Antimicrobial Activity of Some N-Substituted Amides of Long-Chain Fatty Acids

Seventy-three N,N-disubstituted amides of long-chain, principally C(18), fatty acids were screened for antimicrobial activity against bacteria, yeasts, and molds. Amides containing an epoxy group exhibit a broad spectrum of antimicrobial activity which is further enhanced by unsaturation. Mono-unsaturation alone does not contribute a broad level of activity to the N,N-disubstituted amides of the C(18) fatty acids.     

Synthesis and biological activity of mono- and diamides of 2,3-secotriterpene acids

Amides of four types were synthesized derived from 2,3-seco-18αH-oleanane and 2,3-secolupane mono- and dicarboxylic acids. The spectrum of diamide derivatives was expanded with C3-C3′ and C28-C28′ biscondensed amides with two A-secotriterpene backbones obtained by the interaction of monocarboxylic A-seco acids with lysine. Among the synthesized monoand diamide derivatives, potential inhibitors of herpes simplex virus type 1 replication were found, namely, some compounds with an ethyl β-alaninate fragment (EC₅₀ 8.7 and 4.1 μM). The ethyl β-alaninate diamide was shown to combine antiherpetic and anti-HIV activity (EC₅₀ 5.1 μM). For the active compounds, the ratios of maximum tolerable concentrations to EC₅₀ ranged from 9.7 to 40.8. The synthesized amides did not show any marked cytotoxic effects against human rabdomiosarcoma RD TE32, A549 lung carcinoma, and melanoma MS cell lines.     

A new method to prepare amides by bioconversion of corresponding nitriles

Amides of very good chemical quality have been obtained by the bioconversion of the corresponding nitriles using immobilized bacteria with nitrilase activity (nitrile hydratase). The bioreactor was polyvalent since the nitrilase used had a generalized activity and could hydrolyse a large number of nitriles. The present paper shows the polyvalence and simplicity of the process, and the quality of the amides obtained.     

Bile acid derivatives of 5-amino-1,3,4-thiadiazole-2-sulfonamide as new carbonic anhydrase inhibitors: synthesis and investigation of inhibition effects

Bile acid amides (cholan-24-amides) of 5-substituted 1,3,4-thiadiazole-2-sulfonamide have been prepared from lithocholic, deoxycholic, cholic and dehydrocholic acids. Besides, the alcohol functional groups on the cholane ring systems were protected with acetyl group. Amides of the protected cholanes of lithocholic and cholic acids were also synthesized. Later, inhibition effects of these compounds on human carbonic anhydrase isozymes (HCA-I and II) have been investigated in vitro. For the most active compounds, inhibition constants ranged from 66 to 190nM for HCA-II with I(50) (molarity of inhibitor producing a 50% inhibition of CA activity). In addition, in vivo studies were performed for the synthesized compounds in Sprague-Dawley rats. The compounds (11 and 18) showed especially significant inhibition efficacy (p<0.001).     

Identification of reactive toxicants: Structure–activity relationships for amides

A diverse series of amides were evaluated for aquatic toxicity (IGC₅₀) assessed in the Tetrahymena pyriformis population growth impairment assay and for reactivity (EC₅₀) with the model soft nucleophile thiol in the form of the cysteine residue of the tripeptide glutathione. All alkylamides along with some halo-substituted amides are well predicted by the simple hydrophobicity (log K _ow)–electrophilicity (E _lumo) response-surface model [log(IGC⁻¹ ₅₀) = 0.45(log K _ow) − 0.342(E _lumo) − 1.11]. However, 2-halo amides with the halogen at the end of the molecule and α,β-unsaturated primary amides are among those derivatives identified as being more toxic than predicted by the model. Amides, which exhibit excess toxicity, were capable of forming covalent bonds through an S_N2 displacement or a Michael addition. Moreover, only those amides exhibiting excess toxicity were reactive with thiol, suggesting that the reactivity with model nucleophiles such as the thiol group may provide a means of accurately defining reactive toxicants.     

Effects of indole amides on lettuce and onion germination and growth

Auxins, such as indole-3-acetic acid (IAA), are important in plant germination and growth, while physiological polyamines, such as putrescine, are involved in cell proliferation and differentiation, and their concentrations increase during germination. In this work, novel indole amides were synthesized in good yields by monoacylation of morpholine and unprotected symmetrical diamines with indole-3-carboxylic acid, a putative metabolite of IAA, possessing no auxin-like activity. These amides were tested for their effects on seed germination and growth of the radicles and shoots of Lactuca sativa (lettuce) and Allium cepa (onion) seedlings, at 100.0, 1.0, and 0.01 microM concentrations. Germination was generally stimulated, with the exception of amide 3, derived from morpholine, at 100 microM. On radicle and shoot growth, the effect of these compounds was predominantly inhibitory. Compound 3 was the best inhibitor of growth of lettuce and onion, at the highest concentration. Amides, such as propanil, among others, are described as having herbicidal activity.     

The effect of docosahexaenoic acid moiety on the cytotoxic activity of 1,2,4-thiadiazole derivatives

Among 3-(2-aminopropyl)-1,2,4-thiadiazole derivatives containing substitutable secondary amino group and exhibiting cytotoxic activity towards rat C6 glioma cells three compounds with LD₅₀ values ranged from 6 to 48 μM have been chosen. For these compounds amides with docosahexaenoic acid were synthesized and their cytotoxic activity was studied. It was shown that, although docosahexaenoic acid itself was not toxic for C6 glioma cells, its addition to the amino derivatives of 1,2,4-thiadiazole increased or decreased their cytotoxicity. These results demonstrate that acylation of cytotoxic compounds with docosahexaenoic acid does not necessarily lead to the increase of their activity and sometimes can inactivate a parent compound. This fact should be taken into consideration because of possibility of biological attachment of docosahexaenoic acid to the amino group of anti-cancer drugs.     

DL-aminocarnitine and acetyl-DL-aminocarnitine. Potent inhibitors of carnitine acyltransferases and hepatic triglyceride catabolism

DL-Aminocarnitine (3-amino-4-trimethylaminobutyric acid) and acetyl-DL-aminocarnitine (3-acetamido-4-trimethylaminobutyric acid) have been synthesized and the interactions of these compounds with carnitine acetyltransferase and carnitine palmitoyltransferase investigated. As anticipated from the low group transfer potential of amides, carnitine acetyltransferase catalyzes the transfer of acetyl groups from CoASAc to aminocarnitine (Km = 3.8 mM) but does not catalyze detectable transfer from acetylaminocarnitine to CoASH. Acetyl-DL-aminocarnitine is, however, a potent competitive inhibitor of carnitine acetyltransferase (Ki = 24 microM) and is bound to carnitine acetyltransferase about 13-fold more tightly than is acetylcarnitine, with which it is isosteric. DL-Aminocarnitine and, to a lesser extent, acetyl-DL-aminocarnitine are also inhibitors of the carnitine palmitoyltransferase activity of detergent-lysed rat liver mitochondria; in the presence of 1 mM L-carnitine, 5 microM aminocarnitine inhibits palmitoyl transfer by 64%. Significant acylation of aminocarnitine by palmitoyl-CoA was not observed. Neither aminocarnitine nor acetylaminocarnitine is significantly catabolized by mice; aminocarnitine is converted to acetylaminocarnitine in vivo. Both compounds are excreted in the urine. Mice given acetylaminocarnitine catabolize [14C]acetyl-L-carnitine and [14C]palmitate to 14CO2 more slowly than do control animals. Mice given acetylaminocarnitine and then starved are found to reversibly accumulate triglycerides in their livers; mice given the inhibitor but not starved do not show this effect.     

Studies on the Nitrogen Metabolism in Tobacco Plants. A.

The nitrogenous compounds of tobacco saps have been studied both qualitatively and quantitatively and the following results were obtained.

(1) Nitrate nitrogen accounts for 40 to 70% of the total nitrogen and the rest is composed mostly of amino and alkaloid nitrogen.

(2) Amides and basic amino acids compose a large part of the amino and amide nitrogen. Among the amino acids and amides of the tobacco saps glutamine is the highest in the content and asparagine, lysine, leucine and serine follow glutamine.

(3) Topping procedure increased remarkably the alkaloid contents in the sap but decreased the amino acid nitrogen as compared with those of the untopped plant sap.     

Pharmacokinetic studies of naproxen amides of some amino acid esters with promising colorectal cancer chemopreventive activity

Naproxen (nap) is belonging to Non-steriodal anti-inflammatory drugs (NSAIDs) group of drugs that characterized by their free carboxylic group. The therapeutic activity of nap is usually accompanied by GI untoward side effects. Recently synthesized naproxen amides of some amino acid esters prodrugs to mask the free carboxylic group were reported. Those prodrugs showed a promising colorectal cancer chemopreventive activity. The current study aims to investigate the fate and hydrolysis of the prodrugs kinetically in different pH conditions, simulated gastric and intestinal fluids with pHs of 1.2, 5.5 and 7.4 in vitro at 37 °C. The effect of enzymes on the hydrolysis of prodrugs was also studied through incubation of these prodrugs at 37 °C in human plasma and rat liver homogenates. The pharmacokinetic parameters of selected prodrugs and the liberated nap were studied after oral and intraperitoneal administration in male wistar rats. The results showed the hydrolysis of naproxen amides of amino acid esters to nap through two steps first by degradation of the ester moiety to form the amide of nap with amino acid and the second was through the degradation of the amide link to liberate nap. The two reactions were followed and studied kinetically where K₁ and K₂ (rate constants of degradation) is reported. The hydrolysis of prodrugs was faster in liver homogenates than in plasma. The relative bioavailability of the liberated nap in vivo was higher in case of prodrug containing ethyl glycinate moiety than that occupied l-valine ethyl ester moiety. Each of nap. prodrugs containing ethyl glycinate and l-valine ethyl ester moieties appears promising in liberating nap, decreasing direct GI side effect and consequently their colorectal cancer chemopreventive activity.     

Nitrile biotransformation by Aspergillus niger

A nitrile-converting enzyme activity was induced in Aspergillus niger K10 by 3-cyanopyridine. The whole cell biocatalyst was active at pH 3–11 and hydrolyzed the cyano group into acid and/or amide functions in benzonitrile as well as in its meta- and para-substituted derivatives, cyanopyridines, 2-phenylacetonitrile and thiophen-2-acetonitrile. Amides constituted a significant part of the total biotransformation products of 2- and 4-cyanopyridine, 4-chlorobenzonitrile, 4-tolunitrile and 1,4-dicyanobenzene, while -substituted acrylonitriles gave amides as the sole products.     

Hepatoprotective activity of betulonic acid amides containing piperidine or pyrrolidine nitroxide moieties

Betulonic acid amides containing the nitroxyl radical moiety exert an anticholestatic effect in mice. The introduction of piperidine nitroxide moiety into the lupane core increases its hepatoprotective activity. Oral administration of the piperidine nitroxide derivative in a dose of 50 mg/kg does not stimulate transplanted tumor growth and increases lifespan in mice.     

Impact of sex,age and diet on the cysteine/cystine and glutathione/glutathione disulfide plasma redox couples in mice

Age, sex and diet are well-established risk factors for several diseases. In humans, each of these variables has been linked to differences in plasma redox potentials (E_h) of the glutathione/glutathione disulfide (GSH/GSSG) and cysteine/cystine (Cys/CySS) redox couples. Mice have been very useful for modeling human disease processes, but it is unknown if age, sex and diet affect redox couples in mice as they do in humans. The purpose of the present study was to examine the effects of these factors on plasma redox potentials in C57BL/6J mice. We found that age had no effect on either redox couple in either sex. Plasma E_h Cys/CySS and E_h GSH/GSSG were both more oxidized (more positive) in females than in males. A 24-hour fast negated the sex differences in both redox potentials by oxidizing both redox couples in male mice, while having no effect on E_h Cys/CySS and a smaller effect on E_h GSH/GSSG in female mice. A diet with excess sulfur amino acids reduced the plasma E_h Cys/CySS in females to a level comparable to that seen in male mice. Thus, sex-specific differences in plasma E_h Cys/CySS could be normalized by two different dietary interventions. Some of these findings are consistent with reported human studies, while others are not. Most strikingly, mice do not exhibit age-dependent oxidation of plasma redox potentials. Care must be taken when designing and interpreting mouse studies to investigate redox regulation in humans.     

Characterization Of The S' Subsite Specificity Of Trypsin

The S' subsite specificity of bovine trypsin has been studied by partitioning of o-nitrophenylsulfenyl-L-arginyl-trypsin (formed using o-nitrophenylsulfenyl-L-arginine alkyl esters as acyl donors) between various amino acid-derived nucleophiles and water. The data obtained from spectrophotometric measurements confirmed a preference of trypsin for arginine residues in the P'₁-position, which is less marked but quite similar to that of chymotrypsin. The amides of leucine, phenylalanine, methionine, threonine, lysine and valine are better for synthesis than the corresponding methyl esters, and show a moderate nucleophile efficiency, decreasing in that order. Amides of acidic amino acids and D-leucine were ineffective in forming the peptide bond, whereas norvaline amide and dipeptide amides lead to increased aminolysis.     

Synthesis and Antioxidant Ability of Novel Derivatives Based on para‐Coumaric Acid Containing Isobornyl Groups

A series of novel esters and amides was synthesized on the basis of para‐coumaric acid containing isobornyl groups in ortho‐positions relative to the phenolic hydroxy group. Antioxidant properties of the obtained compounds were evaluated and compared on in vitro models: radical‐scavenging ability, antioxidant activity on a substrate containing the lipids of animal brain, cytotoxicity of red blood cells, antioxidant and membrane‐protective properties on the model of oxidative red blood cells hemolysis. Statistically significant relationship was established between the antioxidant activity of the studied compounds in model system containing animal lipids and the parameters reflecting their antioxidant properties on the model of H₂O₂‐induced hemolysis of red blood cells. It was determined that an amide with a morpholine fragment has the highest antioxidant activity. The specified derivative significantly surpassed the reference substances (parent acid, BHT) and was not inferior to the effective antioxidant 2,6‐diisobornyl‐4‐methylphenol in terms of its properties.     

Effect of nitrogen-containing derivatives of the plant triterpenes betulin and glycyrrhetic acid on the growth of MT-4, MOLT-4, CEM, and Hep G2 tumor cells

Derivatives of the available plant triterpenes glycyrrhetic acid and betulin (betulin succinates and amides of betulonic and 18beta-glycyrrhetic acids containing fragments of long-chain amino acids and a peptide) were synthesized. The inhibitory action of these compounds on the growth of MT-4, MOLT-4, CEM. and Hep G2 tumor cells and their effect on the apoptosis of these cells were studied. It was shown that betulonic acid amides are more effective inhibitors of the tumor cell growth than the corresponding amides of glycyrrhetic acid. It was also found that betulonic acid amides containing fragments of caprylic, pelargonic, and undecanoic acids are more effective inhibitors of tumor cell growth than betulinic acid. The 17-dipeptide derivative of betulonic acid N-{N-[3-oxo-20(29)-lupen-28-oyl]-9-aminononanoyl}-3-amino-3-phenylpropionic acid exhibited the maximum inhibitory activity toward the tumor cells studied. Data on the induction of apoptosis in tumor cells by betulin derivatives at a concentration of 10 microg/ml were obtained by flow cytometry. The amides of betulonic acid proved to be the most effective inducers of apoptosis.     

Effect of nitrogen-containing derivatives of the plant triterpenes betulin and glycyrrhetic acid on the growth of MT-4, MOLT-4, CEM,and Hep G2 tumor cells

Derivatives of the available plant triterpenes glycyrrhetic acid and betulin (betulin succinates and amides of betulonic and 18β-glycyrrhetic acids containing fragments of long-chain amino acids and a peptide) were synthesized. The inhibitory action of these compounds on the growth of MT-4, MOLT-4, CEM, and Hep G2 tumor cells and their effect on the apoptosis of these cells were studied. It was shown that betulonic acid amides are more effective inhibitors of the tumor cell growth than the corresponding amides of glycyrrhetic acid. It was also found that betulonic acid amides containing fragments of caprylic, pelargonic, and undecanoic acids are more effective inhibitors of tumor cell growth than betulinic acid. The 17-dipeptide derivative of betulonic acid N-{N-[3-oxo-20(29)-lupen-28-oyl]-9-aminononanoyl}-3-amino-3-phenylpropionic acid exhibited the maximum inhibitory activity toward the tumor cells studied. Data on the induction of apoptosis in tumor cells by betulin derivatives at a concentration of 10 μg/ml were obtained by flow cytometry. The amides of betulonic acid proved to be the most effective inducers of apoptosis.     

The Influences of Jasmonic Acid Methyl Ester on Microtubules in Potato Cells and Formation of Potato Tubers

Amides in a CH₂Cl₂ extract from the fruits of Piper retrofractum were detected by HPLC/APCI-MS. Seven new unsaturated amides, together with six known ones, were isolated, and their structures were determined to be N-isobutyl-2E,4E,12Z-octadecatrienamide (1), N-isobutyl-2E,4E,14Z-eicosatrienamide (2), 1-(octadeca-2E,4E,12Z-trienoyl)piperidine (3), 1-(eicosa-2E,4E,14Z-trienoyl)piperidine (4), 1-(octadeca-2E,4E-dienoyl)piperidine (5), 1-(eicosa-2E,4E-dienoyl)piperidine (6), and 1-(eicosa-2E,14Z-dienoyl)piperidine (7) on the basis of chemical and spectroscopic evidence.     

Treatment of simulated wastewater containing toxic amides by immobilized <Emphasis Type="Italic">Rhodococcus rhodochrous</Emphasis> NHB-2 using a highly compact 5-stage plug flow reactor

Biodegradation of toxic amides by immobilized Rhodococcus rhodochrous NHB-2 has been studied to generate data for future development of reactors for the treatment of simulated wastewater containing various toxic amides. The whole resting cells were immobilized in different matrices like agar, polyacrylamide and alginate. Agar gel beads were selected for the treatment of simulated wastewater containing 100mM each acetamide, propionamide, and 10mM of acrylamide and packed in a highly compact five-stage plug flow reactor. The immobilized bacterium worked well in a broad pH range from 5 to 10, with an optimum at 8.7. The apparent K _m-value for the turnover of acetamide for the resting cells was determined to be around 40mM at pH 8.5 and 55°C, whereas the K _m-value of the purified amidase was predicted to be about 20 mM. This organism exhibited greater turnover of aliphatic amides as compared to aromatic amides. Although these cells showed maximal amide-degrading activity at 55°C, simulated wastewater treatment was carried out at 45°C, because of the greater stability of the amidase activity at that temperature. Of note, indices for overall temperature stability, based on the temperature dependence of apparent first order kinetic temperature denaturation constants, were determined to be –7.9±1.1×10^–4, and –13.7±1.3×10^–4, –14.5±0.7×10^–4, and –13.7±0.8×10^–4°Cmin, for free cells and cells immobilized in alginate, agar and polyacrylamide respectively. After 250min the reactor showed maximum degradation of acetamide, propionamide and acrylamide of about 97, 100 and 90%, respectively by using 883 enzyme activity units per reactor stage. The results of this investigation showed that R. rhodochrous NHB-2 expressing thermostable amidase could be used for the efficient treatment of wastewater containing toxic amides. Therefore, we suggest that this microbe has a very high potential for the detoxification of toxic amides from industrial effluents and other wastewaters.     

Helical structure and orientation of melittin in dispersed phospholipid membranes from amide exchange analysis in situ.

A trapping method combined with high-resolution nuclear magnetic resonance spectroscopy is described for the measurement of hydrogen-deuterium exchange rates for individual amides of polypeptides bound to fully hydrated, dispersed phospholipid bilayers. Exchange rates were measured for 22 of the 24 amide hydrogens of bee venom melittin bound to bilayers composed of egg phosphatidylcholine/phosphatidylserine (88:12, mol/mol) dispersed in 20 mM sodium acetate, pH 4.0. Amides of residues 5-11 and 16-22 had exchange rates suppressed by between 30- and 1000-fold, and the rate suppression exhibited a helical periodicity with amides on the hydrophobic helix face up to 20-fold more stable than those on the hydrophilic face of the helix. These results demonstrate that under the conditions studied melittin adopts a helical conformation with stable helical hydrogen bonds extending to residue 22 and that the helix is oriented with the hydrophobic face directed toward the membrane interior.