatography, its similarities/dissimilarities with reversed phase HPLC and the octanol-water system, as well as its potential to mimic specific interactions with phospholipids.

Structural characteristics of anabolic androgenic steroids contributing to binding to the androgen receptor and to their anabolic and androgenic activities. Applied modifications in the steroidal structure.

Anabolic androgenic steroids (AAS) are synthetic derivatives of testosterone introduced for therapeutic purposes providing enhanced anabolic potency with reduced androgenic effects. Androgens mediate their action through their binding to the androgen receptor (AR) which is mainly expressed in androgen target tissues, such as the prostate, skeletal muscle, liver and central nervous system. This paper reviews some of the wide spectrum of testosterone and synthetic AAS structure modifications related to the intended enhancement in anabolic activity. The structural features of steroids necessary for effective binding to the AR and those which contribute to the stipulation of the androgenic and anabolic activities are also presented.

Metabonomic identification of novel biomarkers in doxorubicin cardiotoxicity and protective effect of the natural antioxidant oleuropein.

Doxorubicin (DXR) is a commonly used antineoplastic agent; however, its use is limited due to cardiotoxicity. Oxidative stress and consequent alterations of cardiac energetics are involved in the development of DXR toxicity. Oleuropein (Oleu) is a phenolic antioxidant, present in olive tree, reported to confer protection against DXR cardiotoxicity. In this study, NMR based‐metabonomics was applied to characterize the metabolic profile of the acute DXR cardiotoxicity in rats and to evaluate the metabolic alterations conferred by co‐treatment with Oleu. Wistar rats were divided into six groups and treated as follows: control group with a single injection of 2 mL normal saline intraperitoneally (i.p.), DXR group with a single dose of 20 mg/kg, i.p and DXR plus Oleu groups with 20mg/kg DXR i.p., and 100 or 200 mg/kg/BW of Oleu i.p. for 5 or 3 consecutive days starting either 2 days before or on the day of DXR administration. Hearts were excised 72 h after DXR treatment and 1H‐NMR spectra of aqueous myocardium extracts were recorded. Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS‐DA) revealed differences in the metabolic profile between control and DXR attributed to several metabolites. A number of them were quantified by integration of the NMR spectra. Myocardial levels of acetate and succinate were increased in DXR compared to controls, while branched amino acids were decreased. These results correlate with nonenzymatic conversion of pyruvate to acetate and of α‐ketoglutarate to succinate by DXR free radicals. Oleu completely restored the changes of metabolites to the normal levels. Acetate and succinate constitute novel biomarkers related to DXR, and Oleu treatment aids the compensation of distressed energy metabolic pathways. Copyright

Peroxisome proliferator-activated receptors (PPARs) in the control of bone metabolism

Peroxisome proliferator‐activated receptors (PPARs) are ligand‐activated nuclear transcription factors that regulate the storage and catabolism of dietary fats. PPARs constitute molecular targets for the treatment of human metabolic disorders, and also play a crucial role in inflammatory‐related disease and cancer. Recent evidence has revealed the presence of three different PPAR isotypes (α, β/δ, and γ) in different cells of the bone tissue, as well as the possible role of PPAR ligands in bone turnover. In the present review, the latest knowledge of the expression of PPARs in bone tissue and the diverse effects of PPAR ligands on bone metabolism is summarized. PPARs, especially of the γ isotype, could be targets for the treatment of diverse bone diseases such as osteoporosis and osteopenia related to either diabetes or aging.

Determination of the dissociation constants of the cephalosporins cefepime and cefpirome using UV spectrometry and pH potentiometry.

UV spectrometry and pH potentiometry were used for the determination and direct characterization of the dissociation constants of cefepime (Cef) and cefpirome. The absorbance/pH profiles at two analytical wavelengths and different conditions were assessed and found to conform to those of diprotic acids. The titration curves indicated a triprotic acid profile with two overlapping dissociation constants. The comparison of the results of both techniques permitted the direct attribution of the three dissociation constants to the carboxylic group at position 4 of the Delta-3 cephem nucleus, the aminothiazole group and the amide group at position 7 of the Delta-3 cephem nucleus. Stability studies of Cef in alkaline solutions were also performed in order to evaluate the accuracy of the measurements carried out for the determination of the third pK(a) value. The experimental pK(a) values were compared to the corresponding predicted values derived by PALLAS/PKALC and Advanced Chemical Development (ACD) software packages.

Schemes of metabolic patterns of anabolic androgenic steroids for the estimation of metabolites of designer steroids in human urine

Unified metabolism schemes of anabolic androgenic steroids (AAS) in human urine based on structure classification of parent molecules are presented in this paper. Principal components analysis (PCA) was applied to AAS molecules referred in the World Anti-Doping Agency (WADA) list of prohibited substances, resulting to their classification into six distinct groups related to structure features where metabolic alterations usually occur. The metabolites of the steroids participating to these six groups were treated using the Excel(c) classification filters showing that common metabolism routes are derived for each of the above PCA classes, leading to the proposed metabolism schemes of the present study. This rule-based approach is proposed for the prediction of the metabolism of unknown, chemically modified steroids, otherwise named as designer steroids. The metabolites of three known, in the literature, AAS are estimated using the proposed metabolism schemes, confirming that their use could be a useful tool for the prediction of metabolic pathways of unknown AAS.

Electrostatic interactions and ionization effect in immobilized artificial membrane retention: A comparative study with octanol–water partitioning

The present study is a continuation of our efforts to investigate the effect of electrostatic interactions and ionization on immobilized artificial membrane (IAM) retention. The previous set of neutral and basic drugs was extended to include acids and ampholytes and analogous buffer conditions in the mobile phase were used, namely morpholinepropanesulfonic acid and phosphate buffer saline, adjusted at pH 7.4. The important contribution of electrostatic forces in IAM retention of positively charged species was further justified by the results of the present study, while analogous electrostatic interactions for ionized acidic drugs were not found to affect significantly the affinity for the IAM stationary phase. The critical role of shielding or exposure of the charged centers on the IAM surface, as a result of the effect of the aqueous component of the mobile phase, was evaluated by the use of water instead of buffer for a number of drugs. Measurements at pH 5.0 demonstrated the effect of ionization in IAM retention despite the partial compensation by electrostatic interactions in the case of protonated basic drugs. Silanophilic interactions were also found to play a potential role as secondary interactions in IAM retention. IAM chromatographic indices were compared to octanol-water distribution coefficients and the corresponding relationships established. Finally, solvation analysis was applied in the aim to gain insight in the balance of forces between IAM retention and octanol-water partitioning. The results showed that apart from electrostatic interactions, there is no significant differentiation between the two systems.