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At least 991 records · Page 55Linked to original sources
PubMed1995

Dicarboxylic acid dipeptide neutral endopeptidase inhibitors.

The synthesis of three series of dicarboxylic acid dipeptide neutral endopeptidase 24.11 (NEP) inhibitors is described. In particular, the amino butyramide 21a exhibited potent NEP inhibitory activity (IC50 = 5.0 nM) in vitro and in vivo. Blood levels of 21a were determined using an ex vivo method by measuring plasma inhibitory activity in conscious rats, mongrel dogs, and cynomolgus monkeys. Free drug concentrations were 10-1500 times greater than the inhibitory constant for NEP over the course of a 6 h experiment. A good correlation of free drug concentrations was obtained when comparing values determined by the ex vivo analysis to those calculated from direct HPLC measurements. Plasma atrial natriuretic factor (exogenous) levels were elevated in rats and dogs after oral administration of 19a. Urinary volume and urinary sodium excretion were also potentiated in anesthetized dogs treated with 21a.

Amino Acid Sequence↗
PubMed1995

New alpha-thiol dipeptide dual inhibitors of angiotensin-I converting enzyme and neutral endopeptidase EC 3.4.24.11.

Dual inhibitors of the two zinc metallopeptidases, neutral endopeptidase (NEP, EC 3.4.24.11) and angiotensin-I converting enzyme, have been the focus of much clinical interest for the treatment of hypertension and congestive heart failure. A novel series of alpha-thio dipeptides containing central cyclic non-natural amino acids were prepared and were evaluated for their ability to inhibit these two metallopeptidases in vitro and in vivo. Most of these compounds were found to be excellent dual inhibitors of ACE and NEP in vitro and several were also found to inhibit angiotensin-I (AI) pressor response in conscious rats when given by intravenous administration. Compound 6n, one of our most potent dual inhibitors in vitro, was found to be more efficacious than captopril in the AI pressor experiment when administered orally to conscious rats. This compound was also found to inhibit plasma NEP activity following oral administration to conscious rats and was more efficacious than acetorphan. The structure-activity relationships and biological activity of these dual inhibitors will be discussed.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Synthesis of novel N-phosphonoalkyl dipeptide inhibitors of human collagenase.

The synthesis of a series of N-phosphonalkyl dipeptides 6 is described. Syntheses were devised that allowed the preparation of single diastereoisomers and the assignment of stereochemistry. The compounds were evaluated in vitro for their ability to inhibit the degradation of radiolabeled collagen by purified human lung fibroblast collagenase. Several of the compounds were potent collagenase inhibitors and were at least 10-fold more potent than their corresponding N-carboxyalkyl analogues. Activity was lost when the phosphonic acid group P(O)(OH)2 was replaced by the phosphinic acid groups P(O)(H)(OH) and P(O)(Me)(OH). At the P1 position, (R)- or (S)-alkyl groups, especially ethyl and methyl (e.g., 12a,b, 52a,b, and 53a,b), or an (R)-phenethyl moiety (55a) conferred high potency (IC50 values in the range 0.23-0.47 microM). (S)-Stereochemistry was preferred for the P1' isobutyl side chain. Structure-activity relationships were also investigated at the P2' site, and interestingly, compounds with basic side chains, such as the guanidine 57a, were equipotent with more lipophilic compounds, such as 52a. As with other series of collagenase inhibitors, potency was enhanced by introducing bicyclic aromatic P2' substituents. The most potent phosphonic acid of the series was the bicyclic aromatic P2' tryptophan analogue 59a (IC50 0.05 microM).

Animals↗
PubMed1994

Studies on neurokinin antagonists. 4. Synthesis and structure-activity relationships of novel dipeptide substance P antagonists: N2-[(4R)-4-hydroxy-1-[(1-methyl-1H-indol-3-yl)carbonyl]-L-prolyl]-N- methyl-N-(phenylmethyl)-3-(2-naphthyl)-L-alaninamide and its related compounds.

As an extension of our studies on discovering a novel substance P (SP) antagonist, we modified the previously reported dipeptide, N2-[N2-(1H-indol-3-ylcarbonyl)-L-lysyl]-N-methyl-N-(phenyl-methyl) -L- phenylalaninamide (2b). The lysine part in 2b was first optimized to a (2S,4R)-hydroxyproline derivative (3h), which is 2-fold more potent than 2b in [3H]SP binding assay using guinea pig lung membranes. Next we modified the 1H-indol-3-ylcarbonyl part in 3h. Introduction of a methyl group at the indole nitrogen enhanced the oral activity, while retaining the binding activity. Finally, we modified the phenylalanine part to culminate in the most potent compound 7k (FK888), which is a potent SP antagonist with NK1 selectivity as well as oral activity.

Animals↗
PubMed1993

Epoxysuccinyl dipeptides as selective inhibitors of cathepsin B.

Epoxysuccinyl dipeptide analogs of E-64 (R-EpsLeuPro-R') (Figure 1) have been synthesized with the carboxylate group on the epoxide ring either free (R = OH) or converted to an ester or an amide (R = EtO or i-BuNH) and with the C-terminal amino acid proline either blocked (R' = OBzl) or free (R' = OH). These compounds were used to investigate the recently reported selectivity of this type of inhibitor for the lysosomal cysteine protease cathepsin B. It was shown that derivatization of the carboxylate on the epoxide ring confers selectivity for cathepsin B over papain only when it is combined to a dipeptidyl moiety with a free negatively charged C-terminal residue. It is proposed that this selectivity reflects interactions with histidine residues on a loop located in the primed subsites of cathepsin B which provides a positively charged anchor for the C-terminal carboxylate group of the inhibitor. The primed subsite loop of cathepsin B is not found in other cysteine proteases of the papain family and offers a unique template for designing selectivity in cysteine protease inhibitors.

Cathepsin B↗
PubMed1992

Preparation and opioid activity of analogues of the analgesic dipeptide 2,6-dimethyl-L-tyrosyl-N-(3-phenylpropyl)-D-alaninamide.

A number of analogues of the recently disclosed analgesic dipeptide 2,6-dimethyl-L-tyrosyl-D-alanine-phenylpropylamide (SC-39566, 2) were prepared. These analogues contained oxymethylene, aminomethylene, ketomethylene, bismethylene, and trans double bond (including vinyl fluoride) isosteric replacements for the amide bond between the D-alanine and phenylpropylamine units in 2. These compounds were tested in opioid binding assays and in the mouse writhing assay for analgesic activity. Though not as potent as 2, the oxymethylene, and trans double bond isosteres showed analgesic activity. The aminomethylene analogues also showed binding activity in subnanomolar concentrations at the mu receptor. The amide bond between 2,6-dimethyl-L-tyrosine and D-alanine units seems to be critical for opioid activity.

Analgesics, Opioid↗
PubMed1992

Renin inhibitors containing new P1-P1' dipeptide mimetics with heterocycles in P1'.

A series of renin inhibitors containing new P1-P1' dipeptide mimetics are presented. The P1-P1' mimetics were obtained from (4S,5S)-3-(tert-butoxycarbonyl)-4-(cyclohexylmethyl)-5-[(omega- mesyloxy)alkyl]-2,2-dimethyloxazolidines 5b, 9, and 11b by nucleophilic substitution of the mesylate groups with the sodium salts of mercapto- and hydroxyheterocycles. Removal of the protecting groups and stepwise acylations with amino acid derivatives provided renin inhibitors with a length of a tripeptide. Replacement of P2 histidine by other amino acids maintained or enhanced renin inhibitory potency. By alteration of P3 phenylalanine, compounds with IC50 values in the nanomolar range and stability against chymotrypsin were obtained. Finally, the effect of the C-terminal heterocycle on the renin inhibition was studied. Compound XVII was examined in vivo for its hypotensive effects. In salt-depleted cynomolgus monkeys, XVII inhibited plasma renin activity and lowered blood pressure after oral administration of a dose of 10 mg/kg.

Animals↗
PubMed1991

Renin inhibitors containing conformationally restricted P1-P1' dipeptide mimetics.

A series of renin inhibitors containing lactam-bridged P1-P1' dipeptide mimetics based on the ACHPA (4(S)-amino-5-cyclohexyl-3(S)-hydroxypentanoic acid) design was studied. The inhibitors were obtained by aldol addition of various lactams with N alpha-Boc-L-cyclohexylalaninal, followed by Boc group removal and acylation with Boc-Phe-His. The aldol diastereomer having the S configuration at the two newly generated stereogenic centers gave optimal enzyme inhibition. Potency was further enhanced in the gamma-lactam ring series by substitution with small hydrophobic groups to mimic the P1' side chain of the renin substrate. Thus, 2(S)-[(Boc-L-phenylalanyl-L-histidyl)amino]-3-cyclohexyl-1(S)-hydroxyl-1 - (1,5,5-trimethyl-2-oxopyrrolidin-3(S)-yl)propane (34) has an IC50 of 1.3 nM in the human plasma renin assay. A variety of substituents on the lactam nitrogen are tolerated and can be used to vary the physical properties of the inhibitor. By using a model of the human renin active site, the conformation of 34 in the enzyme-inhibitor complex is proposed. This modeled conformation is very similar to the solid-state conformation of 2(S)-[(Boc-L-phenylalanyl-L-histidyl)amino]-3-cyclohexyl-1(S)-hydroxyl- 1-(1-methyl-2-oxopyrrolidin-3(S)-yl)propane (36), the structure of which was determined by single-crystal X-ray diffraction analysis. The most potent ACH-PA-lactam renin inhibitors show good selectivity when assayed against other types of aspartic proteinases. By varying the lactam ring substituents, potent and selective inhibitors of cathepsin D and cathepsin E can be obtained.

Animals↗
PubMed1985

Angiotensin converting enzyme inhibitors: N-substituted D-glutamic acid gamma dipeptides.

The preparation of two series of N-carbobenzoxy-gamma-D-glutamyl secondary 2S amino acids and (N-substituted gamma-D-glutamyl)indoline-2(S)-carboxylic acid dipeptides is described. In vitro inhibition of angiotensin converting enzyme (ACE) is reported for each compound, and the structure-activity relationship is discussed. Oral and iv inhibition of AI pressor response in vivo of selected compounds in Table II is also discussed. The most potent compounds in vitro, 3 and 6a, had an ACE IC50 of 7 and 2.7 X 10(-9) M, respectively.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1986

Antibacterial activity of phosphono dipeptides related to alafosfalin.

A series of dipeptides containing N-terminal alanine or leucine and a wide range of P-terminal racemic 1-amino-alkanephosphonates were prepared and tested in vitro for their ability to inhibit the growth of various bacterial species. The results demonstrate that peptides containing 4-amino-4-phosphonobutyric acid and 1-amino-1-methylethanephosphonic acid exhibit antibacterial activity comparable with that observed in the case of peptides containing P-terminal racemic 1-aminoethanephosphonic acid (analogue of alanine) used as a positive control.

Alanine↗
PubMed1979

Dipeptides of O-methyl-L-threonine as potential antimalarials.

L-Leucyl-O-methyl-L-threonine, O-methyl-L-threonyl-L-leucine, and O-methyl-L-threonyl-O-methyl-L-threonine were prepared and compared with O-methyl-L-threonine and L-leucine for antimalarial activity against Plasmodium berghei in mice. O-Methyl-L-threonine significantly prolonged survival time at doses of 160, 320, and 640 mg/kg. O-Methyl-L-threonyl-O-methyl-L-threonine was less active, significantly prolonging survival time only at 640 mg/kg. L-Leucine, as well as the other two dipeptides, exhibited no activity in this test.

Animals↗
PubMed1978

Synthesis and evaluation of bis-dipeptide and bis-tripeptide analogues of actinomycin D.

Six-bis-dipeptide analogues of actinomycin D, all containing two threonyl-D-valine side chains, were prepared. Also two bis-tripeptide analogues containing an additional proline or oxoproline residue were synthesized. None of the compounds bound to DNA in a manner similar to actinomycin D. This lack of strong intercalative binding emphasizes the importance of the pentapeptidolactone side chains in the binding of actinomycin D to DNA and also highlights the deficiences inherent in using only small nucleotide sequences in investigating drug-DNA binding. None of the analogues tested showed any antitumor activity, although actinocylbis(threonyl-D-valine methyl ester) did show 10% of the antibacterial activity of actinomycin D vs. Bacillus subtilis.

Animals↗
PubMed1975

Potential latentiation forms of biologically active compounds based on action of leucine aminopeptidase. Dipeptide derivatives of the tricycloaliphatic alpha-amino acid, adamantanine.

Some glycine, leucine and phenylalanine dipeptide derivatives of the transport inhibitory, tricycloaliphatic alpha-amino acid, adamantanine (1), have been synthesized using classical methods of peptide synthesis with the aim of improving the latter's bioavailability. Although test doses of glycyladamantanine and L-leucyladamantanine appeared to be absorbed in vivo as evidenced by its appearance in the uring following intraperitoneal administration, they were not hydrolyzed by a purified preparation of leucine aminopeptidase in vitro. Indeed, they were inhibitors of this enzyme. Adamantanylglycine, adamantanyl-L-leucine, and adamantanyl-L-phenylalanine were also not hydrolyzed by leucine aminopeptidase.

Amantadine↗
PubMed1987

Synthetic and enzyme inhibition studies of pepstatin analogues containing hydroxyethylene and ketomethylene dipeptide isosteres.

Synthetic details for the preparation of a series of hydroxyethylene and ketomethylene dipeptide isosteres with control of stereochemistry at C(2) are described. Incorporation of the isosteres into peptide sequences derived from pepstatin afforded potent inhibitors of the aspartic protease porcine pepsin. When Leu-OH-Ala or Leu-OH-Phe was substituted for statine [3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid), inhibitors equipotent to the parent compound were obtained, whereas Leu-OH-Gly was a much less effective replacement for statine. A similar trend was evident in the corresponding ketones. The finding that structural features for good substrates do not closely parallel those for good inhibitors is discussed.

Amino Acid Sequence↗
PubMed1987

Synthesis and biological properties of N3-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid dipeptides, a novel group of antimicrobial agents.

A series of dipeptides with N3-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid (FMDP), the irreversible inhibitor of glucosamine-6-phosphate synthetase from bacteria and fungi, have been synthesized and their antibacterial and antifungal properties in vitro evaluated. The results demonstrate that these peptides inhibit the growth of a number of the tested microorganisms, especially pathogenic fungus Candida albicans. The results of competitive antagonism studies indicate specific peptide transport of the peptides via peptide permeases as drug delivery system and gives evidence for the high selectivity of the action upon the cells, as a result of the inhibition of generation of glucosamine.

Amino Acids, Diamino↗
PubMed1987

Renin inhibitors. Dipeptide analogues of angiotensinogen incorporating transition-state, nonpeptidic replacements at the scissile bond.

A series of dipeptide analogues of angiotensinogen have been prepared and evaluated for their ability to inhibit the aspartic proteinase renin. The compounds were derived from the renin substrate by replacing the scissile amide bond with a transition-state mimic and by incorporating bioisosteric replacements for the Val-10 amide bond. Analogue 21a exhibited an IC50 of 7.6 nM against purified human renin, showed high specificity for this enzyme, and produced a hypotensive response in anesthetized, salt-depleted cynomolgus monkeys.

Angiotensinogen↗
PubMed1988

Conformationally constrained renin inhibitory peptides: gamma-lactam-bridged dipeptide isostere as conformational restriction.

A model of the conformation of the enzyme-bound inhibitor of human renin suggested the possibility of a gamma-lactam conformational restriction at the P2-P3 site. Synthetic routes to these gamma-lactam dipeptide isosteres and their incorporation into potential renin inhibitors are described. Peptide VIa,b with a gamma-lactam conformational constraint and a hydroxyethylene isostere at the cleavage site inhibited human plasma renin with an IC50 value of 6.5 nM. The flexibility of these syntheses should make available a number of potential enzyme inhibitors with this structural feature for the study of enzyme-bound conformers.

Angiotensinogen↗
PubMed2002

Design and synthesis of dipeptide nitriles as reversible and potent Cathepsin S inhibitors.

The specificity of the immune response relies on processing of foreign proteins and presentation of antigenic peptides at the cell surface. Inhibition of antigen presentation, and the subsequent activation of T-cells, should, in theory, modulate the immune response. The cysteine protease Cathepsin S performs a fundamental step in antigen presentation and therefore represents an attractive target for inhibition. Herein, we report a series of potent and reversible Cathepsin S inhibitors based on dipeptide nitriles. These inhibitors show nanomolar inhibition of the target enzyme as well as cellular potency in a human B cell line. The first X-ray crystal structure of a reversible inhibitor cocrystallized with Cathepsin S is also reported.

B-Lymphocytes↗