Ivo M. Hais

High-performance liquid chromatographic assay for the separation and characterization of metabolites of the potential cytostatic drug oracine

Oracine (I), a potential cytostatic drug, is enzymically converted to a number of metabolites whose formation has been studied in vitro and in vivo. The metabolites were separated by reversed-phase HPLC and characterized by UV spectra. Preparative TLC served for the isolation of the individual metabolites to allow their identification. Two metabolites were identified by Fourier transform NMR as 11-dihydrooracine (II) and a phenolic product (III). Two further metabolites (IV,V) were characterized. Some minor, presumably 11-dihydro metabolites and an 11-oxo metabolite produced in vitro and in vivo were revealed.

Chromatographic characterization of in vitro metabolites of 5-[2-(N,N-dimethylamino)ethoxy]-7-oxo-7H-benzo-[c]fluorene

Detection reactions and RF values in thin-layer chromatography on silica gel were studied for the antineoplastic drug Ih (benfluron) and related substances. On incubation of Ih with homogenate fractions of mammalian livers the N-oxide Ii and 5-[2-(N,N-dimethylamino)ethoxy]-7-hydroxy-7 H-benzo[c]fluorene (IIh) were established as products, and 5-[2-(N-methylamino)ethoxy]-7-oxo-7 H-benzo[c]fluorene (Ig), 5-[2-(N-methylamino)ethoxy]-7-hydroxy-7 H-benzo[c]fluorene (IIg) and a phenolic product of benfluron (IV) were tentatively identified.

Preliminary thin-layer chromatographic characterization of the rat harderian gland lipid

Abstract The lipid of the Harderian gland, which incorporates a considerable proportion of I-14C-labelled acetate which had been injected into rats (and mice) could not be resolved from the main lipid fraction of the gland by TLC, either before or after saponification. The main lipid and acetate-incorporating fraction agrees in its chromatographic behaviour with the sterol ester band. About 83% of the radioactivity of the lipid extract from the Hardernia gland (24 h after the application of I-14C-acetate) was found in this band. small amounts of free cholesterol were found in the Harderian gland extract. The cholesterol band was not appreciably labelled The main lipid of the unsaponifiable matter of the Harderian gland (about 99% of the radioactivity of this fraction 24 h after 14C-acetate injection) travels in hexane—ethyl acetate (80:20) and chloroform—diethyl ether—acetic acid at a rate slightly below that of dihydrolanosterol. On a AgNO3-impregnated layer it is retarded, with respect to dihydroloanosterol, and more so than lanosterol. The unsaponifiable material gives a dull yellow colour and whitish yellow fluoroscence with the SbCl3—acetic anhydride reagent.

Paper partition chromatography of riboflavin decomposition products. The action of some reducing and oxidizing agents on riboflavin solutions

Abstract The influence of some reducing and oxidizing agents on riboflavin solutions was studied, both in the dark and after irradiation. Sodium sulfite and sodium thiosulfate (except sodium thiosulfate in a neutral medium) seem to protect riboflavin against photolytic decomposition. Riboflavin is attacked by permanganate. The products formed resembed those formed on photolysis. The formation of 27 CX seems to be favored. With hydrogen peroxide, a 54 KI spot and a series of 15–25 spots, with a yellow or bluish-purple fluorscence, are formed. The formation of 27 CX and lumiflavin by alkaline photolysis is inhibited by the presence of hydrogen peroxide.

Separation of E-Z isomeric macrocyclic spermine alkakoids of Verbascum pseudonobile and Verbascum phoeniceum and of their derivatives using thin-layer chromatography

Twelve E-Z isomeric pairs of Verbascum pseudonobile Stoj. et Stef. and Verbascum phoeniceum L. (Scrophulariaceae) macrocyclic spermine alkaloids and of related compounds and six related dihydro derivatives were studied by TLC on silica in nine systems and on alumina in four systems. In most cases the Z isomers exhibited higher retention than their E counterparts. Four E-Z isomeric pairs of cinnamic acid amides were studied for comparison.

Elimination of Benfluron and its Metabolites in the Faeces and Urine of Rats

The study of the biotransformation of the potential cytostatic benfluron has been continued. The elimination of benfluron and of nine of its metabolites whose structure had been established, mainly on the basis of the comparison of their IR, MS and NMR spectra with those of standards, was studied. After oral administration of 500 mg.kg-1 to rats, the amounts of these substances in the faeces and urine were followed up by high-performance liquid chromatography for five days. Striking qualitative and quantitative differences were observed in the elimination of benfluron and its metabolites by both routes.

Diagonal techniques : Introductory remarks

Abstract Diagonal techniques (flat-bed two-dimensional chromatography or electrophoresis with a physical or chemical treatment between the first and second dimensions) were discussed, and their applicability was illustrated by examples. These techniques can be used for the detection of chromatographic artifacts, for better resolution of the components of the sample, and for specific characterization and establishment of “genetic sequences” among the products of complicated reactions.

Factors which influence paper chromatographic RF values : Introductory remarks

Abstract As an introduction to the discussion on the reproducibility of spot positions in paper chromatography, attention is drawn to the role of paper, the volume and composition of solvents (eluents and stationary phases), the atmosphere of the tank (the problems of conditioning and temperature control), development procedures, and additional components of the sample. Correction of the experimental data by means of reference substances and RM calculations is also mentioned.

Tswett's letters to Claparède

The letters written by M. S. Tswett to E. Claparede are presented, both in the original French and in an English translation.

Evaluation of photometric high-performance liquid chromatographic data for the determination of benflurone metabolites in biological materials with and without concomitant use of a standard.

The results produced by a new method of calculation based on the knowledge of the absorption coefficient and instrumental parameters without the concomitant use of a standard were compared with those calculated by the routine external standard method for a model system utilizing the quantification of benzofluorene derivatives. These were present in the incubation mixture of 5-[2-(dimethylamino)ethoxy]-7-oxo-7H-benzo[c]fluorene (benflurone) with the microsomal fraction of rat liver homogenate. Reasonable agreement between the two methods was observed. The potential utility of the new method of calculation is discussed.