A sensitive and specific β-alanyl aminopeptidase-activated fluorogenic probe for the detection of Pseudomonas aeruginosa

We report the synthesis of the sensitive and specific fluorogenic self-immolative substrate 8b, which is hydrolzyed by β-alanyl aminopeptidase (BAP), resulting in a 1,6-elimination and the release of the highly fluorescent hydroxycoumarin 6b. This fluorophore 6b is retained within bacterial colonies, so has potential for the detection of P. aeruginosa (a BAP producer); it also has potential in liquid media due to the rapid and strong signal release from the substrate 8b, and lack of self-quenching or photobleaching.NHMR

Monoclinic paracetamol vs. paracetamol-4,4'-bipyridine co-crystal; what is the difference? a charge density study

Paracetamol (PCM) has two well-documented polymorphic forms at room temperature; monoclinic Form I is more stable than the other orthorhombic Form II. Form II exhibits improved tabletting properties compared to Form I due to low shearing forces; however, difficulties in its manufacture have limited its use in industrial manufacture. Previous studies have found that the introduction of a co-former to form co-crystals would allow the PCM molecule to exist in a conformation similar to that of the orthorhombic form while being more stable at room temperature. Experimental charge density analysis of the paracetamol-4,4′-bipyridine (PCM-44BP) co-crystal system, and its constituent molecules, has been carried out to examine the forces that drive the formation and stabilisation of the co-crystal, while allowing PCM to maintain a packing motif similar to that found in Form II. It is hoped studies on this well-known compound will help apply the knowledge gained to other drug molecules that are less successful. The PCM molecules in the co-crystal were found to exhibit similar packing motifs to that found in Form I, however, intercalation of the 44BP molecule between the PCM layers resulted in a shallower angle between molecular planes, which could result in the required lateral shear. Topological analysis identified more weak interactions in the co-crystal compared to the individual molecules, thus allowing for greater stability as evidenced by the lattice energies. Weak interactions in the PCM-44BP co-crystal were found to range in strength from 4.08–84.33 kJ mol−1, and this variety allowed the PCM-44BP planes to be held together, while a weak π–π interaction (15.14 kJ mol−1) allowed lateral shear to occur, thus mimicking the planes found in Form II PCM and offering the possibility of improved tabletting properties. A comparison of integrated atomic charges between partitions of the PCM molecules in the single and co-crystal found that the hydroxyl and amide groups were involved in greater hydrogen bonding in the co-crystal, resulting in a charge redistribution across the molecule evidenced by a larger molecular dipole moment (µ = 12.34D). These findings, in addition to the co-crystal having the largest lattice energy, form a potential basis with which to predict that the co-crystal exhibits improved solubility and stability profiles. It is anticipated that these findings will contribute to improvements in the formulation and other physical properties of PCM and other pharmaceutical compounds

Experimental and Theoretical Charge Density Distribution in Pigment Yellow 101

The charge density distribution in 2,2'-Dihydroxy-1,1'-naphthalazine (Pigment Yellow 101; P.Y.101) has been determined using high-resolution X-ray diffraction and multipole refinement, along with density functional theory calculations. Topological analysis of the resulting densities highlights the localisation of single/double bonds in the central C=N-N=C moiety of the molecule in its ground state. The density in the N—N is examined in detail, where we show that very small differences between experiment and theory are amplified by use of the Laplacian of the density. Quantification of hydrogen bonds highlights the importance of the intramolecular N—H…O interaction, known to be vital for retention of fluorescence in the solid state, relative to the many but weak intermolecular contacts located. However, a popular method for deriving H-bond strengths from density data appears to struggle with the intramolecular N—H…O interaction. We also show that theoretical estimation of anisotropic displacements for hydrogen atoms brings little benefit overall, and degrades agreement with experiment for one intra-molecular contact.NH&MR

An analysis of the experimental and theoretical charge density distributions of the piroxicam-saccharin co-crystal and its constituents

Experimental and theoretical charge density analyses of piroxicam (1), saccharin (2) and their 1:1 co-crystal complex (3) have been carried out. Electron density distribution (EDD) was determined through the use of high-resolution single crystal X-ray diffraction and the data were modelled using the conventional multipole model of electron density according to the Hansen-Coppens formalism. A method for optimising the core density refinement of sulfur atoms is discussed, with emphasis on the reduction of residual electron density that is typically associated with this atom. The asymmetric unit of complex (3) contains single molecules of saccharin and the zwitterionic form of piroxicam. These are held together by weak interactions (hydrogen bonds, π-π and van der Waals interactions), ranging in strength from 4 to 160 kJmol-1, working together to stabilise the complex;. analysis of the molecular electrostatic potential (MEP) of the complexes showed electron redistribution within the cocrystal, facilitating the formation of these generally weak interactions. Interestingly, in the zwitterionic form of piroxicam, the charge distribution reveals that the positive and negative charges are not associated with the formal charges normally associated with this description, but are distributed over adjacent molecular fragments. The use of anisotropic displacement parameters (ADPs) for hydrogen atoms in the multipole model was also investigated but no improvement in the quality of the topological analysis was found.The University of Sydney Bridging Support Scheme. The Danish National Research Foundation (Center for Materials Crystallography, DNRF-93

A comparison of the experimental and theoretical charge density distributions in two polymorphic modifications of Piroxicam.

Experimental charge density distribution studies of two polymorphic forms of piroxicam, β- piroxicam (1) and piroxicam monohydrate (2), were carried out via high-resolution single crystal X-ray diffraction experiments and multipole refinement. The asymmetric unit of (2) consists of two discrete piroxicam molecules, (2a) and (2b), and two water molecules. Geometry differs between (1) and (2) due to the zwitterionic nature of (2) which results in the rotation of pyridine ring around the C(10)–N(2) bond by approximately 180°. Consequently, the pyridine and amide are no longer co-planar and (2) forms two exclusive, strong hydrogen bonds, H(3) …O(4) and H(2) …O(3), with bond energy of 66.14 kJ mol-1 and 112.82 kJ mol- 1 for (2a), 58.35 kJ mol-1 and 159.51 kJ mol-1 for (2b) respectively. Proton transfer between O(3) and N(3) in (2) results in significant differences in surface electrostatic potentials. This is clarified on calculation of atomic charges in the zwitterion shows the formally positive charge of the pyridyl nitrogen is redistributed over the whole of the pyridine ring instead of concentrated at N-H. Similarly, the negative charge of the oxygen is distributed across the benzothiazinecarboxamide moiety. Multipole derived lattice energy for (1) is -304 kJ mol-1 and that for (2) is -571 kJ mol-1, which is in agreement with the experimentally determined observations of higher solubility and dissolution rates of (1) compared to (2)

Új szintézismódszerek kidolgozása és alkalmazása célzott hatásterületen aktív heterociklusos molekulák szintézisére = Elaboration and application of new synthetic methodologies for the synthesis of heterocyclic molecules of aimed biological activity

Pályázati kutatásunk alapvető célja az volt, hogy néhány, a legutóbbi időkben felismert új szintézis-lehetőséget laboratóriumunkban meghonosítsunk, saját magunk új módszereket dolgozzunk ki, és mindezek segítségével felfedező kutatásokat végezzünk kiemelten fontos területen ható biológiailag aktív molekulák megtalálására és szintézisére. Beszámolhatunk arról, hogy palládium-katalizált C-C és C-N keresztkapcsolások segítségével új gyűrűvázakhoz jutottunk, és alapvető új átalakulásokat kezdeményeztünk az organokatalízis és fluoros technika területén. Módszereink segítségével főként a multidrog-rezisztenciát gátló vegyületek családjában értünk el figyelemre méltó eredményt. Kimutattuk, hogy néhány újszerűen szubsztituált fenotiazin-származék hatása meghaladja a kontrollként vizsgált verapamil hatását. A rezisztencia gátlása különösen a mikróbás fertőzések és tumoros betegségek leküzdésében kiemelt jelentőségű. A leghatékonyabb származékokat egy jövőbeli gyógyszerfejlesztés lead-molekulájaként tekintjük. Munkánk elvégzésébe nagy számban vontunk be graduális és posztgraduális hallgatókat. A kutatási eredményekből 7 PhD értekezés született, ezek közül 4 már sikeres védésre került, emellett két egyetemi záródolgozat is elkészült. Munkánk tudományos értékét a megjelent 18 közlemény fémjelzi, összesített hatástényezőjük 57.5. | The basic aim of the present project activity was to establish recently recognized new synthetic methodologies in our laboratory, to elaborate new procedures, and to apply these novel approaches for identification and synthesis of compounds exhibiting biological activity in important areas of drug research. It is to be emphasized that application of palladium-catalyzed C-C and C-N cross coupling reactions allowed the synthesis of new ring systems, whereas basically new transformations have been initiated in the areas of organocatalysis and fluorous techniques.. The new methods provided the most outstanding reaults in the area of multidrug resistance inhibition. Results of some phenothiazines with unusual substitution pattern exceeded the effect of verapamil used as a reference compound. Resistance inhibition is of primary importance in treatment of microbial infections and tumor diseases. Those synthesized compounds exhibiting the highest effectivity can be regarded as lead compounds for the future drug development. Great number of MSc and PhD students were involved into accomplishment of the project. Seven PhD dissertations were born, four of these have already been successfully defended and, furthermore, two master theses have also been finalized. The scientific value of the research activity is coined by the 18 scientific publications with a cumulative impact factor of 57.5

Mammalian Target of Rapamycin (mTOR) Activity Dependent Phospho-Protein Expression in Childhood Acute Lymphoblastic Leukemia (ALL)

Modern treatment strategies have improved the prognosis of childhood ALL; however, treatment still fails in 25–30% of patients. Further improvement of treatment may depend on the development of targeted therapies. mTOR kinase, a central mediator of several signaling pathways, has recently attracted remarkable attention as a potential target in pediatric ALL. However, limited data exists about the activity of mTOR. In the present study, the amount of mTOR activity dependent phospho-proteins was characterized by ELISA in human leukemia cell lines and in lymphoblasts from childhood ALL patients (n = 49). Expression was measured before and during chemotherapy and at relapses. Leukemia cell lines exhibited increased mTOR activity, indicated by phospho-S6 ribosomal protein (p-S6) and phosphorylated eukaryotic initiation factor 4E binding protein (p-4EBP1). Elevated p-4EBP1 protein levels were detected in ALL samples at diagnosis; efficacy of chemotherapy was followed by the decrease of mTOR activity dependent protein phosphorylation. Optical density (OD) for p-4EBP1 (ELISA) was significantly higher in patients with poor prognosis at diagnosis, and in the samples of relapsed patients. Our results suggest that measuring mTOR activity related phospho-proteins such as p-4EBP1 by ELISA may help to identify patients with poor prognosis before treatment, and to detect early relapses. Determining mTOR activity in leukemic cells may also be a useful tool for selecting patients who may benefit from future mTOR inhibitor treatments

An investigation of the differential effects of ursane triterpenoids from Centella asiatica, and their semisynthetic analogues, on GABAA receptors

The ursane triterpenoids, asiatic acid 1 and madecassic acid 2, are the major pharmacological constituents of Centella asiatica, commonly known as Gotu Kola, which is used traditionally for the treatment of anxiety and for the improvement of cognition and memory. Using the two-electrode voltage-clamp technique, these triterpenes, and some semisynthetic derivatives, were found to exhibit selective negative modulation of different subtypes of the GABAA receptor expressed in Xenopus laevis oocytes. Despite differing by only one hydroxyl group, asiatic acid 1 was found to be a negative modulator of the GABA-induced current at α1 β2 γ2L, α2 β2 γ2L and α5 β3 γ2L GABAA receptors, while madecassic acid 2 was not. Asiatic acid 1 exhibited the greatest effect at α1 β2 γ2L (IC50 37.05 μm), followed by α5 β3 γ2L (IC50 64.05 μm) then α2 β2 γ2L (IC50 427.2 μm) receptors. Conversion of the carboxylic acid group of asiatic acid 1 to a carboxamide group (2α,3β,23-trihydroxy-urs-12-en-28-amide 5) resulted in enhanced inhibition at both the α1 β2 γ2L (IC50 14.07 μm) and α2 β2 γ2L receptor subtypes (IC50 28.41 μm). The results of this study, and the involvement of α5 -containing GABAA receptors in cognition and memory, suggest that asiatic acid 1 may be a lead compound for the enhancement of cognition and memory.12 page(s

Correction: Experimental and theoretical charge density distribution in Pigment Yellow 101

Correction for ‘Experimental and theoretical charge density distribution in Pigment Yellow 101’ by Jonathan J. Du et al., Phys. Chem. Chem. Phys., 2015, DOI: 10.1039/c4cp04302b