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Melanocortin peptides containing a 3-(2-naphthyl)-d-alanine residue in position 7 (DNal(2′)7), reported as melanocortin-3 receptor (MC3R) subtype-specific agonists in two separate publications, were found to lack significant MC3R agonist activity. The cell lines used at the University of Arizona for pharmacological characterization of these peptides, consisting of HEK293 cells stably transfected with human melanocortin receptor subtypes MC1R, MC3R, MC4R, or MC5R, were then obtained and characterized by quantitative polymerase chain reaction (PCR). While the MC1R cell line correctly expressed only hMCR1, the three other cell lines were mischaracterized with regard to receptor subtype expression. The demonstration that a 3-(2-naphthyl)-d-alanine residue in position 7, irrespective of the melanocortin peptide template, results primarily in the antagonism of MC3R and MC4R then allowed us to search the published literature for additional errors. The erroneously characterized DNal(2′)7-containing peptides date back to 2003; thus, our analysis suggests that systematic mischaracterization of the pharmacological properties of melanocortin peptides occurred.

While the urotensinergic system plays a role in influencing various pathologies, its potential remains untapped because of the absence of therapeutically effective urotensin II receptor (UTR) modulators. Herein, we developed analogues of human urotensin II (hU-II) peptide in which, along with well-known antagonist-oriented modifications, the Glu1residue was subjected to single-point mutations. The generated library was tested by a calcium mobilization assay and ex vivo experiments, also in competition with selected ligands. Interestingly, many derivatives showed noncompetitive modulation that was rationalized by the lateral allostery concept applied to a G protein-coupled receptor (GPCR) multimeric model. UPG-108showed an unprecedented ability to double the efficacy of hU-II, while UPG-109and UPG-111turned out to be negative allosteric modulators of UTR. Overall, our investigation will serve to explore and highlight the expanding possibilities of modulating the UTR system through N-terminally modified hU-IIanalogues and, furthermore, will aim to elucidate the intricate nature of such a GPCR system.

Here, we report the design of new analogues of spirooxoindolepyrrolidine nucleus as modulators of p53 activity. Compounds (3R,7aR)-6-(4-chlorobenzyl)-1H-spiro[imidazo[1,5-c]thiazole-3,3′-indoline]-2′,5,7(6H,7aH)-trione (9c) and (3R,7aR)-5′-methyl-6-(3,4,5-trimethoxybenzyl)-1H-spiro[imidazo[1,5-c]thiazole-3,3′-indoline]-2′,5,7(6H,7aH)-trione (10d) are the most potent compounds of this series, inhibiting cell growth of different human tumor cells at submicromolar and micromolar concentrations, respectively. Compound 9cinduces apoptotic cell death in human melanoma cell line M14 at 24 h, while in the same condition, treatment with 10dshowes a clear arrest at G2/M phase inducing delay of cell cycle progression. Possibly, these activities may be due to inhibition of p53−MDM2 interaction and subsequent p53 release and activation.

We investigated the ultrasonication-mediated effects on the Fmoc-based solid-phase peptide synthesis (SPPS). Our study culminated with the development of an ultrasound-assisted strategy (US-SPPS) that allowed for the synthesis of different biologically active peptides (up to 44-mer), with a remarkable savings of material and reaction time. Noteworthy, ultrasonic irradiation did not exacerbate the main side reactions and improved the synthesis of peptides endowed with “difficult sequences”, placing the US-SPPS among the current high-efficient peptide synthetic strategies.

In accordance with their common but also divergent physiological actions, human urotensin II (1) and urotensin II-related peptide (2) could stabilize specific urotensin II receptor (UTR) conformations, thereby activating different signaling pathways, a feature referred to as biased agonism or functional selectivity. Sequential N-methylation of the amides in the conserved core sequence of 1, 2, and fragment U-II4-11(3) shed light on structural requirements involved in their functional selectivity. Thus, 18 N-methylated UTR ligands were synthesized and their biological profiles evaluated using in vitro competition binding assays, ex vivo rat aortic ring bioassays and BRET-based biosensor experiments. Biological activity diverged from that of the parent structures contingent on the location of amide methylation, indicating relevant hydrogen-bond interactions for the function of the endogenous peptides. Conformational analysis of selected N-methyl analogs indicated the importance of specific amide residues of 2for the distinct pharmacology relative to 1and 3.

The development of synthetic macrocycles represents a powerful approach toward the identification of new protein binders or inhibitors of Protein-Protein Interactions (PPI) which are known to play key biological roles in cancer signaling as well as in the regulation of cell division cycle. Structural investigations led to identify “hot loops” sharing common motifs that are mainly involved in PPIs. Most PPIs occur through large and flat surfaces; currently these protein complexes are defined as “undruggable” by conventional drug-discovery approaches, since the identification of small molecules to inhibit these targets is often unreachable. Typically macrocycles are 500-2000 Da in size, having 12-membered, or more, ring architecture: they do not obey the Lipinski’s rule but, for them nature offers many examples as therapeutic agents such as erythromycin (antibiotic), cyclosporin (immunosuppressant) and somatostatin (hormone). Peptide-based macrocycles offer the advantages of directly mimicking secondary structures involved in PPIs and their pharmacological application is related to the potential improvement of lead peptides in terms of potency, selectivity, stability and cell permeation. The promising relevance of cyclopeptides prompted to develop new synthetic methods for cyclization: often biotechnological approaches as well as regioselective reactions have been employed to cyclize peptides rapidly and nearly quantitatively. Moreover, different synthetic strategies in peptidomimetics’ macrocyclization are actually available based on surrogate peptide bonds or NCL (Native Chemical Ligation) methods. In this review we focus on the most common methods for the preparation of cyclopeptides and interesting applications of the last decade.

Antimicrobial peptides (AMPs) are an heterogeneous group of small amino acidic molecules produced by the innate immune system of a variety of organisms encompassing all orders of life from eukaryotes to amphibians, insects and plants. Numerous AMPs have been isolated from natural sources and many others have been de novo designed and synthetically produced. AMPs have antimicrobial activity in the micromolar range and compared with traditional antibiotics, they kill bacteria very rapidly. They act, principally, by the electrostatic attraction to negatively charged bacterial cells and consequently membrane disruption, but their antibacterial activity may also involve interference with metabolic processes or different cytoplasmic targets. AMPs are a group of unique and incredible compounds that may be directed to a therapeutic use either alone or in combination with existing antibiotics.

PTPRJ is a receptor protein tyrosine phosphatase involved in both physiological and oncogenic pathways. We previously reported that its expression is strongly reduced in the majority of explored cancer cell lines and tumor samples; moreover, its restoration blocks in vitrocancer cell proliferation and in vivotumor formation. By means of a phage display library screening, we recently identified two peptides able to bind and activate PTPRJ, resulting in cell growth inhibition and apoptosis of both cancer and endothelial cells. Here, on a previously discovered PTPRJ agonist peptide, PTPRJ-pep19, we synthesized and assayed a panel of nonapeptide analogues with the aim to identify specific amino acid residues responsible for peptide activity. These second-generation nonapeptides were tested on both cancer and primary endothelial cells (HeLa and HUVEC, respectively); interestingly, one of them (PTPRJ-19.4) was able to both dramatically reduce cell proliferation and effectively trigger apoptosis of both HeLa and HUVECs compared to its first-generation counterpart. Moreover, PTPRJ-pep19.4 significantly inhibited in vitrotube formation on Matrigel. Intriguingly, while ERK1/2 phosphorylation and cell proliferation were both inhibited by PTPRJ-pep19.4 in breast cancer cells (MCF-7 and SKBr3), no effects were observed on primary normal human mammary endothelial cells (HMEC). We further characterized these peptides by molecular modeling and NMR experiments reporting, for the most active peptide, the possibility of self-aggregation states and highlighting new hints of structure–activity relationship. Thus, our results indicate that this nonapeptide might represent a great potential lead for the development of novel targeted anticancer drugs.

Acid-catalysed condensation of tryptophan with different α-amino aldehyde derivatives has been explored as a useful route to the synthesis of novel amino acid derived heterocycles and peptidomimetic scaffolds. By this approach, compounds containing a tetrahydro-β-carboline and a novel octahydropyrrolo[3′,2′:3,4]pyrrolo[2,3-b]indole system have been efficiently synthesized. Here we report the characterization of these new compounds and preliminary studies of the reactivity of the tetrahydro-β-carboline system.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Two melanocortin receptors (MC1 and MC3R) have been identified as main transducers of the anti-inflammatory effects of natural and synthetic melanocortins. In this study, we have taken advantage of the recent description of the selective MC3R agonist [D-Trp8]-γ-melanocyte-stimulating hormone (MSH) and of the recessive yellow (e/e) mouse, bearing a nonfunctional MC1R, thereby incrementing our knowledge on this topic. Culturing peritoneal macrophages of recessive yellow (e/e) mice with [D-Trp8]-γ-MSH led to accumulation of cAMP, indicating MC3R receptor functionality: this effect was blocked by a neutralizing antibody against MC3R. Likewise, release of the chemokine KC by urate crystals was attenuated by [D-Trp8]-γ-MSH, and this effect was prevented by synthetic [Ac-Nle4-c[Asp5-2'-Nal7,Lys10]α-MSH(4-10)-NH2 (SHU9119)] and natural [agouti-related protein (AGRP)] MC3R antagonists but not by the MC4R antagonist Ac-Cys-Nle-Arg-His-D-2-Nal-Arg-Trp-Cys-NH2 (HS024). Systemic treatment of mice with [D-Trp8]-γ-MSH inhibited KC release and polymorphonuclear cell accumulation elicited by urate crystals in the murine peritoneal cavity. SHU9119 and AGRP prevented the inhibitory actions of [D-Trp8]-γ-MSH, whereas HS024 was inactive. We also demonstrate here that [D-Trp8]-γ-MSH displays a dual mechanism of action by inducing the anti-inflammatory protein heme-oxygenase 1 (HO-1). Treatment with the HO-1 inhibitor zinc protoporphyrin IX exacerbated the inflammatory response elicited by urate crystals and abrogated the anti-inflammatory effects of [D-Trp8]-γ-MSH. In conclusion, these data support the development of the selective MC3R agonist [D-Trp8]-γ-MSH for the treatment of inflammatory pathologies, based on a dual mechanism of cytokine/chemokine inhibition and induction of the anti-inflammatory protein HO-1.

A short and general synthesis for the preparation of two series of conformationally constrained building block has been elaborated starting from amino acids. The intrinsic tendency of the dipeptide mimetic scaffold to induce β-turn formation was evaluated by computer methods. The results indicate that the diastereomers with the (R) configuration at the C-2 have high propensity to the type II β-turn formation.

Among RGD-dependent integrins, the αvβ3 receptor has recently received increasing attention as a therapeutic target because of its critical role in tumor-induced angiogenesis and metastasis formation. Here, we describe a new peptide antagonist of αvβ3 receptor, designed on the basis of the crystal structure of integrin αvβ3 in complex with c(RGDf[NMe]V) and the NMR structure of echistatin. Cell adhesion assays have demonstrated that the peptide is a potent and selective antagonist of the αvβ3 receptor.

The melanotropin peptides ?-MSH, ?-MSH, and ?-MSH are believed to be the natural ligands for the four melanocortin receptors, MC1R, MC3R, MC4R, and MC5R. However, these peptides generally have low selectivity for these receptors. We report on some approaches to the development of selective agonists and antagonists peptide ligands for these receptors.

Nitric oxide synthase (NOS) catalyses the conversion of L-arginine to nitric oxide (NO) which plays an important role in the regulation of cellular functions and intracellular communications. Three distinct isoforms of NOS have so far been identified, two constitutive and one inducible. All three mammalian isoforms of NOS contain putative CaM-binding domains with the canonical composition. In this paper we report the synthesis and the inhibitory activity on rat neuronal and lung inducible NOS of antisense peptides corresponding to the antisense strand read in 3′ to 5′ (CALM 1) or 5′ to 3′ (CALM 2) direction of the region encoding for the CaM-binding domain of the inducible NOS isoform (residues 503-522). CALM 1 inhibited, at all the concentrations tested (0.01-1 mM), both the inducible and constitutive NOS (IC 50 98 μM and 56 μM, respectively), while CALM 2 (0.01-1 mM) was ineffective on both isoforms. The acetylation of CALM 1 at its amino terminal (CALM 8) completely abolished its inhibitory activity. We also synthesized and analysed the activity of amino terminal truncated analogues (CALM 3-7) of CALM 1, which selectively inhibited the inducible isoform, although less potently than the parent compound. The pentapeptides (CALM A-D) deriving from the cleavage of CALM 1 were ineffective, except the pentapeptide CALM C corresponding to the residues 513-517, which was as potent as the parent compound (IC 50 65 μM).

A series of novel 1,2,3-benzotriazin-4-one derivatives was prepared and evaluated as ligands for 5-HT receptors. Radioligand binding assays proved that the majority of the novel compounds behaved as good to excellent ligands at the 5-HT1Areceptor, some of which were selective with respect 5-HT2Aand 5-HT2Creceptors. Six analogues (1a, 2a, 2b, 2c, 2eand 2i) were selected and further evaluated for their binding affinities on D1, D2dopaminergic and α1-, α2-adrenergic receptors. A o-OCH3derivative (2e) bound at 5-HT1Asites with subnanomolar affinity (IC50=0.059 nM) and shows high selectivity over all considered receptors and may offer a new lead for the development of therapeutically efficacious agents.

We have determined that the peptide lipocortin-5 N-terminus (LIPO-5NT) was able to inhibit rabbit platelet aggregation in a concentration- and time-dependent manner. In order to assess which residues in LIPO-5NT were essential for its activity, an ‘Ala-scan’ was performed by sequentially substituting alanine for each of the first six residues. We demonstrate that replacement of Gln3 by alanine increases inhibition by about 20 times, while substitution of Leu5 gives an increase in activity of about 70 times.

Abstract: The solid-state molecular conformations and crystal structures of three analogues of the CP-96,345 molecule, an important nonpeptidic SP antagonist, namely the (±)-2-(3-phenylbenzilidene)-3-(2-benzylamino) quinuclidine, theo-chloro- and theo-methoxy-derivatives, have been determined by X-ray diffusion analyses and refined to finalR values of 0.055, 0.045, and 0.056, respectively. All three molecules in the solid state show the same disposition of the substituents of the double bond and differences in the conformation mainly caused by the need of releasing intramolecular strains and/or nonbonded interactions. The observed molecular structures are compared to the reported solid-state structure of the CP-96,345 and correlated to the biological activity as NK antagonists.

A series of 2-(3- and 4-substituted phenyl)-3-[3-(N,N-dimethylamino)propyl]-1,3-thiazolidin-4-ones acting as H1-antihistaminics was investigated with a combined Hansch-CoMFA approach. The substituents at the 3- and 4-positions of the phenyl ring have been described through steric, electronic and hydrophobic parameters and correlated with pA2 values. The obtained quantitative models suggest that affinity to the receptor is promoted by hydrophobic and small 4-substituents and by 3- and 4-substituents generating a positive electrostatic potential towards a complementary receptor region.

With the aim of discovering new molecules with K+channel modulating properties, we have synthesized analogues of cromakalim, an important molecule which shows specific affinity toward the K+channels, by replacing the benzopyrane ring with a benzoxazine moiety. As a part of this study, we have synthesized and characterized, in solution and in the solid state as well, the compound ethyl [2,2-dimethyl-6-(Δ2-thiazolin-2-yl)-4H-l,4-benzoxazin-3-one-4-yl]butyrate (V). This compound exhibits in the solid state the following parameters: molecular formula C19H24N2O4S, triclinic, space group $$P\bar 1$$ , Mw= 376.5, a= 12.581(3) Å, b= 5.485(4) Å, c= 14.612(2) Å, α= 91.85(2), β= 108.9(3), γ= 82.04(4), V= 944.7 Å3, Z= 2, d= 1.323 g·cm−3. We describe here the synthesis and discuss the solid-state conformation of this new molecule; when tested on rat aorta ring precontracted with phenylephrine, the compound showed a concentration-dependent relaxation comparable to that measured for cromakalin taken as reference drug.

This work reveals some key factors for the design of a novel generation of selective melanocortin ligands at the MC4 receptor.

The pharmacodynamic and pharmacokinetic properties of bioactive peptides can be modulated by introducing conformational constraints such as intramolecular macrocyclizations, which can involve either the backbone and/or side chains. Herein, we aimed at increasing the α-helicity content of temporin L, an isoform of an intriguing class of linear antimicrobial peptides (AMPs), endowed with a wide antimicrobial spectrum, by the employment of diverse side-chain tethering strategies, including lactam, 1,4-substituted [1,2,3]-triazole, hydrocarbon, and disulfide linkers. Our approach resulted in a library of cyclic temporin L analogues that were biologically assessed for their antimicrobial, cytotoxic, and antibiofilm activities, leading to the development of the first-in-class cyclic peptide related to this AMP family. Our results allowed us to expand the knowledge regarding the relationship between the α-helical character of temporin derivatives and their biological activity, paving the way for the development of improved antibiotic cyclic AMP analogues.

The synthesis of new dihydrothieno[2,3-g and 3,2-g](iso)quinoline-4,9-dione derivatives, as potential templates in development of new cytotoxic agents, was realized using microwave irradiation methodology.

Solid-phase peptide synthesis and microwave-assisted organic synthesis have been combined in order to speed up drug discovery process of macrocyclization products in high purity and good yield.

Cyclooxygenase (COX) is a key enzyme in the biosynthetic pathway leading to the formation of prostaglandins, which are mediators of inflammation. It exists mainly in two isoforms COX-1 and COX-2. The conventional nonsteroidal anti-inflammatory drugs (NSAIDs) have gastrointestinal side effects because they inhibit both isoforms. Recent data demonstrate that the overexpression of these enzymes, and in particular of cyclooxygenases-2, promotes multiple events involved in tumorigenesis; in addition, numerous studies show that the inhibition of cyclooxygenases-2 can delay or prevent certain forms of cancer. Agents that inhibit COX-2 while sparing COX-1 represent a new attractive therapeutic development and offer a new perspective for a further use of COX-2 inhibitors. The present study extends the evaluation of the COX activity to all 203 possible natural tripeptide sequences following a rational approach consisting in molecular modeling, synthesis, and biological tests. Based on data obtained from virtual screening, only those peptides with better profile of affinity have been selected and classified into two groups called S and E. Our results suggest that these novel compounds may have potential as structural templates for the design and subsequent development of the new selective COX-2 inhibitors drugs.

Synthesis and pharmacological activity of a series of N‐aroyl derivatives (I) of kynurenic acid methyl esters, structurally related to NSAID indomethacin are described.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.