(2R)-4-Oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a] pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine: A potent, orally active dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes

Journal of Medicinal Chemistry

Volumn 48, Issue 1, 2005, Pages 141-151

  Kim, Dooseop ^a,b   Wang, Liping ^a,b   Beconi, Maria ^a,b   Eiermann, George J ^a,b   Fisher, Michael H ^a,b   He, Huaibing ^a,b   Hickey, Gerard J ^a,b   Kowalchick, Jennifer E ^a,b   Leiting, Barbara ^a,b   Lyons, Kathryn ^a,b   Marsilio, Frank ^a,b   McCann, Margaret E ^a,b   Patel, Reshma A ^a,b   Petrov, Aleksandr ^a,b   Scapin, Giovanna ^a,b   Patel, Sangita B ^a,b   Roy, Ranabir Sinha ^a,b   Wu, Joseph K ^a,b   Wyvratt, Matthew J ^a,b   Zhang, Bei B ^a,b   Zhu, Lan ^a,b   Thornberry, Nancy A ^a,b   Weber, Ann E ^a,b   more..

^a MERCK RESEARCH LABORATORIES   (United States)

^b Mail Code RY800 C206 ^*

Author keywords

[No Author keywords available]

Indexed keywords

4 OXO 4 [3 (TRIFLUOROMETHYL) 5,6 DIHYDRO[1,2,4]TRIAZOLO[4,3 ALPHA]PYRAZIN 7(8H) YL] 1 (2,4,5 TRIFLUOROPHENYL)BUTAN 2 AMINE; DIPEPTIDYL PEPTIDASE IV INHIBITOR; SITAGLIPTIN; UNCLASSIFIED DRUG;

ANIMAL EXPERIMENT; ANIMAL MODEL; ARTICLE; CONTROLLED STUDY; DOG; DRUG BIOAVAILABILITY; DRUG EFFECT; DRUG EFFICACY; DRUG INHIBITION; DRUG MECHANISM; DRUG POTENCY; DRUG SELECTIVITY; DRUG STRUCTURE; DRUG SYNTHESIS; ENZYME INHIBITION; IN VIVO STUDY; MALE; MONKEY; MOUSE; NON INSULIN DEPENDENT DIABETES MELLITUS; NONHUMAN; RAT;

ADMINISTRATION, ORAL; ANIMALS; ANTIGENS, CD26; BINDING SITES; BIOCHEMISTRY; BLOOD GLUCOSE; CRYSTALLOGRAPHY, X-RAY; DIABETES MELLITUS, TYPE 2; DOGS; DOSE-RESPONSE RELATIONSHIP, DRUG; DRUG EVALUATION, PRECLINICAL; ENZYME INHIBITORS; GLUCAGON; GLUCAGON-LIKE PEPTIDE 1; GLUCOSE TOLERANCE TEST; HYPOGLYCEMIC AGENTS; MICE; MICE, INBRED C57BL; MODELS, MOLECULAR; PEPTIDE FRAGMENTS; PROTEIN CONFORMATION; PROTEIN PRECURSORS; PYRAZINES; RATS; STRUCTURE-ACTIVITY RELATIONSHIP; TRIAZOLES;

EID: 19944427998     PISSN: 00222623     EISSN: None     Source Type: Journal    
DOI: 10.1021/jm0493156     Document Type: Article

References (54)

1. (a) Orsakov C. Glucagon-Like Peptide 1, a New Hormone of the Enteroinsular Axis. Diabetologia 1992, 35, 701-711.
2. (b) Zander, M.; Madsbad, S.; Madsen, J. L.; Holst, J. J. Effect of 6-Week Course of Glucagon-Like Peptide 1 on Glycaemic Control, Insulin Sensitivity, and β-Cell Function in Type 2 Diabetes; a Parallel-Group Study. The Lancet 2002, 359, 824-830.
3. For recent reviews see: (a) Holst, J. J. Glucagon-Like Peptide 1 (GLP-1) a Newly Discovered GI Hormone. Gastroenterology 1994, 107, 1048-1055. (b) Drucker, D. J. Glucagon-Like Peptides. Diabetes 1998, 47, 159-169. (c) Deacon, C. F.; Holst, J. J.; Carr, R. D. Glucagon-Like Peptide 1: A Basis for New Approaches to the Management of Diabetes. Drugs of Today 1999. 35, 159-170. (d) Livingston, J. N.; Schoen, W. R. Glucagon and Glucagon-like Peptide-1. Annu. Rep. Med. Chem. 1999, 34, 189-198.
4. For recent reviews see: (a) Holst, J. J. Glucagon-Like Peptide 1 (GLP-1) a Newly Discovered GI Hormone. Gastroenterology 1994, 107, 1048-1055. (b) Drucker, D. J. Glucagon-Like Peptides. Diabetes 1998, 47, 159-169. (c) Deacon, C. F.; Holst, J. J.; Carr, R. D. Glucagon-Like Peptide 1: A Basis for New Approaches to the Management of Diabetes. Drugs of Today 1999. 35, 159-170. (d) Livingston, J. N.; Schoen, W. R. Glucagon and Glucagon-like Peptide-1. Annu. Rep. Med. Chem. 1999, 34, 189-198.
5. For recent reviews see: (a) Holst, J. J. Glucagon-Like Peptide 1 (GLP-1) a Newly Discovered GI Hormone. Gastroenterology 1994, 107, 1048-1055. (b) Drucker, D. J. Glucagon-Like Peptides. Diabetes 1998, 47, 159-169. (c) Deacon, C. F.; Holst, J. J.; Carr, R. D. Glucagon-Like Peptide 1: A Basis for New Approaches to the Management of Diabetes. Drugs of Today 1999. 35, 159-170. (d) Livingston, J. N.; Schoen, W. R. Glucagon and Glucagon-like Peptide-1. Annu. Rep. Med. Chem. 1999, 34, 189-198.
6. For recent reviews see: (a) Holst, J. J. Glucagon-Like Peptide 1 (GLP-1) a Newly Discovered GI Hormone. Gastroenterology 1994, 107, 1048-1055. (b) Drucker, D. J. Glucagon-Like Peptides. Diabetes 1998, 47, 159-169. (c) Deacon, C. F.; Holst, J. J.; Carr, R. D. Glucagon-Like Peptide 1: A Basis for New Approaches to the Management of Diabetes. Drugs of Today 1999. 35, 159-170. (d) Livingston, J. N.; Schoen, W. R. Glucagon and Glucagon-like Peptide-1. Annu. Rep. Med. Chem. 1999, 34, 189-198.
7. (a) Wettergren, A.; Schjoldager, B.; Martensen, P. E.; Myhre, J.; Christiansen, J.; Holst, J. J. Truncated GLP-1 (Proglucagon 72-107 Amide) Inhibits Gastric and Pancreatic Functions in Man. Dig. Dis. Sci. 1993, 38, 665-673.
8. (b) Nauck, M. A.; Niedereichholz, U., Ettler, R.; Holst, J. J.; Orskov, C.; Ritzel, R.; Schmigel, W. H. Glucagon-Like Peptide-1 Inhibition of Gastric-Emptying Outweighs Its Insulinotropic Effects in Healthy Humans. Am. J. Physiol. 1997, 273, E981-E988.
9. Flint, A.; Raben, A.; Ersboll, A. K.; Holst, J. J.; Astrup, A. The Effect of Physiological Levels of Glucagons-Like Peptide-1 on Appetite, Gastric Emptying, Energy and Substrate Metabolism in Obesity. Int. J. Obes. 2001, 25, 781-792.
10. (a) Reimer, M. K..; Holst, J. J.; Ahren, B. Long-Term Inhibition of Dipeptidyl Peptidase IV Improves Glucose Tolerance and Preservesislet Function in Mice. Eur. J. Endocrin. 2002, 146, 717-727.
11. (b) Pospisilik, J. A.; Martin, J.; Doty, T.; Ehses, J. A.; Pamir, N.; Lynn, F. C.; Piteau, S.; Demuth, H.-U.; McIntosh, C. H. S.; Pederson, R. A. Dipeptidyl Peptidase IV Inhibitor Treatment Stimulates β-Cell Survival and Islet Neogenesis in Streptozotocin-Induced Diabetic Rats. Diabetes 2003, 52, 741-750.
12. (a) Kieffer, T. J.; McIntosh, C. H. S.; Pederson, T. A. Degradation of Glucose-Dependent Insulinotropic Polypeptide and Truncated Glucagon-Like Peptide 1 In Vitro and In Vivo by Dipeptidyl Peptidase IV. Endocrinology 1995, 136, 3585-3596.
13. 2-Terminus in Type II Diabetic Patients and in Healthy Subjects. Diabetes 1995, 44, 1126-1131.
14. For recent reviews see: (a) Villhauer, E. B.; Coppola, G. M.; Hughes, T. E. DPP-IV Inhibition and Therapeutic Potential. Annu. Rep. Med. Chem. 2001, 36, 191-200. (b) Drucker, D. J. Therapeutic Potential of Dipeptidyl Peptidase IV Inhibitors for the Treatment of Type 2 Diabetes. Exp. Opin. Investig. Drugs 2003, 12, 87-100. (c) Sorbera, L. A.; Revel, L.; Castaner, J. P32/ 98: Antidiabetic Dipeptidyl-Peptidase IV Inhibitor. Drugs Future 2001, 26, 859-864. (d) Weber, A. E. Dipeptidyl Peptidase IV Inhibitors for the Treatment of Diabetes. J. Med. Chem. 2004, 47, in press.
15. For recent reviews see: (a) Villhauer, E. B.; Coppola, G. M.; Hughes, T. E. DPP-IV Inhibition and Therapeutic Potential. Annu. Rep. Med. Chem. 2001, 36, 191-200. (b) Drucker, D. J. Therapeutic Potential of Dipeptidyl Peptidase IV Inhibitors for the Treatment of Type 2 Diabetes. Exp. Opin. Investig. Drugs 2003, 12, 87-100. (c) Sorbera, L. A.; Revel, L.; Castaner, J. P32/ 98: Antidiabetic Dipeptidyl-Peptidase IV Inhibitor. Drugs Future 2001, 26, 859-864. (d) Weber, A. E. Dipeptidyl Peptidase IV Inhibitors for the Treatment of Diabetes. J. Med. Chem. 2004, 47, in press.
16. For recent reviews see: (a) Villhauer, E. B.; Coppola, G. M.; Hughes, T. E. DPP-IV Inhibition and Therapeutic Potential. Annu. Rep. Med. Chem. 2001, 36, 191-200. (b) Drucker, D. J. Therapeutic Potential of Dipeptidyl Peptidase IV Inhibitors for the Treatment of Type 2 Diabetes. Exp. Opin. Investig. Drugs 2003, 12, 87-100. (c) Sorbera, L. A.; Revel, L.; Castaner, J. P32/ 98: Antidiabetic Dipeptidyl-Peptidase IV Inhibitor. Drugs Future 2001, 26, 859-864. (d) Weber, A. E. Dipeptidyl Peptidase IV Inhibitors for the Treatment of Diabetes. J. Med. Chem. 2004, 47, in press.
17. For recent reviews see: (a) Villhauer, E. B.; Coppola, G. M.; Hughes, T. E. DPP-IV Inhibition and Therapeutic Potential. Annu. Rep. Med. Chem. 2001, 36, 191-200. (b) Drucker, D. J. Therapeutic Potential of Dipeptidyl Peptidase IV Inhibitors for the Treatment of Type 2 Diabetes. Exp. Opin. Investig. Drugs 2003, 12, 87-100. (c) Sorbera, L. A.; Revel, L.; Castaner, J. P32/ 98: Antidiabetic Dipeptidyl-Peptidase IV Inhibitor. Drugs Future 2001, 26, 859-864. (d) Weber, A. E. Dipeptidyl Peptidase IV Inhibitors for the Treatment of Diabetes. J. Med. Chem. 2004, 47, in press.
18. (a) Zhao, K.; Lim, D. S.; Funaki, T.; Welch, J. T. Inhibition of Dipeptidyl Peptidase IV (DPP-IV) by 2-(2-Amino-1-fluoro-propylidene)- cyclopetanecarbonitrile, a Fluoroolefin Containing Peptidomimetic. Bioorg. Med. Chem. 2003, 11, 207-215.
19. 5-Fold Activity Increase by Optimization of Aromatic Substituents. Bioorg. Med. Chem. Lett. 2004, 14, 1491-1493.
20. (c) Peters, J.-U.; Hunziker, D.; Fischer, H.; Kansy, M.; Weber, S.; Kritter, S.; Müller, A.; Wallier, A.; Ricklin, F.; Boehringer, M.; Poli, S. M.; Csato, M.; Loeffler, B.-M. An Aminomethylpyrimidine DPP-IV Inhibitor with Improved Properties. Bioorg. Med. Chem. Lett. 2004, 14, 3757-3578.
21. (d) Peters, J.-U.; Weber, S.; Kritter, S.; Weiss, P.; A.; Wallier, A.; Zimmerli, D.; Boehringer, Steger, M.; Loeffler, B.-M. Aminomethylpyridines as DPP-IV inhibitors. Bioorg. Med. Chem. Lett. 2004, 14, 3579-3580.
22. (e) Coppola, G. M.; Zhang, Y. L.; Schuster, H. F.; Russell, M. E.; Hughes, T. E. 1-Aminomethylisoquinoline-4-carboxylates as Novel Dipeptidyl Peptidase IV Inhibitors. Bioorg. Med. Chem. Lett. 2000, 10, 1555-1558.
23. (f) Branner, K. A.; Carr, R. D.; Christiansen, L. B.; Elm, T.; Ribel, U. A Structurally Novel Dipeptidyl Peptidase IV Inhibitor: 7-Benzyl-1,3-dimethyl-8- piperazinoxanthine. Presented at the 28th National Medicinal Chemistry Symposium of the American Chemical Society, San Diego, CA, June 8-12, 2002; Abstract 72.
24. (a) Ashworth, D. M.; Atrash, B.; Baker, G. R.; Baxter, A. J.; Jenkins, P. D.; Jones, D. M.; Szelke, M. 4-Cyanothiazolidides as Very Potent, Stable Inhibitors of Dipeptidyl Peptidase IV. Bioorg. Med. Chem. Lett. 1996, 6, 2745-2748.
25. (b) Villhauer, E. B.; Brinkman, J. A.; Naderi, G. B.; Burkey, Dunning, B. E.; Mangold, B. L.; Mone, M. D.; Russell, M. E.; Weldon, S. C.; Hughes, T. E. 1-[2-[(5-Cyanopyridin-2-yl)amino]-ethylamino]-acetyl-2-acetyl]-2-(S) -pyrrolidine: A Potent Selective, and Orally Bioavailable Dipeptidyl Peptidase IV Inhibitor with Antihyperglycemic Properties. J. Med. Chem. 2002, 45, 2362-2365.
26. (c) Villhauer, E. B.; Brinkman, J. A.; Naderi, G. B.; Burkey, B. F.; Dunning, B. E.; Prasad, K.; Mangold, B. L.; Russell, M. E.; Hughes, T. E. 1-[[(3-Hydroxy-1-adamantyl)amino]acetyl]-2-cyano-(S)-pyrrolidine: A Potent Selective, and Orally Bioavailable Dipeptidyl Peptidase IV Inhibitor with Antihyperglycemic Properties. J. Med. Chem. 2003, 46, 2774-2789.
27. (d) Magnin, D. R.; Robl, J. A.; Sulsky, R. B.; Augeri, D. J.; Huang, Y.; Simpkins, L. M.; Taunk, P. C.; Betebenner, D. A.; Robertson, J. G.; Abboa-Offei, B. E.; Wang, A.; Cap, M.; Xin, L.; Tao, L.; Sitkoff, D. F.; Malley, M. F.; Gougoutas, J. Z.; Khanna, A.; Huang, Q.; Han, S.; Parker, R. A.; Hamann, L. G. Synthesis of Novel Potent Dipeptidyl Peptidase IV Inhibitors with Enhanced Chemical Stability: Interplay between the N-Terminal Amino Acid Alkyl Side Chain and the Cyclopropyl Group of α-Aminoacyl-L-cis-4,5-methanoprolinenitrile- Based Inhibitors. J. Med. Chem. 2004, 47, 2587.
28. (e) Parmee, E. R.; He, J.; Mastracchio, A.; Edmondson, S. D.; Colwell, L. E.; Eiermann, G.; Feeney, W. P.; Habulihaz, B.; He, H.; Kilburn, R.; Leiting, B.; Lyons, K.; Marsilio, F.; Patel, R.; Petrov, A.; di Salvo, J.; Wu, J. K.; Thornberry, N. A.; Weber, A. E. 4-Aminocyclohexylglycine Analogs as Potent Dipeptidyl Peptidase IV inhibitors. Bioorg. Med. Chem. Lett. 2004, 14, 43-46.
29. (f) Caldwell, C. G.; Chen, P.; He, J.; Parmee, E. R.; Leiting, B.; Marsilio, F.; Patel, R. A.; Wu, J. K.; Eiermann, G. J.; Petrov, A.; He, H.; Lyons, K. A.; Thornberry, N. A.; Weber, A. E. Fluoropyrrolidine Amides as Dipeptidyl Peptidase IV Inhibitors. Bioorg. Med. Chem. Lett. 2004, 14, 1265-1268.
30. (g) Ashton, W. T.; Dong, H.; Sisco, R. M.; Doss, G. A.; Leiting, B.; Patel, R. A.; Wu, J. K.; Marsilio, F.; Thornberry, N. A.;, Weber, A. E. Diasteroselective Synthesis and Configuration-Dependent Activity of (3-Substituted-cycloalkyl)glycine Pyrrolidides and Thiazolidides as Dipeptidyl Peptidase IV Inhibitors. Bioorg. Med. Chem. Lett. 2004, 14, 859-863.
31. (a) Xu, J.; Ok, H. O.; Gonzalez, E. J.; Colwell, L. F., Jr.; Habulihaz, B.; He, H.; Leiting, B.; Lyona, K. A.; Marsilio, F.; Patel, R. A.; Wu, J. K.; Thornberry, N. A.; Weber, A. E.; Parmee, E. R. Discovery of Potent and Selective β-Homophenylalanine Based Dipeptidyl Peptidase IV Inhibitors. Bioorg. Med. Chem. Lett. 2004, 14, 4759-4762.
32. (b) Brockunier, L.; He, J.; Colwell, L. F., Jr.; Habulihaz, B.; He, H.; Leiting, B.; Lyons, K. A.; Marsilio, F.; Patel, R.; Teffera, Y.; Wu, J. K.; Thornberry, N. A.; Weber, A. E.; Parmee, E. R. Substituted Piperazines as Novel Dipeptidyl Peptidase IV Inhibitors. Bioorg. Med. Chem. Lett. 2004, 14, 4763-4766.
33. Weber, A, E., Kim, D.; Beconi, M.; Eiermann, G.; Fisher, M.; He, H.; Hickey, G.; Jaspal, S.; Leiting, B.; Lyons, K.; Marsilio, F.; McCann, P.; Moller, D. E.; Patel, R.; Petrov, A.; Pryor, K.; Sinha Roy, R.; Wu, J. K; Wyvratt, M.; Zhang, B. B.; Thornberry, N. A. MK-0431 is a Potent, Selective Dipeptidyl Peptidase IV Inhibitor for the Treatment of Type 2 Diabetes. Presented at the American Diabetes Association 64th Scientific Session, Orlando, FL, June 4-8, 2004, Abstract 633-P.
34. U.S. Patent 6,699,871 B2, Mar 2, 2004.
35. Evans, D. A.; Britten, T. C.; Ellman, J. A.; Dorow, R. L. The Asymmetric Synthesis of α-Amino Acids. Electrophilic Azidation of Chiral Imide Enolates, a Practical Approach to the Synthesis of (R)- and (S)-α-Azido Carboxylic Acids. J. Am. Chem. Soc. 1990, 112, 4011.
36. Deng, C.; Groth, U.; Schöllkopf, U. Enantioselective Syntheses of (R)-Amino Acids Using L-Valine as Chiral Agent. Angw. Chem., Int. Ed. Engl. 1981, 20, 798-799.
37. Muller, A.; Vogt, C.; Sewald, N. Synthesis of Fmoc-β-Homoamino Acids by Ultrasound-Promoted Wolff Rearrangement. Synthesis 1988, 837-841.
38. Huynh-Dinh, T.; Sarfati, R. S.; Gouyette, C.; Igolen, J. Synthesis of C-Nucleosides. 17. s-Triazolo[4,3-a]pyrazines. J. Org. Chem. 1979, 44, 1028.
39. (a) Spingarn N. E.; Sartorelli, A. C. Synthesis and Evaluation of the Thiosemicarbazone, Dithiocarbazone, and 2′-Pyrazinyl-hydrazone of Pyrazinecarboxaldehyde as Agents for the Treatment of Iron Overload. J. Med. Chem. 1979, 22, 1314-1316.
40. (b) Nelson, P. J.; Potts, K. T. 1,2,4-Triazoles. VI. The Synthesis of Some s-Triazolo[4,3-a]pyrazines. J. Org. Chem. 1962, 27, 3243.
41. For assay conditions see: Leiting, B.; Pryor, K D.; Wu, J. K.; Marsilio, F.; Patel, R. A.; Craik, C. S.; Ellman, J. A.; Cummings, R. T. Thornberry, N. A. Catalytic Properties and Inhibition of Proline-Specific Dipeptidyl Peptidases II, IV and VII. Biochem. J. 2003, 371, 525-532
42. Abbot, C. A.; Yu, D. M.; Woollatt, E.; Sutherland, G. R.; McCaughan, G. W.; Gorrell, M. D. Cloning, Expression and Chromosomal Localization of a Novel Human Dipeptidyl Peptidase (DPP) IV Homolog, DPP8. Eur. J. Biochem. 2000b, 267, 6140-6150.
43. Olsen, C.; Wagtmann, N. Identification and Characterization of Human DPP9, a Novel Homologue of Dipeptidyl Peptidase IV. Gene, 2002, 299, 185-193.
44. Scallan, M. J.; Raj, B. K. M.; Calvo, B.; Garin-Chesa, P.; Sanz-Moncasi, M. P.; Healey, J. H.; Old, L. J.; Rettig, W. J. Molecular Cloning of Fibroblast Activation Protein Alpha, a Member of the Serine Protease Family Selectively Expressed in Stromal Fibroblast of Epithelical Cancers. Proc. Natl. Acad. Sci. U.S.A. 1994, 91, 5657-5661.
45. McDonald, J. K.; Leibach, F. H.; Grindeland, R. E.; Ellis, S. Purification of Dipeptidyl Aminopeptidase II (Dipeptidyl Arylamidase II) of the Anterior Pituitary Gland. J. Bio. Chem. 1968, 243, 4143-4150.
46. Lankas, G.; Leiting, B.; Sinha Roy, R.; Eiermann, G.; Biftu, T.; Kirn, D.; Ok, H.; Weber, A. E.; Thornberry, N. A. Inhibition of DPP8/9 Results in Toxicity in Preclinical Species: Potential Importance of Selective Dipeptidyl Peptidase IV Inhibition for Treatment of Type 2 DM. Presented at the American Diabetes Association 64th Scientific Session, Orlando, FL, June 4-8, 2004, Abstract 7-OR.
47. (a) Rasmussen, H. B.; Branner, S.; Wiberg, F. C.; Wagtmann, N. Crystal Structure of Human Dipeptidyl Peptidase IV/CD26 in Complex with a Substrate Analog. Nat. Struct. Biol. 2003, 10, 19-25.
48. (b) Engel, M.; Hoffmann, T.; Wagner, L.; Wermann, M.; Heiser, U.; Kiefersauer, R.; Huber, R.; Bode, W.; Demuth, H.-U.; Brandstetter, H. The Crystal Structure of Dipeptidyl Peptidase IV (CD26) Reveals Its Functional Regulation and Enzymatic Mechanism. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 5063-5068.
49. (c) Oefner, C.; D'Arcy, A.; MacSweeney, A.; Pierau, S.; Gardiner, R.; Dale, G. E. High-Resolution Structure of Human Apo Dipeptidyl peptidase IV/CD26 and Its Complex with l-[({2-[(5-lodopyridin-2-yl)amino]ethyl}amino)acetyl]-2- cyano-(S)-pyrrolidine. Acta Crystallogr. 2003, D59, 1206-1212.
50. (d) Thoma, R.; Löffler, B.; Stihle, M.; Huber, W.; Ruf, A.; Hennig, M. Structural Basis of Proline-Specific Exopeptidase Activity as Observed in Human Dipeptidyl Peptidase-IV. Structure 2003, 11, 947-959.
51. It should be noted that the % inhibition as determined using the in vitro assay underestimates the % inhibition achieved in vivo, as compound 1 is a competitive, rapidly reversible inhibitor and assay of plasma DPP-IV activity requires: (1) dilution of plasma which results in a dilution of the total inhibitor, and (2) presence of substrate that competes with inhibitor for binding to the enzyme.
52. Marguet, D.; Baggio, L.; Kobayashi, T.; Bernard, A.-M.; Pierres, M.; Nielsen, P. F.; Ribel, U.; Watanabe, T.; Drucker, D. J.; Wagtmann, N. Enhanced Insulin Secretion and Improved Glucose Tolerance in Mice Lacking CD26. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 6864-6879.
53. Vagin, A.; Teplyakov, A. MOLREP: an automated program for molecular replacement. J. Appl. Crystallogr. 1997, 30, 1022-1025.
54. Brünger, A. T.; Adams, P. D.; Clore, G. M.; DeLano, W. L.; Gros, P.; Grosse-Kunstleve, R. W.; Jiang, J.-S.; Kuszewski, J.; Nilges, M.; Pannu, N. S.; Read, R. J.; Rice, L. M.; Simonson, T.; Warren, G. L. Crystallography & NMR System: a New Software Suite for Macromolecular Structure Determination. Acta Crystallogr. 1988, D54, 905-921.