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V Cavrini

Publications and source records attributed to V Cavrini.

At least 37 records · Page 2Linked to original sources
PubMed2001

Chromatographic (GC-MS, HPLC) and virological evaluations of Salvia sclarea infected by BBWV-I.

Salvia sclarea cultivated at the Herb Garden of Casola-Valsenio (Emilia-Romagna region, Italy) has been found for the first time naturally infected by broad bean wilt fabavirus, serotype I (BBWV-I). Symptomatic plants showed malformed leaves, with chlorotic mosaic followed by yellowing and stunting. BBWV-I was identified by applying virological tests: mechanical inoculations on herbaceous plants, electron microscopy, DAS-ELISA and PAS-ELISA. The essential oil obtained from BBWV-infected material corresponded to 2/3 the quantity of that from healthy material. The GC-MS and HPLC analyses of these oils afforded a comparative analytical profile of the two plant materials attributed to BBWV-I infection. The oils from infected materials showed higher percentages of sesquiterpene hydrocarbons (e.g. germacrene D and beta-caryophyllene), monoterpene alcohols (e.g. alpha-terpineol) and diterpenoids (mainly sclareol). In contrast, lower levels of monoterpene hydrocarbons (e.g. myrcene, limonene and the two ocimene isomers) and the principal components (linalyl acetate and linalool) were observed.

Chromatography, High Pressure Liquid↗
PubMed2001

Analysis and enantioresolution of donepezil by capillary electrophoresis.

The analysis of donepezil, a centrally acting acetylcholine esterase inhibitor, is described by a CZE method suitable for applications in pharmaceutical field. A rapid migration of the analyte was obtained under acidic conditions (pH 3.0); with detection wavelength of 320 nm a LOD of 0.8 x 10(-3) mg/ml was provided. Applications on real sample (pharmaceuticals) were carried out using two different instruments with comparable results in terms of reproducibility and accuracy. The use of chiral selectors in the running buffer allowed the enantioseparation of donepezil; charged cyclodextrins (carboxymethyl-beta-cyclodextrin and sulfated-beta-cyclodextrin) were suitable for the chiral resolution of the analyte. Interesting results were also obtained using human serum albumin. The protein-based CE enantioseparation was carried out at pH 7.4 avoiding the partial filling technique due to the good absorptivity of donepezil at 320 nm. Interestingly, the use of bicine as BGE provided a significative improvement in the enantioresolution compared to that obtained by phosphate buffer.

Cholinesterase Inhibitors↗
PubMed2001

Photostability and phototoxicity studies on diltiazem.

The photostability of diltiazem was studied in aqueous solutions at different pH values. Firstly, the hydrolysis of the drug to desacetyldiltiazem in alkaline medium was evaluated and then the drug photodegradation under exposure to UVA-UVB radiation (solar simulator) was monitored by HPLC methods. The main photoproduct was isolated and characterized as diltiazem-S-oxide on the basis of the NMR and mass spectra. The HPLC method was also applied to the selective analysis of diltiazem in commercial formulations. Tests on mutagenicity and photomutagenicity of the drug were also carried out using Salmonella typhimurium TA 102 strain. In this testing the drug neither was mutagenic nor toxic.

Calcium Channel Blockers↗
PubMed2001

Studies on the photostability and in vitro phototoxicity of Labetalol.

The purpose of this study was to obtain information on the photochemical and phototoxic properties of Labetalol, a beta-blocker drug. Preliminary information on the drug photoreactivity was achieved using a flow system with a photochemical reactor on-line with a diode array detection system. Photophysical and photochemical investigations on the drug were performed in aqueous solutions at different pH values using spectrophotometric and fluorimetric methods; the photodegradation quantum yield was found to be 2.7 x 10(-3) at pH 5.8 and 1.5 x 10(-2) at pH 11.5. Forced photodegradation of labetalol solutions under exposure to UVA--UVB radiations (xenon arc lamp) was monitored by reversed-phase liquid chromatography. The main photodegradation products were isolated and characterized by NMR and mass spectrometry; labetalol was found to give 3-amino-1-phenylbutane and salicylamide-4-carboxaldehyde as the main photoproducts. Preliminary phototoxic testings on human keratinocyte cultures were performed evaluating the viability of the cells by the neutral-red uptake assay; mutagenic and photomutagenicity tests were also carried out based on Salmonella typhimurium strains. As a result, labetalol was found to be photolabile,mainly in alkaline medium, but evidences of significant phototoxic and photomutagenic effects by the drug were not observed.

3T3 Cells↗
PubMed2001

Analysis of amphetamine and congeners in illicit samples by liquid chromatography and capillary electrophoresis.

Screening methods based on liquid chromatography (HPLC) and capillary electrophoresis (CE) have been developed for the identification and determination of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and 3,4-methylenedioxyethylamphetamine in illicit tablets. Diethylpropione, (-)-ephedrine, and 3-amino-1-phenylbutane were also included in the study as amphetamino-related compounds. The HPLC-diode-array detection method involved on-line photochemical derivatization to enhance the selectivity of detection allowing amphetamines to be distinguished from related compounds such as diethylpropione (amfepramone). When the CE approach was adopted, two identification parameters (UV spectra and migration index) were used and the enantioresolution of the racemic amphetamines was achieved using hydroxypropyl-beta-cyclodextrin as chiral selector.

Amphetamine↗
PubMed2000

Photostability of drugs: photodegradation of melatonin and its determination in commercial formulations.

The photostability of melatonin, a hormone used as supplementary drug in the alleviation of jet-lag and other sleep disorders, was studied. The drug photodegradation at different pH values was monitored by HPLC methods. The main photoproduct was isolated and characterised on the basis of the NMR, FTIR, and mass spectra. A HPLC method, in combination with a post-column on-line photochemical derivatisation was developed for the selective and reliable quality control of commercially available melatonin containing products.

Chemistry, Pharmaceutical↗
PubMed2000

Analysis and stability study of retinoids in pharmaceuticals by LC with fluorescence detection.

Liquid chromatographic (HPLC) methods with fluorescence detection at different wavelengths were developed for measurements of retinoic acids (13-cis and all-trans) in pharmaceutical dosage forms and components of 'retinoid solution' (all-trans retinoic acid, vitamin A palmitate and beta-carotene), a galenical of 'Di Bella therapy', using reversed phase columns under isocratic conditions. The stability of all-trans retinoic acid in cream and all-trans retinoic acid and vitamin A palmitate in 'retinoid solution' was investigated. Solid-phase extraction (SPE), using C18 sorbent was applied to the analysis of retinoic acids (9-cis, 13-cis and all-trans) in the 'retinoid solution' to obtain a practical and reliable sample clean-up. The results showed that these preparations (cream and solution) can be conveniently stored in the dark (t.a. or 2-8 degrees C): under these conditions about 86-87% of the all-trans retinoic acid initial concentration in both formulations and about 73-78% of vitamin A palmitate in the 'retinoid solution' remained after 90 days, while under sunlight exposure rapid degradation of the drugs was observed.

Chromatography, High Pressure Liquid↗
PubMed2000

SAR of 9-amino-1,2,3,4-tetrahydroacridine-based acetylcholinesterase inhibitors: synthesis, enzyme inhibitory activity, QSAR, and structure-based CoMFA of tacrine analogues.

In this study, we attempted to derive a comprehensive SAR picture for the class of acetylcholinesterase (AChE) inhibitors related to tacrine, a drug currently in use for the treatment of the Alzheimer's disease. To this aim, we synthesized and tested a series of 9-amino-1,2,3,4-tetrahydroacridine derivatives substituted in the positions 6 and 7 of the acridine nucleus and bearing selected groups on the 9-amino function. By means of the Hansch approach, QSAR equations were obtained, quantitatively accounting for both the detrimental steric effect of substituents in position 7 and the favorable electron-attracting effect exerted by substituents in positions 6 and 7 of the 9-amino-1,2,3,4-tetrahydroacridine derivatives. The three-dimensional (3D) properties of the inhibitors were taken into consideration by performing a CoMFA analysis on the series of AChE inhibitors made by 12 9-amino-1,2,3, 4-tetrahydroacridines and 13 11H-indeno[1,2-b]quinolin-10-ylamines previously developed in our laboratory. The alignment of the molecules to be submitted to the CoMFA procedure was carried out by taking advantage of docking models calculated for the interactions of both the unsubstituted 9-amino-1,2,3,4-tetrahydroacridine and 11H-indeno[1,2-b]quinolin-10-ylamine with the target enzyme. A highly significant CoMFA model was obtained using the steric field alone, and the features of such a 3D QSAR model were compared with the classical QSAR equations previously calculated. The two models appeared consistent, the main aspects they had in common being (a) the individuation of the strongly negative contribution of the substituents in position 7 of tacrine and (b) a tentative assignment of the hydrophobic character to the favorable effect exerted by the substituents in position 6. Finally, a new previously unreported tacrine derivative designed on the basis of both the classical and the 3D QSAR equations was synthesized and kinetically evaluated, to test the predictive ability of the QSAR models. The 6-bromo-9-amino-1,2,3,4-tetrahydroacridine was predicted to have a pIC(50) value of 7.31 by the classical QSAR model and 7.40 by the CoMFA model, while its experimental IC(50) value was equal to 0.066 (+/-0.009) microM, corresponding to a pIC(50) of 7.18, showing a reasonable agreement between predicted and observed AChE inhibition data.

Chemical Phenomena↗
PubMed2000

Stereoselective binding of 2,3-substituted 3-hydroxypropionic acids on an immobilised human serum albumin chiral stationary phase: stereochemical characterisation and quantitative structure-retention relationship study.

The binding characteristics of a series of 2,3-substituted 3-hydroxypropionic acids, with anti-inflammatory properties, bearing two chiral centres, were studied by HPLC upon HSA (human serum albumin)-based stationary phase. The compounds were analysed in their stereoisomeric erythro and threo forms and the chromatographic conditions for enantioseparation of the erythro and threo forms were studied on human serum albumin stationary phase. The enantiomer elution order was determined by injection of the enriched samples or by carrying out the CD spectra of each enantiomeric fraction. The absolute configuration of the single enantiomers was assigned on the basis of their CD spectra. A QSRR study was performed by subjecting the chromatographic data of the compounds to multiparameter regression analysis against various molecular descriptors to have insight into the chiral recognition mechanism. The lipophilicity appeared to be the most important parameter in determining the affinity to the protein, the compounds' capacity factors being linearly correlated to the experimental RP-HPLC partition coefficients (log k'w). The enantioselectivity factors (alpha) related to the enantiomers of the erythro and threo forms were studied taking into consideration both the physico-chemical parameters and the conformational behaviour of the compounds.

Chromatography, High Pressure Liquid↗
PubMed2000

Design of experiments for capillary electrophoretic enantioresolution of salbutamol using dermatan sulfate.

Statistical experimental design was used for the optimization and for robustness evaluation of a capillary electrophoretic method developed for the enantioresolution of salbutamol. Dermatan sulfate was used as chiral selector. The goal of the study was to obtain an efficient and fast separation. An eight-run Plackett-Burman matrix was used during the optimization process for the screening of the factors and to adjust the experimental domain under study. Response surface methodology was adopted after the screening phase to obtain information about how the factors percentage of chiral selector, pH and voltage affected the considered responses resolution and analysis time. The Derringer desirability function, which makes it possible to combine results obtained for properties measured on different scales, was used to simultaneously optimize the two responses. Robustness testing was carried out using a Plackett-Burman matrix. The method was found robust as regards the response resolution while voltage and chiral selector were found to be critical factors for the robustness of analysis time response. The proposed CE method permitted the complete enantioseparation of racemic salbutamol and was applied to its chiral resolution in spiked urine samples.

Adrenergic beta-Agonists↗
PubMed2000

HPLC-fluorescence determination of equilin and equilenin in postmenopausal women's urine.

A high-performance liquid chromatographic (HPLC) method with fluorescence detection (lambda(ex) = 280 nm; lambda(em) = 410 and 312 nm) in combination with a post-column on-line photochemical derivatization is described for the determination of equilin and equilenin in urine from normal postmenopausal women after therapy with conjugated oestrogens. The column effluents were subjected on-line to UV irradiation (254 nm) and the photo-induced modifications were useful for the identification of the analytes. The conjugated (sulphate and glucuronide) forms were analysed after enzymatic or chemical hydrolysis and extracted with chloroform. Solid-phase extraction using strong anion-exchange sorbent was applied to the analysis of unconjugated oestrogen fraction to obtain a practical and reliable sample clean-up. The HPLC separations were achieved using ODS columns with a mobile phase consisting of 0.05 M triethylamine phosphate buffer (pH 4.0)-acetonitrile (64:36, v/v) at a flow rate of 1.0 mL/min. The method was accurate and reproducible; for the equilin and equilenin separation isocratic conditions were satisfactory, allowing a sensitive detection in urine samples with a detection limit of about 50 fmol for equilin (lambda(ex) = 280 nm; lambda(em) = 312 nm, after photoderivatization) and 10 fmol for equilenin (lambda(ex) = 280 nm; lambda(em) = 410 nm).

Chromatography, High Pressure Liquid↗
PubMed2000

Reliable assay of extreme enantiomeric purity values by a new circular dichroism based HPLC detection system.

A new sensitive, selective, and versatile circular dichroism (CD)-based HPLC detection system was used for the validation of the enantiomeric purity assay in the quality control of chiral drugs upon nonchiral stationary phases. The precision and the accuracy of the method were checked for selected samples showing values of the anisotropy factor on the order of 10(-1) to 10(-4). Very high accuracy has been obtained also in the case of extreme enantiomeric purity values (</=1% or >/=99% e.p.) and of a low anisotropy factor (g = 2 x 10(-4)) compound. The high selectivity of this detection system allows a selective monitoring of analytes in complex mixtures and makes the baseline stable.

Chromatography, High Pressure Liquid↗
PubMed2000

Analysis of ACE-inhibitors by CE using alkylsulfonic additives.

Capillary electrophoresis (CE) was applied to the determination of angiotensin-converting enzyme (ACE) inhibitors in pharmaceuticals (tablets). Since a free solution CE system failed to reach a complete separation of closely related compounds (lisinopril, ramipril, benazepril, quinapril), alkylsulfonic additives (sodium heptansulfonate and (+)-10-camphorsulphonic acid) were added to the running buffer: improved separations were obtained suggesting a favourable effect of ion-pairing interactions between analytes and additives. The separations were carried out in acidic medium and a systematic investigation of electrophoretic parameters was made to evaluate the performance of the selected additives. Under the optimized conditions, ramipril and benazepril in their commercial dosage forms were determined confirming the applicability of the developed CE approach to the analysis of pharmaceutical samples; the results were also compared with those obtained applying a previously described and validated HPLC method.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Acetylcholinesterase inhibitors for potential use in Alzheimer's disease: molecular modeling, synthesis and kinetic evaluation of 11H-indeno-[1,2-b]-quinolin-10-ylamine derivatives.

Continuing our work on tetracyclic tacrine analogues, we synthesized a series of acetylcholinesterase (AChE) inhibitors of 11H-indeno-[1,2-b]-quinolin-10-ylaminic structure. Selected substituents were placed in synthetically accessible positions of the tetracyclic nucleus, in order to explore the structure-activity relationships (SAR) and the mode of action of this class of anticholinesterases. A molecular modeling investigation of the binding interaction of the lead compound (1a) with the AChE active site was performed, from which it resulted that, despite the rather wide and rigid structure of 1a, there may still be the possibility to introduce some small substituent in some positions of the tetracycle. However, from the examination of the experimental IC50 values, it derived that the indenoquinoline nucleus probably represents the maximum allowable molecular size for rigid compounds binding to AChE. In fact, only a fluorine atom in position 2 maintains the AChE inhibitory potency of the parent compound, and, actually, increases the AChE-selectivity with respect to the butyrylcholinesterase inhibition. By studying the kinetics of AChE inhibition for two representative compounds of the series, it resulted that the lead compound (1a) shows an inhibition of mixed type, binding to both the active and the peripheral sites, while the more sterically hindered analogue 2n seems to interact only at the external binding site of the enzyme. This finding seems particularly important in the context of Alzheimer's disease research in the light of recent observations showing that peripheral AChE inhibitors might decrease the aggregating effects of the enzyme on the beta-amyloid peptide (betaA).

Acetylcholinesterase↗
PubMed1999

Semisynthetic chondroitins as chiral buffer additives in capillary electrophoresis.

Chemically oversulfated galactosaminoglycans with potential as therapeutic agents (inhibitors of human leukocyte elastase) were tested as chiral selectors in capillary electrophoresis of basic racemates. The high anionic character of these compounds provides them with anodic mobility in acidic buffer; using uncoated capillaries, the enantioresolution of racemic basic drugs was obtained at pH 2.5. Dimethindene, chloroquine and chlorpheniramine were enantioresolved applying negative voltage (-15 kV) while the other analytes (propranolol, pindolol, tetrahydrozoline and cloperastine) exhibited catodic migration. The addition of organic solvents to the running buffer was evaluated in order to increase the resolution; methanol provides the best results and in general, baseline separation of the analytes was reached. The studied oversulfated mucopolysaccharide, shows the same ionic character of heparin but presents different stereochemistry and sites of sulfation. A comparison with heparin, used in the same acidic conditions, may underline the role of ionic, spatial and steric features of glycosaminoglycans in the enantiorecognition.

Anions↗
PubMed1999

Analytical study of penicillamine in pharmaceuticals by capillary zone electrophoresis.

The ability of capillary zone electrophoresis in the development of analytical methods devoted to the quality control of the thiol drug penicillamine is shown. Using 50 mM phosphate running buffer (pH 2.5), good quantitations of underivatized penicillamine and its disulfide were achieved; detection at 200 nm allowed checking the presence of the disulfide impurity in pharmaceuticals. The use of 1,1-[ethenylidenebis(sulfonyl)]bis-benzene as a thiol specific reagent resulted in an increased sensitivity for the quantitation of D-penicillamine (limit of detection at 200 nm wavelength was 1.5 microM). Introducing beta-cyclodextrin as chiral selector in the running buffer, enantioseparation of D-L-penicillamine was obtained; for this purpose (+)-camphor-10-sulfonic acid, a chiral ion-pairing reagent, was found to be an essential additive in obtaining a baseline separation. The resulting enantioseparative system was validated in order to evaluate the presence of the toxic L-penicillamine enantiomer in pharmaceutical samples.

Disulfides↗
PubMed1999

Photodegradation studies on Atenolol by liquid chromatography.

The photostability of the beta-blocker drug Atenolol was evaluated at pH 9, 7.4 and 4.0. The drug was exposed to UVA-UVB radiations and the photoproducts were detected by reversed phase LC methods. The photodegradation was found to increase with the pH value decreasing. The major photodegradation product at pH 7.4 was identified as 2-(4-hydroxyphenyl)acetamide. The LC method developed for routine analyses (column: C-18 Alltima; mobile phase: TEA acetate (pH 4; 0.01 M)-acetonitrile 96:4) was found to be suitable for the stability indicating determination of Atenolol in pharmaceutical dosage forms.

Adrenergic beta-Antagonists↗