Prevalence of type 2 diabetes has increased dramatically in the last decades. Current medicines a... more Prevalence of type 2 diabetes has increased dramatically in the last decades. Current medicines are not yet capable to efficiently prevent or reverse progression of the disease and its associated comorbidities. As a consequence, there is a great need for novel antidiabetic drugs. Treatments of type 2 diabetes that are based on enhanced and sustained action of insulinotropic incretin hormones such as GLP-1 have received much attention in the past years. Treatment strategies include administration of: 1) GLP-1 analogues that are resistant to degradation by the serine protease DPP-IV, and 2) small molecule DPP-IV inhibitors that are able to provide sustained action of endogenous GLP-1, again by preventing its degradation. This review summarizes recent research results for the second approach. It briefly touches upon the advantages that treatment of type 2 diabetes with DPP-IV inhibitors may offer over current medications. In the main section, several important structural classes of DPP-IV inhibitors are described and compared based on literature data. Specific attention is given to the analysis of several X-ray structures of enzyme-inhibitor co-crystals. Finally, as clinical data are steadily emerging for some of the most advanced development candidates, the last section of this review is providing a brief overview of some efficacy data from recent clinical studies with DPP-IV inhibitors.
Inhibition of dipeptidyl peptidase IV (DPP-IV), the main glucagon-like peptide 1 (GLP1)-degrading... more Inhibition of dipeptidyl peptidase IV (DPP-IV), the main glucagon-like peptide 1 (GLP1)-degrading enzyme, has been proposed for the treatment of type II diabetes. We expressed and purified the ectodomain of human DPP-IV in Pichia pastoris and determined the X-ray structure at 2.1 A resolution. The enzyme consists of two domains, the catalytic domain, with an alpha/beta hydrolase fold, and a beta propeller domain with an 8-fold repeat of a four-strand beta sheet motif. The beta propeller domain contributes two important functions to the molecule that have not been reported for such structures, an extra beta sheet motif that forms part of the dimerization interface and an additional short helix with a double Glu sequence motif. The Glu motif provides recognition and a binding site for the N terminus of the substrates, as revealed by the complex structure with diprotin A, a substrate with low turnover that is trapped in the tetrahedral intermediate of the reaction in the crystal.
Junctional adhesion molecules (JAMs) are a family of immunoglobulin-like single-span transmembran... more Junctional adhesion molecules (JAMs) are a family of immunoglobulin-like single-span transmembrane molecules that are expressed in endothelial cells, epithelial cells, leukocytes and myocardia. JAM has been suggested to contribute to the adhesive function of tight junctions and to regulate leukocyte trans migration. We describe the crystal structure of the recombinant extracellular part of mouse JAM (rsJAM) at 2.5 A resolution. rsJAM consists of two immunoglobulin-like domains that are connected by a conformationally restrained short linker. Two rsJAM molecules form a U-shaped dimer with highly complementary interactions between the N-terminal domains. Two salt bridges are formed in a complementary manner by a novel dimerization motif, R(V,I,L)E, which is essential for the formation of rsJAM dimers in solution and common to the known members of the JAM family. Based on the crystal packing and studies with mutant rsJAM, we propose a model for homophilic adhesion of JAM. In this model...
Venom-derived peptide toxins can modify the gating characteristics of excitatory channels in neur... more Venom-derived peptide toxins can modify the gating characteristics of excitatory channels in neurons. How they bind and interfere with the flow of ions without directly blocking the ion permeation pathway remains elusive. Here we report the crystal structure of the trimeric chicken Acid-sensing ion channel 1 in complex with the highly selective gating modifier Psalmotoxin 1 at 3.0 Å resolution. The structure reveals the molecular interactions of three toxin molecules binding at the proton-sensitive acidic pockets of Acid-sensing ion channel 1 and electron density consistent with a cation trapped in the central vestibule above the ion pathway. A hydrophobic patch and a basic cluster are the key structural elements of Psalmotoxin 1 binding, locking two separate regulatory regions in their relative, desensitized-like arrangement. Our results provide a general concept for gating modifier toxin binding suggesting that both surface motifs are required to modify the gating characteristics of an ion channel.
Novel hexahydrospiro[piperidine-4,1&a... more Novel hexahydrospiro[piperidine-4,1'-pyrrolo[3,4-c]pyrroles that act as potent and selective orphanin FQ/nociceptin (N/OFQ) receptor (NOP) agonists were identified. The best compound, (+)-5a, potently inhibited 3H-N/OFQ binding to the NOP receptor (K(i) = 0.49 nM) but was >1000-fold less potent in binding to MOP, KOP, and DOP opiate receptors. Further, (+)-5a potently stimulated GTP gamma S binding to NOP membranes (EC50 = 65 nM) and inhibited forskolin-mediated cAMP accumulation in NOP-expressing cells (EC50 = 9.1 nM) with a potency comparable to that of the natural peptide agonist N/OFQ. These results indicate that (+)-5a is a highly selective and potent small-molecule full agonist of the NOP receptor.
ABSTRACT Starting from (−)-quinic acid, the title compound was synthesized in seven chemical step... more ABSTRACT Starting from (−)-quinic acid, the title compound was synthesized in seven chemical steps and an overall yield of 35−38%. The route of the improved Gilead synthesis was not changed. However, significant improvements in each step led to a doubled overall yield, a 30% reduction in the number of unit operations, and an excellent quality (≥99%) of the resulting epoxide. A highly regioselective method for the dehydration of a quinic acid to a shikimic acid derivative and for the reduction of a cyclic ketal was found. Alternatively, the title compound was synthesized in six chemical steps and 63−65% yield from commercially available (−)-shikimic acid. Compared to the optimized quinic acid route, the production time was reduced by about 50%. The quality of epoxide produced from either natural product was equivalent. Therefore (−)-shikimic acid is the preferred raw material. The absolute configuration of the epoxide was determined by X-ray single crystal structure analysis and it was demonstrated that the epoxide was stereoisomerically pure.
The development of 8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]d... more The development of 8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-ones 3 starting from (RS)-8-acenaphten-1-yl-1-phenyl-1,3, 8-triazaspiro[4.5]decan-4-one 1 is reported. The synthesis and the binding affinities at human OFQ and opioid (micro, kappa, delta) receptors of the stereoisomers 3a-f are described. In vitro the most selective compound, (1S,3aS)-8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-one 3c, was found to act as a full agonist at the OFQ receptor in the GTPgamma(35)S binding test. It turned out to be selective versus a variety of other neurotransmitter systems. When tested in vivo following intraperitoneal injection, compound 3c was found to decrease neophobia in a novel environment and to exhibit dose-dependent anxiolytic-like effects in the elevated plus-maze procedure, thus confirming the effects observed following intracerebroventricular infusion of the OFQ peptide in rat.
Prevalence of type 2 diabetes has increased dramatically in the last decades. Current medicines a... more Prevalence of type 2 diabetes has increased dramatically in the last decades. Current medicines are not yet capable to efficiently prevent or reverse progression of the disease and its associated comorbidities. As a consequence, there is a great need for novel antidiabetic drugs. Treatments of type 2 diabetes that are based on enhanced and sustained action of insulinotropic incretin hormones such as GLP-1 have received much attention in the past years. Treatment strategies include administration of: 1) GLP-1 analogues that are resistant to degradation by the serine protease DPP-IV, and 2) small molecule DPP-IV inhibitors that are able to provide sustained action of endogenous GLP-1, again by preventing its degradation. This review summarizes recent research results for the second approach. It briefly touches upon the advantages that treatment of type 2 diabetes with DPP-IV inhibitors may offer over current medications. In the main section, several important structural classes of DPP-IV inhibitors are described and compared based on literature data. Specific attention is given to the analysis of several X-ray structures of enzyme-inhibitor co-crystals. Finally, as clinical data are steadily emerging for some of the most advanced development candidates, the last section of this review is providing a brief overview of some efficacy data from recent clinical studies with DPP-IV inhibitors.
Inhibition of dipeptidyl peptidase IV (DPP-IV), the main glucagon-like peptide 1 (GLP1)-degrading... more Inhibition of dipeptidyl peptidase IV (DPP-IV), the main glucagon-like peptide 1 (GLP1)-degrading enzyme, has been proposed for the treatment of type II diabetes. We expressed and purified the ectodomain of human DPP-IV in Pichia pastoris and determined the X-ray structure at 2.1 A resolution. The enzyme consists of two domains, the catalytic domain, with an alpha/beta hydrolase fold, and a beta propeller domain with an 8-fold repeat of a four-strand beta sheet motif. The beta propeller domain contributes two important functions to the molecule that have not been reported for such structures, an extra beta sheet motif that forms part of the dimerization interface and an additional short helix with a double Glu sequence motif. The Glu motif provides recognition and a binding site for the N terminus of the substrates, as revealed by the complex structure with diprotin A, a substrate with low turnover that is trapped in the tetrahedral intermediate of the reaction in the crystal.
Junctional adhesion molecules (JAMs) are a family of immunoglobulin-like single-span transmembran... more Junctional adhesion molecules (JAMs) are a family of immunoglobulin-like single-span transmembrane molecules that are expressed in endothelial cells, epithelial cells, leukocytes and myocardia. JAM has been suggested to contribute to the adhesive function of tight junctions and to regulate leukocyte trans migration. We describe the crystal structure of the recombinant extracellular part of mouse JAM (rsJAM) at 2.5 A resolution. rsJAM consists of two immunoglobulin-like domains that are connected by a conformationally restrained short linker. Two rsJAM molecules form a U-shaped dimer with highly complementary interactions between the N-terminal domains. Two salt bridges are formed in a complementary manner by a novel dimerization motif, R(V,I,L)E, which is essential for the formation of rsJAM dimers in solution and common to the known members of the JAM family. Based on the crystal packing and studies with mutant rsJAM, we propose a model for homophilic adhesion of JAM. In this model...
Venom-derived peptide toxins can modify the gating characteristics of excitatory channels in neur... more Venom-derived peptide toxins can modify the gating characteristics of excitatory channels in neurons. How they bind and interfere with the flow of ions without directly blocking the ion permeation pathway remains elusive. Here we report the crystal structure of the trimeric chicken Acid-sensing ion channel 1 in complex with the highly selective gating modifier Psalmotoxin 1 at 3.0 Å resolution. The structure reveals the molecular interactions of three toxin molecules binding at the proton-sensitive acidic pockets of Acid-sensing ion channel 1 and electron density consistent with a cation trapped in the central vestibule above the ion pathway. A hydrophobic patch and a basic cluster are the key structural elements of Psalmotoxin 1 binding, locking two separate regulatory regions in their relative, desensitized-like arrangement. Our results provide a general concept for gating modifier toxin binding suggesting that both surface motifs are required to modify the gating characteristics of an ion channel.
Novel hexahydrospiro[piperidine-4,1&a... more Novel hexahydrospiro[piperidine-4,1'-pyrrolo[3,4-c]pyrroles that act as potent and selective orphanin FQ/nociceptin (N/OFQ) receptor (NOP) agonists were identified. The best compound, (+)-5a, potently inhibited 3H-N/OFQ binding to the NOP receptor (K(i) = 0.49 nM) but was >1000-fold less potent in binding to MOP, KOP, and DOP opiate receptors. Further, (+)-5a potently stimulated GTP gamma S binding to NOP membranes (EC50 = 65 nM) and inhibited forskolin-mediated cAMP accumulation in NOP-expressing cells (EC50 = 9.1 nM) with a potency comparable to that of the natural peptide agonist N/OFQ. These results indicate that (+)-5a is a highly selective and potent small-molecule full agonist of the NOP receptor.
ABSTRACT Starting from (−)-quinic acid, the title compound was synthesized in seven chemical step... more ABSTRACT Starting from (−)-quinic acid, the title compound was synthesized in seven chemical steps and an overall yield of 35−38%. The route of the improved Gilead synthesis was not changed. However, significant improvements in each step led to a doubled overall yield, a 30% reduction in the number of unit operations, and an excellent quality (≥99%) of the resulting epoxide. A highly regioselective method for the dehydration of a quinic acid to a shikimic acid derivative and for the reduction of a cyclic ketal was found. Alternatively, the title compound was synthesized in six chemical steps and 63−65% yield from commercially available (−)-shikimic acid. Compared to the optimized quinic acid route, the production time was reduced by about 50%. The quality of epoxide produced from either natural product was equivalent. Therefore (−)-shikimic acid is the preferred raw material. The absolute configuration of the epoxide was determined by X-ray single crystal structure analysis and it was demonstrated that the epoxide was stereoisomerically pure.
The development of 8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]d... more The development of 8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-ones 3 starting from (RS)-8-acenaphten-1-yl-1-phenyl-1,3, 8-triazaspiro[4.5]decan-4-one 1 is reported. The synthesis and the binding affinities at human OFQ and opioid (micro, kappa, delta) receptors of the stereoisomers 3a-f are described. In vitro the most selective compound, (1S,3aS)-8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-one 3c, was found to act as a full agonist at the OFQ receptor in the GTPgamma(35)S binding test. It turned out to be selective versus a variety of other neurotransmitter systems. When tested in vivo following intraperitoneal injection, compound 3c was found to decrease neophobia in a novel environment and to exhibit dose-dependent anxiolytic-like effects in the elevated plus-maze procedure, thus confirming the effects observed following intracerebroventricular infusion of the OFQ peptide in rat.
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