Olivera Čudina

17β-carboxamide steroids – in vitro prediction of human skin permeability and retention using PAMPA technique

In this paper, twenty-two 17β-carboxamide steroids were synthesized from five corticosteroids (hydrocortisone, prednisolone, methylprednisolone, dexamethasone and betamethasone) in two steps. The first step was periodic acid oxydation of these corticosteroids to corresponding cortienic acids and the second step was amidation of thus obtained cortienic acids with esterified l-amino acids. These compounds are potential soft corticosteroids with local anti-inflammatory activity in the skin. Parallel artificial membrane permeability assay (PAMPA) was applied in order to predict permeability and retention of these compounds in human skin. Comparison of permeability and retention parameters between 17β-carboxamide steroids and corresponding corticosteroids was performed. Compounds with significantly higher retention were identified and the derivative that does not have significantly higher permeability was underlined. Molecular structures of all compounds were optimized by use of Gaussian semiempirical/PM3 method. Geometrical, thermodynamic, physicochemical and electronical molecular parameters of the optimized structures were calculated and quantitative structure-property relationship (QSPR) analysis was performed in order to explain permeability and retention of these compounds. ANN-, PLS- and MLR-QSPR models were created. Quality of these models was evaluated by commonly used statistical parameters and the most reliable models were selected. Analyzing descriptors in the selected models, main molecular properties that influence permeability and retention in the PAMPA artificial membrane were identified. Based on these data, further structural modifications could be applied in order to increase retention without significant increase of permeability, which can positively affect potential local anti-inflammatory activity of these compounds. Selected QSPR models could be used as in silico tool for predicting human skin permeability and retention of novel 17β-carboxamide steroids without performing PAMPA experiments.

Quantitative analysis of cyproterone acetate and ethinylestradiol in tablets by use of planar chromatography

This paper describes a simple, rapid, and reliable HPTLC procedure for the determination of cyproterone acetate and ethinylestradiol in tablets. Identification and determination were performed on 10 cm × 20 cm LiChrospher silica gel 60 F254 HPTLC plates with cyclohexane—ethyl acetate, 6 + 4 (v/v), as mobile phase. Calibration plots were established showing the dependence of response (peak area) on amount chromatographed. The ranges validated were 250–4000 ng (r = 0.9923) and 100–500 ng (r = 0.9996) for cyproterone acetate and ethinylestradiol, respectively. The suitability of this HPTLC method for quantitative determination of the compounds was proved by validation of precision and accuracy. The method was used for determination of the compounds in commercial pharmaceutical dosage forms (Androcur 10 mg and Diane 35 tablets). The method is simple, reproducible, and accurate and can be used as a more effective option than other chromatographic techniques in routine quality control.

A PAMPA Assay as Fast Predictive Model of Passive Human Skin Permeability of New Synthesized Corticosteroid C-21 Esters

The permeation properties of twenty newly synthesized α-alkoxyalkanoyl and α-aryloxyalkanoyl C-21 esters of standard corticosteroids: Fluocinolone acetonide, dexamethasone, triamcinolone acetonide and hydrocortisone were established using a PAMPA assay (70% silicone oil and 30% isopropyl myristate). The data were compared with parent corticosteroids with addition of mometasone furoate and hydrocortisone acetate. All newly synthesized corticosteroid C-21 esters have effective permeability coefficients higher then -6, mostly followed with high values of retention factors and low permeation. The examined compounds were grouped through relationship between obtained retention factors and permeation parameters (groups I–III). The classification confirmed group I (membrane retentions as well as permeation lower then 30%) for all corticosteroid standards except mometasone furoate, a potent topical corticosteroid which, with high membrane retention (81%) and low permeation (7.7%) fits into group III. The largest number of new synthesized corticosteroids C-21 esters, among them all fluocinolone acetonide C-21 esters, have high membrane retentions (32.4%–86.5%) and low permeations (1.3%–27.1%), fitting in group III. The classification was related to previously obtained anti-inflammatory activity data for the fluocinolone acetonide C-21 esters series. According to the PAMPA results the new synthesized esters could be considered as potential new prodrugs with useful benefit/risk ratio.

Biopartitioning micellar chromatography as a predictive tool for skin and corneal permeability of newly synthesized 17β-carboxamide steroids

In this paper, human skin and corneal permeability of twenty-two newly synthesized 17β-carboxamide steroids was predicted using biopartitioning micellar chromatography (BMC). These compounds are potential soft glucocorticoids with local anti-inflammatory activity when applied to the skin or eye. BMC systems are used to simulate physicochemical properties of human skin (BMC-skin) and cornea (BMC-cornea). Micellar mobile phase, consisted of 0.04 M solution of polyoxyethylene (23) lauryl ether (Brij 35), was prepared at different pH values - 5.50 (BMC-skin) and 7.50 (BMC-cornea). Retention factors (k), obtained by use of BMC, were calculated for all newly synthesized 17β-carboxamide steroids as well as for parent glucocorticoids (hydrocortisone, prednisolone, methylprednisolone, dexamethasone and betamethasone). Good correlation was obtained between BMC-skin retention factors and permeability coefficients calculated by use of the artificial membrane that simulates stratum corneum of the human skin. Quantitative structure-retention relationship (QSRR) study was performed in order to explain retention factors of these compounds in the tested BMC systems. ANN-QSRR(k), PLS-QSRR(k) and MLR-QSRR(k) models, created by use of BMC-skin retention data, were compared and optimal model (PLS-QSRR(k)) was selected. Molecular descriptors of the selected model indicate that lipophilicity and number of short C-C fragments of tested compounds have the strongest influence on the retention in the BMC-skin system and presumably on their in vivo permeability through human skin. The same model can be applied to the BMC-cornea system and the same conclusion can be drawn for corneal permeability. This model could be used as a predictive tool for the synthesis of novel 17β-carboxamide steroids with desirable permeability through human skin or cornea, depending on their potential pharmacological application.

Phenylpropiophenone derivatives as potential anticancer agents: synthesis, biological evaluation and quantitative structure-activity relationship study.

Series of twelve chalcone and propafenone derivatives has been synthesized and evaluated for anticancer activities against HeLa, Fem-X, PC-3, MCF-7, LS174 and K562 cell lines. The 2D-QSAR and 3D-QSAR studies were performed for all compounds with cytotoxic activities against each cancer cell line. Partial least squares (PLS) regression has been applied for selection of the most relevant molecular descriptors and QSAR models building. Predictive potentials of the created 2D-QSAR and 3D-QSAR models for each cell line were compared, by use of leave-one-out cross-validation and external validation, and optimal QSAR models for each cancer cell line were selected. The QSAR studies have selected the most significant molecular descriptors and pharmacophores of the chalcone and propafenone derivatives and proposed structures of novel chalcone and propafenone derivatives with enhanced anticancer activity on the HeLa, Fem-X, PC-3, MCF-7, LS174 and K562 cells.

An application of second-order UV-derivative spectrophotometry for study of solvolysis of a novel fluocinolone acetonide ester.

A novel topical corticosteroid FA-21-PhP, 2-phenoxypropionate ester of fluocinolone acetonide, has been synthesized in order to investigate the possibility of decreasing systemic side effects. In this study model system for in vitro solvolytic reaction of FA-21-PhP has been analyzed in ethanol/water (90:10, v/v) with excess of sodium hydrogen carbonate. The selected conditions have been used as in vitro model for activation of corticosteroid C-21 ester prodrug. The second-order derivative spectrophotometric method (DS) using zero-crossing technique was developed for monitoring ternary mixture of solvolysis. Fluocinolone acetonide (FA) as a solvolyte was determined in the mixture in the concentration range 0.062-0.312 mM using amplitude (2)D(274.96). Experimentally determined LOD value was 0.0295 mM. The accuracy of proposed DS method was confirmed with HPLC referent method. Peak area of parent ester FA-21-PhP was used for solvolysis monitoring to ensure the initial stage of changes. Linear relationship in HPLC assay for parent ester was obtained in the concentration range 0.054-0.54 mM, with experimentally determined LOD value of 0.0041 mM. Investigated solvolytic reaction in the presence of excess of NaHCO(3) proceeded via a pseudo-first-order kinetic with significant correlation coefficients 0.9891 and 0.9997 for DS and HPLC, respectively. The values of solvolysis rate constant calculated according to DS and HPLC methods are in good accordance 0.038 and 0.043 h(-1), respectively.

Investigation of Solvolysis Kinetics of New Synthesized Fluocinolone Acetonide C-21 Esters—An In Vitro Model for Prodrug Activation

In this study the solvolysis of newly synthesized fluocinolone acetonide C-21 esters was analysed in comparison with fluocinonide during a 24-hour period of time. The solvolysis was performed in an ethanol-water (90:10 v/v) mixture using the excess of NaHCO3. The solvolytic mixtures of each investigated ester have been assayed by a RP-HPLC method using isocratic elution with methanol-water (75:25 v/v); flow rate 1 mL/min; detection at 238 nm; temperature 25 °C. Solvolytic rate constants were calculated from the obtained data. Geometry optimizations and charges calculations were carried out by Gaussian W03 software. A good correlation (R = 0.9924) was obtained between solvolytic rate constants and the polarity of the C-O2 bond of those esters. The established relation between solvolytic rate constant (K) and lipophilicity (cLogP) with experimental anti-inflammatory activity could be indicative for topical corticosteroid prodrug activation.

Spectrophotometric Determination of Fluorometholone in Pharmaceuticals Using 1,4-Dihydrazinophthalazine

Abstract A sensitive and simple spectrophotometric method for the determination of fluorometholone in pharmaceutical formulations using 1,4-dihydrazinophthalazine (1,4-DHPHT; dihydralazine) as the reagent is presented. The yellow coloured dihydralazinohydrazone of fluorometholone was obtained, after heating at 85 °C for 2 hrs in acidified 1-propanol as a solvent. The prepared dihydralazinophthalazone shows a maximum at 380 nm with molar absorptivity of 1.91x104 lmol−1 cm−1. Beers law is obeyed up to 12 μg/ml of fluorometholone. The method applied for the determination of fluorometholone in pharmaceutical formulations gave precise and reproducible results; recoveries were 97.43% (RSD=2.67%) and 98.25% (RSD=2.56%) for ointment and suppositories, respectively.

Design, Synthesis, and Local Anti‐Inflammatory Activity of 17β‐Carboxamide Derivatives of Glucocorticoids

Molecular docking studies were performed on 18 17β‐carboxamide steroids in order to select compounds with potential local anti‐inflammatory activity. These derivatives are amides of cortienic acids (obtained from hydrocortisone, prednisolone, and methylprednisolone) with methyl or ethyl esters of six amino acids. Interactions with the glucocorticoid receptor (GR), binding energies and ligand efficiency values of these compounds were compared with dexamethasone and cortienic acid obtained from prednisolone (inactive metabolite). On the basis of molecular docking studies, seven compounds were selected and their binding affinities for the GR were predicted by use of the exponential model created in this study. Subsequently, selected compounds were synthesized in good yields by use of modified N,N′‐dicyclohexylcarbodiimide (DCC)/1‐hydroxybenzotriazole (HOBt) coupling procedure. Finally, the local anti‐inflammatory activity of the synthesized compounds was examined by use of the croton oil‐induced ear edema test. In vivo evaluation of systemic side effects as well as in silico prediction of metabolism were performed on the derivative with the best local anti‐inflammatory activity. The combination of molecular docking studies and the exponential model for the GR binding affinity prediction could be used as an in silico tool for the rational design of novel 17β‐carboxamide steroids with potentially better biological profile than dexamethasone.

Biopartitioning Micellar Chromatography-Partition Coefficient Micelle/Water as a Potential Descriptor for Hydrophobicity in Prediction of Oral Drug Absorption

Biopartitioning micellar chromatography (BMC), which is useful to mimic the drug partitioning process in biological systems, was used as a method for determination of partition coefficients micelle/water (P m/w ) of a set of structurally diverse drugs. BMC is a chromatographic system consisting of polyoxyethylene (23) lauryl ether (Brij 35) micellar mobile phase prepared in physiological conditions and C18 reversed stationary phase. The retention factors were determined for all selected and studied compounds and a correlation between P m/w and oral drug absorption values were obtained. In order to study the similarity between the BMC system and other natural systems of biomembranes, the retention data on BMC were compared with permeability data obtained in Parallel artificial membrane permeation assays (PAMPA lipid model). Molecular descriptors that are believed to influence transcellular transport and oral drug absorption have been calculated in order to obtain a predictive and reliable model for drug permeability. Results presented in this paper indicate that a proposed descriptor for hydrophobicity P m/w , provided, from a statistical point of view, is a better model than other hydrophobicity descriptors.