Reversed-phase liquid chromatography with octadecylsilyl, immobilized artificial membrane and cholesterol columns in correlation studies with in silico biological descriptors of newly synthesized antiproliferative and analgesic active compounds

Predicting biophysical properties of small molecules from chromatographic measurements and the solvation parameter model

Biopartitioning processes are challenging to study and often require the sacrifice of multiple animals. Therefore, it is more practical and cost-effective to correlate these processes with easily determined properties, such as chromatographic retention data, or to make predictions based on structural descriptors such as quantitative structure-property relationships or linear free energy relationships. Abraham's solvation parameter model uses six solute properties to characterize the interactions responsible for the transfer of neutral compounds between immiscible phases in chromatographic or biological systems. This review discusses the prediction of biological properties of small molecules from chromatographic measurements and the solvation parameter model. It covers the characteristics of solute descriptors in the solvation parameter model, as well as experimental approaches for their determination. Additionally, it explores recent applications of the solvation parameter model in characterizing biological systems and its use in identifying surrogate chromatographic models for predicting biological properties.

Comparison of HPLC, HPTLC, and In Silico Lipophilicity Parameters Determined for 5-Heterocyclic 2-(2,4-Dihydroxyphenyl)-1,3,4-thiadiazoles

The 5-heterocyclic 2-(2,4-dihydroxyphenyl)-1,3,4-thiadiazoles were obtained as potential biologically active compounds. Lipophilicity is one of the most important physicochemical properties of compounds and was already taken into account during the drug candidates design and development. The lipophilicity of compounds was determined using the computational (log P) and chromatography (log kw, RMw) methods. The experimental ones included the reverse-phase column high performance liquid chromatography RP (HPLC) with C8, C18, phosphatidylcholine (IAM), and cholesterol stationary phases and the thin layer chromatography (RP-HPTLC) with C8 and C18 stationary phases and various organic modifiers under the isocratic conditions. Descriptive statistics, correlation, and PCA analyses were used to compare the obtained results. For lipophilicity estimation of the tested compounds by HPTLC, dioxane and MeOH seem to be particularly beneficial as organic modifiers. The chromatographic lipophilicity parameters log kw (RMw) were well correlated and highly redundant (85%) compared with those calculated. Most compounds possess lipophilicity parameters within the recommended range for drug candidates.

Modeling the Blood-Brain Barrier Permeability of Potential Heterocyclic Drugs via Biomimetic IAM Chromatography Technique Combined with QSAR Methodology

Penetration through the blood-brain barrier (BBB) is desirable in the case of potential pharmaceuticals acting on the central nervous system (CNS), but is undesirable in the case of drug candidates acting on the peripheral nervous system because it may cause CNS side effects. Therefore, modeling of the permeability across the blood-brain barrier (i.e., the logarithm of the brain to blood concentration ratio, log BB) of potential pharmaceuticals should be performed as early as possible in the preclinical phase of drug development. Biomimetic chromatography with immobilized artificial membrane (IAM) and the quantitative structure-activity relationship (QSAR) methodology were successful in modeling the blood-brain barrier permeability of 126 drug candidates, whose experimentally-derived lipophilicity indices and computationally-derived molecular descriptors (such as molecular weight (MW), number of rotatable bonds (NRB), number of hydrogen bond donors (HBD), number of hydrogen bond acceptors (HBA), topological polar surface area (TPSA), and polarizability (α)) varied by class. The QSARs model established by multiple linear regression showed a positive effect of the lipophilicity (log kw, IAM) and molecular weight of the compound, and a negative effect of the number of hydrogen bond donors and acceptors, on the log BB values. The model has been cross-validated, and all statistics indicate that it is very good and has high predictive ability. The simplicity of the developed model, and its usefulness in screening studies of novel drug candidates that are able to cross the BBB by passive diffusion, are emphasized.

Retention Behavior of Anticancer Thiosemicarbazides in Biomimetic Chromatographic Systems and In Silico Calculations

Chromatographic methods, apart from in silico ones, are commonly used rapid techniques for the evaluation of certain properties of biologically active compounds used for their prediction of pharmacokinetic processes. Thiosemicarbazides are compounds possessing anticancer, antimicrobial, and other valuable biological activities. The aim of the investigation was to estimate the lipophilicity of 1-aryl-4-(phenoxy)acetylthiosemicarbazides, to predict their oral adsorption and the assessment of their % plasma-protein binding (%PPB). RP-HPLC chromatographic techniques with five diversified HPLC systems, including columns with surface-bonded octadecylsilanes (C-18), phosphatidylcholine (immobilized artificial membrane, IAM), cholesterol (Chol), and α1-acid glycoprotein (AGP) and human serum albumin (HSA), were applied. The measured lipophilicity of all investigated compounds was within the range recommended for potential drug candidates. However, some derivatives are strongly bonded to HSA (%PPB ≈ 100%), which may limit some pharmacokinetic processes. HPLC determined lipophilicity descriptors were compared with those obtained by various computational approaches.

Thermal Investigations of Annelated Triazinones-Potential Analgesic and Anticancer Agents

In this article, for the first time, TG-DSC and TG-FTIR investigations of potential pharmaceutics, i.e., analgesic and anticancer active annelated triazinones (1-9) have been presented. The thermal behaviour of these molecules was established in oxidative and inert conditions. The solid-liquid phase transition for each compound (1-9) was documented by one sharp DSC peak confirming the high purity of each sample studied. All the molecules were characterised in terms of calorimetric changes and mass changes during their heating. They revealed high thermal stability in oxidative and inert conditions. The observed tendency in thermal stability changes in relation to a substituent present at the phenyl moiety was found to be similar in air and nitrogen. It was confirmed that annelated triazinones 1-9 were stable up to a temperature range of 241-296 °C in air, and their decomposition process proceeded in two stages under oxidative conditions. In addition, it was established that their thermal stability in air decreased in the following order of R at the phenyl moiety: 4-Cl > 3,4-Cl2 > H > 3-Cl > 4-CH3 > 2-CH3 > 3-CH3 > 2-Cl > 2-OCH3. The volatile decomposition products of the investigated molecules were proposed by comparing the FTIR spectra collected during their thermogravimetric analysis in nitrogen with the spectra from the database of reference compounds. None of annelated triazinones 1-9 underwent any polymorphic transformation during thermal studies. All the compounds proved to be safe for erythrocytes. In turn, molecules 3, 6, and 9 protected red blood cells from oxidative damage, and therefore may be helpful in the prevention of free radical-mediated diseases.

Comparison of supercritical fluid chromatographic methods to predict the skin permeability of pharmaceutical and cosmetic compounds

Supercritical fluid chromatography (SFC) was explored as an alternative for liquid chromatography to predict the skin permeability of pharmaceutical and cosmetic compounds. Nine dissimilar stationary phases were applied to screen a test set of 58 compounds. The experimental retention factors (log k), in addition to two sets of theoretical molecular descriptors, were applied to model the skin permeability coefficient. Different modelling approaches, i.e. multiple linear regression (MLR) and partial least squares (PLS) regression, were used. In general, the MLR models performed better than the PLS models for a given descriptor set. The results obtained on a cyanopropyl (CN) column provided the best correlation with the skin permeability data. The retention factors obtained on this column were included in a simple MLR model, together with the octanol-water partition coefficient and the number of atoms (r² = 0.81, RMSEC = 0.537 or 20.5% and RMSECV = 0.580 or 22.1%). The overall best MLR model included the chromatographic descriptor from a phenyl column and 18 descriptors (r² = 0.98, RMSEC = 0.167 or 6.2% and RMSECV = 0.238 or 8.9%). This model showed a good fit, on top of very good predictive features. However, stepwise MLR models with a reduced complexity could also be determined, with the best performance parameters obtained with the CN-column based retention and eight descriptors (r² = 0.95, RMSEC = 0.282 or 10.7% and RMSECV = 0.353 or 13.4%). SFC thus provides a suitable alternative to the liquid chromatographic techniques previously applied to model the skin permeability.

Combined Micellar Liquid Chromatography Technique and QSARs Modeling in Predicting the Blood-Brain Barrier Permeation of Heterocyclic Drug-like Compounds

The quantitative structure-activity relationship (QSAR) methodology was used to predict the blood-brain permeability (log BB) for 65 synthetic heterocyclic compounds tested as promising drug candidates. The compounds were characterized by different descriptors: lipophilicity, parachor, polarizability, molecular weight, number of hydrogen bond acceptors, number of rotatable bonds, and polar surface area. Lipophilic properties of the compounds were evaluated experimentally by micellar liquid chromatography (MLC). In the experiments, sodium dodecyl sulfate (SDS) as the effluent component and the ODS-2 column were used. Using multiple linear regression and leave-one-out cross-validation, we derived the statistically significant and highly predictive quantitative structure-activity relationship models. Thus, this study provides valuable information on the expected properties of the substances that can be used as a support tool in the design of new therapeutic agents.

Application of a Screen-Printed Sensor Modified with Carbon Nanofibers for the Voltammetric Analysis of an Anticancer Disubstituted Fused Triazinone

In this paper, we propose the first analytical procedure-using a screen-printed carbon electrode modified with carbon nanofibers (SPCE/CNFs)-for the detection and quantitative determination of an electroactive disubstituted fused triazinone, namely 4-Cl-PIMT, which is a promising anticancer drug candidate. The electrochemical performances of the sensor were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square-wave adsorptive stripping voltammetry (SWAdSV). The presence of carbon nanofibers on the sensor surface caused a decrease in charge-transfer resistance and an increase in the active surface compared to the bare SPCE. Under the optimised experimental conditions, the proposed voltammetric procedure possesses a good linear response for the determination of 4-Cl-PIMT in the two linear ranges of 0.5-10 nM and 10-100 nM. The low limits of detection and quantification were calculated at 0.099 and 0.33 nM, respectively. In addition, the sensor displays high reproducibility and repeatability, as well as good selectivity. The selectivity was improved through the use of a flow system and a short accumulation time. The SWAdSV procedure with SPCE/CNFs was applied to determine 4-Cl-PIMT in human serum samples. The SWAdSV results were compared to those obtained by the ultra-high-performance liquid chromatography coupled with electrospray ionization/single-quadrupole mass spectrometry (UHPLC-ESI-MS) method.

Comparison of in-silico modelling and reversed-phase liquid chromatographic retention on an octadecyl silica column to predict skin permeability of pharmaceutical and cosmetic compounds

This study focuses on the in-silico modelling of the skin permeability using a test set of pharmaceutical and cosmetic compounds. Two sets of theoretical molecular descriptors, obtained from the E-Dragon and Vega ZZ software programs, were used in the models. Different linear regression methods, i.e. Multiple Linear Regression (MLR) and Partial Least Squares (PLS) regression, were applied for modelling and estimating the skin permeability. The best model was obtained using a stepwise MLR approach on the E-Dragon descriptor set. In a second step, the retention of the test set compounds was measured on a C18 column at two pH levels: pH 5.5 and pH 7. Different organic-modifier fractions were applied in the mobile phase to be able to extrapolate the retention factors to a log k_w value, with k_w the estimated retention factor in an aqueous mobile phase without organic modifier. Thereafter it was examined whether combining this chromatographic descriptor with the theoretical descriptors could improve the modelling of the skin permeability. The chromatographic descriptor often did not show an added value compared to the models containing only theoretical descriptors. Therefore, the in-silico models were preferred, and these models could be useful to predict the skin permeability of pharmaceutical and cosmetic compounds.

Biomimetic Chromatographic Studies Combined with the Computational Approach to Investigate the Ability of Triterpenoid Saponins of Plant Origin to Cross the Blood-Brain Barrier

Biomimetic (non-cell based in vitro) and computational (in silico) studies are commonly used as screening tests in laboratory practice in the first stages of an experiment on biologically active compounds (potential drugs) and constitute an important step in the research on the drug design process. The main aim of this study was to evaluate the ability of triterpenoid saponins of plant origin to cross the blood-brain barrier (BBB) using both computational methods, including QSAR methodology, and biomimetic chromatographic methods, i.e., High Performance Liquid Chromatography (HPLC) with Immobilized Artificial Membrane (IAM) and cholesterol (CHOL) stationary phases, as well as Bio-partitioning Micellar Chromatography (BMC). The tested compounds were as follows: arjunic acid (Terminalia arjuna), akebia saponin D (Akebia quinata), bacoside A (Bacopa monnieri) and platycodin D (Platycodon grandiflorum). The pharmacokinetic BBB parameters calculated in silico show that three of the four substances, i.e., arjunic acid, akebia saponin D, and bacoside A exhibit similar values of brain/plasma equilibration rate expressed as logPSFubrain (the average logPSFubrain: -5.03), whereas the logPSFubrain value for platycodin D is -9.0. Platycodin D also shows the highest value of the unbound fraction in the brain obtained using the examined compounds (0.98). In these studies, it was found out for the first time that the logarithm of the analyte-micelle association constant (logKMA) calculated based on Foley's equation can describe the passage of substances through the BBB. The most similar logBB values were obtained for hydrophilic platycodin D, applying both biomimetic and computational methods. All of the obtained logBB values and physicochemical parameters of the molecule indicate that platycodin D does not cross the BBB (the average logBB: -1.681), even though the in silico estimated value of the fraction unbound in plasma is relatively high (0.52). As far as it is known, this is the first paper that shows the applicability of biomimetic chromatographic methods in predicting the penetration of triterpenoid saponins through the BBB.

The oxygenated products of cryptotanshinone by biotransformation with Cunninghamella elegans exerting anti-neuroinflammatory effects by inhibiting TLR 4-mediated MAPK signaling pathway

Cryptotanshinone (1), a major bioactive constituent in the traditional Chinese medicinal herb Dan-Shen Salvia miltiorrhiza Bunge, has been reported to possess remarkable pharmacological activities. To improve its bioactivities and physicochemical properties, in the present study, cryptotanshinone (1) was biotransformed with the fungus Cunninghamella elegans AS3.2028. Three oxygenated products (2-4) at C-3 of cryptotanshinone (1) were obtained, among them 2 was a new compound. Their structures were elucidated by comprehensive spectroscopic analysis including HRESIMS, NMR and ECD data. All of the biotransformation products (2-4) were found to inhibit significantly lipopolysaccharide-induced nitric oxide production in BV2 microglia cells with the IC₅₀ values of 0.16-1.16 μM, approximately 2-20 folds stronger than the substrate (1). These biotransformation products also displayed remarkably improved inhibitory effects on the production of inflammatory cytokines (IL-1β, IL-6, TNF-α, COX-2 and iNOS) in BV-2 cells via targeting TLR4 compared to substrate (1). The underlying mechanism of 2 was elucidated by comparative transcriptome analysis, which suggested that it reduced neuroinflammatory mainly through mitogen-activated protein kinase (MAPK) signaling pathway. Western blotting results revealed that 2 downregulated LPS-induced phosphorylation of JNK, ERK, and p38 in MAPK signaling pathway. These findings provide a basal material for the discovery of candidates in treating Alzheimer's disease.

Predicting the Blood-Brain Barrier Permeability of New Drug-Like Compounds via HPLC with Various Stationary Phases

The permeation of the blood-brain barrier is a very important consideration for new drug candidate molecules. In this research, the reversed-phase liquid chromatography with different columns (Purosphere RP-18e, IAM.PC.DD2 and Cosmosil Cholester) was used to predict the penetration of the blood-brain barrier by 65 newly-synthesized drug-like compounds. The linear free energy relationships (LFERs) model (log BB = c + eE + sS + aA + bB + vV) was established for a training set of 23 congeneric biologically active azole compounds with known experimental log BB (BB = C_blood/C_brain) values (R² = 0.9039). The reliability and predictive potency of the model were confirmed by leave-one-out cross validation as well as leave-50%-out cross validation. Multiple linear regression (MLR) was used to develop the quantitative structure-activity relationships (QSARs) to predict the log BB values of compounds that were tested, taking into account the chromatographic lipophilicity (log k_w), polarizability and topological polar surface area. The excellent statistics of the developed MLR equations (R² > 0.8 for all columns) showed that it is possible to use the HPLC technique and retention data to produce reliable blood-brain barrier permeability models and to predict the log BB values of our pharmaceutically important molecules.

Two novel classes of fused azaisocytosine-containing congeners as promising drug candidates: Design, synthesis as well as in vitro, ex vivo and in silico studies

Searching for new less toxic anticancer drug candidates is a big challenge from a medical point of view. The present investigation was aimed at describing two independent synthetic approaches based on isosteric replacements, spectroscopic characteristics, in vitro anticancer and ex vivo antihaemolytic activities of novel molecules (9-22) and correlations between their standardised lipophilicity indices, computed log P_average values and pharmacokinetic descriptors. Two novel protocols for annelation of the triazinone template on hydrazinylideneimidazolidines (1-8) (showing a high reactivity towards electrophilic reagents, such as ethyl trifluoropyruvate and ethyl 3-methyl-2-oxobutyrate) were developed for the first time, giving rise to two original classes of highly conjugated azaisocytosine-containing molecules (9-16 and 17-22). Both syntheses proceeded under basic conditions to yield the most probable intermediates (e.g. hemiaminals and imines), which in refluxing two-component solvent mixtures or a suitable solvent cyclised through closing the triazinone ring on functionalised imidazolidines in both cases. All fused azaisocytosine-containing congeners were investigated with the purpose of preselecting possible drug candidates with a better selectivity that could be suitable for further more detailed drug development studies. The majority of test molecules revealed strong antiproliferative effects in most tumour cell cultures and they were more cytotoxic against tumour cells than anticancer drug - pemetrexed. These cytotoxicities may be associated with the activation of initiator and executioner caspases (confirmed for compound 12) which are inducers of apoptosis. Simultaneously, three bioisosteres bearing the trifluoromethyl moiety at the C-3 and the ortho substitution at the phenyl ring (10, 12 and 13) proved to be the most promising in terms of selectivity as they were less or equally toxic to normal cells as pemetrexed. It was shown that isosteric replacement of the ethyl group in antitumour active congeners by the trifluoromethyl or isopropyl group was favourable for the selectivity of the designed drug-like molecules. Almost all new compounds revealed the protective effects in an ex vivo model of oxidatively stressed rat erythrocytes (better or comparable than that of ascorbic acid/Trolox), proving that they are safe to red blood cells. The statistically significant and predictive QSAR equations were derived that describe relationships between some pharmacokinetic descriptors (such as log K_{a, HSA}, f_{u, brain}, Caco-2, log K_p) and lipophilicity parameters of test molecules. Among all molecules with anticancer profile, the possible drug candidates seem to be 10, 12, 13, 19 and 21 which are the least toxic for normal cells, deprived of haemolytic effects on oxidatively-stressed red blood cells and have the optimum pharmacokinetic descriptors in terms of their lipophilicity parameters. Because of a high development potential they should be utilised in further more extended in vivo investigations aimed at developing novel less toxic anticancer agents.

Main active constituent identification in Guanxinjing capsule, a traditional Chinese medicine, for the treatment of coronary heart disease complicated with depression

Guanxinjing capsules (GXJCs) are used in traditional Chinese medicine as a common therapy for coronary heart disease (CHD) complicated with depression. In this study, we aimed to identify the main active constituents in GXJCs and to investigate the mechanisms of GXJC action on CHD complicated with depression. The chemical constituent profile of the GXJC was identified by UHPLC-LTQ-Orbitrap assay, and oral bioavailability was evaluated to screen the GXJC drug-like chemical constituents. A total of 16 GXJC drug-like chemical constituents were identified. Then, putative targets of the GXJC drug-like chemical constituents were predicted using MedChem Studio, with 870 genes found to be the putative targets of these molecules. After that, a GXJC putative target-known CHD/depression therapeutic target network was constructed, and four topological features, including degree, betweenness, closeness and K-coreness, were calculated. According to the topological feature values of the GXJC putative targets, 14 main active constituents were identified because their corresponding putative targets had topological importance in the GXJC putative target-known CHD/depression therapeutic target network, which were defined as the candidate targets of GXJC against CHD complicated with depression. Functionally, these candidate targets were significantly involved in several CHD/depression-related pathways, including repairing pathological vascular changes, reducing platelet aggregation and inflammation, and affecting patient depression. This study identified a list of main active constituents of GXJC acting on CHD complicated with depression using an integrative pharmacology-based approach that combined active chemical constituent identification, drug target prediction and network analysis. This method may offer an efficient way to understand the pharmacological mechanisms of traditional Chinese medicine prescriptions.

Screening therapeutics according to their uptake across the blood-brain barrier: A high throughput method based on immobilized artificial membrane liquid chromatography-diode-array-detection coupled to electrospray-time-of-flight mass spectrometry

The Blood-Brain Barrier (BBB) plays an essential role in protecting the brain tissues against possible injurious substances. In the present work, 79 neutral, basic, acidic and amphoteric structurally unrelated analytes were considered and their chromatographic retention coefficients on immobilized artificial membrane (IAM) stationary phase were determined employing a mass spectrometry (MS)-compatible buffer based on ammonium acetate. Their BBB passage predictive strength was evaluated and the statistical models based on IAM indexes and in silico physico-chemical descriptors showed solid statistics (r² (n - 1) = 0.78). The predictive strength of the indexes achieved by the MS-compatible method was comparable to that achieved by employing the more "biomimetic" Dulbecco's phosphate buffered saline, even if some differences in the elution order were observed. The method was transferred to the MS, employing a diode-array-detection coupled to an electrospray ionization source and a time-of-flight analyzer. This setup allowed the simultaneous analysis of up to eight analytes, yielding a remarkable acceleration of the analysis time.

Biologically important hydrazide-containing fused azaisocytosines as antioxidant agents

OBJECTIVES

Two important classes of hydrazide-containing fused azaisocytosines were evaluated as possible antioxidants and characterised by UV spectroscopy.

METHODS

2,2-Diphenyl-1-picrylhydazyl (DPPH), nitric oxide (NO), hydrogen peroxide (H₂O₂) scavenging potencies and reducing power of molecules were evaluated.

RESULTS

The strongest DPPH scavengers were found to be 9, showing the potency superior to that of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) and comparable to that of ascorbic acid (AA), and 6, revealing the antioxidant potency superior to that of BHA, BHT, PG and Trolox. In turn, 3 and 9 were the most promising NO scavengers, exhibiting the potency superior to that of BHA, BHT (3 and 9) and AA (3). The most potent H₂O₂ scavengers proved to be 10 and 9 showing similar or even better neutralising potency than that of Trolox, BHT and BHA. Simultaneously, the majority of hydrazides revealed higher ferric reducing abilities than that of AA and BHT. Some structure-activity relationships were explored. A possible mechanism for the DPPH radical scavenging ability of hydrazide-containing molecules was proposed.

DISCUSSION

Hydrazides 3, 6 and 9 with an antioxidant potential better or comparable to that of the well-known antioxidants are proposed as new antioxidant candidates.

Lipophilicity Evaluation of Some N1-Arylidene-Thiosemicarbazones and 1,3,4-Thiadiazolines with Antimicrobial Activity

A

The lipophilic character of 20 previously reported compounds-derivatives of N 1 -arylidene-thiosemicarbazone (series ) and their corresponding 1,3,4-thiadiazolines (series )-has been determined by reversed-phase thin-layer chromatography, using i -propanol-water mixtures as eluents. Principal component analysis (PCA) allowed an objective estimation of the retention behavior of the tested compounds and also afforded to obtain a 2D scatterplot, described by the first two principal components, which had the effect of separating the compounds from each other most effectively. With the use of clustering methods ( K -means clustering) based on PCA data, the studied compounds were grouped into two congeneric classes. When comparing the obtained lipophilicity parameters' values with the antibacterial properties of the tested compounds, we noticed that the lipophilic character had no significant influence on their growth inhibitory activity.

Synthesis, lipophilicity and antimicrobial activity evaluation of some new thiazolyl-oxadiazolines

BACKGROUND AND AIMS

Synthesis of new potential antimicrobial agents and evaluation of their lipophilicity.

METHODS

Ten new thiazolyl-oxadiazoline derivatives were synthesized and their structures were validated by 1H-NMR and mass spectrometry. The lipophilicity of the compounds was evaluated using the principal component analysis (PCA) method. The necessary data for applying this method were obtained by reverse-phase thin-layer chromatography (RP-TLC). The antimicrobial activities were tested in vitro against four bacterial strains and one fungal strain.

RESULTS

The lipophilicity varied with the structure but could not be correlated with the antimicrobial activity, since this was modest.

CONCLUSIONS

We have synthesized ten new heterocyclic compounds. After their physical and chemical characterization, we determined their lipophilicity and screened their antimicrobial activity.

Structure-retention behaviour of biologically active fused 1,2,4-triazinones--correlation with in silico molecular properties

The chromatographic behaviour and significant lipophilicity/hydrophobicity indices (log k(w), S, φ(0)) are presented for 21 biologically active fused 1,2,4-triazinones based on the linear relationship: log k = log k(w)-Sφ established for the retention on LC-18 HPLC column, using as mobile phases mixtures of three organic modifiers with water. The effect of these mobile phase modifiers on the chromatographic behaviour of solutes was established and the organic modifier of choice is suggested. The complex correlation of slopes versus intercepts obtained for acetonitrile, contrary to linear ones obtained for methanol and dioxane are disclosed. The observed difference in retention mechanism for acetonitrile compared to methanol and dioxane is explained by intermolecular interactions encoded in lipophilicity. Linear correlations with statistically significant levels between log kw values determined from three different chromatographic systems were obtained. The relationships between log k(w) constants (derived from the linear model for methanol-water mobile phases) and predicted log P and log S values by the use of various computational methods were investigated and these were established with high correlation coefficients. The predicted log P values plotted against φ(0 (MeOH)) indices showed the best fit. Principal component analysis was used to compare various lipophilicity parameters of the solutes and their in silico biological descriptors relevant to optimal pharmacokinetics profile. The similarities and dissimilarities between all the variables and molecular structures of solutes are presented. Statistically significant correlations were found between the chromatographic lipophilicity indices and the calculated pharmacokinetic descriptors: fraction unbound in brain (f(u, brain)), oral bioavailability (%F), permeability and intestinal absorption in jejunum (Caco-2), skin permeation (log K(p)) and blood/brain concentration (log BB).

Chemo- and bioinformatics resources for in silico drug discovery from medicinal plants beyond their traditional use: a critical review

An overview of databases andin silicotools for discovery of the hidden therapeutic potential of medicinal plants.