Giuseppina Sanna

Antiviral activity of benzimidazole derivatives. II. Antiviral activity of 2-phenylbenzimidazole derivatives

Seventy-six 2-phenylbenzimidazole derivatives were synthesized and evaluated in cell-based assays for cytotoxicity and antiviral activity against a panel of 10 RNA and DNA viruses. The most commonly affected viruses were, in decreasing order, CVB-2, BVDV, Sb-1, HSV-1, and YFV, while HIV-1 and VSV were not affected, and RSV, VV and Reo-1 were only susceptible to a few compounds. Thirty-nine compounds exhibited high activity (EC(50)=0.1-10microM) against at least one virus, and four of them were outstanding for their high and selective activity against VV (24, EC(50)=0.1microM) and BVDV (50, 51, and 53 with EC(50)=1.5, 0.8, and 1.0microM, respectively). The last compounds inhibited at low micromolar concentrations the NS5B RdRp of BVDV and also of HCV, the latter sharing structural similarity with the former. The considered compounds represent attractive leads for the development of antiviral agents against poxviruses, pestiviruses and even HCV, which are important human and veterinary pathogens.

Cytotoxic Phloroglucinols from the Leaves of Myrtus communis

Bioactivity-guided fractionation of a dichloromethane extract of the leaves of Myrtus communis led to the isolation of phloroglucinol derivatives. The structures of the new myrtucommulones J, K, and L (1-3) and the previously known myrtucommulone A (4) were elucidated on the basis of extensive 1D and 2D NMR experiments as well as high-resolutionmass spectrometry. Myrtucommulone J was obtained as a tautomeric pair (1/1a). The compounds were tested in vitro for their cytotoxic and antibacterial activities.

Disubstituted thiourea derivatives and their activity on CNS: Synthesis and biological evaluation

A series of new thiourea derivatives of 1,2,4-triazole have been synthesized. The difference in structures of obtained compounds are directly connected with the kind of isothiocyanate (aryl/alkyl). The (1)H NMR, (13)C NMR, MS methods were used to confirm structures of obtained thiourea derivatives. The molecular structure of (1, 17) was determined by an X-ray analysis. Two of the new compounds (8 and 14) were tested for their pharmacological activity on animal central nervous system (CNS) in behavioural animal tests. The results presented in this work indicate the possible involvement of the serotonergic system in the activity of 8 and 14. In the case of 14 is also a possible link between its activity and the endogenous opioid system. All obtained compounds were tested for antibacterial activity against gram-positive cocci, gram-negative rods and antifungal activity. Compounds (1, 2, 5, 7, 9) showed significant inhibition against gram-positive cocci. Microbiological evaluation was carried out over 20 standard strains and 30 hospital strains. Selected compounds (1-13) were examined for cytotoxicity, antitumor, and anti-HIV activity.

N-acylated and N,N’-diacylated imidazolidine-2-thione derivatives and N,N’-diacylated tetrahydropyrimidine-2(1H)-thione analogues: synthesis and antiproliferative activity

Fifty-one acylthioureas (ATUs) incorporating imidazolidine-2-thione or its upper cyclohomologue were prepared by parallel synthesis and evaluated against a high number of human cancer cell lines for antiproliferative activity. ATUs 1o (3,5-dichlorobenzoyl), 1s (2-furoyl), 3s (2-furoyl) and 1t (2-thenoyl) displayed activity against leukemia, melanoma LOX IMVI, non-small cell lung NCI-H522, renal 786-0, CAKI-1, SN12C, UO-31 and breast MCF7, MDA-MB-435, T-47D cancer cell lines in the 0.3-9.7 microM concentration range. Compound 14s exhibited selectivity for melanoma SK-MEL-5 (GI(50)<5 nM); 1s for leukemia MOLT-4 (GI(50): 300 nM); 1q, 3b and 3q for renal cancer UO-31 (GI(50): 70-200 nM); 8s, 9s for non-small cell lung cancer EKVX (GI(50): 300, 10 nM) and 3j for HOP-92 (GI(50): 700 nM) cell line.

Novel modifications in the series of O-(2-phthalimidoethyl)-N-substituted thiocarbamates and their ring-opened congeners as non-nucleoside HIV-1 reverse transcriptase inhibitors

The structure-activity relationships (SARs) of N-aryl-O-(2-phthalimidoethyl)thiocarbamates (C-TCs) and their imide ring-opened congeners (O-TCs) as non-nucleoside HIV-1 reverse transcriptase inhibitors were further investigated. The SAR strategy involved modifications of the N-phenyl ring followed by the hybridization of the most promising N-aryl and O-(2-phthalimidoethyl) substructures. The role of stereochemistry and tert-butyl substitution of the phthalimidoethyl moiety on activity was also investigated. Seventy-six analogues were prepared by parallel solution-phase synthesis. Twenty-two C-TCs displayed nanomolar activity against wild-type HIV-1 and a number of analogues were effective against the Y181C mutant. Compound 56 combined the highest activity so far identified against Y181C (EC(50)=1.3 microM) with good potency against the K103R mutant (EC(50)=4.8 microM). Docking simulations helped to rationalize the SARs.

Synthesis of Novel Uracil Non‐Nucleoside Derivatives as Potential Reverse Transcriptase Inhibitors of HIV‐1

Novel emivirine and TNK‐651 analogues 5a–d were synthesized by reaction of chloromethyl ethyl ether and / or benzyl chloromethyl ether, respectively, with uracils having 5‐ethyl and 6‐(4‐methylbenzyl) or 6‐(3,4‐dimethoxybenzyl) substituents. A series of new uracil non‐nucleosides substituted at N‐1 with cyclopropylmethyloxymethyl 9a–d, 2‐phenylethyloxymethyl 9e–h, and 3‐phenylprop‐1‐yloxymethyl 9i–l were prepared on treatment of the corresponding uracils with the appropriate acetals 8a–c. Some of the tested compounds showed good activity against HIV‐1 wild type. Among them, 1‐cyclopropylmethyloxymethyl‐5‐ethyl‐6‐(3,5‐dimethylbenzyl)uracil 9c and 5‐ethyl‐6‐(3,5‐dimethylbenzyl)‐1‐(2‐phenylethyloxymethyl)uracil 9g showed inhibitory potency equally to emivirine against HIV‐1 wild type. Furthermore, compounds 9c and 9g showed marginal better activity against NNRTI resistant mutants than emivirine.

Parallel synthesis, molecular modelling and further structure–activity relationship studies of new acylthiocarbamates as potent non-nucleoside HIV-1 reverse transcriptase inhibitors

The structure-activity relationships (SARs) of acylthiocarbamates (ATCs), a new class of non-nucleoside HIV-1 reverse transcriptase inhibitors, have been expanded. Sixty-six new analogues were prepared by parallel solution-phase synthesis. In general, the potency of new ATCs was better than that of the first series and O-[2-phthalimidoethyl] 4-chlorophenyl(3-nitrobenzoyl) thiocarbamate turned out to be the most potent ATC so far synthesized (EC(50)=1.5nM). Several ATCs were active at micromolar concentrations against HIV-1 strains carrying the RT Y181C mutation and one of them was also moderately active against the K103R variant. Docking simulations were carried out to rationalize the most relevant SARs.

5-Acetyl-2-arylbenzimidazoles as antiviral agents. Part 4

Within a project aimed at discovering new Flaviviridae inhibitors, new variously substituted 2-phenylbenzimidazoles were synthesized and evaluated in cell-based assays for cytotoxicity and antiviral activity against viruses representatives of the three genera of the Flaviviridae family, i.e.: Pestivirus (BVDV), Flavivirus (YFV) and Hepacivirus (HCV). Title compounds were also tested against RNA viruses representative of other single-stranded, positive-sense (ssRNA(+)) negative-sense (RNA(-)), or double-stranded (dsRNA) genomes, as well as against representatives of two DNA virus families. Nine compounds showed activity against BVDV (EC(50) = 0.8-8.0 μM), compound 31 being the most potent (EC(50) = 0.80 μM) and selective (SI = CC(50)/EC(50) = >100). When tested in an HCV replicon assay, compound 31 resulted again the most potent, displaying an EC(50) value of 1.11 μM and an SI of 100. Besides inhibiting BVDV, two compounds (35 and 38) showed a moderate activity also against YFV (EC(50) = 13 μM). Interestingly, 35 was moderately active also against RSV (EC(50) = 25 μM).

Synthesis of Novel Fluoro Analogues of MKC442 as Microbicides

Novel analogues of MKC442 (6-benzyl-1-(ethoxymethyl)-5-isopropylpyrimidine-2,4(1H,3H)-dione) were synthesized by reaction of 6-[(3,5-dimethylphenyl)fluoromethyl]-5-ethyluracil (5) with ethoxymethyl chloride and formaldehyde acetals. The Sonogashira reaction was carried out on the N1-(p-iodobenzyl)oxy]methyl derivative of compound 5 using propagyl alcohol to afford compound 12 (YML220). The latter compound was selected for further studies since it showed the most potent and selective activity in vitro against wild-type HIV-1 and non-nucleoside reverse transcriptase inhibitor-, nucleoside reverse transcriptase inhibitor-, and protease inhibitor-resistant mutants and a wide range of HIV-1 clinical isolates. 12 also showed microbicidal activity in long-term assays with heavily infected MT-4 cells.

Parallel one-pot synthesis and structure–activity relationship study of symmetric formimidoester disulfides as a novel class of potent non-nucleoside HIV-1 reverse transcriptase inhibitors

The molecular duplication of non-nucleoside reverse transcriptase inhibitor (NNRTI) O-(2-phthalimidoethyl)-N-arylthiocarbamates (C-TCs) led to the identification of symmetric formimidoester disulfides (DSs) as a novel class of potent NNRTIs. The lead compound 1 [dimer of the isothiocarbamic form of TC O-(2-phthalimidoethyl)-N-phenylthiocarbamate] turned out to prevent the wild-type HIV-1 multiplication in MT-4 cell culture with an EC(50) value of 0.35 microM. In order to perform a structure-activity relationship (SAR) study, we prepared 40 analogues of 1 by an unprecedented one-pot method of solution-phase parallel synthesis. The SAR strategy was focused on the variation of the N-aryl portion (mono-, di- and trisubstitution of the phenyl ring and its replacement with a 1-naphthyl, cyclopropyl or benzyl group) and of the 2-phthalimidoethyl moiety (introduction of a methyl on the phthalimide substructure, replacement of the phthalimide moiety with a phenyl ring and elongation of the ethyl linker). Most DSs proved to inhibit the wild-type HIV-1 replication in cell-based assays and 15 of them were active at nanomolar concentrations. The most potent congeners (11, 15, 16, 17, 18, 19, 20 and 32, EC(50): 10-70 nM) shared the N-para-substituted phenyl moiety. Compound 17 tested in enzyme assay against recombinant wild-type reverse transcriptase displayed an IC(50) value of 0.74 microM. Compounds 19 and 33 were active at micromolar concentrations against the clinically relevant Y181C and/or K103R resistant mutants.