Márta Kraszni

Complementary fragmentation pattern analysis by gas chromatography-mass spectrometry and liquid chromatography tandem mass spectrometry confirmed the precious lignan content of Cirsium weeds

In this paper, as novelties to the field, it is confirmed at first, that the fruits of Cirsium species, regarded as injurious weeds, do contain lignans, two, different butyrolactone-type glycoside/aglycone pairs: the well known arctiin/arctigenin and the particularly rare tracheloside/trachelogenin species. These experiences were supported by gas chromatography-mass spectrometry (GC-MS), by liquid chromatography tandem mass spectrometry (LC-MS/(MS)) and by nuclear magnetic resonance (NMR) spectroscopy. The study reflects the powerful impact of the complementary chromatographic mass fragmentation evidences resulting in the identification and quantification, the extremely rare, with on line technique not yet identified and described, tracheloside/trachelogenin pair lignans, without authentic standard compounds. Fragmentation pattern analysis of the trimethylsilyl (TMS) derivative of trachelogenin, based on GC-MS, via two different fragmentation pathways confirmed the detailed structure of the trachelogenin molecule. The complementary chromatographic evidences have been unambiguously confirmed, by (1)H and (13)C NMR analysis of trachelogenin, isolated by preparative chromatography. Identification and quantification of the fruit extracts of four Cirsium (C.) species (C. arvense, C. canum, C. oleraceum, and C. palustre), revealed that (i) all four species do accumulate the tracheloside/trachelogenin or the arctiin/arctigenin butyrolactone-type glycoside/aglycone pairs, (ii) the overwhelming part of lignans are present as glycosides (tracheloside 9.1-14.5 mg/g, arctiin 28.6-39.3 mg/g, expressed on dry fruit basis), (iii) their acidic and enzymatic hydrolyses to the corresponding aglycones, to trachelogenin and arctigenin are fast and quantitative and (iv) the many-sided beneficial trachelogenin and arctigenin can be prepared separately, without impurities, excellent for medicinal purposes.

HPCE Analysis of Hydrolysing Morphine Derivatives. Quantitation of Decomposition Rate and Mobility

SummaryHigh performance capillary electrophoretic conditions were optimised on the basis of protonation constants and hydrolysis rate constants (if relevant) of 6 opiate compounds. Protonation constants were determined by pH-potentiometry, the progress of hydrolysis was followed by capillary electrophoresis, hydrolysis rate constants of ester-type compounds were elucidated by kinetic studies of the time- and pH-dependence of the decomposition. Using these physico-chemical parameters, the analysis circumstances were designed to keep thein situ hydrolysis rate negligible for every compound, which has not been the case in reported previous HPCE determinations of acetylated derivatives. Our calculated charge-related mobility differences and experimental CZE findings justified those earlier statements that capillary zone electrophoresis is insufficient to separate these compounds. The method development for diacetylmorphine, 3-acetylmorphine, 6-acetylmorphine, morphine, acetylcodeine and codeine resulted in the use of a micellar elecktrokinetic system operating at pH=8.0, applying 50 mM sodium dodecyl sulfate micelle-forming agent and 7.5% acetonitrile additive in the background electrolyte.

The role of harmonized, gas and liquid chromatography mass spectrometry in the discovery of the neolignan balanophonin in the fruit wall of Cirsium vulgare

In order to identify and quantify fruit-lignans of Cirsium vulgare - authors introduced a special analysis system: with particular attention to the lignans enrichment/separation course. These synchronized, germination and enzymatic hydrolysis processes were followed by complementary gas and liquid chromatography, coupled with special mass selective detections (GC-MS, LC-MS/MS, LC-TOF/MS) and confirmed by nuclear magnetic resonance (NMR) spectroscopy. Mass fragmentations and NMR evidences, proved that the two main medicinal lignan constituents of the fruits of Cirsium vulgare are the neolignan-type, free balanophonin and the butyrolactone-type tracheloside. As novelty to the field, these two lignans of different chemical structures could be quantitatively extracted, separately from each others, without impurities. Balanophonin and tracheloside do accumulate in the fruits of C. vulgare, separately: balanophonin was found, in enormous high concentrations, in the fruit wall (23.2-24.9 mg/g), while in embryo part tracheloside was determined (20.3mg/g), exclusively. Consequently, the optimum source of balanophonin proved to be the fruit wall, while tracheloside, - providing trachelogenin upon enzymatic hydrolysis, - could be obtained from the embryo parts of fruits. As further novelties of the study balanophonin was identified and quantified at the first time with on-line chromatographic technique, in free form, without authentic standard compound.

Concentration and basicity of histamine rotamers

A method was developed and applied to determine the populations and site- and conformer-specific basicities of histamine rotamers in three distinct states of protonation. The method that has been developed also allows the determination of molecule- and position-specific standard gauche and trans1H NMR coupling constants, and the subsequent rotamer analysis from NMR spin systems with a single observed coupling constant, introducing simplifying allowances of symmetry origin. Synthesis and NMR analysis of a reference histamine derivative have also been carried out. The trans rotamers of histamine were found to exist in 41, 38 and 50% in the neutral, monocationic and dicationic forms, respectively, providing quantitative, experimental evidence for the preferential thermodynamic properties of the trans species over the two enantiomeric, statistically favoured g conformers in any ionisation form. Quantification of the rotamer- and site-specific basicities resulted in increased amino and decreased imidazole basicities in the gauche rotamer, indicating the formation of intramolecular hydrogen bonds in the monocationic form.

Interaction of indomethacin and ciprofloxacin in the cornea following phototherapeutic keratectomy.

BackgroundWe report a case in which stromal deposits were produced due to drug interaction in a 61-year-old patient following phototherapeutic keratectomy (PTK).MethodsIn our case, the patient herself added the use of indomethacin eye drops to the prescribed topical antibiotic treatment and eye gel (5× ciprofloxacin plus 3× indomethacin, eye gel overnight) following PTK. At 5 days the central stroma was not reepithelialised; instead, whitish, round deposits were found in the stroma. Mixing indomethacin and ciprofloxacin eye drops 1:1, the pH of the mixture changed to 5.6, and a yellow precipitate was formed; this was analysed by 1H-NMR spectroscopy. To investigate the solubility of the two drugs at the pH of the mixture, the pH of each solution was independently set to 5.6 by addition of hydrochloric acid or sodium hydroxide.ResultsIn the precipitate both indomethacin and ciprofloxacin were detected. After setting the pH to 5.6, a yellow precipitate was observed in the indomethacin solution; however, the ciprofloxacin solution remained clear.ConclusionsInteraction may occur if ciprofloxacin and indomethacin are used together. It is better to avoid the use of the two drugs at the same time, particularly in the case of a large epithelial defect when stromal deposition of the drugs may be produced.

Species-Specific Hydrolysis Kinetics of N-Methylated Heroin Derivatives

The hydroxide-catalyzed hydrolysis of 3,6-diacetylmorphine (heroin) was shown to take place predominantly via its positively charged form. N-Methylated quaternary derivatives of heroin bearing a permanent positive charge were synthesized, and thus, hydrolysis kinetics of these cationic species could be studied over a wide pH range. Specific rate equations were introduced to characterize either the simultaneous or the consecutive decompositions. The kinetic constants determined for the diester are distinctive for the site of hydrolysis. The rate of 6-acetyl-N-methylmorphine was quantified in terms of microscopic kinetic constants of hydrolysis, in which the protonation state of the phenolic OH group had also been taken into account. The site-specific data indicate that the 3-acetoxy moiety is hydrolyzed 6 – 12 times faster than the 6-acetoxy function. The latter, previously ignored minor pathway was shown to represent a non-negligible 10% of the overall decomposition process. Protonation of the 3-O− site accelerates the rate of hydrolysis of the 6-acetoxy moiety by a factor of 4, and replacement of the adjacent OH group by MeO or AcO substituents slows the rate of hydrolysis slightly, presumably due to the increased local hydrophobicity caused by the alkyl or acyl moiety.

Population, basicity and partition of short-lived conformers. Characterization of baclofen and pregabalin, the biaxial, doubly rotating drug molecules

ABSTRACT Populations, protonation constants and octanol‐water partition coefficients were determined and assigned specifically to fast interconverting individual conformers, exemplified in baclofen and pregabalin, the GABA‐related drug molecules of biaxial, double rotations. Rotamer statuses along both axes in water and octanol were elucidated from 1H NMR vicinal coupling constants. Conformer abundances were obtained by the appropriate combination of the rotamer populations in the two adjacent moieties in the molecule. The bulky aromatic group in baclofen versus the aliphatic side chain of pregabalin explains why baclofen exists mainly in trans‐trans conformeric form, throughout the pH range, unlike pregabalin that has no any highly dominant form. Characteristically enough, for pregabalin, the lipophilicity of the conformers is primarily influenced by the conformation state. Conformers in gauche state are of higher lipophilicity. The conformers of the two compounds were ranked by their membrane‐influx and –outflow propensities. Graphical abstract Figure. No Caption available.