Gunnar Lindeberg

Uppsala University, Uppsala, Uppsala, Sweden

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Publications (48)148.45 Total impact

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    ABSTRACT: Herein, novel hepatitis C virus NS3/4A protease inhibitors based on a P2 pyrimidinyloxyphenylglycine in combination with various regioisomers of an aryl acyl sulfonamide functionality in P1 are presented. The P1' 4-(trifluoromethyl)phenyl side chain was shown to be particularly beneficial in terms of inhibitory potency. Several inhibitors with K i-values in the nanomolar range were developed and included identification of promising P3-truncated inhibitors spanning from P2-P1'. Of several different P2 capping groups that were evaluated, a preference for the sterically congested Boc group was revealed. The inhibitors were found to retain inhibitory potencies for A156T, D168V, and R155K variants of the protease. Furthermore, in vitro pharmacokinetic profiling showed several beneficial effects on metabolic stability as well as on apparent intestinal permeability from both P3 truncation and the use of the P1' 4-(trifluoromethyl)phenyl side chain.
    ACS Medicinal Chemistry Letters 03/2014; 5(3):249-254. · 3.31 Impact Factor
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    ABSTRACT: The overexpression of gastrin-releasing peptide receptor (GRPR) in cancer can be used for peptide-receptor mediated radionuclide imaging and therapy. We have previously shown that an antagonist analog of bombesin RM26 conjugated to 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA) via a diethyleneglycol (PEG2) spacer (NOTA-PEG2-RM26) and labeled with 68Ga can be used for imaging of GRPR-expressing tumors. In this study, we evaluated if a variation of mini-PEG spacer length can be used for optimization of targeting properties of the NOTA-conjugated RM26. A series of analogs with different PEG-length (n = 2, 3, 4, 6) was synthesized, radiolabeled and evaluated in vitro and in vivo. The IC50 values of natGa-NOTA-PEGn-RM26 (n = 2, 3, 4, 6) were 3.1 ± 0.2, 3.9 ± 0.3, 5.4 ± 0.4 and 5.8 ± 0.3 nM, respectively. In normal mice all conjugates demonstrated similar biodistribution pattern, however 68Ga-NOTA-PEG3-RM26 showed lower liver uptake. Biodistribution of 68Ga-NOTA-PEG3-RM26 was evaluated in nude mice bearing PC-3 (prostate cancer) and BT-474 (breast cancer) xenografts. High uptake in tumors (4.6 ± 0.6%ID/g and 2.8 ± 0.4%ID/g for PC-3 and BT-474 xenografts, respectively) and high tumor-to-background ratios (tumor/blood of 44 ± 12 and 42 ± 5 for PC-3 and BT-474 xenografts, respectively) were found already at 2 h p.i. of 68Ga-NOTA-PEG3-RM26. Results of this study suggest that variation in the length of the PEG spacer can be used for optimization of targeting properties of peptide-chelator conjugates. However, the influence of the mini-PEG length on biodistribution is minor when di-, tri-, tetra- and hexaethylene glycol are compared.
    Molecules 01/2014; 19(7):10455-10472. · 2.43 Impact Factor
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    ABSTRACT: The gastrin-releasing peptide receptor (GRPR/BB2) is a molecular target for the visualization of prostate cancer. This work focused on the development of high-affinity, hydrophilic, antagonistic, bombesin-based imaging agents for PET and SPECT. The bombesin antagonist analog D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH<sub>2</sub> ([D-Phe<sup>6</sup>,Sta<sup>13</sup>,Leu<sup>14</sup>]bombesin[6-14]) was synthesized and conjugated to 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA) via a diethylene glycol (PEG<sub>2</sub>) linker. The resulting conjugate, NOTA-PEG2-[D-Phe<sup>6</sup>,Sta<sup>13</sup>,Leu<sup>14</sup>]bombesin[6-14] (NOTA-P2-RM26), was labeled with <sup>68</sup>Ga (T<sub>1/2</sub>=68 min, positron emitter) and <sup>111</sup>In (T<sub>1/2</sub>=2.8 days, gamma emitter). The labeling stability, specificity, inhibition efficiency (IC<sub>50</sub>) and dissociation constant (K<sub>D</sub>) of both labeled compounds as well as their cellular retention and internalization were investigated. The pharmacokinetics of the dual isotope (<sup>111</sup>In/<sup>68</sup>Ga)-labeled peptide in both NMRI mice and PC-3 tumor-bearing mice was also studied. NOTA-P2-RM26 was labeled with <sup>111</sup>In and <sup>68</sup>Ga at a radiochemical yield of >98%. Both conjugates were shown to have high specificity and binding affinity for GRPR. The K<sub>D</sup> value was determined to be 23±13 pM for the <sup>111</sup>In-labeled compound in a saturation binding experiment. In addition, <sup>nat</sup>In- and <sup>nat</sup>Ga-NOTA-P2-RM26 showed low nanomolar binding inhibition concentrations (IC<sub>50</sub>=1.24±0.29 nM and 0.91±0.19 nM, respectively) in a competitive binding assay. The internalization rate of the radiolabeled conjugates was slow. The radiometal-labeled tracers demonstrated rapid blood clearance via the kidney and GRPR-specific uptake in the pancreas in normal mice. Tumor targeting and biodistribution studies in mice bearing PC-3 xenografts displayed high and specific uptake in tumors (8.1±0.4 %ID/g for <sup>68</sup>Ga and 5.7±0.3 %ID/g for <sup>111</sup>In) and high tumor-to-background ratios (tumor/blood: 12±1 for <sup>68</sup>Ga and 10±1 for <sup>111</sup>In) after only 1 h p.i. of 45 pmol of peptide. The xenografts were visualized by gamma and microPET cameras shortly after injection. In conclusion, the antagonistic bombesin analog NOTA-PEG<sub>2</sub>-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH<sub>2</sub> (NOTA-P2-RM26) is a promising candidate for prostate cancer imaging using PET and SPECT/CT.
    Bioconjugate Chemistry 06/2013; · 4.58 Impact Factor
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    ABSTRACT: Peptides mimicking the C-terminus of the small subunit (R2) of Mycobacterium tuberculosis ribonucleotide reductase (RNR) can compete for binding to the large subunit (R1) and thus inhibit RNR activity. Moreover, it has been suggested that the binding of the R2 C-terminus is very similar in M. tuberculosis and Salmonella typhimurium. Based on modeling studies of a crystal structure of the holocomplex of the S. typhimurium enzyme, a benzodiazepine-based turn mimetic was identified and a set of novel compounds incorporating the benzodiazepine scaffold was synthesized. The compounds were evaluated in a competitive fluorescence polarization assay and in an RNR activity assay. These studies revealed that the compounds incorporating the benzodiazepine scaffold have the ability to compete for the M. tuberculosis R2 binding site with low-micromolar affinity.
    Bioorganic & medicinal chemistry 01/2013; · 2.82 Impact Factor
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    ABSTRACT: Expression of the gastrin-releasing peptide receptor (GRPR) in prostate cancer suggests that this receptor can be used as a potential molecular target to visualize and treat these tumors. We have previously investigated an antagonist analog of bombesin (D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2, RM26) conjugated to 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA) via a diethylene glycol (PEG2) spacer (NOTA-P2-RM26) labeled with (68)Ga and (111)In. We found that this conjugate has favorable properties for in vivo imaging of GRPR-expression. The focus of this study was to develop a (18)F-labelled PET agent to visualize GRPR. NOTA-P2-RM26 was labeled with (18)F using aluminum-fluoride chelation. Stability, in vitro binding specificity and cellular processing tests were performed. The inhibition efficiency (IC50) of the [(nat)F]AlF-NOTA-P2-RM26 was compared to that of the (nat)Ga-loaded peptide using (125)I-Tyr(4)-BBN as the displacement radioligand. The pharmacokinetics and in vivo binding specificity of the compound were studied. NOTA-P2-RM26 was labeled with (18)F within 1 h (60-65% decay corrected radiochemical yield, 55 GBq/µmol). The radiopeptide was stable in murine serum and showed high specific binding to PC-3 cells. [(nat)F]AlF-NOTA-P2-RM26 showed a low nanomolar inhibition efficiency (IC50=4.4±0.8 nM). The internalization rate of the tracer was low. Less than 14% of the cell-bound radioactivity was internalized after 4 h. The biodistribution of [(18)F]AlF-NOTA-P2-RM26 demonstrated rapid blood clearance, low liver uptake and low kidney retention. The tumor uptake at 3 h p.i. was 5.5±0.7 %ID/g, and the tumor-to-blood, -muscle and -bone ratios were 87±42, 159±47, 38±16, respectively. The uptake in tumors, pancreas and other GRPR-expressing organs was significantly reduced when excess amount of non-labeled peptide was co-injected. The low uptake in bone suggests a high in vivo stability of the Al-F bond. High contrast PET image was obtained 3 h p.i. The initial biological results suggest that [(18)F]AlF-NOTA-P2-RM26 is a promising candidate for PET imaging of GRPR in vivo.
    PLoS ONE 01/2013; 8(12):e81932. · 3.53 Impact Factor
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    ABSTRACT: Macrocyclization is a commonly used strategy to preorganize HCV NS3 protease inhibitors in their bioactive conformation. Moreover, macrocyclization generally leads to greater stability and improved pharmacokinetic properties. In HCV NS3 protease inhibitors, it has been shown to be beneficial to include a vinylated phenylglycine in the P2 position in combination with alkenylic P1' substituents. A series of 14-, 15- and 16-membered macrocyclic HCV NS3 protease inhibitors with the linker connecting the P2 phenylglycine and the alkenylic P1' were synthesized by ring-closing metathesis, using both microwave and conventional heating. Besides formation of the expected macrocycles in cis and trans configuration as major products, both ring-contracted and double-bond migrated isomers were obtained, in particular during formation of the smaller rings (14- and 15-membered rings). All inhibitors had K(i)-values in the nanomolar range, but only one inhibitor type was improved by rigidification. The loss in inhibitory effect can be attributed to a disruption of the beneficial π-π interaction between the P2 fragment and H57, which proved to be especially deleterious for the d-phenylglycine epimers.
    Bioorganic & medicinal chemistry 08/2011; 19(16):4917-27. · 2.82 Impact Factor
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    ABSTRACT: Macrocyclic analogues of angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) targeting the insulin-regulated aminopeptidase (IRAP) have been designed, synthesized, and evaluated biologically. Replacement of His(4)-Pro(5)-Phe(6) by a 2-(aminomethyl)phenylacetic acid (AMPAA) moiety and of Val(1) and Ile(3) by amino acids bearing olefinic side chains followed by macrocyclization provided potent IRAP inhibitors. The impact of the ring size and the type (saturated versus unsaturated), configuration, and position of the carbon-carbon bridge was assessed. The ring size generally affects the potency more than the carbon-carbon bond characteristics. Replacing Tyr(2) by β(3)hTyr or Phe is accepted, while N-methylation of Tyr(2) is deleterious for activity. Removal of the carboxyl group in the C-terminal slightly reduced the potency. Inhibitors 7 (K(i) = 4.1 nM) and 19 (K(i) = 1.8 nM), both encompassing 14-membered ring systems connected to AMPAA, are 10-fold more potent than Ang IV and are also more selective over aminopeptidase N (AP-N). Both compounds displayed high stability against proteolysis by metallopeptidases.
    Journal of Medicinal Chemistry 06/2011; 54(11):3779-92. · 5.61 Impact Factor
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    ABSTRACT: The insulin-regulated aminopeptidase (IRAP) localized in areas of the brain associated with memory and learning is emerging as a new promising therapeutic target for the treatment of memory dysfunctions. The angiotensin II metabolite angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) binds with high affinity to IRAP and inhibits this aminopeptidase (K(i) = 62.4 nM). Furthermore, Ang IV has been demonstrated to enhance cognition in animal models and is believed to play an important role in cognitive processes. It is herein reported that displacement of the C-terminal tripeptide His(4)-Pro(5)-Phe(6) with a phenylacetic acid functionality combined with a constrained macrocyclic system in the N-terminal affords potent IRAP inhibitors that are less peptidic in character than the hexapeptide Ang IV. Configurational analysis of three pairs of diastereomeric Ang IV analogues was performed using a combination of solution NMR spectroscopic methods, Monte Carlo conformational searches, and NAMFIS calculations. The compounds encompassing l-amino acids only (4, 8, and 12) showed significantly higher bioactivity compared to their lld-epimers (5, 9, and 13). The best inhibitors in the series, compounds 8 and 12, incorporating a 13- and 14-membered disulfide ring system, respectively, and both with a β(3)-homotyrosine residue (β(3)hTyr) replacing Tyr(2), exhibit K(i) values of 3.3 and 5.2 nM, respectively.
    Journal of Medicinal Chemistry 11/2010; 53(22):8059-71. · 5.61 Impact Factor
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    ABSTRACT: Phenylglycine has proved to be a useful P2 residue in HCV NS3 protease inhibitors. A novel pi-pi-interaction between the phenylglycine and the catalytic H57 residue of the protease is postulated. We hypothesized that the introduction of a vinyl on the phenylglycine might strengthen this pi-pi-interaction. Thus, herein is presented the synthesis and inhibitory potency of a series of acyclic vinylated phenylglycine-based HCV NS3 protease inhibitors. Surprisingly, inhibitors based on both D- and L-phenylglycine were found to be effective inhibitors, with a slight preference for the d-epimers. Furthermore, prime-side alkenylic extension of the C-terminal acylsulfonamide group gave significantly improved inhibitors with potencies in the nanomolar range (approximately 35 nM), potencies which were retained on mutant variants of the protease.
    Bioorganic & medicinal chemistry 07/2010; 18(14):5413-24. · 2.82 Impact Factor
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    ABSTRACT: Ribonucleotide reductase (RNR) is a viable target for new drugs against the causative agent of tuberculosis, Mycobacterium tuberculosis. Previous work has shown that an N-acetylated heptapeptide based on the C-terminal sequence of the smaller RNR subunit can disrupt the formation of the holoenzyme sufficiently to inhibit its function. Here the synthesis and binding affinity, evaluated by competitive fluorescence polarization, of several truncated and N-protected peptides are described. The protected single-amino acid Fmoc-Trp shows binding affinity comparable to the N-acetylated heptapeptide, making it an attractive candidate for further development of non-peptidic RNR inhibitors.
    Journal of Peptide Science 03/2010; 16(3):159-64. · 2.07 Impact Factor
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    ABSTRACT: Substance P 1-7 (SP(1-7), H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-OH) is the major bioactive metabolite of substance P. The interest in this heptapeptide originates from the observation that it modulates, and in certain cases opposes the effects of the parent peptide, e.g., the nociceptive effect. The mu-opioid receptor agonist endomorphin-2 (EM-2, H-Tyr-Pro-Phe-Phe-NH(2)) has been found to also interact with the specific binding site of SP(1-7) with only a 10-fold lower affinity compared to the native peptide. Considering the smaller size of EM-2 compared to the target heptapeptide, it was selected as a lead compound in the development of low-molecular-weight ligands to the SP(1-7) binding site. An alanine scan and truncation study led to the unexpected discovery of the dipeptide H-Phe-Phe-NH(2) (K(i) = 1.5 nM), having equal affinity as the endogenous heptapeptide SP(1-7.) Moreover, the studies show that the C-terminal phenylalanine amide is crucial for the affinity of the dipeptide.
    Journal of Medicinal Chemistry 02/2010; 53(6):2383-9. · 5.61 Impact Factor
  • C. KUEHN, G. LINDEBERG, A. GOGOLL, A. HALLBERG
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 29(1).
  • M. LARHED, G. LINDEBERG, A. HALLBERG
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 28(7).
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    ABSTRACT: Analogues of the hexapeptide angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr(2) and a phenylacetic or benzoic acid moiety replacing His(4)-Pro(5)-Phe(6) have been synthesized and evaluated in biological assays. The analogues inhibited the proteolytic activity of cystinyl aminopeptidase (CAP), frequently referred to as the insulin-regulated aminopeptidase (IRAP), and were found less efficient as inhibitors of aminopeptidase N (AP-N). The best Ang IV mimetics in the series were approximately 20 times less potent than Ang IV as IRAP inhibitors. Furthermore, it was found that the ligands at best exhibited a 140 times lower binding affinity to the membrane-bound IRAP/AT4 receptor than Ang IV. Although the best compounds still exert lower activities than Ang IV, it is notable that these compounds comprise only two amino acid residues and are considerably less peptidic in character than the majority of the Ang IV analogues previously reported as IRAP inhibitors in the literature.
    Bioorganic & medicinal chemistry 06/2008; 16(14):6924-35. · 2.82 Impact Factor
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    ABSTRACT: We have recently identified a specific binding site for the tachykinin peptide substance P (SP) fragment SP(1-7) in the rat spinal cord. This site appeared very specific for SP(1-7) as the binding affinity of this compound highly exceeded those of other SP fragments. We also observed that endomorphin-2 (EM-2) exhibited high potency in displacing SP(1-7) from this site. In the present work using a [(3)H]-labeled derivative of the heptapeptide we have identified and characterized [(3)H]-SP(1-7) binding in the rat ventral tegmental area (VTA). Similarly to the [(3)H]-SP(1-7) binding in the spinal cord the affinity of unlabeled SP(1-7) to the specific site in VTA was significantly higher than those of other SP fragments. Further, the tachykinin receptor NK-1, NK-2 and NK-3 ligands showed no or negligible binding to the identified site. However, the mu-opioid peptide (MOP) receptor agonists DAMGO, EM-1 and EM-2 did, and significant difference was observed in the binding affinity between the two endomorphins. As recorded from displacement curves the affinity of EM-2 for the SP(1-7) site was 4-5 times weaker than that for SP(1-7) but about 5 times higher than that of EM-1. The opioid receptor antagonists naloxone and naloxonazine showed weak or negligible binding. It was concluded that the specific site identified for SP(1-7) binding in the rat VTA is distinct from the MOP receptor although it exhibits high affinity for EM-2.
    Peptides 06/2008; 29(10):1820-4. · 2.52 Impact Factor
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    ABSTRACT: Some of the biological effects demonstrated after administration of substance P (SP) in vivo can indirectly be attributed to the fragmentation of the undecapeptide to its N-terminal bioactive fragment SP(1-7). This heptapeptide (H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-OH) is a major bioactive metabolite from SP that frequently exerts similar biological effects as the parent peptide but also, in several cases, completely opposite actions. Specific binding sites for the heptapeptide SP(1-7) that are separate from the SP preferred NK receptors have been identified. In this study we demonstrate that (a) the C-terminal part of the SP metabolite SP(1-7) is most important for binding as deduced from an Ala scan and that a replacement of Phe(7) for Ala is deleterious, (b) truncation of the N-terminal amino acid residues of SP(1-7) delivers peptides with retained binding activity, although with somewhat lower binding affinities than SP(1-7) and (c) a C-terminal amide group as a replacement for the terminal carboxy group of SP(1-7) and for all of the truncated ligands synthesized affords approximately 5-10-fold improvements of the binding affinities.
    Neuropeptides 03/2008; 42(1):31-7. · 2.07 Impact Factor
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    ABSTRACT: Angiotensin IV analogs encompassing aromatic scaffolds replacing parts of the backbone of angiotensin IV have been synthesized and evaluated in biological assays. Several of the ligands displayed high affinities to the insulin-regulated aminopeptidase (IRAP)/AT(4) receptor. Displacement of the C-terminal of angiotensin IV with an o-substituted aryl acetic acid derivative delivered the ligand 4, which exhibited the highest binding affinity (K(i) = 1.9 nM). The high affinity of this ligand provides support to the hypothesis that angiotensin IV adopts a gamma-turn in the C-terminal of its bioactive conformation. Ligand (4) inhibits both human IRAP and aminopeptidase N-activity and induces proliferation of adult neural stem cells at low concentrations. Furthermore, ligand 4 is degraded considerably more slowly in membrane preparations than angiotensin IV. Hence, it might constitute a suitable research tool for biological studies of the (IRAP)/AT(4) receptor.
    Journal of Peptide Science 08/2007; 13(7):434-44. · 2.07 Impact Factor
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    ABSTRACT: Four tripeptides corresponding to the C-terminal region of angiotensin II were synthesized. One of these peptides (Ac-His-Pro-Ile) showed moderate binding affinity for the AT2 receptor. Two aromatic histidine-related scaffolds were synthesized and introduced in the tripeptides to give eight new peptidomimetic structures. Three of the new peptide-derived druglike molecules exhibited selective, nanomolar affinity for the AT2 receptor. These ligands may become lead compounds in the future development of novel classes of selective AT2 receptor agonists.
    Journal of Medicinal Chemistry 05/2007; 50(7):1711-5. · 5.61 Impact Factor
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    ABSTRACT: Molecular modeling and inhibitory potencies of tetrapeptide protease inhibitors of HCV NS3 proposed phenylglycine as a new promising P2 residue. The results suggest that phenylglycine might be capable of interacting with the NS3 (protease-helicase/NTPase) in ways not possible for the common P2 proline-based inhibitors. Thus, a series of tripeptides, both linear and macrocyclic, based on p-hydroxy-phenylglycine in the P2 position were prepared and their inhibitory effect determined. When the p-hydroxy group was replaced by methoxy, isoquinolin-, or quinolinyloxy functions, inhibitors with improved potencies were obtained. The P2 phenylglycine-based inhibitors were further optimized by C-terminal extension to acyl sulfonamides and by P1-P3 cyclization, which gave products with inhibition constants in the nanomolar range ( approximately 75nM).
    Bioorganic & Medicinal Chemistry 03/2007; 15(3):1448-74. · 2.90 Impact Factor

Publication Stats

308 Citations
148.45 Total Impact Points

Institutions

  • 1992–2014
    • Uppsala University
      • • Department of Medicinal Chemistry
      • • Department of Pharmaceutical Biosciences
      • • Division of Analytical Pharmaceutical Chemistry
      Uppsala, Uppsala, Sweden
  • 2006
    • Université de Sherbrooke
      • Division of Endocrinology
      Sherbrooke, Quebec, Canada