Valentina Straniero

Thiazole- and imidazole-containing peptidomimetic inhibitors of protein farnesyltransferase.

Mimetics of the C-terminal CAAX tetrapeptide of Ras protein were designed replacing internal dipeptide AA with 4-amino-2-phenylbenzoic acid and cysteine (C) with 2-amino-4-thiazolyl-, 2-mercapto-4-thiazolyl-, 2-mercapto-4-imidazolyl- and 2-methylmercapto-4-thiazolyl-acetic or propionic acid. The compound in which C is replaced by 2-amino-4-thiazolylacetic acid inhibited FTase activity in the low nanomolar range and showed antiproliferative effect on rat aortic smooth muscle cells interfering with Ras farnesylation. On the basis of these results, 2-aminothiazole can be considered as an alternative to heterocycles, such as pyridine and imidazole, normally used in FTase inhibitors designed as non-thiol CAAX mimetics.

6-methoxy-7-benzofuranoxy and 6-methoxy-7-indolyloxy analogues of 2-[2-(2,6-Dimethoxyphenoxy)ethyl]aminomethyl-1,4-benzodioxane (WB4101):1 discovery of a potent and selective α1D-adrenoceptor antagonist.

Previous results have shown that replacement of one of the two o-methoxy groups at the phenoxy residue of the potent, but not subtype-selective, α1-AR antagonist (S)-WB4101 [(S)-1] by phenyl, or by ortho,meta-fused cyclohexane, or especially by ortho,meta-fused benzene preferentially elicits α1D-AR antagonist affinity. Such observations inspired the design of four new analogues of 1 bearing, in lieu of the 2,6-dimethoxyphenoxy residue, a 6-methoxy-substituted 7-benzofuranoxy or 7-indolyloxy group or, alternatively, their corresponding 2,3-dihydro form. Of these new compounds, which maintain, rigidified, the characteristic ortho heterodisubstituted phenoxy substructure of 1, the S enantiomer of the dihydrobenzofuranoxy derivative exhibited the highest α1D-AR antagonist affinity (pA2 9.58) with significant α1D/α1A and α1D/α1B selectivity. In addition, compared both to α1D-AR antagonists structurally related to 1 and to the well-known α1D-AR antagonist BMY7378, this derivative had modest 5-HT1A affinity and neutral α1-AR antagonist behavior.

Benzodioxane-benzamides as new bacterial cell division inhibitors.

A SAR study was performed on 3-substituted 2,6-difluorobenzamides, known inhibitors of the essential bacterial cell division protein FtsZ, through a series of modifications first of 2,6-difluoro-3-nonyloxybenzamide and then of its 3-pyridothiazolylmethoxy analogue PC190723. The study led to the identification of chiral 2,6-difluorobenzamides bearing 1,4-benzodioxane-2-methyl residue at the 3-position as potent antistaphylococcal compounds.

Predicting the physicochemical profile of diastereoisomeric histidine-containing dipeptides by property space analysis

OBJECTIVES This study aimed at measuring the lipophilicity and ionization constants of diastereoisomeric dipeptides, interpreting them in terms of conformational behavior, and developing statistical models to predict them. METHODS A series of 20 dipeptides of general structure NH(2)-L-X-(L or D)-His-OMe was designed and synthetized. Their experimental ionization constants (pK(1), pK(2) and pK(3)) and lipophilicity parameters (log P(N) and log D(7.4)) were measured by potentiometry. Molecular modeling in three media (vacuum, water, and chloroform) was used to explore and sample their conformational space, and for each stored conformer to calculate their radius of gyration, virtual log P (preferably written as log P(MLP), meaning obtained by the molecular lipophilicity potential (MLP) method) and polar surface area (PSA). Means and ranges were calculated for these properties, as was their sensitivity (i.e., the ratio between property range and number of rotatable bonds). RESULTS Marked differences between diastereoisomers were seen in their experimental ionization constants and lipophilicity parameters. These differences are explained by molecular flexibility, configuration-dependent differences in intramolecular interactions, and accessibility of functional groups. Multiple linear equations correlated experimental lipophilicity parameters and ionization constants with PSA range and other calculated parameters. CONCLUSION This study documents the differences in lipophilicity and ionization constants between diastereoisomeric dipeptides. Such configuration-dependent differences are shown to depend markedly on differences in conformational behavior and to be amenable to multiple linear regression.

Exploring the space of histidine containing dipeptides in search of novel efficient RCS sequestering agents.

The study reports a set of forty proteinogenic histidine-containing dipeptides as potential carbonyl quenchers. The peptides were chosen to cover as exhaustively as possible the accessible chemical space, and their quenching activities toward 4-hydroxy-2-nonenal (HNE) and pyridoxal were evaluated by HPLC analyses. The peptides were capped at the C-terminus as methyl esters or amides to favor their resistance to proteolysis and diastereoisomeric pairs were considered to reveal the influence of configuration on quenching. On average, the examined dipeptides are less active than the parent compound carnosine (βAla + His) thus emphasizing the unfavorable effect of the shortening of the βAla residue as confirmed by the control dipeptide Gly-His. Nevertheless, some peptides show promising activities toward HNE combined with a remarkable selectivity. The results emphasize the beneficial role of aromatic and positively charged residues, while negatively charged and H-bonding side chains show a detrimental effect on quenching. As a trend, ester derivatives are slightly more active than amides while heterochiral peptides are more active than their homochiral diastereoisomer. Overall, the results reveal that quenching activity strongly depends on conformational effects and vicinal residues (as evidenced by the reported QSAR analysis), offering insightful clues for the design of improved carbonyl quenchers and to rationalize the specific reactivity of histidine residues within proteins.

Affinity and activity profiling of unichiral 8-substituted 1,4-benzodioxane analogues of WB4101 reveals a potent and selective α1B-adrenoceptor antagonist

Unichiral 8-substituted analogues of 2-[(2-(2,6-dimethoxyphenoxy)ethyl)aminomethyl]-1,4-benzodioxane (WB4101) were synthesized and tested for binding affinity at cloned human α(1a)-, α(1b)-and α(1d)-adrenoreceptor (α(1a)-, α(1b)-and α(1d)-AR) and at native rat 5-HT(1A) receptor and for antagonist affinity at α(1A)-, α(1B)-and α(1D)-AR and at α(2A/D)-AR. Among the selected 8-substituents, namely fluorine, chlorine, methoxyl and hydroxyl, only the last caused significant decrease of α(1) binding affinity in comparison with the lead compound. Functional tests on the S isomers confirmed the detrimental effect of OH positioned in proximity to benzodioxane O(1). For the other three substituents (F, Cl, OMe), the α(1A) and the α(1D) antagonist affinities were generally lower than the α(1a) and α(1d) binding affinities, but not the α(1B) antagonist affinity, which was similar and sensibly higher compared to α(1b) binding affinity in the case of F and OMe respectively. This trend confers significant α(1B)-AR selectivity, in particular, to the 8-methoxy analogue of (S)-WB4101, a new potent (pA(2) 9.58) α(1B)-AR antagonist. The S enantiomers of all the tested compounds were proved to act as α(1)-AR inverse agonists in a vascular model.

Identification of 1-butyl-3-(1-(4-methyl)naphtoyl)indole detected for the first time in “herbal high” products on the Italian market

The results of the analysis of some herbal products and powders adulterated with alkylindoles recovered on the Italian market between 2010 and 2011 are reported. Besides the well-known alkyindoles JWH-018 and JWH-073, other derivatives such as JWH-250 and AM-694 have been detected and for the first time in Italy 1-butyl-3-(1-(4-methyl)naphthoyl)indole (compound 1), the 4-methylnaphthoyl analogue of JWH-073. This compound as well as the other alkylindoles has been synthesized and characterized by (1)H NMR, (13)C NMR, DSC, GC/MS, and elemental analysis. The quantitative analyses of the samples have been carried out by means of the GC/FID method developed in our laboratory for the analysis of herbal high products containing naphthoylindoles; the quantity of the cannabimimetic substances ranged from 6 mg/g to 47 mg/g.

Farnesyltransferase inhibitors: CAAX mimetics based on different biaryl scaffolds

Mimetics of the C-terminal CAAX tetrapeptide of Ras protein were designed as farnesyltransferase (FTase) inhibitors (FTIs) by replacing AA with o-aryl or o-heteroaryl substituted p-hydroxy- or p-aminobenzoic acid, while maintaining the replacement of C with 1,4-benzodioxan-2-ylmethyl or 2-amino-4-thiazolylacetyl residue as in previous CAAX mimetics. Both FTase inhibition and antiproliferative effect were showed by two thiazole derivatives, namely those with 1-naphthyl (10 and 10a) or 3-furanyl (15 and 15a) in the central spacer, and by the benzodioxane derivative with 2-thienyl (6 and 6a) in the same position. Accumulation of unprenylated RAS was demonstrated in cells incubated with 15a. Consistently with FTIs literature, such results delineate the biaryl scaffold not only as a spacer but also as a sensible area of these mimetic molecules, where modifications at the branching aromatic ring are not indifferent and should be matter of further investigation.

2,6-Difluorobenzamide Inhibitors of Bacterial Cell Division Protein FtsZ: Design, Synthesis, and Structure-Activity Relationships

A wide variety of drug‐resistant microorganisms are continuously emerging, restricting the therapeutic options for common bacterial infections. Antimicrobial agents that were originally potent are now no longer helpful, due to their weak or null activity toward these antibiotic‐resistant bacteria. In addition, none of the recently approved antibiotics affect innovative targets, resulting in a need for novel drugs with innovative antibacterial mechanisms of action. The essential cell division protein filamentous temperature‐sensitive Z (FtsZ) has emerged as a possible target, thanks to its ubiquitous expression and its homology to eukaryotic β‐tubulin. In the latest years, several compounds were shown to interact with this prokaryotic protein and selectively inhibit bacterial cell division. Recently, our research group developed interesting derivatives displaying good antibacterial activities against methicillin‐resistant Staphylococcus aureus, as well as vancomycin‐resistant Enterococcus faecalis and Mycobacterium tuberculosis. The aim of the present study was to summarize the structure–activity relationships of differently substituted heterocycles, linked by a methylenoxy bridge to the 2,6‐difluorobenzamide, and to validate FtsZ as the real target of this class of antimicrobials.

From 2-Aminomethyl-1,4-benzodioxane Enantiomers to Unichiral 2-Cyano- and 2-Carbonyl-Substituted Benzodioxanes via Dichloroamine

2-Substituted 1,4-benzodioxanes, such as 2-cyano-, 2-methoxycarbonyl-, 2-aminocarbonyl-, and 2-formyl-1,4-benzodioxane, are key synthons that for the most part are never described as enantiomers or are inadequately characterized for enantiomeric purity. They were prepared by quantitative N,N-dichlorination of (R)- and (S)-2-aminomethyl-1,4-benzodioxane and successive functional group conversions in high yields without any racemization of the stereogenic benzodioxane C(2).