Search

The cultivar Bianchera is an autochthonous variety from the eastern part of northern Italy, but it is also cultivated in the Slovenian and Croatian peninsula of Istria where it is named Belica (Slovenia) and Bjelica (Croatia). The properties of oleocanthal, a natural anti-inflammatory ibuprofen-like compound found in commercial monocultivar extra virgin olive oils, were determined by means of both quantitative 1HNMR (qNMR) and HPLC analyses, where qNMR was identified as a rapid and reliable method for determining the oleocanthal content. The total phenolic content (TPC) was determined by means of the Folin&ndash, Ciocalteau method and the major phenols present in the olive oils were also quantified by means of HPLC analyses. All these analyses confirmed that the cultivar Bianchera was very rich in polyphenols and satisfied the health claim provided by the EU Commission Regulation on the polyphenols content of olive oils and their beneficial effects on human health.

A library of dihydropyrimidinones was synthesized via a &ldquo, one-pot&rdquo, three component Biginelli reaction using different aldehydes in combination with &beta, dicarbonyl compounds and urea. Selected 2-thiooxo and 2-imino analogs were also obtained with the Biginelli reaction from thiourea and guanidine hydrochloride, respectively. The products were screened in vitro for their &beta, secretase inhibitory activity. The majority of the compounds resulted to be active, with IC50 in the range 100 nM&ndash, 50 &mu, M.

New heteroaryl HIV-protease inhibitors bearing a carbamoyl spacer were synthesized in few steps and high yield, from commercially available homochiral epoxides. Different substitution patterns were introduced onto a given isopropanoyl-sulfonamide core that can have either H or benzyl group. The in vitro inhibition activity against recombinant protease showed a general beneficial effect of both carbamoyl moiety and the benzyl group, ranging the IC50 values between 11 and 0.6 nM. In particular, benzofuryl and indolyl derivatives showed IC50 values among the best for such structurally simple inhibitors. Docking analysis allowed to identify the favorable situation of such derivatives in terms of number of interactions in the active site, supporting the experimental results. The inhibition activity was also confirmed in HEK293 mammalian cells and was maintained against protease mutants. Furthermore, the metabolic stability was comparable with that of the commercially available inhibitors.

Estrogens play a key role in cellular proliferation of estrogen-receptor-positive (ER+) breast cancers (BCs). Suppression of estrogen production by competitive inhibitors of the enzyme aromatase (AIs) is currently one of the most effective therapies against ER + BC. Yet, the development of acquired resistance, after prolonged treatments with AIs, represents a clinical major concern. Serendipitous findings indicate that aromatase may be non-competitively inhibited by clinically employed drugs and/or industrial chemicals. Here, by performing in silico screening on two putative allosteric sites, molecular dynamics and free energy simulations, supported by enzymatic and cell-based assays, we identified five leads inhibiting the enzyme via a non-active site-directed mechanism. This study provides new compelling evidences for the existence of an allosteric regulation of aromatase and for the possibility of exploiting it to modulate estrogens biosynthesis. Such modulation can aptly reduce side effects caused by the complete estrogen deprivation therapy, and, possibly, delay/avoid the onset of resistance. (C) 2019 Elsevier Masson SAS. All rights reserved.

Chlorogenic acids are secondary metabolites in diverse plants. Some chlorogenic acids extracted from traditional medicinal plants are known for their healing properties, e.g., against viral infections. Also, green coffee beans are a rich source of chlorogenic acids, with 5-O-caffeoylquinic acid being the most abundant chlorogenic acid in coffee. We previously reported the synthesis of the regioisomers of lactones, bearing different substituents on the quinidic core. Here, 3,4-O-dicaffeoyl-1,5-γ-quinide and three dimethoxycinnamoyl-γ-quinides were investigated for in vitro antiviral activities against a panel of 14 human viruses. Whereas the dimethoxycinnamoyl-γ-quinides did not show any antiviral potency in cytopathogenic effect reduction assays, 3,4-O-dicaffeoyl-1,5-γ-quinide exerted mild antiviral activity against herpes simplex viruses, adenovirus, and influenza virus. Interestingly, when the compounds were evaluated against respiratory syncytial virus, a potent antiviral effect of 3,4-O-dicaffeoyl-1,5-γ-quinide was observed against both subtypes of respiratory syncytial virus, with EC50 values in the submicromolar range. Time-of-addition experiments revealed that this compound acts on an intracellular post-entry replication step. Our data show that 3,4-O-dicaffeoyl-1,5-γ-quinide is a relevant candidate for lead optimization and further mechanistic studies, and warrants clinical development as a potential anti-respiratory syncytial virus drug.

The four-step conversion of a series of N-Boc-protected l-amino acid methyl esters into enantiopure N-Boc allylamines by a modified Julia olefination is described. Key steps include the reaction of a lithiated phenylalkylsulfone with amino esters, giving chiral β-ketosulfones, and the reductive elimination of related α-acetoxysulfones. The overall transformation takes place under mild conditions, with good yields, and without loss of stereochemical integrity, being in this respect superior to the conventional Julia reaction of α-amino aldehydes.

Peptidomimetic inhibitors of HIV-1 PR are still a key resource in the fight against AIDS. Here we describe the synthesis and biological activity of HIV-1 PR inhibitors based on four novel dihydroxyethylene isosteres of the Phe-Pro and Pro- Pro dipeptides. The isosteres, containing four stereogenic centers, were synthesized in high yield and excellent stereoselectivity via the cyclization of epoxy amines derived from α-amino acids. The inhibitors were assembled by coupling the isosteres with suitable flanking groups and were screened against recombinant HIV PR showing activities in the subnanomolar to micromolar range. Two Phe-Pro-based inhibitors active at the nanomolar level were further investigated: both inhibitors combine the ability to suppress HIV-1 replication in infected MT-2 cells with low cytotoxicity against the same cells, thereby displaying a high therapeutic index. These results demonstrate the potential of the new Phe-Pro dihydroxyethylene isostere as a core unit of powerful HIV-1 PR inhibitors.

A series of new thienyl ring containing analogues of nelfinavir and saquinavir with different substitution patterns were synthesized from suitable enantiopure diols. Their inhibitory activity against wild type recombinant HIV-1 protease was evaluated. In general thienyl groups spaced from the core by a methylene group gave products showing IC(50) in the nanomolar range, irrespective of the type and the substitution pattern of the heterocycle. The range of activity of the two most active compounds is substantially maintained or even increased against two commonly selected mutants, under drug pressure, such as V32I and V82A.

The anthranilic acid diamides represent the more recent class of nonpeptide CCK(1) receptor antagonists. This class is characterized by the presence of anthranilic acid, used as a molecular scaffold, and two pharmacophores selected from the C-terminal tetrapeptide of CCK. The lead compound coded VL-0395, endowed with sub-micromolar affinity towards CCK(1) receptors, was characterized by the presence of Phe and 2-indole moiety at the C- and N-termini of anthranilic acid, respectively. Herein we describe the first step of the anthranilic acid C-terminal optimization using, instead of Phe, aminoacids belonging to the primary structure of CCK-8 and other not coded residues. Thus we demonstrate that the CCK(1) receptor affinity depends on the nature of the aminoacidic side chain as well as that the free carboxy group of the alpha-aminoacids is crucial for the binding. The R enantiomers of the most active compounds represent the eutomers of this class of antagonists confirming thus the stereo preference of the receptor. Moreover this SAR study demonstrates that the receptor binding pocket, that host the aminoacidic side chain, results much more tolerant respect to that accommodating the indole ring. As a result, an appropriate variation of the aminoacidic side chain could provide a better CCK(1) receptor affinity diorthosis.

The aspartic protease of HIV-1 represents a valid therapeutic target of antiviral agents suitable for the treatment of AIDS. We have designed peptidomimetic inhibitors for this enzyme with a hydroxyethylenediamine core, based on a molecular modeling approach that predicts the effectiveness of the designed compounds in terms of computed enzyme-inhibitor complexation Gibbs free energies. This structurebased molecular design was then combined with a synthetic strategy that couples stereochemical control with full flexibility in the choice of the central core side chains and of the flanking residues. A series of peptidomimetic inhibitors was thus assembled from readily available amino acids and carboxylic acids and -Phe-ω[CH2-(r/s)CHOH]-Phe- cores. The IC50 values for these compounds ranged from 3 nM to 80 μM, allowing a QSAR analysis and identification of factors that determine the inhibition potency of the compounds. Predicted ADME-related properties of the inhibitor candidates span a range of pharmacokinetics profiles, which allows selection of a potent and bioavailable lead compound for further development.

Bis-arylidenecycloalkanones structurally related to the nonselective isopeptidase inhibitor G5 were synthesized and tested for cytotoxic activity against glioblastoma cells. Cytotoxicities correlate well with Hammett σ constants for substituted arylidene groups, confirming the proposed inhibition mechanism. A new inhibitor (2c) based on the 4-hydroxycyclohexanone scaffold, which favors apoptosis over necrosis, was selected for further development. 2c inhibited representative deubiquitinases with micromolar IC50, and its proapoptotic activity was studied on several cancer cell lines. Inhibitor 2c was conjugated to PEG via dicarbamate and diester linkers. While the dicarbamate was inactive, the diester (2cPE) behaves like a prodrug and is converted into the active species 2c by secreted esterase activities. Finally, 2cPE was also tested in vivo on A549 lung carcinoma xenografts generated in mice. Intravenous treatment with 2cPE led to a significant reduction in primary tumor growth, without appreciable toxicity to mice.

Bac7 is a proline-rich antimicrobial peptide, selective for Gram-negative bacteria, which acts intracellularly after membrane translocation. Progressively shortened fragments of Bac7 allowed determining the minimal sequence required for entry and antimicrobial activity as a 16-residue, N-terminal fragment, while further shortening led to a marked decrease in both functions. Furthermore, two N-terminal arginine residues were required for efficient translocation and activity. Analogues in which these residues were omitted, or where the side chain steric or physicochemical characteristics were systematically altered, were tested on different Escherichia coli strains, including a mutant with a destabilized outer membrane and one lacking the relevant SbmA membrane transport protein. H-bonding capacity, stereochemistry, and charge, in that order, played a determining role for efficient transit through both the outer and cytoplasmic membranes. Our studies allowed building a more detailed model for the mode-of-action of Bac7, and confirming its potential as an anti-infective agent, also suggesting it may be a vehicle for internalization of other antibiotic cargo.

Despite the fact that HIV-Protease is an over 20 years old target, computational approaches to rational design of its inhibitors still have a great potential to stimulate the synthesis of new compounds and the discovery of new, potent derivatives, ever capable to overcome the problem of drug resistance. This review deals with successful examples of inhibitors identified by computational approaches, rather than by knowledge-based design. Such methodologies include the development of energy and scoring functions, docking protocols, statistical models, virtual combinatorial chemistry. Computations addressing drug resistance, and the development of related models as the substrate envelope hypothesis are also reviewed. In some cases, the identified structures required the development of synthetic approaches in order to obtain the desired target molecules; several examples are reported.

A new pseudopeptide epoxide inhibitor, designed for irreversible binding to HIV protease (HIV-PR), has been synthesized and characterized in solution and in the solid state. However, the crystal structure of the complex obtained by inhibitor–enzyme cocrystallization revealed that a minor isomer, with inverted configuration of the epoxide carbons, has been selected by HIV-PR during crystallization. The structural characterization of the well-ordered pseudopeptide, inserted in the catalytic channel with its epoxide group intact, provides deeper insights into inhibitor binding and HIV-PR stereoselectivity, which aids development of future epoxide-based HIV inhibitors.

New structurally simple indolic non peptidic HIV Protease inhibitors were synthesized from (S)- glycidol by regioselective methods. Following the concept of targeting the protein backbone, different substitution patterns were introduced onto the common stereodefined isopropanolamine core modifying the type of functional group on the indole, the position of the functional group on the indole and the type of the nitrogen containing group (sulfonamides or perhydroisoquinoline), alternatively. The systematic study on in vitro inhibition activity of such compounds confirmed the general beneficial effect of the 5-indolyl substituents in presence of arylsulfonamide moieties, which furnished activities in the micromolar range. Preliminary docking analysis allowed to identify several key features of the binding mode of such compounds to the protease.

Multidrug efflux pump inhibitors have a great potential as pharmacological agents that increase the drug susceptibility of bacterial pathogens. Our study was focused on the synthesis and evaluation of the efficiency of resistance-nodulation-division (RND) family efflux pump inhibitors. The efficiency of these inhibitors was investigated on Salmonella enterica ser. typhimurium cells using tetraphenylphosphonium (TPP(+) ) and ethidium cations as the efflux pump substrates. Results of our study indicated that efficiency of the inhibitors depends on the cell outer membrane permeability and method of the assay used. Temperature of the incubation medium and a solvent of the inhibitor used have only minor effect on results of the assay.

Synthesis and biological evaluation of a new series of potential HIV-1 protease inhibitors incorporating different heterocycles are described. The variation of heteroatom in such molecules has displayed totally different biological activities and a benzothiophene containing inhibitor has shown high potency against wild type HIV-1 protease with IC50 = 60 nM, thanks to the lower desolvation penalty to be payed by such hydrophobic moiety.

The anthranilic acid diamides represent the most recent class of nonpeptide CCK(1) receptor (CCK(1)-R) antagonists. Herein we describe the second phase of the anthranilic acid C-terminal optimization using nonproteinogenic amino acids containing a phenyl ring in their side chain. The Homo-Phe derivative 2 (VL-0797) enhanced 12-fold the affinity for the rat CCK(1)-R affinity and 15-fold for the human CCK(1)-R relative to the reference compound 12 (VL-0395). The eutomer of 2 (6) exhibited a nanomolar range affinity toward the human CCK(1)-R and was at least 400-fold selective for the CCK(1)-R over the CCK(2)-R. Molecular docking in the modeled CCK(1)-R and its validation by site-directed mutagenesis experiments showed that the 6 binding site overlaps that occupied by the C-terminal bioactive region of the natural agonist CCK. Owing to their interesting properties, new compounds provided by this study represent a solid basis for further advances aimed at synthesis of clinically valuable CCK(1)-R antagonists.

Discovery by co-crystallization: High-resolution electron-density maps of HIV-1 aspartyl protease complexed with a potent Phe–Pro isostere-based inhibitor (shown) allowed the determination of the stereochemistry of the inhibitor and an initial assessment of the inhibition properties of this compound without its purification from the epimeric mixture.

An efficient method has been developed for the synthesis of a versatile intermediate bearing azido, hydroxyl and ester functions, a useful precursor for peptidomimetic compounds. The two main features for this synthesis were the use of the Sharpless asymmetric dihydroxylation on thiophene acrylate and the subsequent regioselective ring opening by sodium azide of the cyclic sulfite. Highly chemoselective reduction of the azido alcohol led to a key compound which was utilized for the synthesis of two analogues of commercial anti HIV PR such as nelfinavir and saquinavir. The biological activity and molecular modelling study on these two new potential drugs have been evaluated.

Recently we described an innovative class of non-peptide CCK 1 antagonists keeping appropriate pharmacophoric groups on the anthranilic acid employed as a molecular scaffold. The lead compound obtained, VL-0395 , characterized by the presence of Phe and the 2-indole moiety at the C- and N-termini of anthranilic acid, respectively, is endowed with submicromolar affinity towards CCK 1 receptors. Thus, we have prepared and tested on CCK receptors a library of VL-0395 analogues in order to investigate the precise topological and essential key interactions of the 2-indole group of the lead with the CCK 1 receptor. The obtained results confirm that this group establishes very specific interactions with this receptor sub-site and may be viewed as a “needle” group.

Having successfully obtained new CCK 1 ligands holding appropriate groups on the anthranilic acid dimer used as molecular scaffold we were interested in increasing their micromolar affinity for the CCK 1 receptors by modifying the spatial relationship of the main pharmacophoric groups. Since, we have proposed simplified analogues reducing the anthranilic acid dimer to a monomer. In this stage of our research program we have prepared and tested on CCK receptors a series of N -substituted anthranilic acid derivatives keeping a Phe residue at the C-terminal site. The indole-2-carbonyl group imparts the best CCK 1 receptor binding affinity (compound 1 : IC 50 =197.5 nM) while a sharp decrease in binding affinity is observed for the other indole containing derivatives. Moreover, in order to support the different binding behaviour observed for the synthesized compounds, a conformational investigation was carried out. Finally, on the basis of the main pharmacophoric groups of the obtained new lead compound ( 1 ) (coded VL-0395 ) a receptor binding hypothesis has been provided.

4-Acyl-1H-1,2,3-triazoles are formed from diethylaluminum azide and α′-(N,N-dibenzylamino)-α,β-unsaturated ketones by [3+2] cycloaddition of azide, followed by 1,5 hydride transfer to the β carbon of the triazoline side chain and fragmentation of the tertiary amino group promoted by coordination of the latter to the Lewis acid. The structure of a triazole product is confirmed by X-ray crystallography.

We have extended a highly flexible method for rapidly assembling aspartic protease inhibitors to produce symmetric and asymmetric monohydroxyethylene peptidomimetics. This method is based on the prior synthesis of the central non-cleavable peptide-bond isostere [NH(2)-P(1)psiP1'-NH(2); psi=hydroxyethylene isostere, HNCH(Bz)CHOHCH(2)CH(Bz)NH], with the possibility of accurately controlling its stereochemistry (S,S,S or S,R,S), and subsequently adding appropriate flanking units, chosen from commercially available amino acids, aromatic carboxylic acids, or phenoxyacetic acid (Poa) derivatives. The method was used to make asymmetric inhibitors of general formula Kyn-Xaa-PhepsiPhe-dmPoa, (Kyn=kynurenic acid, Xaa=Val, Thr or D-thienylglycine, M(r)=716-754) and symmetric inhibitors of formula xPoa-PhepsiPhe-xPoa (xPoa=Poa or dimethyl-, hydroxy-, formyl- or acetyl-Poa, M(r)=553-609), with logP(o/w) values ranging from 4.1 to 7.6. Inhibition of HIV-PR did not depend on the stereochemistry of the hydroxyl group, while it depended markedly on the substituents present on the Poa residues, with dmPoa being preferred over Poa or its more hydrophilic derivatives. Conversely, inhibition of Candida albicans Sap2 was higher for the S,S,S epimers, and Poa or its hydrophilic derivatives were preferred over dmPoa.

A series of new N-substituted anthranilic acid dimer derivatives having a C-terminal Phe residue was synthesized and evaluated for their affinity for CCK receptors. These compounds resulted from a blended approach based firstly on the use of an alternative substructure embedded within asperlicin and secondly on the derivatization of this template with substituents chosen considering the C-terminal primary structure of the endogenous ligand. Although these compounds exhibited a regnylogical-type organization similar to that of CCK-4, they are characterized by about 1000-fold greater affinity for CCK-A receptor than the C-terminal tetrapeptide.

Diethylaluminium cyanide is a highly selective reagent for the ring opening of 2,3-epoxyalcohols under mild conditions; the reaction takes place at C-3, with inversion of configuration, to give 1-cyano-2,3-diols.

2,3-Epoxyalcohols react with diethylaluminium azide under mild conditions to give 3-azido-1,2-diols resulting from the regio- and stereoselective attack of the nucleophile at the epoxide C-3. The high regioselectivity (>25:1) observed with both cis and trans substituted epoxides is not affected by bulky substituents at C-3. The method has been successfully applied also to the synthesis of diaminodiol dipeptide isosteres.

the effects of water and hydrophobic solvents on the stability of the open and closed forms of R. miehei lipase were evaluated with different solvent models. Desolvation of arginine 86 at the water-lipid interface plays a key role in the activation process, while the contribution from hydrophobic stabilization of the open form is less important.