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PubMed1990

Synthesis of human renin inhibitory peptides, angiotensinogen transition-state analogs containing a retro-inverso amide bond.

The experimental details for the synthesis of human renin inhibitors are described. In order to avoid metabolic degradation of the Phe-His (P3-P2) amide bond in transition-state analogs, structurally modified acyl residues (P4-P3) were incorporated into the inhibitors. Compound 1a, which contained 2-(1-naphthylmethyl)-3-(N-phenethylcarbamoyl)propionyl residue (P4-P3) with a retro-inverso amide bond, L-histidine, and norstatine isoamylamide residue (P1-P1) as a transition-state mimic, had potent human renin inhibitory activity, and it lowered blood pressure when administered orally to common marmosets.

Amides↗
PubMed2004

Study on the stevioside analogues of steviolbioside, steviol, and isosteviol 19-alkyl amide dimers: synthesis and cytotoxic and antibacterial activity.

A new group of steviolbioside amide dimers 2a-g, derivatives 2h-i and their related steviol and isosteviol amide dimers 3a and 4a were prepared by reacting aliphatic alkylamine and alkyldiamines with PyBOP and DIEA. The synthesized compounds had cytotoxic effects on cancer and human embryonic lung cells. Compounds 3a, 4a, 2b and 2h were cytotoxic to cancer cells and to a lesser extent to human embryo lung cells. Compounds 2f, 2g and 4 of this series had favorable antibacterial effects, and were superior to penicillin G at inhibiting growth of Bacillus subtilis (BCRC 10029). The cytotoxicity and antibacterial effects may depend on the dimerization and derivative moieties in relation to the respective aglycons.

Amides↗
PubMed2004

New insecticidal amides from petroleum ether extract of dried Piper nigrum L. whole fruits.

The petroleum ether extract of dried ground whole fruits of Piper nigrum L. afforded 20 compounds (1-20) including two new insecticidal amides named as pipnoohine (1), and pipyahyine (2), seven reported for the first time from this plant (12, 13, 15-17, 19, 20), and eleven known compounds (3-11, 14, 18). The structure of 1 has been elucidated as (2E,4E,12Z)-N-(4-methylpentyl)octadeca-2,4,12-trienamide and that of 2 as (2E,4E,11E)-12-(benzo[1,3]dioxol-5-yl)-N-(3-methylbutyl)dodeca-2,4,11-trien-amide through extensive ID-, 2D-NMR spectral studies and chemical reactions. The known compounds have been identified through comparison of their spectral data with those reported in literature. 1 and 2 exhibited toxicity at 35.0 and 30.0 ppm respectively against fourth instar larvae of Aedes aegypti L. by WHO method.

Alkanes↗
PubMed2004

Preparation of Weinreb amides using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM).

Weinreb amides were successfully prepared from the corresponding carboxylic acids using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) in the solvents, methanol, isopropyl alcohol, and acetonitrile, which can solubilize DMT-MM. A variety of carboxylic acids were converted to the corresponding Weinreb amides in excellent yields by simply mixing with DMT-MM and N,O-dimethylhydroxylamine hydrochloride.

2-Propanol↗
PubMed2005

pH dependence of amide chemical shifts in natively disordered polypeptides detects medium-range interactions with ionizable residues.

A growing number of natively disordered proteins undergo a folding/binding process that is essential for their biological function. An interesting question is whether these proteins have incompletely solvated regions that drive the folding/binding process. Although the presence of predominantly hydrophobic buried regions can be easily ascertained by high-sensitivity differential scanning calorimetry analysis, the identification of those residues implicated in the burial requires NMR analysis. We have selected a partially solvated natively disordered fragment of Escherichia coli, thioredoxin, C37 (38-108), for full NMR spectral assignment. The secondary chemical shifts, temperature coefficients, and relaxation rates (R(1) and R(2)) of this fragment indicate the presence of a flexible backbone without a stable hydrogen bond network near neutral pH. (1)H-(15)N heteronuclear single quantum coherence analysis of the pH dependence of amide chemical shifts in fragment C37 within pH 2.0 and 7.0 suggests the presence of interactions between nonionizable residues and the carboxylate groups of four Asp and four Glu residues. The pH midpoints (pH(m)) of the amides in the ionizable residues (Asp or Glu) and, consequently, the shifts in the pH(m) (DeltapH(m)) of these residues with respect to model tetrapeptides, are sequence-dependent; and the nonionizable residues that show pH dependence cluster around the ionizable ones. The same pH dependence has been observed in two fragments: M37 (38-73) and C73 (74-108), ruling out the participation of long-range interactions. Our studies indicate the presence of a 15-residue pH-dependent segment with the highest density of ionizable sites in the disordered ensembles of fragments C37 and M37. The observed correlations between ionizable and nonionizable residues in this segment suggest the organization of the backbone and side chains through local and medium-range interactions up to nine residues apart, in contrast to only a few interactions in fragment C73. These results agree qualitatively with the predominantly hydrophobic buried surface detected only in fragments C37 and M37 by highly sensitive differential scanning calorimetry analysis. This work offers a sensitive and rapid new tool to obtain clues about local and nonlocal interactions between ionizable and nonionizable residues in the growing family of natively disordered small proteins with full NMR assignments.

Amides↗
PubMed2006

Fatty acid amide hydrolase: a potential target for next generation therapeutics.

Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipid mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of Delta(9)-tetrahydrocannabinol, the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA at its receptors is limited by cellular uptake through a specific membrane transporter, followed by intracellular degradation by a fatty acid amide hydrolase (FAAH). Growing evidence demonstrates that FAAH is the critical regulator of the endogenous levels of AEA, suggesting that it may serve as an attractive therapeutic target for the treatment of human disorders. In particular, FAAH inhibitors may be next generation therapeutic drugs of potential value for the treatment of pathologies in the central nervous system and in the periphery. Here, the potential applications of these inhibitors for human disease will be reviewed, with an emphasis on the properties of hydro(pero)xy-anandamides. In fact, these oxygenated derivatives of AEA are the most powerful inhibitors of FAAH of natural origin as yet discovered. In addition, new insights into the promoter region of FAAH gene will be presented, and the therapeutic potential of mimetics of transcription factors of this gene in the management of human infertility will be discussed.

Amidohydrolases↗
PubMed2000

Titanium(IV) isopropoxide mediated solution phase reductive amination on an automated platform: application in the generation of urea and amide libraries.

Amine libraries and their derivatives are important targets for high throughput synthesis because of their versatility as medicinal agents and agrochemicals. As a part of our efforts towards automated chemical library synthesis, a titanium(IV) isopropoxide mediated solution phase reductive amination protocol was successfully translated to automation on the Trident(TM) library synthesizer of Argonaut Technologies. An array of 24 secondary amines was prepared in high yield and purity from 4 primary amines and 6 carbonyl compounds. These secondary amines were further utilized in a split synthesis to generate libraries of ureas, amides and sulfonamides in solution phase on the Trident(TM). The automated runs included 192 reactions to synthesize 96 ureas in duplicate and 96 reactions to synthesize 48 amides and 48 sulfonamides. A number of polymer-assisted solution phase protocols were employed for parallel work-up and purification of the products in each step.

Amides↗
PubMed2002

Cascade synthesis with (triphenylphosphoranylidene)-ethenone as a versatile reagent for fast synthesis of heterocycles and unsaturated amides under microwave dielectric heating.

A general procedure for the synthesis of a large variety of compounds comprising an alpha, beta,-unsaturated carbonyl functionality was developed. The use of one-pot cascade synthesis with (triphenylphosphora-nylidene)ethenone as a versatile reagent for various formations including heterocycles of different ring sizes and unsaturated amides in combination with microwave dielectric heating is described. The method was used to synthesize a small library of unsaturated amides.

Amides↗
PubMed2006

Synthesis and antimelanoma activity of reversed amide analogues of N-acetyl-4-S-cysteaminylphenol.

The melanin biosynthetic pathway from tyrosine is a potential target for combating malignant melanoma. N-Acetyl-4-S-cysteaminylphenol 1 is a previously synthesized analogue of tyrosine that probably acts by this pathway. It interferes with cell growth and proliferation via selective oxidation in melanocytes to an oquinone that can alkylate cellular nucleophiles. We previously synthesized a range of analogues of the original lead compound 1 most of which displayed greater cytotoxicity than 1. Eighteen new analogues with the amide group reversed have now been synthesized and tested for antimelanoma activity. Most of these reverse amides showed greater cytotoxicity than N-acetyl-4-S-cysteaminylphenol towards five representative melanoma cell lines. The highest cytotoxicity was observed for the piperidine and hexamethyleneimine derivatives 7, 8, 12, 13, and 17 and the catechol 18. The most active compound, 7, had cytotoxicity comparable to cisplatin against the five melanoma cell lines. The moderate activity of 7 and 18 against SK-Mel-24 (non-tyrosinase containing) and an ovarian cell line suggests that interference with the melanin pathway may not be the only mode of action of these compounds. Assays of some of the compounds as substrates for tyrosinase showed that the catechol 18 was the best substrate and that the piperidine derivative 7 was the best substrate of the phenolic compounds synthesized.

Amides↗
PubMed1991

Adhesiveness of amide monomers to tooth substrate.

Seven types of amide monomers, methacryloyl tyrosine amide (MTYA), p-methacryloxybenzamide (p-MBA), p-methacryloxybutoxybenzamide (p-MBBA), o-methacryloxybutoxybenzamide (o-MBBA), p-methacryloxybutoxy phenylpropionamide (p-MBPPA), 3,5-dimethacryloxybenzamide (3,5-DMBA), and 3,5-di (methacryloxybutoxy)benzamide (3,5-DMBBA), were prepared for use as bonding agents. The monomers were dissolved in HEMA. Bovine enamel was etched with 40% phosphoric acid, and bovine dentin was etched with 10% citric acid before being primed with MTYA.G.H. The tensile bond strengths between bovine enamel or dentin and experimental adhesives were measured after one day immersion in water at 37 degrees C. HEMA was used as a control adhesive. When bonding to etched enamel, the bond strengths of composite resins with o-MBBA and 3,5-DMBA were significantly higher than those with HEMA. The bond strengths of composites with MTYA, p-MBA, p-MBBA, 3,5-DMBBA and p-MBPPA were almost the same as those with HEMA. When bonding to dentin, the bond strengths of composite resin with MTYA and p-MBBA were significantly higher than those with HEMA.

Acid Etching, Dental↗
PubMed2000

Chalcone, acyl hydrazide, and related amides kill cultured Trypanosoma brucei brucei.

BACKGROUND: Protozoan parasites of the genus Trypanosoma cause disease in a wide range of mammalian hosts. Trypanosoma brucei brucei, transmitted by tsetse fly to cattle, causes a disease (Nagana) of great economic importance in parts of Africa. T. b. brucei also serves as a model for related Trypanosoma species, which cause human sleeping sickness. MATERIALS AND METHODS: Chalcone and acyl hydrazide derivatives are known to retard the growth of Plasmodium falciparum in vitro and inhibit the malarial cysteine proteinase, falcipain. We tested the effects of these compounds on the growth of bloodstream forms of T. b. brucei in cell culture and in a murine trypanosomiasis model, and investigated their ability to inhibit trypanopain-Tb, the major cysteine proteinase of T. b. brucei. RESULTS: Several related chalcones, acyl hydrazides, and amides killed cultured bloodstream forms of T. b. brucei, with the most effective compound reducing parasite numbers by 50% relative to control populations at a concentration of 240 nM. The most effective inhibitors protected mice from an otherwise lethal T. b. brucei infection in an in vivo model of acute parasite infection. Many of the compounds also inhibited trypanopain-Tb, with the most effective inhibitor having a Ki value of 27 nM. Ki values for trypanopain-Tb inhibition were up to 50- to 100-fold lower than for inhibition of mammalian cathepsin L, suggesting the possibility of selective inhibition of the parasite enzyme. CONCLUSIONS: Chalcones, acyl hydrazides, and amides show promise as antitrypanosomal chemotherapeutic agents, with trypanopain-Tb possibly being one of their in vivo targets.

Amides↗
PubMed2001

Study on the secondary structure of protein in amide I band from human colon cancer tissue by Fourier-transform infrared spectroscopy.

BACKGROUND: Fourier-transform infrared spectroscopy (FT-IR) is a powerful tool for study of the secondary conformation of intact protein in biological tissues and for diagnosis of disease states. The purpose of this study is to utilize FT-IR as a diagnostic tool to estimate the secondary structure of amide I in normal and cancer tissue of human colon. METHODS: Pairs of tissue samples from colon cancer and histologically normal mucosa tissue 5-10 cm from the tumor were obtained from a patient who underwent partial colectomy. In the present study we investigated the changes in the secondary structure of amide I of normal and malignant human colon tissue using FT-IR microspectroscopy with attenuated total reflectance. Secondary-derivative analysis relative to the original and curve-fitting analysis infrared spectra were also carried out. RESULTS: The conformational changes of the secondary structure of protein in normal and cancerous human colon tissue were (1) the composition of alpha-helixes increased in human cancerous colon tissue (15.30%) compared to normal colon tissue (11.72%); (2) beta-sheets which were 46.8% in healthy tissue decreased to 30.71% in cancer tissue; (3) beta-turns increased from 26.28% in normal tissue to 38.48% in cancer tissue; and (4) the composition of random coils was not significantly different between normal tissue (15.12%) and cancer tissue (15.51%). CONCLUSION: Our data demonstrate that protein in colon cancer displays abnormal FT-IR spectra. The conformational changes of the secondary structure of this protein in terms of alpha-helixes, beta-sheets and beta-turns were observed in normal and cancerous tissue from the same individual were compared.

Aged↗
PubMed2001

[Preparation and evaluation of amide-octyl-bonded phase for the separation of basic substances in reversed-phase liquid chromatography].

A new bonded-phase, amide-octyl-bonded phase (AOBP), with an internal polar functional group-amide was firstly prepared in domestic by two-step reaction process. The amino phase was formed in the first step and further modified in the second step by attaching an alkyl chain via reaction of an acid chloride with the amino ligand. Characterization of prepared packing was carried out with elemental analysis and Fourier transform infrared (FTIR) spectrometry. Hydrophobicity, selectivity and silanophilic activity of AOBP were evaluated by using organic components including acidic, bascic and neutral analytes and methanol-water as binary mobile phase. The applicable ranges of pH and stability of AOBP were also evaluated. The results showed that AOBP has excellent chromatographic properties and resistance to hydrolysis between pH = 2.5-7.5, It can be used for the separation of basic solutes efficiently.

1-Octanol↗
PubMed2003

The role of alpha-amidated neuropeptides in hydroid development--LWamides and metamorphosis in Hydractinia echinata.

Peptides are increasingly attracting attention as primary signals in the control of development. Even though a large number of peptides have been characterized in cnidarians, little experimental evidence addresses their endogenous role. The life cycle of Hydractinia echinata includes metamorphosis from planula larva into the adult stage of the polyp. This process of stage conversion includes internal signalling, which controls cell cycle activity, cell differentiation, cell death and proportion-controlled morphogenesis. LWamide peptides are considered to be part of the control system. We implemented methods to silence gene activity by dsRNAi in Hydractinia and show a substantial knock-down of LWamide gene activity. In addition, LWamide function was knocked-out pharmacologically by targeting the biosynthesis of amidated peptides and thus preventing functional LWamides. Here we show that extinction of bioactive LWamides from planulae causes loss of metamorphosis competence, a deficiency which can be rescued by synthetic LWamide peptides. Thus, it is shown that LWamides are indispensable and act by conveying outer metamorphosis stimuli to target cells within the animal. Considering non-availability of genetic analysis and the so-far limited success in expressing transgenes in hydroids, gene functions are difficult to analyse in hydroids. The approach as outlined here is suitable for functional analysis of genes encoding amidated peptides in hydroids.

Amides↗
PubMed2003

Cannabinoid CB2 receptors and fatty acid amide hydrolase are selectively overexpressed in neuritic plaque-associated glia in Alzheimer's disease brains.

The endocannabinoid system is still poorly understood. Recently, the basic elements that constitute it, i.e., membrane receptors, endogenous ligands, and mechanisms for termination of the signaling process, have been partially characterized. There is a considerable lack of information, however, concerning the distribution, concentration, and function of those components in the human body, particularly during pathological events. We have studied the status of some of the components of the endocannabinoid system, fatty acid amide hydrolase and cannabinoid CB1 and CB2 receptors, in postmortem brains from patients with Alzheimer's disease. Using specific polyclonal antibodies, we have performed immunohistochemical analysis in hippocampus and entorhinal cortex sections from brains of Alzheimer's disease patients. Our results show that both fatty acid amide hydrolase and cannabinoid CB2 receptors are abundantly and selectively expressed in neuritic plaque-associated astrocytes and microglia, respectively, whereas the expression of CB1 receptors remains unchanged. In addition, the hydrolase activity seems to be elevated in the plaques and surrounding areas. Thus, some elements of the endocannabinoid system may be postulated as possible modulators of the inflammatory response associated with this neurodegenerative process and as possible targets for new therapeutic approaches.

Aged↗
PubMed2005

Effect of (Ala8,13,18)-magainin II amide on human trophoblast cells in vitro.

Magainins are cationic peptides with anti-bacterial and anti-tumor properties. The anti-nidatory function of a synthetic analogue of magainin, (Ala8,13,18)-magainin II amide, has earlier been reported, and it has been indicated that placental trophoblast cells could be a target of magainin resulting in its contragestational action. The aim of the present study was to examine the effect of (Ala8,13,18)-magainin II amide (100 ng/ml and 1000 ng/ml) on attachment efficiency, viability, differentiation in terms of hCG secretion and invasive function of isolated first trimester, human placental trophoblast cells grown on rat-tail collagen type-I matrix in primary cell culture. In the present experimental model, magainin was not found to affect human trophoblast cell functions in vitro.

Amides↗