Elisa Durini

Synthesis and Study of 5′-Ester Prodrugs of N6-Cyclopentyladenosine, a Selective A1 Receptor Agonist

AbstractPurpose. A series of 5′-esters of N6-cyclopentyladenosine (CPA) were prepared with the aim to improve stability and bioavailability of selective A1 agonists. Log P values, stability, affinity, and activity toward human adenosine A1 receptors were evaluated. Methods. An appropriate synthetic procedure was adopted to avoid concomitant deamination at position 6. Log P values were obtained by the Mixxor system. The stability of CPA and its 5′-ester was evaluated in human plasma and whole blood and analyzed with high-performance liquid chromatography. The affinities to human A1 receptor expressed by N6-cyclohexyladenosine cells were obtained by binding experiments. The activities were evaluated by measurements of the inhibition of forskolin stimulated 3′-5′-cyclic adenosine monophosphate, performing competitive binding assays. Results. All prodrugs were more lipophilic than CPA, and their hydrolysis, in whole blood and in plasma, was found related, respectively, to the length and hindrance of 5′-substituents. Affinity and activity values indicated a very weak interaction toward adenosine A1 receptor of the intact prodrugs. Conclusions. We propose 5′-esters of CPA, characterized by suitable lipophilicity and elevated degree of stability in physiological fluids, as possible canditates for CPA prodrugs.

Peptide T-araC conjugates: solid-phase synthesis and biological activity of N4-(acylpeptidyl)-araC.

Due to the capability of peptidyl derivatives of araC to behave as prodrugs of this antimetabolite, and because of the well known biological properties of peptide T and its analogues (in particular that of targeting CD4+ cells), new peptide T-araC conjugates were prepared and tested in vitro for antiproliferative activity. The aim was that of specifically delivering the antitumor drug to CD4+ cells. N4-(Acylpeptidyl)-derivatives of araC were synthesized by a new general approach involving solid-phase synthesis, which allows mild conditions, avoids the usually required protection of the glycoside portion of nucleosides and affords high yields of the final products. After the demonstration that peptide T-araC conjugates were able to activate chemotaxis by binding CD4 receptor on monocyte membranes, the antiproliferative activity was evaluated against a panel of leukemia lymphoma and carcinoma cell lines derived from human tumors, three CD4+ cell lines included. Title compounds resulted effective as antiproliferative agents at concentrations 4- to 10-fold higher than those of araC alone, did not preferentially inhibit CD4+ cells and proved stable not only in cell culture medium containing 20% FCS, but also in human plasma. All this suggests their potential utility in vivo.

Design and Synthesis of Phosphonoacetic Acid (PPA) Ester and Amide Bioisosters of Ribofuranosylnucleoside Diphosphates as Potential Ribonucleotide Reductase Inhibitors and Evaluation of Their Enzyme Inhibitory, Cytostatic and Antiviral Activity

Continuing our investigations on inhibitors of ribonucleotide reductase (RNR), the crucial enzyme that catalyses the reduction of ribonu-cleotides to deoxyribonucleotides, we have now prepared and evaluated 5′-phosphonoacetic acid, amide and ester analogues of adenosine, uridine and cytidine with the aim to verify both substrate specificity and contribution to biological activity of diphosphate mimic moieties. A molecular modelling study has been conducted on the RNR R1 subunit, in order to verify the possible interaction of the proposed bioisosteric moieties. The study compounds were finally tested on the recombinant murine RNR showing a degree of inhibition that ranged from 350 μM for the UDP analogue 5′-deoxy-5′-N-(phosphon-acetyl)uridine sodium salt (amide) to 600 μM for the CDP analogue 5′-O-[(diethyl-phosphon)acetyl]cytidine (ester). None of the tested compounds displayed noteworthy cytostatic activity at 100–500 μM concentrations, whereas ADP analogue 5′-N-[(diethyl-phosphon) acetyl]adenosine (amide) and 5′-deoxy-5′-N-(phos-phon-acetyl)adenosine sodium salt (amide) showed a moderate inhibitory activity (EC50: 48 μM) against HSV-2 and a modest inhibitory activity (EC50: 110 μM) against HIV-1, respectively.

Protective effects of Fe-Aox29, a novel antioxidant derived from a molecular combination of Idebenone and vitamin E, in immortalized fibroblasts and fibroblasts from patients with Friedreich Ataxia.

Friedreich Ataxia (FRDA), the most frequent inherited ataxia, is not only characterized by progressive gait and limb ataxia, but in most cases is also accompanied by a severe hypertrophic cardiomyopathy. This life threatening symptom can be ameliorated by the administration of idebenone, a short chain quinone antioxidant, supporting additional evidence that oxidative stress plays a major role in the pathogenesis of this disease. In this study we analyze the combinatorial effect of different antioxidants on cell viability of FRDA fibroblasts and of RAT-1 immortalized fibroblasts exposed to oxidative stress. We find that an equimolar mixture of idebenone and vitamin E is more potent than each of the compound alone. Increased potency was also obtained with a novel synthetic antioxidant (Fe-Aox29) combining the active groups from both idebenone and vitamin E. These results indicate, that idebenone and vitamin E might act synergistically to counteract oxidative stress in fibroblasts from FRDA patients.

Hindered nucleoside analogs as antiflaviviridae agents

Flaviviridae are an important family of viruses, responsible for widely spread diseases such as dengue and West Nile fever and hepatitis C. Despite the severity of the related diseases, no effective antiviral treatments for infection are available. Following our discovery of adenosine-hindered analogs as potent antiflaviviridae agents, we have continued our investigation on guanosine and inosine derivatives, which were evaluated for activity against BVDV, YFV, DENV, and WNV viruses in cell-based assays. The present study allowed us to identify some newer features that led to improve the antiviral potency (down to the µM range) and to selectively inhibit BVDV and YFV viruses. The molecular modeling results were consistent with the hypothesis that test analogs act as RNA-dependent RNA polymerase (RdRp) inhibitors by interacting with a surface allosteric binding pocket.

Prodrugs of Ara-CMP and Ara-AMP with a S-acyl-2-thioethyl (SATE) biolabile phosphate protecting group: synthesis and biological evaluation

The bis(S-pivaloyl-2-thioethyl) phosphotriesters of Ara-C and Ara-A were synthesized as potential bioreversible mononucleotide prodrugs. Some N- and O-acylated derivatives were also prepared with the aim to modify the lipophilicity of the title pronucleotides. Compounds were tested for their antitumor/antiviral activity against a variety of tumor cells and viruses.

Pyrazole Related Nucleosides 5.1 Synthesis and Biological Activity of 2′-Deoxy- 2′, 3′-dideoxy- and Acyclo-analogues of 4-Iodo-1-β-D-ribofuranosyl-3-carboxymethyl Pyrazole (IPCAR)

Abstract Continuing our studies on the structure-activity relationships (SAR) of 4-iodo-1-β-D-ribofuranosyl-3-carboxymethyl pyrazole (IPCAR), the ribofuranosyl moiety has been substituted with acyclic chains, namely 1-[(2-hydroxyethoxy)methyl]- and 1-[(1,3-dihydroxy-2-propoxy)methyl]-pyrazole derivatives (4, 5 and 8, 9 respectively), with the 2′-deoxy-β-D-ribofuranosyl group (12 and 13) and finally with the 2′,3′-dideoxy-D-glycero-pentofuranosyl-moiety (16 and 17). None of the new compounds display any interesting biological activity.

Hyaluronic Acid Fillers in Soft Tissue Regeneration

Abstract Over the last years, hyaluronic acid (HA) injectable dermal fillers (DFs) have become the most popular agents for soft tissue contouring and volumizing. HA fillers are characterized by most of the properties that an ideal DF should have, due to HA unique chemical‐physical properties, biocompatibility, biodegradability, and versatility. Therefore, HA DFs have revolutionized the filler market with a high number of products, which differ in terms of HA source, cross‐linkage (agent and degree), HA concentration, hardness, cohesivity, consistency, inclusion or lack of anesthetic, indication, and longevity of correction. The article first provides a general introduction to DF world, and an overview of the different materials is available for fillers. Second, it describes the characteristics and the peculiarities of HA fillers, their differences from the other available materials, and therefore the reasons at the base of their success. Moreover, an update regarding the main Food and Drug Administration (FDA) approved fillers is presented.

Design, synthesis and biological evaluation of novel hydroxy-phenyl-1H-benzimidazoles as radical scavengers and UV-protective agents

Abstract An ever-increasing incidence of skin neoplastic diseases is registered. Therefore, it is important to protect the skin from the UV radiation that reaches the epidermis and dermis but also to block ROS generated by them. Our attention was attracted in developing new compounds provided with both UV filtering and antioxidant capacities. To this end, 2-phenyl-1H-benzimidazole-5-sulfonic acid (PBSA), a known UV filter, was selected as lead compound for its lack of antioxidant activity, high water solubility and good safety profile. PBSA was sequentially modified introducing hydroxyls on the phenyl ring and also substituting the functional group in position 5 of the benzimidazole ring. At the end of the synthetic study, a new, very potent class of antioxidants has been obtained. Surprisingly some of the developed molecules, while devoid of significant UV-filtering activity was endowed with potent UV-filtering booster capability if associated with known commercial UVB and UVA filters.

7-deazainosine derivatives: synthesis and characterization of 7- and 7,8-substituted pyrrolo [2,3-d]pyrimidine ribonucleosides.

The synthesis of model 7 deazapurine derivatives related to tubercidin and toyocamycin has been performed. Tubercidin derivatives were obtained by simple conversion of the amino group of the heterocyclic moiety of the starting 7-deazadenosine compounds, into a hydroxyl group. Preparation of toyocamycin derivatives was accomplished by treatment of the silylated 6-bromo-5-cyanopyrrolo[2,3-d]pyrimidin-4-one with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-ribofuranose. The glycosylation reaction afforded a mixture of 8-bromo 7-cyano 2′,3′,5′ tri-O-benzoyl 7-deazainosine and 6-bromo-5-cyano-3-(2′,3′,5′-tri-O-benzoyl-β-d-ribofuranosyl)pyrrolo[2,3-d]-pyrimidin-4-one isomers: The structures were assigned on the basis of NMR spectroscopy studies. Next deprotection treatment gave the novel 7-deazainosine ribonucleosides.