ABSTRACT
CONTEXT: The cryptolepines originate from the roots of the climbing shrub Cryptolepis sanguinolenta (Lindi) Schitr(Periplocaeae) which is used in Central and West Africa in traditional medicine for the treatment of malaria. OBJECTIVES: Evaluation for the first time of a series of chloro- and aminoalkylamino derivatives of neo- and norneocryptolepines for potential schistosomicidal and molluscicidal activities. MATERIALS AND METHODS: A series of chloro- and aminoalkylamino substituted neo- and norneocryptolepine derivatives were synthesized. They were tested in vitro against viable Schistosoma mansoni Sambon mature worms in culturemedium with fetal serum and antibiotics and in dechlorinated water against the snail vector Biomphalaria alexandrina Ehrenberg. Active compounds were further subjected to determination of their IC50 values. RESULTS: Results showed that six neocryptolepine and two norneocryptolepine derivatives had in vitro schistosomicidal activity on Egyptian and Puerto Rican strains of S. mansoni. The most effective derivative (2-chloro-5-methyl-N-(2-morpholin-4-ethyl)-5H-indolo[2,3b]quinoline-11-amine) has IC50 and IC90 1.26 and 4.05 µM and 3.54 and 6.83 µM with the Egyptian and Puerto Rican strains of Schistosoma, respectively. All eight derivatives showed molluscicidal activity against the vector snail B. alexandrina. The most active compound (2-chloro-11-(4-methylpiperazin-1-yl)-6H-indolo[2,3-b] quinoline) has LC50 0.6 and LC90 3.9 ppm after 24 h. DISCUSSION AND CONCLUSIONS: The findings demonstrate that introducing chloro- and aminoalkylamino side chain initiated both schistosomicidal and molluscicidal activities in these derivatives. The structureactivity relationship of this series of compounds is discussed.
Subject(s)
Alkaloids/pharmacology , Molluscacides/pharmacology , Quinolines/pharmacology , Schistosomicides/pharmacology , Alkaloids/administration & dosage , Alkaloids/chemical synthesis , Animals , Biomphalaria/drug effects , Cryptolepis/chemistry , Egypt , Inhibitory Concentration 50 , Lethal Dose 50 , Medicine, African Traditional , Molluscacides/administration & dosage , Molluscacides/chemical synthesis , Puerto Rico , Quinolines/administration & dosage , Quinolines/chemical synthesis , Schistosoma mansoni/drug effects , Schistosomicides/administration & dosage , Schistosomicides/chemical synthesis , Structure-Activity Relationship , Time FactorsABSTRACT
Recent drug discovery programs targeting urokinase plasminogen activator (uPA) have resulted in nonpeptidic inhibitors consisting of amidine or guanidine functional groups attached to aromatic or heteroaromatic scaffolds. There is a general problem of poor oral bioavailability of these charged inhibitors. In this paper, we report the synthesis and evaluation of a series of naphthamide and naphthalene sulfonamides as uPA inhibitors containing non-basic groups as substitute for amidine or guanidine groups.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Urokinase-Type Plasminogen Activator/antagonists & inhibitors , Amides/chemical synthesis , Amides/chemistry , Amides/pharmacology , Binding, Competitive , Biological Availability , Enzyme Inhibitors/chemistry , Hydrogen-Ion Concentration , Inhibitory Concentration 50 , Molecular Structure , Naphthalenes/chemical synthesis , Naphthalenes/chemistry , Naphthalenes/pharmacology , Protein Binding/drug effects , Sulfonamides/chemical synthesis , Sulfonamides/chemistry , Sulfonamides/pharmacologyABSTRACT
This work represents the first directed study to identify modification points in the topology of a representative DPP8/9-inhibitor, capable of rendering selectivity for DPP8 over DPP9. The availability of a DPP8-selective compound would be highly instrumental for studying and untwining the biological roles of DPP8 and DPP9 and for the disambiguation of biological effects of nonselective DPP-inhibitors that have mainly been ascribed to blocking of DPPIV's action. The cell-permeable DPP8/9-inhibitor 7 was selected as a lead and dissected into several substructures that were modified separately for evaluating their potential to contribute to selectivity. The obtained results, together with earlier work from our group, clearly narrow down the most probable DPP8-selectivity imparting modification points in DPP8/9 inhibitors to parts of space that are topologically equivalent to the piperazine ring system in 7. This information can be considered of high value for future design of compounds with maximal DPP8 selectivity.
Subject(s)
Dipeptidases/antagonists & inhibitors , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/antagonists & inhibitors , Isoindoles/chemistry , Isoindoles/pharmacology , Amino Acid Sequence , Dipeptidases/metabolism , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Humans , Isoindoles/chemical synthesis , Kinetics , Models, Chemical , Molecular Structure , Sequence Homology, Amino Acid , Structure-Activity RelationshipABSTRACT
Cysteine proteases of the papain superfamily are present in nearly all eukaryotes and also play pivotal roles in the biology of parasites. Inhibition of cysteine proteases is emerging as an important strategy to combat parasitic diseases such as sleeping sickness, Chagas disease, and leishmaniasis. Inspired by the inâ vivo antiparasitic activity of the vinylsulfone-based cysteine protease inhibitors, a series of α-ketoheterocycles were developed as reversible inhibitors of a recombinant L.â mexicana cysteine protease, CPB2.8. Three isoxazoles and especially one oxadiazole compound are potent reversible inhibitors of CPB2.8; however, inâ vitro whole-organism screening against a panel of protozoan parasites did not fully correlate with the observed inhibition of the cysteine protease.
Subject(s)
Antiprotozoal Agents/chemistry , Cysteine Proteases/chemistry , Cysteine Proteinase Inhibitors/chemistry , Heterocyclic Compounds/chemistry , Leishmania mexicana/enzymology , Antiprotozoal Agents/chemical synthesis , Antiprotozoal Agents/pharmacology , Cell Line , Cysteine Proteases/metabolism , Cysteine Proteinase Inhibitors/chemical synthesis , Cysteine Proteinase Inhibitors/pharmacology , Heterocyclic Compounds/chemical synthesis , Heterocyclic Compounds/pharmacology , Humans , Kinetics , Leishmania infantum/drug effects , Plasmodium falciparum/drug effects , Trypanosoma brucei brucei/drug effects , Trypanosoma cruzi/drug effectsABSTRACT
In this paper, we present the biochemical and biological evaluation of N-arylmethyl-substituted iminoribitol derivatives as potential chemotherapeutic agents against trypanosomiasis. Previously, a library of 52 compounds was designed and synthesized as potent and selective inhibitors of Trypanosoma vivax inosine-adenosine-guanosine nucleoside hydrolase (IAG-NH). However, when the compounds were tested against bloodstream-form Trypanosoma brucei brucei, only one inhibitor, N-(9-deaza-adenin-9-yl)methyl-1,4-dideoxy-1,4-imino-d-ribitol (UAMC-00363), displayed significant activity (mean 50% inhibitory concentration [IC(50)] +/- standard error, 0.49 +/- 0.31 microM). Validation in an in vivo model of African trypanosomiasis showed promising results for this compound. Several experiments were performed to investigate why only UAMC-00363 showed antiparasitic activity. First, the compound library was screened against T. b. brucei IAG-NH and inosine-guanosine nucleoside hydrolase (IG-NH) to confirm the previously demonstrated inhibitory effects of the compounds on T. vivax IAG-NH. Second, to verify the uptake of these compounds by T. b. brucei, their affinities for the nucleoside P1 and nucleoside/nucleobase P2 transporters of T. b. brucei were tested. Only UAMC-00363 displayed significant affinity for the P2 transporter. It was also shown that UAMC-00363 is concentrated in the cell via at least one additional transporter, since P2 knockout mutants of T. b. brucei displayed no resistance to the compound. Consequently, no cross-resistance to the diamidine or the melaminophenyl arsenical classes of trypanocides is expected. Third, three enzymes of the purine salvage pathway of procyclic T. b. brucei (IAG-NH, IG-NH, and methylthioadenosine phosphorylase [MTAP]) were investigated using RNA interference. The findings from all these studies showed that it is probably not sufficient to target only the nucleoside hydrolase activity to block the purine salvage pathway of T. b. brucei and that, therefore, it is possible that UAMC-00363 acts on an additional target.
Subject(s)
Adenosine/analogs & derivatives , Antiprotozoal Agents/pharmacokinetics , N-Glycosyl Hydrolases/antagonists & inhibitors , Trypanosoma brucei brucei/drug effects , Trypanosomiasis, African/drug therapy , Adenosine/chemistry , Adenosine/pharmacokinetics , Animals , Antiprotozoal Agents/chemistry , Carrier Proteins/metabolism , Gene Knockdown Techniques , Melarsoprol/chemistry , Mice , Models, Chemical , N-Glycosyl Hydrolases/genetics , Pentamidine/chemistry , RNA, Small Interfering , Trypanosoma brucei brucei/enzymology , Trypanosoma brucei brucei/genetics , Trypanosomiasis, African/metabolismABSTRACT
Metacaspase (MCA) is an important enzyme in Trypanosoma brucei, absent from humans and differing significantly from the orthologous human caspases. Therefore MCA constitutes a new attractive drug target for antiparasitic chemotherapeutics, which needs further characterization to support the discovery of innovative drug candidates. A first series of inhibitors has been prepared on the basis of known substrate specificity and the predicted catalytic mechanism of the enzyme. In this Letter we present the first inhibitors of TbMCA2 with low micromolar enzymatic and antiparasitic activity in vitro combined with low cytotoxicity.
Subject(s)
Caspase Inhibitors , Cysteine Proteinase Inhibitors/chemistry , Cysteine Proteinase Inhibitors/pharmacology , Trypanocidal Agents/chemistry , Trypanocidal Agents/pharmacology , Trypanosoma brucei brucei/enzymology , Animals , Caspases/metabolism , Catalysis , Drug Design , Substrate SpecificityABSTRACT
A series of chloro- and aminoalkylamino-substituted neocryptolepine (5-methyl-5H-indolo[2,3-b]quinoline) derivatives were synthesized and evaluated as antiplasmodial agents. The evaluation also included cytotoxicity (MRC5 cells), inhibition of beta-hematin formation, and DNA interactions (DNA-methyl green assay). Introduction of aminoalkylamino chains increased the antiplasmodial activity of the neocryptolepine core substantially. The most efficient compounds showed antiplasmodial activities in the nanomolar range. N(1),N(1)-Diethyl-N(4)-(5-methyl-5H-indolo[2,3-b]quinolin-8-yl)pentane-1,4-diamine 11c showed an IC(50) of 0.01 microM and a selectivity index of 1800.
Subject(s)
Alkaloids/chemical synthesis , Alkaloids/pharmacology , Antimalarials/chemical synthesis , Antimalarials/pharmacology , Drug Design , Plasmodium falciparum/drug effects , Quinolines/chemical synthesis , Quinolines/pharmacology , Alkaloids/chemistry , Alkaloids/metabolism , Animals , Antimalarials/chemistry , Antimalarials/metabolism , DNA, Protozoan/metabolism , Mice , Quinolines/chemistry , Quinolines/metabolismABSTRACT
Diseases caused by parasitic protozoa remain a major health problem, mainly due to old toxic drugs and rising drug resistance. Nucleoside hydrolases are key enzymes of the purine salvage pathway of parasites from the Trypanosomatidae family and are considered as possible drug targets. N-Arylmethyl substituted iminoribitols have been developed as selective nanomolar affinity inhibitors against the purine-specific nucleoside hydrolase of Trypanosoma vivax. The current paper describes the crystal structures of the T. vivax nucleoside hydrolase in complex with two of these inhibitors, to 1.3 and 1.85 A resolution. These high resolution structures provide an accurate picture of the mode of binding of these inhibitors and their mechanism of transition-state mimicry, and are valuable tools to guide further inhibitor design. Comparison of the current structures with previously solved structures of the enzyme in complex with ground-state and transition-state-analogue inhibitors also allows for the elucidation of a detailed molecular mechanism of active-site loop opening/closing. These loop movements can be coupled to the complex kinetic mechanism of the T. vivax nucleoside hydrolase.
Subject(s)
Enzyme Inhibitors/pharmacology , N-Glycosyl Hydrolases/chemistry , Trypanosoma vivax/enzymology , Animals , Crystallography, X-Ray , Enzyme Inhibitors/chemistry , Models, Molecular , N-Glycosyl Hydrolases/antagonists & inhibitors , Protein ConformationABSTRACT
The purine metabolism of Trypanosoma and Leishmania spp. provides a good target in the search for new selective drugs. Bicyclic N-arylmethyl-substituted iminoribitols were developed as inhibitors of T. vivax nucleoside hydrolase, a key enzyme of the purine salvage pathway. The obtained results and structure-activity data confirmed our model for inhibitor binding with a hydrogen bond between a nitrogen atom of the nucleobase mimetic and the protonated Asp40 from the enzyme. This interaction depends on an optimal pK(a) value, which can be influenced by the electronic properties of the substituents. These compounds are potent, selective inhibitors of nucleoside hydrolase and are inactive toward human nucleoside phosphorylase.
Subject(s)
Enzyme Inhibitors/chemical synthesis , N-Glycosyl Hydrolases/antagonists & inhibitors , Ribitol/analogs & derivatives , Enzyme Inhibitors/pharmacology , Magnetic Resonance Spectroscopy , Models, Molecular , Ribitol/chemical synthesis , Ribitol/pharmacology , Spectrometry, Mass, Electrospray IonizationABSTRACT
To obtain selective and potent inhibitors of dipeptidyl peptidases 8 and 9, we synthesized a series of substituted isoindolines as modified analogs of allo-Ile-isoindoline, the reference DPP8/9 inhibitor. The influence of phenyl substituents and different P2 residues on the inhibitors' affinity toward other DPPs and more specifically, their potential to discriminate between DPP8 and DPP9 will be discussed. Within this series compound 8j was shown to be a potent and selective inhibitor of DPP8/9 with low activity toward DPP II.
Subject(s)
Dipeptidases/antagonists & inhibitors , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Indoles/chemistry , Chemistry, Pharmaceutical/methods , Drug Design , Enzyme Inhibitors/chemistry , Humans , Inhibitory Concentration 50 , Lysine/chemistry , Models, Chemical , Molecular Structure , Nitriles/chemistry , Peptides/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Dipeptide derivatives bearing various P2 residues and pyrrolidine derivatives as P1 mimics were evaluated in order to identify lead structures for the development of DPP8 and DPP9 inhibitors. Structure-activity-relationship data obtained in this way led to the preparation of a series of alpha-aminoacyl ((2S, 4S)-4-azido-2-cyanopyrrolidines). These compounds were shown to be nanomolar DPP8/9 inhibitors with modest overall selectivity toward DPP IV and DPP II.
Subject(s)
Dipeptidases/antagonists & inhibitors , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Chemistry, Pharmaceutical/methods , Dipeptides/chemistry , Drug Design , Enzyme Inhibitors/chemistry , Humans , Inhibitory Concentration 50 , Lysine , Models, Chemical , Molecular Structure , Nitriles/chemistry , Peptides/chemistry , Pyrrolidines/chemistry , Structure-Activity RelationshipABSTRACT
A key enzyme within the purine salvage pathway of parasites, nucleoside hydrolase, is proposed as a good target for new antiparasitic drugs. We have developed N-arylmethyl-iminoribitol derivatives as a novel class of inhibitors against a purine specific nucleoside hydrolase from Trypanosoma vivax. Several of our inhibitors exhibited low nanomolar activity, with 1,4-dideoxy-1,4-imino-N-(8-quinolinyl)methyl-d-ribitol (UAMC-00115, K(i) 10.8nM), N-(9-deaza-adenin-9-yl)methyl-1,4-dideoxy-1,4-imino-d-ribitol (K(i) 4.1nM), and N-(9-deazahypoxanthin-9-yl)methyl-1,4-dideoxy-1,4-imino-d-ribitol (K(i) 4.4nM) being the three most active compounds. Docking studies of the most active inhibitors revealed several important interactions with the enzyme. Among these interactions are aromatic stacking of the nucleobase mimic with two Trp-residues, and hydrogen bonds between the hydroxyl groups of the inhibitors and amino acid residues in the active site. During the course of these docking studies we also identified a strong interaction between the Asp40 residue from the enzyme and the inhibitor. This is an interaction which has not previously been considered as being important.
Subject(s)
N-Glycosyl Hydrolases/antagonists & inhibitors , Ribitol/analogs & derivatives , Trypanocidal Agents/chemistry , Trypanosoma vivax/enzymology , Animals , Aspartic Acid , Binding Sites , Computer Simulation , Enzyme Inhibitors/chemistry , Hydrogen Bonding , Models, Molecular , Protein Binding , Ribitol/chemistry , Ribitol/pharmacology , Structure-Activity Relationship , TryptophanABSTRACT
A set of small nonpeptidic diaryl phosphonate inhibitors was prepared. Some of these inhibitors show potent and highly selective irreversible uPA inhibition. The biochemical and modeling data prove that the combination of a benzylguanidine moiety with a diaryl phosphonate ester results in optimized molecules for derivatizing the serine alcohol in the uPA active site. Selected compounds show significant antimetastatic effects in the BN-472 rat mammary carcinoma model. We report in this paper a preclinical proof of concept that selective, irreversible uPA inhibitors could be valuable in antimetastatic therapy.
Subject(s)
Antineoplastic Agents/chemical synthesis , Guanidines/chemical synthesis , Mammary Neoplasms, Animal/drug therapy , Organophosphonates/chemical synthesis , Urokinase-Type Plasminogen Activator/antagonists & inhibitors , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Female , Guanidines/chemistry , Guanidines/pharmacology , Mammary Neoplasms, Animal/pathology , Models, Molecular , Neoplasm Metastasis , Organophosphonates/chemistry , Organophosphonates/pharmacology , Rats , Structure-Activity RelationshipABSTRACT
Dipeptide-derived compounds, bearing various P2 residues and a diaryl pyrrolidin-2-yl phosphonate at the P1 position, were evaluated as dipeptidyl peptidase 8 (DPP8) inhibitors. With these products, irreversible inhibition of DPP8 was observed. To obtain inhibitors with an improved activity and selectivity profile, a set of selected analogues containing a diaryl isoindolin-1-ylphosphonate at P1 was synthesized and evaluated. Within this latter series, compound 2e was shown to be a potent, irreversible inhibitor of DPP8, demonstrating very low affinity for DPP IV and DPP II.
Subject(s)
Dipeptidases/antagonists & inhibitors , Dipeptides/chemical synthesis , Isoindoles/chemical synthesis , Organophosphonates/chemical synthesis , Pyrrolidines/chemical synthesis , Dipeptidases/chemistry , Dipeptides/chemistry , Isoindoles/chemistry , Kinetics , Organophosphonates/chemistry , Pyrrolidines/chemistry , Structure-Activity RelationshipABSTRACT
The synthesis of novel dipeptidyl alpha-fluorovinyl sulfones using a Horner-Wadsworth-Emmons approach on N-Boc-l-phenylalaninal is described. Inhibitory assays against a Leishmania mexicana cysteine protease (CPB2.8DeltaCTE) revealed low biological activity. Relative rates of Michael additions of 2'-(phenethyl)thiol with vinyl sulfone and alpha-fluorovinyl sulfone were determined, and ab initio calculations on several Michael acceptor model structures were performed; both were in agreement with the biological testing results.
Subject(s)
Cysteine Endopeptidases , Cysteine Proteinase Inhibitors/chemical synthesis , Dipeptides/chemical synthesis , Animals , Binding Sites/drug effects , Cysteine Endopeptidases/metabolism , Cysteine Proteinase Inhibitors/pharmacology , Dipeptides/pharmacology , Leishmania mexicana/drug effects , Leishmania mexicana/enzymology , Leishmania mexicana/growth & development , Leishmaniasis, Cutaneous/drug therapy , Leishmaniasis, Cutaneous/enzymology , Leishmaniasis, Cutaneous/parasitology , Models, MolecularABSTRACT
Dipeptidyl peptidase IV (DPP IV) is a validated target for the treatment of type 2 diabetes, with several inhibitors currently in phase 3 clinical trials. This review will mainly focus on proline-specific dipeptidyl peptidases related to DPP IV: fibroblast activation protein (FAP), dipeptidyl peptidase 8 (DPP8), dipeptidyl peptidase 9 (DPP9) and dipeptidyl peptidase II (DPP II). The biochemical and biological properties of these enzymes will be discussed, as well as the therapeutic potential of their inhibition. The development of potent and selective inhibitors for each of these peptidases will be described.
Subject(s)
Dipeptidyl Peptidase 4/metabolism , Serine Proteinase Inhibitors/pharmacology , Dipeptidyl Peptidase 4/chemistry , Dipeptidyl-Peptidase IV Inhibitors , Drug Design , HumansABSTRACT
This paper describes the structure-activity relationship in a series of tripeptidyl diphenyl phosphonate irreversible urokinase plasminogen activator (uPA) inhibitors, originally derived from an arginyltripeptide. uPA is considered an interesting target in anticancer drug design. The selectivity of these inhibitors for uPA is enhanced by the optimization of the P4 position. The most interesting compound shows an IC(50) of 5 nM, with a selectivity index of more than 3000 toward other Arg/Lys-specific proteases such as tissue-type plasminogen activator, plasmin, factor Xa, and thrombin. A synthetic strategy for the preparation of small libraries of diphenyl phosphonate analogues of capped tripeptides is described. It is shown that uPA is irreversibly inhibited, and interactions with the active site were modeled. Finally, a diparacetamol phosphonate analogue was developed to circumvent the release of cytotoxic phenol.
Subject(s)
Oligopeptides/chemical synthesis , Organophosphonates/chemical synthesis , Urokinase-Type Plasminogen Activator/antagonists & inhibitors , Urokinase-Type Plasminogen Activator/chemistry , Animals , Binding Sites , Humans , Mice , Models, Molecular , Oligopeptides/chemistry , Organophosphonates/chemistry , Structure-Activity RelationshipABSTRACT
In this paper, we report the synthesis of diastereomerically pure N-(4-substituted-2,4-diaminobutanoyl)piperidines. These compounds were prepared to investigate the influence of the 4-substitution on the dipeptidyl peptidase II (DPP II) activity and selectivity of the parent N-(2,4-diaminobutanoyl)piperidine. The (4S)-methyl compound showed subnanomolar inhibition, comparable with the parent compound. The (4R)-methyl group or bigger substituents decreased the activity.
Subject(s)
Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/antagonists & inhibitors , Piperidines/chemistry , Piperidines/pharmacology , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Amination , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Inhibitory Concentration 50 , Molecular Structure , Piperidines/chemical synthesis , Protease Inhibitors/chemistry , StereoisomerismABSTRACT
The feasibility of the fluoro-olefin function as a peptidomimetic group in inhibitors for dipeptidyl peptidase IV and II (DPP IV and DPP II) is investigated by evaluation of N-substituted Gly-Psi[CF=C]pyrrolidines, Gly-Psi[CF=C]piperidines, and Gly-Psi[CF=C](2-cyano)pyrrolidines. Of this later class, the (Z)- and (E)-fluoro-olefin analogues were prepared and chemical stability in comparison with the parent amide was checked. Most of these compounds exhibited a strong binding preference toward DPP II with IC(50) values in the low micromolar range, while only low DPP IV inhibitory potential is seen.
Subject(s)
Alkenes/chemical synthesis , Dipeptidyl Peptidase 4/chemistry , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/antagonists & inhibitors , Peptides/chemistry , Protease Inhibitors/chemical synthesis , Alkenes/chemistry , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/chemistry , Drug Stability , Models, Molecular , Nitriles/chemical synthesis , Nitriles/chemistry , Piperidines/chemical synthesis , Piperidines/chemistry , Protease Inhibitors/chemistry , Pyrrolidines/chemical synthesis , Pyrrolidines/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Using 1-[(S)-2,4-diaminobutanoyl]piperidine as lead compound, we developed a large series of highly potent and selective dipeptidyl peptidase II (DPP II) inhibitors. gamma-Amino substitution with arylalkyl groups, for example, a 2-chlorobenzyl moiety, resulted in a DPP II inhibitor with an IC(50) = 0.23 nM and a high selectivity toward DPP IV (IC(50) = 345 microM). Furthermore, it was shown that the basicity of the gamma-amino is important and that alpha-amino substitution is not favorable. Piperidine-2-nitriles did not show an increase in potency but rather reduced the selectivity. Introduction of a 4-methyl or a 3-fluorine on piperidine improved selectivity and preserved the high potency.