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PubMed1992

Analogs of the delta opioid receptor selective cyclic peptide [2-D-penicillamine,5-D-penicillamine]-enkephalin: 2',6'-dimethyltyrosine and Gly3-Phe4 amide bond isostere substitutions.

In order to develop systemically-active opioid peptides, the delta-selective, opioid pentapeptide [D-Pen2,D-Pen5]-enkephalin (DPDPE) was modified by esterification and by substitution of 2',6'-dimethyltyrosine for tyrosine to yield 4. Compound 4 was on the order of 8- and 800-fold more active than DPDPE in both delta and mu opioid radioligand binding assays, respectively, in rat neural membrane suspensions. Compound 4 was considerably more potent than DPDPE at inhibiting contractions of electrically-stimulated mouse vas deferens in vitro, and this effect was very sensitive to naltrindole, a delta-selective opioid antagonist. These observations can be taken as indication that 4 exerts its effects through delta opioid receptors. This interpretation is supported by the finding that the EC50 value of 4 derived in the smooth muscle assay is very similar to that derived in NG108-15 neuroblastoma cells, a preparation devoid of mu receptors. Unlike DPDPE, 4 exhibited significant, naloxone-sensitive, antinociceptive activity when administered systemically, as measured by inhibition of phenylbenzquinone-induced stretching in mice (ED50 = 2.1 mg/kg). Compound 4 also displayed significant antinociceptive activity following systemic administration as measured by its action in mice to increase latencies for tail withdrawal from radiant heat (ED50 = 50 mg/kg). Compound 4 did not produce morphine-like discriminative stimulus effects in rats trained to discriminate 3.0 mg/kg morphine from vehicle at doses ranging from 30 to 120 mg/kg. This observation can be interpreted as indication that within this dosage range there is an absence of morphine-like subjective effects. Physical dependence, however, could be induced in mice at higher doses of 4 under a progressively-graded, 4-day dose regimen. Congeners of 4 with amide bond surrogates for the Gly-Phe amide bond (oxymethylene, trans-double bond, and bismethylene isosteres) in the cyclic core of DPDPE were prepared in an attempt to increase the antinociceptive activity of 4. While some of the congeners were active in the in vitro assays, they did not display significant antinociceptive activity following systemic administration. The preparation of all the compounds was accomplished by solution-phase methods. The mechanisms which might underlie the biological and systemic activity of 4 are discussed.

Amides↗
PubMed1989

Potential tumor- or organ-imaging agents. 29. Radioiodinated esters and amides of 20-hydroxy- and 20-aminopregn-5-en-3 beta-ols.

Radioiodinated benzoyl esters and amides of epimeric 20-hydroxy- and 20-aminopregn-5-en-3 beta-ols were synthesized in an effort to find an agent that would be rapidly and selectively taken up by adrenal cortical tissue. Achievement of such a goal would provide a basis for the development of adrenal imaging agents superior to those currently available for clinical use. The iodobenzoyl derivatives were obtained by treating the appropriate epimer with 2-iodobenzoic acid in the presence of dicyclohexylcarbodiimide and 4-(dimethylamino)pyridine. The resulting esters and amides were readily labeled with radioiodine by isotope exchange with sodium iodide-125 in pivalic acid. Tissue distribution studies in female rats revealed that only the esters displayed appreciable adrenal specificity, and the ester having the same configuration at C-20 as cholesterol was significantly better than the corresponding C-20 epimer.

Adrenal Cortex↗
PubMed1981

Induction of differentiation of leukemia cells in vitro by N-substituted amides, lactams, and 2-pyridones.

N-Substituted amides, lactams, and 2-pyridones were examined for their ability to induce leukemic cell differentiation in vitro. These substituted amides were effective inducers of the differentiation of murine erythroleukemia (Friend) cells, as judged by the cellular accumulation of hemoglobin. N-Substitution increases the effectiveness of all classes of agents as inducers of maturation as judged by an increase in potency. N-Cyclohexylacetamide appeared to be a particularly effective compound, causing 92% of the population to synthesize hemoglobin at a concentration which was not inhibitory to cell replication. In the lactam series, an increase in ring size was paralleled by an increase in the potency of unsubstituted compounds, but ring size had less effect on N-substituted lactams. Increasing the chain length of the N-alkyl substituent had little additional effect on a series of lactam and 2-pyridone derivatives; however, some decrease in maximal induction occurred with butyl- and hexyl-substituted 2-pyridones. N-Isopropyl-2-pyridone, selected for further study, was as good an inducer of the HL60 human promyelocytic leukemia as it was of the Friend murine erythroleukemia.

Amides↗
PubMed1990

Inhibition of human leukocyte elastase. 2. Inhibition by substituted cephalosporin esters and amides.

A variety of 7 alpha-methoxycephalosporin ester and amide sulfones were prepared and tested to determine the structure-activity relations for inhibition of human leukocyte elastase (HLE), a serine protease which has been implicated in several degenerative lung and tissue diseases. The most potent IC50 values were obtained with neutral, lipophilic derivatives, with the esters being more active than the amides. However, the best time-dependent inhibition in this series was observed with the p- and m-carboxybenzyl esters 7b and 7c. These results are discussed in terms of the proposed mechanism of inhibition as well as a molecular modeling study using the recently solved X-ray crystal structure of HLE.

Amides↗
PubMed1982

Syntheses of alpha- and gamma-substituted amides, peptides, and esters of methotrexate and their evaluation as inhibitors of folate metabolism.

N-[4-[[(Benzyloxy)carbonyl]methylamino]benzoyl]-L-glutamic acid alpha-benzyl ester (2) and gamma-benzyl ester (6) served as key intermediates in syntheses of precursors to amides and peptides of methotrexate (MTX) involving both the alpha- and gamma-carboxyl groupings of the glutamate moiety. Coupling of 2 and 6 at the open carboxyl grouping with amino compounds was affected by the mixed anhydride method (using isobutyl chloroformate); carboxyl groupings of amino acids coupled with 2 and 6 were protected as benzyl esters. N-[4-[[(Benzyloxy)carbonyl]methylamino]benzoyl]-L-glutamic acid gamma-methyl ester (5), a precursor to MTX gamma-methyl ester, was prepared from L-glutamic acid gamma-methyl ester and 4-[[(benzyloxy)carbonyl]methylamino]benzoyl chloride (1) in a manner similar to that used to prepare 2 and 6. The precursor to MTX alpha-methyl ester was prepared from gamma-benzyl ester 6 by treatment with MeI in DMF containing (i-Pr)2NEt. Benzyl and (benzyloxy)carbonyl protective groupings were removed by hydrogenolysis, and the deprotected side-chain precursors were converted to alpha- and gamma-substituted amides, peptides, and esters of MTX by alkylation with 6-(bromomethyl)-2,4-pteridinediamine hydrobromide (12). Biochemical-pharmacological studies on the prepared compounds aided in establishing that the alpha-carboxyl grouping of the glutamate moiety contributes to the binding of MTX to dihydrofolate reductase while the gamma-carboxyl does not. Other studies on the peptide MTX-gamma-Glu (13h) are concerned with the contribution toward antifolate activity of this metabolite of MTX. The compounds prepared were also evaluated and compared with MTX with respect to cytotoxicity toward H.Ep.-2 cells and effect on L1210 murine leukemia.

Amides↗
PubMed1984

Synthesis and antiarrhythmic and parasympatholytic properties of substituted phenols. 2. Amides.

Thirty amides patterned after the antiarrhythmic drug changrolin were synthesized and their antiarrhythmic and parasympatholytic activities were assessed. There was no correlation between antiarrhythmic and parasympatholytic activities. Several of the amides were found to be potent antiarrhythmic agents that possessed low parasympatholytic activity. All of the compounds appear to act by a class I mechanism.

Amides↗
PubMed1987

Thromboxane synthetase inhibitors and antihypertensive agents. 3. N-[(1H-imidazol-1-yl)alkyl]heteroaryl amides as potent enzyme inhibitors.

The title compounds were prepared as the heterocyclic analogues of thromboxane (TX) synthetase inhibitors and antihypertensive agents previously reported from our laboratories. These compounds were at least as active TX synthetase inhibitors as their benzene isosteres with the indole derivatives 50-55 having the most potent enzyme inhibiting activity measured to date in our laboratories. The best compound, 54, is more than 200-fold more potent than the standard, dazoxiben. In contrast, the antihypertensive activity of these series of compounds was no better than their benzene counterparts and is far lower than the isoindoledione derivatives prepared in a related series. The structure-activity relationship results from this study were similar to our previous observations and include the fact that the amide moiety effectively replaces a carboxylic acid for potent TX synthetase inhibition and that a four to six methylene unit separation (approximately 8.5 A) between amide and imidazole moieties achieves maximal activity.

Amides↗
PubMed2002

Arylaminoethyl amides as novel non-covalent cathepsin K inhibitors.

A series of N(alpha)-benzyloxycarbonyl- and N(alpha)-acyl-L-leucine(2-phenylaminoethyl)amide derivatives were prepared and evaluated for their inhibitory activity against rabbit and human cysteine proteases cathepsins K, L, and S. These data indicate that N(alpha)-acyl-alpha-amino acid-(arylaminoethyl)amides represent a new class of selective non-covalent inhibitors of cathepsin K. Compounds 4b, 4e, and 4g exhibit high potency toward rabbit and human cathepsin K (IC(50) < 0.006 microM) and are characterized by an excellent selectivity profile vs human cathepsins L and S.

Amides↗
PubMed2003

Phenethyl amides as novel noncovalent inhibitors of hepatitis C virus NS3/4A protease: discovery, initial SAR, and molecular modeling.

The discovery of novel, reversible and competitive tripeptide inhibitors of the Hepatitis C virus NS3/4A serine protease is described. These inhibitors are characterized by the presence of a C-terminal phenethyl amide group, which extends into the prime side of the enzyme. Initial SAR together with molecular modeling and data from site-directed mutagenesis suggest an interaction of the phenethyl amide group with Lys-136.

Amides↗
PubMed2005

Discovery of a potent, selective, and efficacious class of reversible alpha-ketoheterocycle inhibitors of fatty acid amide hydrolase effective as analgesics.

Fatty acid amide hydrolase (FAAH) degrades neuromodulating fatty acid amides including anandamide (endogenous cannabinoid agonist) and oleamide (sleep-inducing lipid) at their sites of action and is intimately involved in their regulation. Herein we report the discovery of a potent, selective, and efficacious class of reversible FAAH inhibitors that produce analgesia in animal models validating a new therapeutic target for pain intervention. Key to the useful inhibitor discovery was the routine implementation of a proteomics-wide selectivity screen against the serine hydrolase superfamily ensuring selectivity for FAAH coupled with systematic in vivo examinations of candidate inhibitors.

Amidohydrolases↗
PubMed2005

Dicarboxylic acid azacycle l-prolyl-pyrrolidine amides as prolyl oligopeptidase inhibitors and three-dimensional quantitative structure-activity relationship of the enzyme-inhibitor interactions.

A series of dicarboxylic acid azacycle l-prolyl-pyrrolidine amides was synthesized, and their inhibitory activity against prolyl oligopeptidase (POP) from porcine brain was tested. Three different azacycles were tested at the position beyond P3 and six different dicarboxylic acids at the P3 position. l-Prolyl-pyrrolidine and l-prolyl-2(S)-cyanopyrrolidine were used at the P2-P1 positions. The IC(50) values ranged from 0.39 to 19000 nM. The most potent inhibitor was the 3,3-dimethylglutaric acid azepane l-prolyl-2(S)-cyanopyrrolidine amide. Molecular docking (GOLD) was used to analyze binding interactions between different POP inhibitors of this type and the POP enzyme. The data set consisted of the novel inhibitors, inhibitors published previously by our group, and well-known reference compounds. The alignments were further analyzed using comparative molecular similarity indices analysis. The binding of the inhibitors was consistent at the P1-P3 positions. Beyond the P3 position, two different binding modes were found, one that favors lipophilic structures and one that favors nonhydrophobic structures.

Amides↗
PubMed2006

Design, synthesis, and molecular modeling of a novel amide-linked cyclic GnRH analogue cyclo(4-9)[Lys4,D-Trp6,Glu9]GnRH: stimulation of gonadotropin gene expression.

This report describes the rational design, synthesis, and pharmacological properties of an amide-linked cyclic analogue of gonadotropin-releasing hormone (GnRH) namely Cyclo(4-9)[Lys(4),d-Trp(6),Glu(9)]GnRH. The conformationally restricted analogue is characterized by reduced flexibility of the peptide strand due to the introduction of a beta-turn mimetic through 4,9 residue amide cyclization. The cyclic analogue was found to stimulate gonadotropin gene expression in the goldfish pituitary with similar potency compared to two native forms of GnRH. Simulation studies based on ROE connectivities in linear GnRH and potency of cyclic analogue supports the His(2), Trp(3), Tyr(5) clustering considered important for triggering receptor activation.

Amides↗
PubMed2006

Pyrrolizidine esters and amides as 5-HT4 receptor agonists and antagonists.

A series of pyrrolizidine esters, amides, and ureas was prepared and tested for 5-HT(4) and 5-HT(3) receptor binding, 5-HT(4) receptor agonism in the rat tunica muscularis mucosae (TMM) assay, and for 5-HT(3) receptor-mediated functional antagonism in the Bezold-Jarisch reflex assay. Several pyrrolizidine derivatives were identified with high affinity for the 5-HT(4) receptor, including benzamide 12a (SC-53116), a potent and selective 5-HT(4) partial agonist that exhibits efficacy in promoting antral contractions and activity in promoting gastric emptying in canine models. Also discovered were 5-HT(4) receptor antagonists, including imidazopyridine amide 12h (SC-53606), which is a potent and selective 5-HT(4) receptor antagonist with a pA(2) value of 8.13 in the rat TMM assay. N-Methyl indole ester 13d was identified as a potent 5-HT(4) antagonist with a pA(2) value of 8.93. High selectivity was observed for these pyrrolizidine derivatives versus other monoamine receptors, including 5-HT(1), 5-HT(2), D(1), D(2), alpha(1), alpha(2), and beta receptors.

Amides↗
PubMed1996

Mapping the melatonin receptor. 4. Comparison of the binding affinities of a series of substituted phenylalkyl amides.

A series of 2-, 3-, and 4-substituted phenylalkyl amides were prepared as potential melatonin analogs in order to investigate the nature of the binding site of the melatonin receptor in chicken brain. The length of the alkyl chain was systematically varied from n = 1 to 4, and methoxyl substituents were incorporated into the phenyl ring at the 2-, 3-, and 4-positions. The maximum binding affinity was found to occur when n = 3 and when the methoxyl substituent was in the 3-position, the direct analog of the carbon framework of melatonin in which the 1,2-atoms of the indole ring have been removed. Whereas there was only a relatively small decrease in binding affinity for the corresponding 2-methoxy derivatives, 4-methoxyl substitution led to a large decrease in binding affinity, suggesting that the binding sites for the side chain and methoxyl group could not now be occupied at the same time. As in the indole analogs of melatonin, replacement of the methyl group of the amide by a longer alkyl chain led to an increase in binding affinity for ethyl and propyl with a subsequent decrease in binding affinity for butyl chains. Thus N-propanoyl-3-(3-methoxyphenyl)propanamine (6f) has a binding affinity of 5.6 nM, a remarkably high affinity for so simple a compound. Substitution of halogen for 3-methoxyl in the propanamide series gave a series of compounds with lower, but still substantial, binding affinities, the 3-chloro derivative 7e showing the highest affinity, 113 nM. In the case of the 3-fluoro propanamides, a maximum in the binding affinity was not observed in the series synthesized, and these derivatives will merit further exploration. These results demonstrate the utility of simple, readily modified phenylalkylamines as a "framework" for studying the effect of changes in the nature and position of substituents on the melatonin receptor binding affinity.

Amides↗
PubMed1997

Cyclic urea amides: HIV-1 protease inhibitors with low nanomolar potency against both wild type and protease inhibitor resistant mutants of HIV.

Cyclic urea amides, a novel series of HIV-1 protease (HIV PR) inhibitors, have increased activity against drug-resistant mutants of the HIV PR. The design strategy for these inhibitors is based on the hypotheses that (i) the hydrogen-bonding interactions between the inhibitor and the protease backbone will remain constant for wild-type and mutant enzymes and (ii) inhibitors which are capable of forming many nonbonded interactions, distributed throughout the active site, will experience a lower percent change in binding energy as a result of mutation in the target enzyme than those that form fewer interactions by partial occupation of the active site. The cyclic urea amide, SD146, forms 14 hydrogen bonds and 191 van der Waals contacts to HIV PR. SD146 is a very potent antiviral agent (IC90 = 5.1 nM) against wild-type HIV and maintains the same or improved level of high potency against a range of mutant strains of HIV with resistance to a wide variety of HIV protease inhibitors.

Amides↗
PubMed1998

N-(benzyloxycarbonyl)glycine esters and amides as new anticonvulsants.

Glycine is a small neutral amino acid exhibiting weak anticonvulsant activities in vivo. Recently, studies have demonstrated that N-(benzyloxycarbonyl)glycine (1) antagonized seizures superior to glycine in addition to activity in the maximal electroshock (MES) test, a convulsive model where glycine is inactive. In the present study a series of ester and amide derivatives of 1 as well as esters of N-(3-phenylpropanoyl)glycine (5) have been prepared. The compounds were evaluated in the MES test as well as in several chemically induced seizure models. Among the derivatives investigated, N-(benzyloxycarbonyl)glycine benzylamide (16) was the most potent compound exhibiting an anticonvulsant activity in the MES test comparable to the drug phenytoin. Median effective doses (ED50) of 4.8 and 11.6 mg/kg were determined at 30 min and 3 h after i.p. administration, respectively. Compound 16 also effectively suppressed tonic seizures in different chemically induced models such as the strychnine, 3-mercaptopropionic acid, and pentylenetetrazole tests. Moreover, the compound studied here did not show acute neurotoxicity in the rotorod test up to a dose of 150 mg/kg. It is concluded that N-(benzyloxycarbonyl)glycine amides, especially 16, are potent anticonvulsant agents.

3-Mercaptopropionic Acid↗
PubMed1998

alpha-Substituted malonester amides: tools to define the relationship between ACAT inhibition and adrenal toxicity.

We prepared a series of alpha-substituted malonester amides that were evaluated for their ability to inhibit acyl-CoA:cholesterol O-acyl transferase activity in vitro and to lower plasma total cholesterol levels in a variety of cholesterol-fed animal models. Compounds of this series were also useful in examining the relationship between adrenal toxicity and ACAT inhibition. One compound from this series, 9f, was a potent inhibitor of ACAT in both the microsomal and cellular assays. It was also bioavailable as determined by both a bioassay and a HPLC-UV assay. This compound was evaluated in both guinea pig and dog models of adrenal toxicity and compared to tetrazole amide 15. In the most sensitive species, the dog, both of these compounds achieved good plasma levels; however, compound 9f caused adrenal necrosis, whereas compound 15 had no effect on the adrenal gland. This adds to the growing body of evidence that the adrenal toxicity observed with ACAT inhibitors may not be mechanism related.

Adrenal Glands↗
PubMed2000

Secondary amides of (R)-3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid as inhibitors of pyruvate dehydrogenase kinase.

N'-methyl-N-(4-tert-butyl-1,2,5,6-tetrahydropyridine)thiourea, SDZ048-619 (1), is a modest inhibitor (IC(50) = 180 microM) of pyruvate dehydrogenase kinase (PDHK). In an optimization of the N-methylcarbothioamide moiety of 1, it was discovered that amides with a small acyl group, in particular appropriately substituted amides of (R)-3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid, are inhibitors of PDHK. Utilizing this acyl moiety, herein is reported the rationale leading to the optimization of a series of acylated piperazine derivatives. Methyl substitution of the piperazine at the 2- and 5-positions (with S and R absolute stereochemistry) markedly increased the potency of the lead compound (>1,000-fold). Oral bioavailability of the compounds in this series is good and is optimal (as measured by AUC) when the 4-position of the piperazine is substituted with an electron-poor benzoyl moiety. (+)-1-N-[2,5-(S, R)-Dimethyl-4-N-(4-cyanobenzoyl)piperazine]-(R)-3,3, 3-trifluoro-2-hydroxy-2-methylpropanamide (14e) inhibits PDHK in the primary enzymatic assay with an IC(50) of 16 +/- 2 nM, enhances the oxidation of [(14)C]lactate into (14)CO(2) in human fibroblasts with an EC(50) of 57 +/- 13 nM, diminishes lactate significantly 2.5 h post-oral-dose at doses as low as 1 micromol/kg, and increases the ex vivo activity of PDH in muscle, liver, and fat tissues in normal Sprague-Dawley rats. These PDHK inhibitors, however, do not lower glucose in diabetic animal models.

Amides↗