Tandem mass spectrometric study of annelation isomers of the novel thieno[3',2':4,5]pyrido[2,3-d]pyridazine ring system

In the present communication, we describe tandem combinations of Suzuki - condensation ring closure reactions to obtain a novel thieno[3 -,2 -:4,5]pyrido[2,3-d]pyridazine ring system. These compounds were studied by tandem mass spectrometry in detail and characteristic fragmentations were observed, which can be useful to confirm the presence of N -substituted pyridazine ring in synthesized compounds. © ARKAT-USA,Inc

Development of oral site-specific pellets containing flavonoid extract with antioxidant activity

Abstract Herbal medicines are recognized as an effective treatment of common diseases, mainly associated with oxidative stress. Therefore developing drug delivery systems of these biological active ingredients are gaining interest. Parsley (Petroselinum crispum L.) is a well-known culinary herb and its leaf contains high amount of apigenin, therefore it is suitable as a natural source of this flavonoid. Apigenin possess many health effects such as antioxidant, anti-inflammatory and anticancer activities. Unfortunately, these benefits are limited due to the low water solubility and bioavailability, it was recently classified as BCS II group compound. Therefore the aim of this study was to develop a carrier system for Petroselinum crispum extract, containing high amount of apigenin. Microcrystalline cellulose inert pellet cores were chosen and enteric coatings were applied. The produced multiparticulates had spherical shape, narrow size distribution and low moisture content. 10% (w/w) Eudragit® L 30 D-55 and 15% (w/w) Eudragit® FS 30 D coating was adequate for the modified release in vitro. The layered pellets demonstrated antioxidant activity. It was concluded that development of oral site-specific pellets containing flavonoid extract successful and the therapeutic effectiveness could be hypothesized

Synthesis, characterisation and systematic comparison of FITC-labelled GnRH-I, -II and -III analogues on various tumour cells

Targeted tumour therapy is in the focus of recent cancer research. GnRH analogues are able to deliver anticancer agents selectively into tumour cells which highly express GnRH receptors. However, the effectiveness of different analogues as targeting moiety in drug delivery systems is rarely compared and the investigated types of cancers are also limited. Therefore, we prepared selectively labelled, fluorescent derivatives of GnRH-I, -II, and -III analogues which successfully used for drug targeting. In this manuscript we investigated these analogues solubility, stability, passive membrane permeability and compared their cellular uptake by various cancer cells. We found that these labelled GnRH conjugates provide great detectability, without undesired cytotoxicity and passive membrane permeability. The introduced experiments with these conjugates proved their reliable tracking, quantification and comparison. Cellular uptake efficiency was studied on human breast, colon, pancreas and prostate cancer cells (MCF-7, HT-29, BxPC-3, LNCaP) and on dog kidney cells (MDCK). Each of the three conjugates were taken up by GnRH-I receptor expressing cells, but the different cells preferred different analogues. Furthermore, we demonstrated for the first time the high cell surface expression of GnRH-I receptors and the effective cellular uptake of GnRH analogues on human pharynx tumour (Detroit-562) cells. In summary, our presented results detail that the introduced conjugates could be innovative tools for the examination of the GnRH based drug delivery systems on various cells and offer novel information about these peptides

Quantitative comparison of tandem mass spectra obtained on various instruments

The similarity between two tandem mass spectra, which were measured on different instruments, was compared quantitatively using the similarity index (SI); defined as the dot product of the square root of peak intensities in the respective spectra. This function was found to be useful for comparing energy dependent tandem mass spectra obtained on various instruments. Spectral comparisons show the similarity index in a 2D “heat map”; indicating which collision energy combinations result in similar spectra; and how good this agreement is. The results and methodology can be used in the pharma industry to design experiments and equipment well suited for good reproducibility. We suggest that to get good long term reproducibility, it is best to adjust the collision energy to yield a spectrum very similar to a reference spectrum. It is likely to yield better results than using the same tuning file, which e.g. does not take into account that contamination of the ion source due to extended use may influence instrument tuning. The methodology may be used to characterize energy dependence on various instrument types; to optimize instrumentation; and to study the influence or correlation between various experimental parameters

Optimization and Development of Albumin–Biopolymer Bioconjugates with Solubility-Improving Properties

Bioconjugation is an emerging field in the food and pharmaceutical industry. Due to its biocompatibility and high ligand binding capacity, albumin is widely used in modern drug delivery systems. However, the protein is sensitive to environmental stresses; albumin conjugates, on the other hand, have improved functional properties. Biopolymers are gaining interest due to their biodegradability and safety, compared to synthetic polymers. In this study, albumin–biopolymer bioconjugates were prepared by nonenzymatic Maillard reaction at 60 °C and 80% relative humidity. This nonenzymatic conjugation takes place between reducing sugars and available amino groups of a protein in certain conditions. The optimal molar ratio and time for the conjugation were studied by several investigation methods, including circular dichroism and fluorescence spectroscopy, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), and determination of available amino groups with ortho-phthaldialdehyde (OPA) assay. All of the measurements provided evidence for the covalent bonding of albumin and biopolymers, resulting in bioconjugates. Based on the results, a higher molar ratio and longer time are necessary to complete the reaction with the available amino groups. However, the optimal parameters are specific to each given biopolymer. The rheological behavior of the conjugates is characteristic of the initial biopolymer, which can be useful in drug development. Moreover, both the physical characteristics of albumin and the solubility-improving capacity were enhanced. Therefore, the potential use of albumin–biopolymer bioconjugates in the pharmaceutical industry could be considered

Exposure to Batrachochytrium dendrobatidis affects chemical defences in two anuran amphibians, Rana dalmatina and Bufo bufo

BACKGROUND: Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis, one of the major causes of worldwide amphibian biodiversity loss. Many amphibians exhibit skin-based chemical defences, which may play an important role against invading pathogens, but whether the synthesis of these chemical compounds is enhanced or suppressed in the presence of pathogens is largely unknown. Here we investigated direct and indirect effects of larval exposure to the globally distributed and highly virulent Bd-GPL strain on skin secreted chemical defences and life history traits during early ontogeny of agile frogs (Rana dalmatina) and common toads (Bufo bufo). RESULTS: Exposure to Bd during the larval stage did not result in enhanced synthesis of the antimicrobial peptide Brevinin-1 Da in R. dalmatina tadpoles or in increased production of bufadienolides in B. bufo tadpoles. However, exposure to Bd during the larval stage had a carry-over effect reaching beyond metamorphosis: both R. dalmatina and B. bufo froglets contained smaller quantities of defensive chemicals than their Bd-naïve conspecifics in the control treatment. Prevalence of Bd and infection intensities were very low in both larvae and metamorphs of R. dalmatina, while in B. bufo we observed high Bd prevalence and infection intensities, especially in metamorphs. At the same time, we did not find a significant effect of Bd-exposure on body mass or development rate in larvae or metamorphs in either species. CONCLUSIONS: The lack of detrimental effect of Bd-exposure on life history traits, even parallel with high infection intensities in the case of B. bufo individuals, is surprising and suggests high tolerance of local populations of these two species against Bd. However, the lowered quantity of defensive chemicals may compromise antimicrobial and antipredatory defences of froglets, which may ultimately contribute to population declines also in the absence of conspicuous mass-mortality events

Foszforheterociklusok szintézise és hasznosítása = The synthesis and use of phosporus heterocycles

A kutatás három fő szálon futott, egyrészt az 5- és 6-tagú, másrészt a 7- és 8-tagú - ez utóbbi esetben áthidalt - P-heterociklusok területén, harmadrészt egy inverz Wittig-típusú reakció témájában. Újfajta foszfol- és a 3-as helyzetben foszforfunkciót tartalmazó 1,2,3,6-tetra- és 1,2,3,4,5,6-hexahidrofoszfinin P-ligandokat (ill. ez utóbbiak prekurzorait) tettük hozzáférhetővé, amelyeket átmeneti fémkomplexekké is átalakítottunk. A P-ligandok és a komplexek térszerkezetét felderítettük és ez utóbbiak egy részét katalizátorként is kipróbáltuk. Jónéhány dibenzooxafoszforint - közöttük optikai aktivitással rendelkező származékokat is - előállítottunk. A ligandok platina-komplexeit is elkészítettük. A kutatás másik vonalán új 7-foszfanorbornén, ill. 2-foszfabiciklo[2.2.2]oktén 2-oxid származékokat vezettünk be, egyrészt új szubsztituensek, másrészt új dienofilek alkalmazásával. A prekurzorokat reakcióképes intermedierek képzésén át foszforilezési reakciókban hasznosítottuk. Tanulmányoztuk a reakciók mechanizmusát és oxafoszfabiciklookténeket is vizsgáltunk. A harmadik témában a P-aril gyűrűs foszfin-oxidok és a dialkilacetiléndikarboxilát béta-oxofoszforánokat eredményező reakcióinak mechanizmusát derítettük fel és megfontoltuk az oxafoszfetének mint intermedierek lehetőségét. A béta-oxofoszforánokat kerülő szintézissel is hozzáférhetővé tettük és tanulmányoztuk néhány jellemző reakciójukat. | The research was performed in three topics, on one hand in the topic of 5- and 6-membered P-heterocycles, on the other hand in the field of 7- and 8-membered P-cycles including bridged derivatives, and finally in the topic of the inverse Wittig type reaction. New phosphole and 1,2,3,6-tetra- and 1,2,3,4,5,6-hexahydrophosphinine P-ligands - these latter with exocyclic P-function in position three - were made available that were also transformed to transition metal complexes. Stereostructure of the P-ligands and complexes was evaluated and a part of the latter was tested as catalyst. A number of dibenzooxaphosphorines and their platinum complexes were also prepared. In the second line of the research, new 7-phosphanorbornene- and 2-phosphabicyclo[2.2.2]octene 2-oxide derivatives were introduced and utilized in fragmentation related phosphorylation of nucleophiles. Beside the mechanistic studies, oxaphosphabicyclooctenes were also studied. In the third topic, the mechanism of the inverse Wittig type reaction of cyclic phosphine oxides and dialkyl acetylenedicarboxylate resulting in beta-oxophosphoranes was studied. Oxaphosphetes were considered as possible intermediates. The beta-oxophosphoranes were also prepared by an independent synthesis and some of their reactions were investigated