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  • 1. Dethoff, Elizabeth A
    et al.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Chugh, Jeetender
    Casiano-Negroni, Anette
    Al-Hashimi, Hashim M
    Visualizing transient low-populated structures of RNA2012In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 491, no 7426, p. 724-728Article in journal (Refereed)
    Abstract [en]

    The visualization of RNA conformational changes has provided fundamental insights into how regulatory RNAs carry out their biological functions. The RNA structural transitions that have been characterized so far involve long-lived species that can be captured by structure characterization techniques. Here we report the nuclear magnetic resonance visualization of RNA transitions towards 'invisible' excited states (ESs), which exist in too little abundance (2-13%) and for too short a duration (45-250 μs) to allow structural characterization by conventional techniques. Transitions towards ESs result in localized rearrangements in base-pairing that alter building block elements of RNA architecture, including helix-junction-helix motifs and apical loops. The ES can inhibit function by sequestering residues involved in recognition and signalling or promote ATP-independent strand exchange. Thus, RNAs do not adopt a single conformation, but rather exist in rapid equilibrium with alternative ESs, which can be stabilized by cellular cues to affect functional outcomes.

  • 2. Honarparvar, Bahareh
    et al.
    Makatini, Maya M
    Pawar, Sachin A
    Petzold, Katja
    School of Chemistry, University of KwaZulu-Natal, Durban 4001 (South Africa).
    Soliman, Mahmoud ES
    Arvidsson, Per I
    Sayed, Yasien
    Govender, Thavendran
    Maguire, Glenn EM
    Kruger, Hendrik G
    Pentacycloundecane-diol-based HIV-1 protease inhibitors: biological screening, 2D NMR, and molecular simulation studies2012In: ChemMedChem, ISSN 1860-7179, E-ISSN 1860-7187, Vol. 7, no 6, p. 1009-1019Article in journal (Refereed)
    Abstract [en]

    Novel compounds incorporating a pentacycloundecane (PCU) diol moiety were designed, synthesized, and evaluated as inhibitors of the wild-type C-South African (C-SA) HIV-1 protease. Seven compounds are reported herein, three of which displayed IC(50) values in the 0.5-0.6 μM range. The cytotoxicity of PCU cage peptides toward human MT-4 cells appears to be several orders of magnitude less toxic than the current antiviral medications ritonavir and lopinavir. NMR studies based on the observed through-space (1)H,(1)H distances/contacts in the EASY-ROESY spectra of three of the considered PCU peptide inhibitors enabled us to describe their secondary solution structure. Conserved hydrogen bonding interactions were observed between the hydroxy group of the PCU diol inhibitors and the catalytic triad (Asp25, Ile26, Gly27) of HIV protease in docking and molecular dynamics simulations. The biological significance and possible mode of inhibition by PCU-based HIV protease inhibitors discussed herein facilitates a deeper understanding of this family of inhibitors and their potential application to a vast number of alternative diseases related to proteases.

  • 3. Makatini, Maya M
    et al.
    Petzold, Katja
    School of chemistry, University of KwaZulu Natal, Durban, South Africa.
    Alves, Cláudio Nahum
    Arvidsson, Per I
    Honarparvar, Bahareh
    Govender, Patrick
    Govender, Thavendran
    Kruger, Hendrik G
    Sayed, Yasien
    Jerônimo, Lameira
    Maguire, Glenn EM
    Soliman, Mahmoud ES
    Synthesis, 2D-NMR and molecular modelling studies of pentacycloundecane lactam-peptides and peptoids as potential HIV-1 wild type C-SA protease inhibitors2013In: Journal of enzyme inhibition and medicinal chemistry (Print), ISSN 1475-6366, E-ISSN 1475-6374, Vol. 28, no 1, p. 78-88Article in journal (Refereed)
    Abstract [en]

    In this study, eight non-natural peptides and peptoids incorporating the pentacycloundecane (PCU) lactam were designed and synthesized as potential inhibitors of the wild type C-SA HIV-protease. Five of these inhibitors gave IC(50) values ranging from 0.5 up to 0.75 µM against the resistance-prone wild type C-South African HIV-protease. NMR EASY-ROESY studies enabled us to describe the secondary structure of three of these compounds in solution. The 3D structures of the selected cage peptides were also modelled in solution using QM/MM/MD simulations. Satisfactory agreement between the NMR observations and the low energy calculated structures exists. Only one of these inhibitors (11 peptoid), which showed the best IC(50)(0.5 µM), exhibited a definable 3-D structure in solution. Autodock4 and AutodockVina were used to model the potential interaction between these inhibitors and the HIV-PR. It appears that the docking results are too crude to be correlated with the relative narrow range of experimental IC(50) values (0.5-10 µM). The PCU-peptides and peptoides were several orders less toxic (145 μM for 11 and 102 μM for 11 peptoid) to human MT-4 cells than lopinavir (0.025 μM). This is the first example of a polycyclic cage framework to be employed as an HIV-PR transition state analogue inhibitor and can potentially be utilized for other diseases related proteases.

  • 4. Makatini, Maya M
    et al.
    Petzold, Katja
    School of Chemistry, University of KwaZulu Natal, Varsity Drive, Durban 4001, South Africa.
    Arvidsson, Per I
    Honarparvar, Bahareh
    Govender, Thavendran
    Maguire, Glenn EM
    Parboosing, Raveen
    Sayed, Yasien
    Soliman, Mahmoud ES
    Kruger, Hendrik G
    Synthesis, screening and computational investigation of pentacycloundecane-peptoids as potent CSA-HIV PR inhibitors2012In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 57, p. 459-467Article in journal (Refereed)
    Abstract [en]

    Herein, we present the first pentacycloundecane (PCU) diol peptoid derived HIV protease inhibitors with IC(50) values ranging from 6.5 to 0.075 μM. Five derivatives were synthesized in an attempt to understand the structure activity relationship of this class of compounds for HIV protease inhibition. NMR spectroscopy (new Efficient Adiabatic Symmetrized Rotating Overhauser Effect Spectroscopy, EASY-ROESY) was employed to determine the predominant conformation of the active compound. In this study docking studies and MD simulations provided insight into the binding theme of this class of peptoid inhibitors to the CSA-HIV PR active site. Conserved and stable hydrogen bonding between the hydroxyl groups of the inhibitors and the active site Asp25/Asp25' residues were observed from the docking and along the MD trajectories.

  • 5. Makatini, Maya M
    et al.
    Petzold, Katja
    School of Chemistry, University of KwaZulu-Natal, Varsity Drive, Durban 4001, South Africa.
    Sriharsha, Shimoga N
    Ndlovu, N
    Soliman, Mahmoud ES
    Honarparvar, Bahareh
    Parboosing, Raveen
    Naidoo, Anneta
    Arvidsson, Per I
    Sayed, Yasien
    Govender, Patrick
    Maguire, Glenn EM
    Kruger, Hendrik G
    Govender, Thavendran
    Synthesis and structural studies of pentacycloundecane-based HIV-1 PR inhibitors: a hybrid 2D NMR and docking/QM/MM/MD approach2011In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 46, no 9, p. 3976-3985Article in journal (Refereed)
    Abstract [en]

    Pentacycloundecane (PCU) lactam-peptide based HIV protease inhibitors were synthesized and nanomolar activity against the resistance-prone wild type C-South African HIV protease is reported. NMR investigations indicated that the activity is related to the chirality of the PCU moiety and its ability to induce conformations of the coupled peptide side chain. EASY-ROESY NMR experiments gave information about the 3D structure of the cage peptides and 3D solution structure could be linked to the experimental IC(50) activity profile of the considered inhibitors. QM/MM/MD simulations of the inhibitors in solution confirmed the NMR observed conformations. Docking experiments and QM/MM/MD simulations of the inhibitor-HIV PR complexes were also performed. These computational results complimented the experimental inhibition activities and enabled us to report a unique binding mode for PCU-based inhibitors at the active site of HIV-protease enzyme. A conserved hydrogen bonding pattern between the norstatine type functional group of the PCU hydroxylactam and active site residues, ASP25/ASP25', was observed in all active compounds. The biological significance and possible mode of inhibition by PCU-based HIV PR inhibitors discussed herein provide us with a deeper understanding of the mode of action of these novel inhibitors. The PCU-peptides are between 6000 and 8500 time less toxic to human MT-4 cells than Lopinavir. This potentially creates new application avenues for these putative inhibitors to be investigated against a vast number of other disease-related proteases.

  • 6. Makatini, Maya M
    et al.
    Petzold, Katja
    School of Chemistry, University of KwaZulu-Natal, Durban 4001, South Africa.
    Sriharsha, Shimoga N
    Soliman, Mahmoud ES
    Honarparvar, Bahareh
    Arvidsson, Per I
    Sayed, Yasien
    Govender, Patrick
    Maguire, Glenn EM
    Kruger, Hendrik G
    Govender, Thavendran
    Pentacycloundecane-based inhibitors of wild-type C-South African HIV-protease2011In: Bioorganic & Medicinal Chemistry Letters, ISSN 0960-894X, E-ISSN 1090-2120, Vol. 21, no 8, p. 2274-2277Article in journal (Refereed)
    Abstract [en]

    In this study, we present the first account of pentacycloundecane (PCU) peptide based HIV-protease inhibitors. The inhibitor exhibiting the highest activity made use of a natural HIV-protease substrate peptide sequence, that is, attached to the cage (PCU-EAIS). This compound showed nanomolar IC(50) activity against the resistance-prone wild type C-South African HIV-protease (C-SA) catalytic site via a norstatine type functional group of the PCU hydroxy lactam. NMR was employed to determine a logical correlation between the inhibitory concentration (IC(50)) results and the 3D structure of the corresponding inhibitors in solution. NMR investigations indicated that the activity is related to the chirality of the PCU moiety and its ability to induce conformations of the coupled peptide side chain. The results from docking experiments coincided with the experimental observed activities. These findings open up useful applications for this family of cage peptide inhibitors, considering the vast number of alternative disease related proteases that exist.

  • 7.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Bäckström, AnnaUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Petzold, KatjajUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Gröbner, GerhardUmeå University, Faculty of Science and Technology, Department of Chemistry.Wai, SNUmeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).Carlsson, SvenUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Schleucher, JürgenUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Arnqvist, AnnaUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Helicobacter pylori outer membrane vesicles and properties for intimate host interactions2007Conference proceedings (editor) (Refereed)
  • 8.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Nygård Skalman, Lars
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Schleucher, Jurgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Endocytosis of Helicobacter pylori vesiclesManuscript (preprint) (Other academic)
  • 9.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Carlsson, Sven
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Haas, Rainer
    Max-von-Pettenkofer-Institute of Hygiene and Medical Microbiology, Dept of Bacteriology, Munich, Germany.
    Backert, Steffen
    School of Biomolecular and Biomedical Sciences, University College Dublin, Ireland.
    Nyunt Wai, Sun
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Characterization of Helicobacter pylori vesicles and their cognate properties for intimate host interactionsManuscript (preprint) (Other academic)
  • 10.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Tegtmeyer, Nicole
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Carlsson, Sven
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Haas, Rainer
    Backert, Steffen
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Biochemical and functional characterization of Helicobacter pylori vesicles2010In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 77, no 6, p. 1539-1555Article in journal (Refereed)
    Abstract [en]

    Helicobacter pylori can cause peptic ulcer disease and/or gastric cancer. Adhesion of bacteria to the stomach mucosa is an important contributor to the vigor of infection and resulting virulence. H. pylori adheres primarily via binding of BabA adhesins to ABO/Lewis b (Leb) blood group antigens and the binding of SabA adhesins to sialyl-Lewis x/a (sLex/a) antigens. Similar to most Gram-negative bacteria, H. pylori continuously buds off vesicles and vesicles derived from pathogenic bacteria often include virulence-associated factors. Here we biochemically characterized highly purified H. pylori vesicles. Major protein and phospholipid components associated with the vesicles were identified with mass spectroscopy and NMR. A subset of virulence factors present was confirmed by immunoblots. Additional functional and biochemical analysis focused on the vesicle BabA and SabA adhesins and their respective interactions to human gastric epithelium. Vesicles exhibit heterogeneity in their protein composition, which were specifically studied in respect to the BabA adhesin. We also demonstrate that the oncoprotein, CagA, is associated with the surface of H. pylori vesicles. Thus, we have explored mechanisms for intimate H. pylori vesicle-host interactions and found that the vesicles carry effector-promoting properties that are important to disease development.

  • 11.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Medical Biochemistry and Biophsyics.
    NMR studies of host-pathogen interactions2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the use of Nuclear Magnetic Resonance (NMR) for characterizing two host-pathogen interactions: The behavior of a regulatory RNA of the Hepatitis B virus (HBV) and the attachment of Helicobacter pylori (H. pylori) to the gastric mucosa. NMR is a powerful tool in biomedicine, because molecules ranging from small ligands to biomacromolecules can be studied with atomic resolution. Different NMR experiments are designed to determine structures, or to monitor interactions, folding, stability or motion.

    Paper I describes the analysis of the motions of a regulatory RNA of HBV. The NMR structure of the RNA had revealed before that several well-conserved nucleotides adopt multiple conformations. Therefore an analysis of possible underlying motions was undertaken using two different NMR techniques, one of which (off-resonance ROESY) was applied to nucleic acids for the first time. The observed motions suggest an explanation why the structurally poorly defined nucleotides are highly conserved.

    In paper II we improved the ROESY NMR experiment, which is used to measure internuclear distances for structure determination of medium-sized molecules. Using a small protein and an organometallic complex as examples, we demonstrated that the new EASY ROESY experiment yields clean spectra that can directly be integrated to derive interatomic distances.

    H. pylori, the bacterium involved in peptic ulcer disease and gastric cancer, survives in the harsh acidic environment of the stomach. It possesses many membrane proteins which mediate adherence, raising the question, if their activity is related to membrane composition. In paper III & IV we analyzed therefore the phospholipid composition of H. pylori membranes.

    In paper III, an advanced method for the analysis of the phospholipid composition of biological membranes was developed. The two-dimensional semi-constant-time 31P,1H-COSY experiment combines information from phosphorus and hydrogen atoms of phospholipids for their unambiguous identification. Furthermore, the high resolution of the two-dimensional experiment allows the quantification of phospholipids where conventional methods fail.

    In paper IV we applied the new experiment to analyze the lipid composition of whole H. pylori cells, their inner and outer membranes, and of vesicles shed by the bacterium. The goal of this study was to characterize the vesicles which are suggested to play a role in the inflammation process. We established that the outer membrane and the vesicles have similar phospholipid compositions, suggesting that the vesicles are largely derived from the outer membrane.

    The NMR results presented here elucidate details of molecular systems engaged in pathogenicity, as basis for therapeutic strategies against these pathogens.

  • 12.
    Petzold, Katja
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Al-Hashimi, Hashim M
    RNA structure: adding a second dimension2011In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 3, no 12, p. 913-915Article in journal (Refereed)
  • 13.
    Petzold, Katja
    et al.
    Umeå University, Faculty of Medicine, Medical Biochemistry and Biophsyics.
    Duchardt, Elke
    Flodell, Sara
    Larsson, Göran
    Umeå University, Faculty of Medicine, Medical Biochemistry and Biophsyics.
    Kidd-Ljunggren, Karin
    Wijmenga, Sybren
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Medical Biochemistry and Biophsyics.
    Conserved nucleotides in an RNA essential for hepatitis B virus replication show distinct mobility patterns2007In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 35, no 20, p. 6854-6861Article in journal (Refereed)
  • 14.
    Petzold, Katja
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jürgen, Schleucher
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Semiconstant-Time P,H-COSY NMR: Analysis of Complex Mixtures of Phospholipids Originating from Helicobacter pylori2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 40, p. 14150-1Article in journal (Refereed)
    Abstract [en]

    Lipids play a central role in numerous biological events, ranging from normal physiological processes to host−pathogen interactions. The proposed semiconstant-time 31P,1H−COSY NMR experiment provides identification of known and structural characterization of unknown phospholipids in complex membrane extracts with high sensitivity, based on the combination of their 1H and 31P chemical shifts and coupling patterns. Furthermore, the spectra allow quantification of phospholipid composition. Analysis of the phospholipid composition of Helicobacter pylori, the causative agent of peptic ulcer disease, showed the presence of uncommon phospholipids. This novel NMR approach allows the study of changes in membrane composition in response to biological stimuli and opens up the possibility of identifying soluble phosphorus species in a number of research fields.

  • 15.
    Petzold, Katja
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Öhman, Anders
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Backman, Lars
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Folding of the αΙΙ-spectrin SH3 domain under physiological salt conditions2008In: Archives of Biochemistry and Biophysics, ISSN 0003-9861, E-ISSN 1096-0384, Vol. 474, no 1, p. 39-47Article in journal (Refereed)
    Abstract [en]

    The SH3 domain has often been used as a model for protein folding due to its typical two-state behaviour. However, recent experimental data at low pH as well as molecular dynamic simulations have indicated that the folding process of SH3 probably is more complicated, and may involve intermediate states. Using both kinetic and equilibrium measurements we have obtained evidence that under native-like conditions the folding of the spectrin SH3 domain does not follow a classic two-state behaviour. The curvature we observed in the Chevron plots is a strong indication of a non-linear activation energy relationship due to the presence of high-energy intermediates. In addition, circular dichroism measurements indicated that refolding after thermal denaturation did not follow the same pattern as thermal unfolding but rather implied less cooperativity and that the refolding transition increased with increasing protein concentration. Further, NMR experiments indicated that upon refolding the SH3 domain gave rise to more than one conformation. Therefore, our results suggest that the folding of the SH3 domain of II-spectrin does not follow a classical two-state process under high-salt conditions and neutral pH. Heterogeneous folding pathways, which can include folding intermediates as well as misfolded intermediates, might give a more reasonable insight into the folding behaviour of the II-spectrin SH3 domain.

  • 16.
    Robertsson, Joacim
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Petzold, Katja
    Umeå University, Faculty of Science and Technology, Chemistry.
    Löfvenberg, Lars
    Backman, Lars
    Umeå University, Faculty of Science and Technology, Chemistry.
    Folding of Spectrin's SH3 Domain in the Presence of Spectrin Repeats2005In: Cellular & Molecular Biology Letters, Vol. 10, p. 595-612Article in journal (Refereed)
    Abstract [en]

    The multifunctional protein spectrin contains several different structural motifs, such as spectrin repeats and a SH3 domain. Both triple-helix spectrin repeats and the SH3 domain are believed to form independent structural entities. In a-spectrins the SH3 domain is localized to repeat 9, where it is positioned between helix B and helix C in the repeat unit. The presence of SH3 in repeat 9 decreases the thermal stability considerably of this repeat unit while another insert in helix C does not seem to affect the stability. Addition of one or two adjacent repeat units increases the thermal stability from ca 25°C to ~41 and ~48°C, respectively. Despite the differences in thermal stability, the folding properties of peptides comprising the SH3 domain only or together with one or more repeats are more or less the same.

  • 17. Shaikh, M
    et al.
    Petzold, Katja
    School of Chemistry, University of KwaZulu-Natal, Durban, South Africa .
    Kruger, HG
    du Toit, K
    Synthesis and NMR elucidation of homoisoflavanone analogues2011In: Structural Chemistry, ISSN 1040-0400, E-ISSN 1572-9001, Vol. 22, no 1, p. 161-166Article in journal (Refereed)
    Abstract [en]

    A series of five homoisoflavanone analogues have been synthesized from the corresponding 3,5-methoxy phenols via chroman-4-one in three steps. The complete NMR elucidation of these homoisoflavanone analogues is reported. The use of 2D NMR techniques (COSY, NOESY, HSQC and HMBC) proved to be very useful tools in the elucidation of homoisoflavanone analogues. The homoisoflavanone analogues exhibit an AA'BB' spin pattern in the ring B of the homoisoflavanone. These homoisoflavanone analogues are potential antifungal and anti-inflammatory agents.

  • 18.
    Thiele, Christina Marie
    et al.
    Technical University Darmstadt.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    EASY ROESY: reliable cross-peak integration in adiabatic symmetrized ROESY2009In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 3, p. 585-588Article in journal (Refereed)
    Abstract [en]

    Estimates of intramolecular distances are essential for structure determination. For medium-sized molecules, ROESY NMR is the method of choice for obtaining distances. However, the integration of ROESY cross-peaks is problematic due to the offset dependence of theintegrals and/or TOCSY artefacts. We here present EASY ROESY (rEliable Adiabatic SYmmetrized ROESY), which yields reliable intramolecular distances without sample-specific setup.

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