P. Roveri

Use of 4-(6-methylnaphthalen-2-yl)-4-oxobut-2-enoic acid as a reagent for the spectrophotometric and fluorimetric determination of aliphatic thiol drugs

The aroylacrylic acid 4-(6-methylnaphthalen-2-yl)-4-oxobut-2-enoic acid is proposed as a useful reagent for the spectrophotometric and fluorimetric determination of aliphatic thiol compounds. Under mild reaction conditions (pH 7.4, room temperature) the compound reacts rapidly (reaction complete in 15 min) and selectively with thiol compounds to give stable fluorescent thiol adducts. The adducts can be determined in the presence of the reagent excess by spectrophotometric (conventional and second- or third-derivative procedures) and fluorimetric (λem.= 445 nm, λex.= 300 nm) methods. All the described procedures have been successfully applied to the determination of thiol drugs such as N-acetylcysteine, mercaptopropionylglycine and captopril in commerical dosage forms.

High-performance liquid chromatographic determination of aliphatic thiols with aroylacrylic acids as fluorogenic percolumn derivatization reagents

Abstract The use of the methyl ester of 4-(6-methoxynaphthalen-2-yl)-4-oxo-2-butenoic acid as a fluorogenic labelling regent for the high-performance liquid chromatography (HPLC) of biologically important thiols (glutathione, cysteine, acetylcysteine, homocysteine, cysteamine, sodium 2-mercaptoethanesulphonate and thiola) was investigated. The compound reacts selectively and rapidly (10 min at ambient temperature and pH 7.5) with the thiols to give fluorescent adducts that can be separated by reversed-phase HPLC and detected fluororimetrically (λem = 450 nm; λem = 310 nm). Applications to the determination of l -cysteine and mesna in pharmaceutical formulations are described.

2-Bromoacetyl-6-methoxynaphthalene : a useful fluorescent labelling reagent for HPLC analysis of carboxylic acids

SummaryThe use of 2-bromoacetyl-6-methoxynaphthalene as a fluorogenic labelling reagent in pre-column derivatization for the HPLC separation of biologically active carboxylic acids (fatty acids and bile acids) has been investigated. The compound reacts (30 min. at 70°C) with carboxylic acids to give fluorescent esters that can be separated by reversedphase HPLC and detected at λ ex. 300 nm, λ em. 460 nm. The experimental conditions for the derivatization and chromatographic separation are discussed. Applications to the determination of valproic acid and chenodeoxycholic acid in pharmaceutical formulations are described.

GC-MS analysis of incenses for possible presence of allergenic nitromusks.

A Gas chromatographic method with mass detector was developed to identify and determine nitromusks in incense sticks of different origin (India, China, Tibet). The proposed method was found useful to correlate dermatological allergic reactions with the use and composition of commercial incense sticks. The incense sticks were powdered, extracted with methanol and after the addition of 1-eicosanol as internal standard, injected into the GC-MS, using 25 m bonded phase fused capillary column methyl, 5% phenyl silicone (0.32 mm I.D., 0.25 microns film thickness). Musk ambrette was identified and determined in one kind of chinese incense together with musk ketone and musk xylene. The latter compound was also found alone in another kind of chinese incense.

HPLC-fluorescence determination of bile acids in pharmaceuticals and bile after derivatization with 2-bromoacetyl-6-methoxynaphthalene.

2-Bromoacetyl-6-methoxynaphthalene was used as a pre-chromatographic fluorescent labelling reagent for the high-performance liquid chromatographic (HPLC) analysis of bile acids. The derivatization reaction was performed in an aqueous medium in the presence of tetrahexylammonium bromide by ultrasonication at 40 degrees C to give fluorescent esters which were separated by reversed-phase HPLC and detected fluorimetrically (lambda ex = 300 nm, lambda em = 460 nm). Applications to the determination of ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) in their pharmaceutical formulations are described. The method was also applied to the determination of free and conjugated bile acids in human bile samples.

Analysis of Semipermanent Hair Dyes by HPLC with On-Line Post-Column Photochemical Derivatisation

SummaryThe development of a selective and sensitive HPLC method for the determination of semipermanent hair colorants in cosmetic formulations is proposed. The separation and identification of N-hydroxyalkyl nitrophenylenediamines and nitroaminophenols were performed by HPLC with on-line, post-column, photochemical derivatisation, using a reversed phase, ion-pair system with 1,8-diaminooctane and heptansulfonate in the mobile phase. Two UV spectra (photoreactor on and off) were obtained for each analyte, adding information for confirming peak identity. Analyte-modified spectral properties were used to increase the method sensitivity. The proposed method was successfully applied to quality control and stability studies of cosmetic formulations.

HPLC-fluorescence determination of chlorocresol and chloroxylenol in pharmaceuticals

The use of 2-chloro-6,7-dimethoxy-3-quinolinecarboxaldehyde as a fluorogenic labelling reagent in pre-column derivatization for the HPLC separation of chlorophenols has been investigated. The compound reacts (50 min at 110 degrees C) with 2- and 4-chlorophenols to give fluorescent ethers that can be separated by reversed-phase HPLC and detected at lambda exc = 360 nm, lambda em = 500 nm. The experimental conditions for derivatization and chromatographic separation are discussed. Applications for the determination of chlorocresol (4-chloro-3-cresol) and chloroxylenol (4-chloro-3,5-xylenol) in pharmaceutical formulations (creams, ointments) are described.

Analysis of thiols by HPLC after fluorescent prelabelling with 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid

SummaryThe use of 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid as a fluorogenic reagent in pre-column derivatization for the high-performance liquid chromatography (HPLC) of biologically important thiols (L-cysteine, glutathione, N-acetylcysteine, homocysteine and mercaptopropionylglycine) was investigated. The aroylacrylic acid reacts selectively and rapidly (15 min. at room temperature) with the thiol compounds to give stable fluorescent adducts which can be separated by reversedphase HPLC and detected fluorometrically (λex 300nm); λem 445nm). The experimental conditions for the thiol derivatization and chromatographic separation are discussed. Applications to the determination of N-acetylcysteine, mercaptopropionylglycine and cysteine are described.

Thin-Layer Chromatography of Aliphatic Thiols After Fluorescent Labelling with Methyl 4-(6-Methoxynaphthalen-2-yl)-4-oxo-2-butenoate

Abstract Aliphatic thiols of biopharmaceutical (cysteine N-acetylcysteine, homocysteine, captopril, glutathione, mercaptop ropionylglycine) and cosmetic (thioglycolic acid monothioglycerol, ammonium thiolactate) interest react under-mild reaction conditions (10 min at room temperature) with methyl 4-(6-methoxynaphthalen-2-yl)-4-oxo-2-butenoate to give fluorescent adducts which can be separated on TLC silica gel plates. The fluorescent spots are visualized on irradiation at 254 and 366 nm.

[Synthesis of 2-methoxynaphthalene derivatives as potential anti-inflammatory agents].

Compounds having 2-methoxynaphthalene as their parent nucleus were synthesized and evaluated for antiinflammatory effect according to the carrageenin paw edema method in rats. The synthetic routes for the preparation of isomeric 1,2- and 2,6-disubstituted derivatives are described. Replacement of the alpha-methylacetic moiety in naproxen by 4-hydroxybutyric acid side chain did not cause loss of activity.