Publications by authors named "Jan Balzarini"

676 Publications

γ-Ketobenzyl-Modified Nucleoside Triphosphate Prodrugs as Potential Antivirals.

J Med Chem 2020 11 13;63(22):13745-13761. Epub 2020 Nov 13.

Organic Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics and Natural Sciences, Universität Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany.

The antiviral activity of nucleoside reverse transcriptase inhibitors is often hampered by insufficient phosphorylation. Nucleoside triphosphate analogues are presented, in which the γ-phosphate was covalently modified by a non-bioreversible, lipophilic 4-alkylketobenzyl moiety. Interestingly, primer extension assays using human immunodeficiency virus reverse transcriptase (HIV-RT) and three DNA-polymerases showed a high selectivity of these γ-modified nucleoside triphosphates to act as substrates for HIV-RT, while they proved to be nonsubstrates for DNA-polymerases α, β, and γ. In contrast to d4TTP, the γ-modified d4TTPs showed a high resistance toward dephosphorylation in cell extracts. A series of acyloxybenzyl-prodrugs of these γ-ketobenzyl nucleoside triphosphates was prepared. The aim was the intracellular delivery of a stable γ-modified nucleoside triphosphate to increase the selectivity of such compounds to act in infected versus noninfected cells. Delivery of γ-ketobenzyl-d4TTPs was proven in T-lymphocyte cell extracts. The prodrugs were potent inhibitors of HIV-1/2 in cultures of infected CEM/0 cells and more importantly in thymidine kinase-deficient CD4 T-cells.
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http://dx.doi.org/10.1021/acs.jmedchem.0c01293DOI Listing
November 2020

γ-Non-Symmetrically Dimasked TriPPPro Prodrugs as Potential Antiviral Agents against HIV.

ChemMedChem 2021 Feb 17;16(3):499-512. Epub 2020 Nov 17.

Organic Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics and Natural Sciences, Universität Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany.

Nucleoside analogue reverse transcriptase inhibitors (NRTI) and nucleoside analogue monophosphate prodrugs are used in combination antiretroviral therapy (cART). The design of antivirally active nucleoside triphosphate prodrugs is a recent and an important advancement in the field of nucleoside analogue drug development. Here, we report on TriPPPro-derivatives of nucleoside analogue triphosphates (NTPs) that comprised two different acyloxybenzyl-masks at the γ-phosphate of the NTP aiming to achieve the metabolic bypass. Thus, γ-non-symmetrically dimasked TriPPPro-compounds (γ-(AB,ab)-d4TTPs) were synthesized and they proved to be active against HIV-1 and HIV-2 in cultures of infected wild-type human CD4 T-lymphocyte (CEM/0) cells and more importantly also in thymidine kinase-deficient CD4 T-cells (CEM/TK-). From hydrolysis studies both in phosphate buffer (PB, pH 7.3) and CEM cell extracts, there was surprisingly no differentiation in the cleavage of the two acyloxybenzyl prodrug-masks. However, if within one of the two acyloxybenzyl groups a short PEG-type methoxytriglycol group was introduced, the "standard" acyloxybenzyl-mask was cleaved with high preference.
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http://dx.doi.org/10.1002/cmdc.202000712DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7894357PMC
February 2021

Skin Damages-Structure Activity Relationship of Benzimidazole Derivatives Bearing a 5-Membered Ring System.

Molecules 2020 Sep 21;25(18). Epub 2020 Sep 21.

Department of Life Sciences and Biotechnology, Master Course in Cosmetic Science and Technologies, University of Ferrara, 44121 Ferrara, Italy.

In the search for scaffolds for multifunctional compounds we investigated the structure activity relationship of a class of benzimidazole derivatives bearing 5-membered ring. The newly synthesized and the already known compounds were divided into three classes that present different substituent at 5 position of the benzimidazole ring (-H, -COOH or -SOH) and different heterocycle at position 2 (thiophene, furan or pyrrole). All the derivatives were synthesized and tested to determine their photoprotective profile against UV rays, in vitro antioxidant capacity against different radicals (DPPH and FRAP test), antifungal inhibitory activity (dermatophytes and ), antiviral and antiproliferative activity. A Structure-Activity Relationship study indicated compound , bearing a pyrrole heterocycle on the benzimidazole ring, as the best multifunctional derivative of the series and as potential candidate for the development of drugs especially in case of melanoma.
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http://dx.doi.org/10.3390/molecules25184324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7570844PMC
September 2020

Water-soluble fullerene-based nanostructures with promising antiviral and myogenic activity.

Chem Commun (Camb) 2020 Sep;56(70):10203-10206

Skolkovo Institute of Science and Technology, Nobel St. 3, Moscow, 143026, Russia. and IPCP RAS, Semenov Prospect 1, Chernogolovka, 142432, Russia.

Here we report a straightforward method for the synthesis of a water-soluble C60 fullerene derivative decorated with five residues of phosphonic acid. Self-assembly of the synthesized compound in aqueous solution leads to the formation of nanostructures with unprecedented myogenic and antiviral activity.
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http://dx.doi.org/10.1039/d0cc03928dDOI Listing
September 2020

Design, synthesis and evaluation of benzothiazole derivatives as multifunctional agents.

Bioorg Chem 2020 08 2;101:103960. Epub 2020 Jun 2.

Department of Life Sciences and Biotechnology, Master Course in Cosmetic Science and Technologies, University of Ferrara, via L. Borsari 46, 44121 Ferrara, Italy.

Oxidative stress is the product or aetiology of various multifactorial diseases; on the other hand, the development of multifunctional compounds is a recognized strategy for the control of complex diseases. To this end, a series of benzothiazole derivatives was synthesized and evaluated for their multifunctional effectiveness as antioxidant, sunscreen (filter), antifungal and antiproliferative agents. Compounds were easily synthesized via condensation reaction between 2-aminothiophenols and different benzaldehydes. SAR study, particularly in position 2 and 6 of benzothiazoles, led to the identification of 4g and 4k as very interesting potential compounds for the design of multifunctional drugs. In particular, compound 4g is the best blocker of hERG potassium channels expressed in HEK 293 cells exhibiting 60.32% inhibition with IC = 4.79 μM.
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http://dx.doi.org/10.1016/j.bioorg.2020.103960DOI Listing
August 2020

Prodrugs of γ-Alkyl-Modified Nucleoside Triphosphates: Improved Inhibition of HIV Reverse Transcriptase.

Angew Chem Int Ed Engl 2020 12 30;59(49):22063-22071. Epub 2020 Sep 30.

Organic Chemistry, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany.

The development of nucleoside triphosphate prodrugs is one option to apply nucleoside reverse transcriptase inhibitors. Herein, we report the synthesis and evaluation of d4TTP analogues, in which the γ-phosphate was modified covalently by lipophilic alkyl residues, and acyloxybenzyl prodrugs of these γ-alkyl-modified d4TTPs, with the aim of delivering of γ-alkyl-d4TTP into cells. Selective formation of γ-alkyl-d4TTP was proven with esterase and in CD4 -cell extracts. In contrast to d4TTP, γ-alkyl-d4TTPs proved highly stable against dephosphorylation. Primer extension assays with HIV reverse transcriptase (RT) and DNA-polymerases α, β or γ showed that γ-alkyl-d4TTPs were substrates for HIV-RT only. In antiviral assays, compounds were highly potent inhibitors of HIV-1 and HIV-2 also in thymidine-kinase-deficient T-cell cultures (CEM/TK ). Thus, the intracellular delivery of such γ-alkyl-nucleoside triphosphates may potentially lead to nucleoside triphosphates with a higher selectivity towards the viral polymerase that can act in virus-infected cells.
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http://dx.doi.org/10.1002/anie.202003073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756582PMC
December 2020

Synthesis and Biological Evaluation of New Antitubulin Agents Containing 2-(3',4',5'-trimethoxyanilino)-3,6-disubstituted-4,5,6,7-tetrahydrothieno[2,3-]pyridine Scaffold.

Molecules 2020 Apr 7;25(7). Epub 2020 Apr 7.

Dipartimento di Scienze della Vita e Biotecnologie, Università di Ferrara, 44121 Ferrara, Italy.

Two novel series of compounds based on the 4,5,6,7-tetrahydrothieno[2,3-]pyridine and 4,5,6,7-tetrahydrobenzo[]thiophene molecular skeleton, characterized by the presence of a 3',4',5'-trimethoxyanilino moiety and a cyano or an alkoxycarbonyl group at its 2- or 3-position, respectively, were designed, synthesized, and evaluated for antiproliferative activity on a panel of cancer cell lines and for selected highly active compounds, inhibition of tubulin polymerization, and cell cycle effects. We have identified the 2-(3',4',5'-trimethoxyanilino)-3-cyano-6-methoxycarbonyl-4,5,6,7-tetrahydrothieno[2,3-]pyridine derivative and its 6-ethoxycarbonyl homologue as new antiproliferative agents that inhibit cancer cell growth with IC values ranging from 1.1 to 4.7 μM against a panel of three cancer cell lines. Their interaction with tubulin at micromolar levels leads to the accumulation of cells in the G2/M phase of the cell cycle and to an apoptotic cell death. The cell apoptosis study found that compounds and were very effective in the induction of apoptosis in a dose-dependent manner. These two derivatives did not induce cell death in normal human peripheral blood mononuclear cells, suggesting that they may be selective against cancer cells. Molecular docking studies confirmed that the inhibitory activity of these molecules on tubulin polymerization derived from binding to the colchicine site.
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http://dx.doi.org/10.3390/molecules25071690DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181277PMC
April 2020

Design, synthesis and biological evaluation of 2-alkoxycarbonyl-3-anilinoindoles as a new class of potent inhibitors of tubulin polymerization.

Bioorg Chem 2020 04 18;97:103665. Epub 2020 Feb 18.

Rega Institute for Medical Research, KU Leuven, Laboratory of Virology and Chemotherapy, Leuven, Belgium.

A new class of inhibitors of tubulin polymerization based on the 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)indole molecular skeleton was synthesized and evaluated for antiproliferative activity, inhibition of tubulin polymerization and cell cycle effects. The results presented show that the methoxy substitution and location on the indole nucleus plays an important role in inhibition of cell growth, and the most favorable position for the substituent was at C-6. In addition, a small-size ester function (methoxy/ethoxycarbonyl) at the 2-position of the indole core was desirable. Also, analogues that were alkylated with methyl, ethyl or n-propyl groups or had a benzyl moiety on the N-1 indolic nitrogen retained activity equivalent to those observed in the parent N-1H analogues. The most promising compounds of the series were 2-methoxycarbonyl-3-(3',4'.5'-trimethoxyanilino)-5-methoxyindole 3f and 1-methyl-2-methoxycarbonyl-3-(3',4'.5'-trimethoxyanilino)-6-methoxy-indole 3w, both of which target tubulin at the colchicine site with antitubulin activities comparable to that of the reference compound combretastatin A-4.
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http://dx.doi.org/10.1016/j.bioorg.2020.103665DOI Listing
April 2020

Direct arylation of CCl and CCl with carboxylic acids: a synthetic avenue to water-soluble fullerene derivatives with promising antiviral activity.

Chem Commun (Camb) 2020 Jan;56(8):1179-1182

Skolkovo Institute of Science and Technology, Nobel St. 3, Moscow, 143026, Russia.

We report unprecedented Friedel-Crafts arylation of chlorofullerenes C60Cl6 and C70Cl8 with unprotected carboxylic acids as an efficient single-step synthesis of the inherently stable water-soluble fullerene derivatives. Using this method, a series of previously unaccessible compounds was obtained without chromatographic purification in almost quantitative yields. Promising anti-HIV activity comparable to characteristics of commercial drugs was demonstrated for some of these compounds.
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http://dx.doi.org/10.1039/c9cc08400bDOI Listing
January 2020

Potent antiviral activity of carbohydrate-specific algal and leguminous lectins from the Brazilian biodiversity.

Medchemcomm 2019 Mar 14;10(3):390-398. Epub 2019 Jan 14.

Rega Institute for Medical Research , Department of Microbiology and Immunology , KU Leuven , 3000 Leuven , Belgium . Email:

Brazil has one of the largest biodiversities in the world. The search for new natural products extracted from the Brazilian flora may lead to the discovery of novel drugs with potential to treat infectious and other diseases. Here, we have investigated 9 lectins extracted and purified from the Northeastern Brazilian flora, from both leguminous species: (ConBr), (ConM), (DLasiL) and (DSclerL), and algae (AML), (BSL), (HML), (MEL) and (SfL). They were exposed to a panel of 18 different viruses, including HIV and influenza viruses. Several lectins showed highly potent antiviral activity, often within the low nanomolar range. DSclerL and DLasiL exhibited EC values (effective concentration of lectin required to inhibit virus-induced cytopathicity by 50%) of 9 nM to 46 nM for HIV-1 and respiratory syncytial virus (RSV), respectively, DLasiL also inhibited feline corona virus at an EC of 5 nM, and DSclerL, ConBr and ConM showed remarkably low EC values ranging from 0.4 to 6 nM against influenza A virus strain H3N2 and influenza B virus. For HIV, evidence pointed to the blockage of entry of the virus into its target cells as the underlying mechanism of antiviral action of these lectins. Overall, the most promising lectins based on their EC values were DLasiL, DSclerL, ConBr, ConM, SfL and HML. These novel findings indicate that lectins from the Brazilian flora may provide novel antiviral compounds with therapeutic potential.
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http://dx.doi.org/10.1039/c8md00508gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6430086PMC
March 2019

Alpha-carboxynucleoside phosphonates: direct-acting inhibitors of viral DNA polymerases.

Future Med Chem 2019 01 16;11(2):137-154. Epub 2019 Jan 16.

Department of Chemistry, Analytical & Biological Chemistry Research Facility, Synthesis & Solid State Pharmaceutical Centre, University College, Cork, Ireland.

Acyclic nucleoside phosphonates represent a well-defined class of clinically used nucleoside analogs. All acyclic nucleoside phosphonates need intracellular phosphorylation before they can bind viral DNA polymerases. Recently, a novel class of alpha-carboxynucleoside phosphonates have been designed to mimic the natural 2'-deoxynucleotide 5'-triphosphate substrates of DNA polymerases. They contain a carboxyl group in the phosphonate moiety linked to the nucleobase through a cyclic or acyclic bridge. Alpha-carboxynucleoside phosphonates act as viral DNA polymerase inhibitors without any prior requirement of metabolic conversion. Selective inhibitory activity against retroviral reverse transcriptase and herpesvirus DNA polymerases have been demonstrated. These compounds have a unique mechanism of inhibition of viral DNA polymerases, and provide possibilities for further modifications to optimize and fine tune their antiviral DNA polymerase spectrum.
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http://dx.doi.org/10.4155/fmc-2018-0324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362432PMC
January 2019

Dolutegravir Monotherapy of Simian Immunodeficiency Virus-Infected Macaques Selects for Several Patterns of Resistance Mutations with Variable Virological Outcomes.

J Virol 2019 01 4;93(2). Epub 2019 Jan 4.

McGill University AIDS Centre Lady Davis Institute for Medical Research, Montreal, Quebec, Canada.

Drug resistance remains a major concern for human immunodeficiency virus (HIV) treatment. To date, very few resistance mutations have emerged in first-line combination therapy that includes the integrase strand transfer inhibitor (INSTI) dolutegravir (DTG). , DTG selects for several primary mutations that induce low-level DTG resistance; secondary mutations, while increasing the level of resistance, however, further impair replication fitness, which raised the idea that DTG monotherapy may be feasible. The simian immunodeficiency virus (SIV) rhesus macaque model of HIV infection can be useful to explore this concept. Nine macaques were infected with virulent SIVmac251 and started on DTG monotherapy during either acute ( = 2) or chronic infection ( = 7). Within 4 weeks of treatment, all animals demonstrated a reduction in viremia of 0.8 to 3.5 log RNA copies/ml plasma. Continued treatment led to overall sustained benefits, but the outcome after 10 to 50 weeks of treatment was highly variable and ranged from viral rebound to near pretreatment levels to sustained suppression, with viremia being 0.5 to 5 logs lower than expected based on pretreatment viremia. A variety of mutations previously described to confer low-level resistance of HIV-1 to DTG or other INSTI were detected, and these were sometimes followed by mutations believed to be compensatory. Some mutations, such as G118R, previously shown to severely impair the replication capacity , were associated with more sustained virological and immunological benefits of continued DTG therapy, while other mutations, such as E92Q and G140A/Q148K, were associated with more variable outcomes. The observed variability of the outcomes in macaques warrants avoidance of DTG monotherapy in HIV-infected people. A growing number of anti-HIV drug combinations are effective in suppressing virus replication in HIV-infected persons. However, to reduce their cost and risk for toxicity, there is considerable interest in simplifying drug regimens. A major concern with single-drug regimens is the emergence of drug-resistant viral mutants. It has been speculated that DTG monotherapy may be a feasible option, because DTG may have a higher genetic barrier for the development of drug resistance than other commonly used antiretrovirals. To explore treatment initiation with DTG monotherapy, we started SIV-infected macaques on DTG during either acute or chronic infection. Although DTG initially reduced virus replication, continued treatment led to the emergence of a variety of viral mutations previously described to confer low-level resistance of HIV-1 to DTG, and this was associated with variable clinical outcomes. This unpredictability of mutational pathways and outcomes warns against using DTG monotherapy as initial treatment for HIV-infected people.
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http://dx.doi.org/10.1128/JVI.01189-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6321921PMC
January 2019

Novel Conjugated Unsaturated Ketones with Submicromolar Potencies Towards some Leukemic and Colon Cancer Cells.

Med Chem 2019 ;15(4):430-438

Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, 104 Clinic Place, Saskatoon, Saskatchewan S7N 2Z5, Canada.

Background: Cancer continues to be the major health burden worldwide. There is an urgent need for the development of novel antineoplastic compounds to treat this devastating condition. Various alkylating anticancer drugs have been employed in the clinic for treating cancers. Unsaturated conjugated ketones are a group of alkylators which are of significant interest as potent antineoplastic agents.

Objective: The goal of this study is to discover unsaturated conjugated ketones which are novel potent cytotoxins displaying growth-inhibitory properties towards neoplasms and also to serve as cytotoxic warheads in drug development.

Methods: A variety of 3,5-bis (benzylidene)-4-piperidones 2a-n were synthesized and evaluated against a number of neoplastic cell lines. The short-term neurotoxicity of 2a-k, n was evaluated in mice by i.p. administration using doses level of 30, 100 and 300 mg/kg. Statistical correlations for determining structure-activity relationships were performed using an SPSS software.

Results: A number of compounds display cytotoxic potencies in the region of 10-7 to 10-8 M and some of the structural features contributing to the cytotoxicity were identified. Compounds 2a-d, 2h demonstrated substantially higher cytotoxic potencies compared to melphalan and 5- fluorouracil against a panel of leukemic and colon cancer cell lines. These lead cytotoxins comply with drug-likeness properties. In general, the antineoplastics 2 are well tolerated in mice using a short-term neurotoxicity screening.

Conclusion: In general, this group of compounds comprises excellent cytotoxic agents, which warrant their further development as cytotoxic warheads.
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http://dx.doi.org/10.2174/1573406414666181015142633DOI Listing
June 2019

Symmetrical Diamidates as a Class of Phosphate Prodrugs to Deliver the 5'-Monophosphate Forms of Anticancer Nucleoside Analogues.

ChemMedChem 2018 11;13(21):2305-2316

School of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff, CF10 3NB, UK.

The application of phosphorodiamidate technology to pyrimidine and purine nucleosides with anticancer activity to potentially overcome the resistance mechanisms associated with parent nucleosides is reported. Sixteen symmetrical phosphorodiamidates were prepared from the natural amino acids l-alanine and glycine. All the compounds were evaluated for their cytotoxic activity against a wide panel of solid and leukaemic tumour cell lines. In addition, a carboxypeptidase Y assay was performed on a representative phosphorodiamidate in order to reveal the putative bioactivation pathway for the reported phosphorodiamidate-type prodrugs.
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http://dx.doi.org/10.1002/cmdc.201800504DOI Listing
November 2018

Synthesis and Antiviral Activity of Water-Soluble Polycarboxylic Derivatives of [60]Fullerene Loaded with 3,4-Dichlorophenyl Units.

Chem Biodivers 2018 Nov 29;15(11):e1800293. Epub 2018 Oct 29.

Institute for Problems of Chemical Physics of RAS, Semenov Prospect 1, Chernogolovka, 142432, Russia.

We have synthesized a series of water-soluble polycarboxylic derivatives of [60]fullerene with a gradually changed polarity by combining three to five polar (ionic) malonate addends with two to zero hydrophobic dichlorobenzene units and explored their antiviral activity. It has been shown that decreasing the number of the ionogenic carboxylic groups in the molecules enhanced their antiviral activity against HIV-1 and suppressed their action against HIV-2. The obtained results implied that the charged states and hydrophobicity of the water-soluble polycarboxylic fullerene derivatives affect significantly their biological properties.
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http://dx.doi.org/10.1002/cbdv.201800293DOI Listing
November 2018

Design, synthesis, in vitro antiproliferative activity and apoptosis-inducing studies of 1-(3',4',5'-trimethoxyphenyl)-3-(2'-alkoxycarbonylindolyl)-2-propen-1-one derivatives obtained by a molecular hybridisation approach.

J Enzyme Inhib Med Chem 2018 Dec;33(1):1225-1238

d Department of Biochemistry and Molecular Biology, Research Institute in Biomedical and Health Sciences (IUIBS) , University of Las Palmas de Gran Canaria (ULPGC) , Spain.

Inhibition of microtubule function using tubulin targeting agents has received growing attention in the last several decades. The indole scaffold has been recognized as an important scaffold in the design of novel compounds acting as antimitotic agents. Indole-based chalcones, in which one of the aryl rings was replaced by an indole, have been explored in the last few years for their anticancer potential in different cancer cell lines. Eighteen novel (3',4',5'-trimethoxyphenyl)-indolyl-propenone derivatives with general structure 9 were synthesized and evaluated for their antiproliferative activity against a panel of four different human cancer cell lines. The highest IC values were obtained against the human promyelocytic leukemia HL-60 cell line. This series of chalcone derivatives was characterized by the presence of a 2-alkoxycarbonyl indole ring as the second aryl system attached at the carbonyl of the 3-position of the 1-(3',4',5'-trimethoxyphenyl)-2-propen-1-one framework. The structure-activity relationship (SAR) of the indole-based chalcone derivatives was investigated by varying the position of the methoxy group, by the introduction of different substituents (hydrogen, methyl, ethyl or benzyl) at the N-1 position and by the activity differences between methoxycarbonyl and ethoxycarbonyl moieties at the 2-position of the indole nucleus. The antiproliferative activity data of the novel synthesized compounds revealed that generally N-substituted indole analogues exhibited considerably reduced potency as compared with their parent N-unsubstituted counterparts, demonstrating that the presence of a hydrogen on the indole nitrogen plays a decisive role in increasing antiproliferative activity. The results also revealed that the position of the methoxy group on the indole ring is a critical determinant of biological activity. Among the synthesized derivatives, compound 9e, containing the 2-methoxycarbonyl-6-methoxy-N-1H-indole moiety exhibited the highest antiproliferative activity, with IC values of 0.37, 0.16 and 0.17 μM against HeLa, HT29 and MCF-7 cancer cell lines, respectively, and with considerably lower activity against HL-60 cells (IC: 18 μM). This derivative also displayed cytotoxic properties (IC values ∼1 μM) in the human myeloid leukemia U-937 cell line overexpressing human Bcl-2 (U-937/Bcl-2) via cell cycle progression arrest at the G-M phase and induction of apoptosis. The results obtained also demonstrated that the antiproliferative activity of this molecule is related to inhibition of tubulin polymerisation. The presence of a methoxy group at the C5- or C6-position of the indole nucleus, as well as the absence of substituents at the N-1-indole position, contributed to the optimal activity of the indole-propenone-3',4',5'-trimethoxyphenyl scaffold.
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http://dx.doi.org/10.1080/14756366.2018.1493473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116705PMC
December 2018

Synthesis of Guanine α-Carboxy Nucleoside Phosphonate (G-α-CNP), a Direct Inhibitor of Multiple Viral DNA Polymerases.

J Org Chem 2018 09 22;83(17):10510-10517. Epub 2018 Aug 22.

School of Chemistry and School of Pharmacy, Analytical and Biological Chemistry Research Facility, Synthesis and Solid State Pharmaceutical Centre , University College Cork , Cork , Ireland.

The synthesis of guanine α-carboxy nucleoside phosphonate (G-α-CNP) is described. Two routes provide access to racemic G-α-CNP 9, one via base construction and the other utilizing Tsuji-Trost allylic substitution. The latter methodology was also applied to the enantiopure synthesis of both antipodes of G-α-CNP, each of which showing interesting antiviral DNA polymerase activity. Additionally, we report an improved multigram scale preparation of the cyclopentene building block 10, starting material for the preferred Tsuji-Trost route to 9.
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http://dx.doi.org/10.1021/acs.joc.8b01124DOI Listing
September 2018

Engineering Lactobacillus rhamnosus GG and GR-1 to express HIV-inhibiting griffithsin.

Int J Antimicrob Agents 2018 Nov 21;52(5):599-607. Epub 2018 Jul 21.

KU Leuven, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium; University of Antwerp, Department of Bioscience Engineering, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address:

Probiotic bacteria are being explored for the in situ delivery of various therapeutic agents. In this study, we aimed to express two HIV-inhibiting lectins, actinohivin (AH) and griffithsin (GRFT), in the probiotic strains Lactobacillus rhamnosus GG and L. rhamnosus GR-1 for gastrointestinal and vaginal mucosal delivery, respectively. Constructs were generated for the intracellular and extracellular production of AH and GRFT under the control of the promoter of their Major Secreted Protein Msp1. Also, intracellular expression of GRFT was investigated under the control of the nisA promoter from the inducible nisin-controlled expression (NICE) system. For the extracellular localization, the signal leader peptide of Msp1/p75 from L. rhamnosus GG was translationally fused with the genes encoding AH and GRFT. Construction of recombinant strains expressing the AH monomer and dimer was unsuccessful, probably due to the intracellular toxicity of AH for the lactobacilli. On the other hand, recombinant strains for intra- and extracellular production of GRFT by L. rhamnosus GG and GR-1 were successfully constructed. The highest expression levels of recombinant GRFT were observed for the constructs under the control of the inducible nisA promoter and we demonstrated anti-HIV activity against an M-tropic and a T-tropic HIV-1 strain. We can conclude that recombinant Lactobacillus expressing anti-HIV lectins could contribute to the development of enhanced probiotic strains that are able to inhibit HIV transmission and subsequent replication, although further research and development are required.
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http://dx.doi.org/10.1016/j.ijantimicag.2018.07.013DOI Listing
November 2018

2-Amino-3-methylcarboxy-5-heptyl-thiophene (TJ191) is a selective anti-cancer small molecule that targets low TβRIII-expressing malignant T-cell leukemia/lymphoma cells.

Oncotarget 2018 Jan 15;9(5):6259-6269. Epub 2017 Dec 15.

Rega Institute for Medical Research, Department of Microbiology and Immunology, KU Leuven, 3000 Leuven, Belgium.

Current chemotherapy regimens often include non-specific cytostatic/cytotoxic drugs, which do not distinguish between normal and tumor cells, therefore causing considerable systemic toxicity. We previously reported the synthesis and anti-proliferative activity of a novel synthetic 2-aminothiophene-3-carboxylic acid ester derivative TJ191 that selectively targets certain cancer cells without affecting the proliferation of other cancer cells or normal fibroblasts or immune cells (over 600-fold selectivity). In a panel of ten human T-cell leukemia/lymphoma cell lines and peripheral blood mononuclear cells (PBMCs), we now found that transforming growth factor β type III receptor (TβRIII) expression correlates inversely with TJ191 sensitivity, but not with sensitivity against classical chemotherapeutic drugs, thus serving as a predictive marker for TJ191 sensitivity. Accordingly, CRISPR/Cas9-mediated knock-out of TβRIII partially restored the susceptibility of TJ191-resistant cells to this novel compound. Our findings highlight TJ191 as a potent and selective anti-cancer molecule with pronounced activity against human malignant T-cells expressing low levels of TβRIII.
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http://dx.doi.org/10.18632/oncotarget.23501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5814210PMC
January 2018

2-Alkoxycarbonyl-3-arylamino-5-substituted thiophenes as a novel class of antimicrotubule agents: Design, synthesis, cell growth and tubulin polymerization inhibition.

Eur J Med Chem 2018 Jan;143:683-698

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia Pediatrica, Università di Padova, 35131 Padova, Italy. Electronic address:

Microtubules are recognized as crucial components of the mitotic spindle during cell division, and, for this reason, the microtubule system is an attractive target for the development of anticancer agents. Continuing our search strategy for novel tubulin targeting-compounds, a new series of 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)-5-aryl/heteroarylthiophene derivatives was designed, synthesized and demonstrated to act as tubulin polymerization inhibitors at the colchicine site. A structure-activity relationship study on the phenyl at the 5-position of the thiophene ring was performed by introducing a variety of substituents containing electron-releasing and electron-withdrawing groups, with the 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)thiophene scaffold being the minimum structural requirement for activity. Of the tested compounds, derivatives 4a, 4c, 4i and 4k possessed the highest overall potency and displayed high antiproliferative activities at submicromolar concentrations, with IC values ranging from 0.13 to 0.84 μM against four different cancer cell lines. Three agents (4a, 4c and 4i) in the present series had similar effects, and these were comparable to those of the reference compound combretastatin A-4 (CA-4) as inhibitors of tubulin assembly. The antitubulin effects correlated with the cytostatic activities and indicate that these compounds inhibit cell growth through inhibition of tubulin polymerization by binding at the colchicine site. Compound 4c, containing the 2'-thienyl ring at the 5-position of the 2-methoxycarbonyl-3-(3',4',5'-trimethoxyanilino)thiophene scaffold, exhibited substantial antiproliferative activity with a mean IC value of 140 nM, inhibited tubulin polymerization with an IC value of 1.2 μM, similar to that of CA-4 (IC: 1.1 μM), and induced apoptosis in HeLa cells.
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http://dx.doi.org/10.1016/j.ejmech.2017.11.096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5791907PMC
January 2018

Virtual Screening of Acyclovir Derivatives as Potential Antiviral Agents: Design, Synthesis, and Biological Evaluation of New Acyclic Nucleoside ProTides.

J Med Chem 2017 09 19;60(18):7876-7896. Epub 2017 Sep 19.

Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University , Cardiff, CF10 3NB, U.K.

Following our findings on the anti-human immunodeficiency virus (HIV) activity of acyclovir (ACV) phosphate prodrugs, we herein report the ProTide approach applied to a series of acyclic nucleosides aimed at the identification of novel and selective antiviral, in particular anti-HIV agents. Acyclic nucleoside analogues used in this study were identified through a virtual screening using HIV-reverse transcriptase (RT), adenylate/guanylate kinase, and human DNA polymerase γ. A total of 39 new phosphate prodrugs were synthesized and evaluated against HIV-1 (in vitro and ex vivo human tonsillar tissue system) and human herpes viruses. Several ProTide compounds showed substantial potency against HIV-1 at low micromolar range while the parent nucleosides were not effective. Also, pronounced inhibition of herpesvirus replication was observed. A carboxypeptidase-mediated hydrolysis study was performed for a selection of compounds to assess the formation of putative metabolites and support the biological activity observed.
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http://dx.doi.org/10.1021/acs.jmedchem.7b01009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731253PMC
September 2017

The ProTide Prodrug Technology: From the Concept to the Clinic.

J Med Chem 2018 03 24;61(6):2211-2226. Epub 2017 Aug 24.

Laboratory of Virology and Chemotherapy , Rega Institute for Medical Research , Herestraat 49 , 3000 Leuven , Belgium.

The ProTide technology is a prodrug approach developed for the efficient intracellular delivery of nucleoside analogue monophosphates and monophosphonates. In this approach, the hydroxyls of the monophosphate or monophosphonate groups are masked by an aromatic group and an amino acid ester moiety, which are enzymatically cleaved-off inside cells to release the free nucleoside monophosphate and monophosphonate species. Structurally, this represents the current end-point of an extensive medicinal chemistry endeavor that spans almost three decades. It started from the masking of nucleoside monophosphate and monophosphonate groups by simple alkyl groups and evolved into the sophisticated ProTide system as known today. This technology has been extensively employed in drug discovery, and it has already led to the discovery of two FDA-approved (antiviral) ProTides. In this work, we will review the development of the ProTide technology, its application in drug discovery, and its role in the improvement of drug delivery and efficacy.
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http://dx.doi.org/10.1021/acs.jmedchem.7b00734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075648PMC
March 2018

Surface Glycans: A Therapeutic Opportunity for Kinetoplastid Diseases.

Trends Parasitol 2017 10 28;33(10):775-787. Epub 2017 Jul 28.

Instituto de Parasitología y Biomedicina 'López-Neyra', Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18016-Armilla (Granada), Spain. Electronic address:

Trypanosomal diseases are in need of innovative therapies that exploit novel mechanisms of action. The cell surface of trypanosomatid parasites is characterized by a dense coat of glycoconjugates with important functions in host cell recognition, immune evasion, infectivity, and cell function. The nature of parasite surface glycans is highly dynamic and changes during differentiation and in response to different stimuli through the action of glycosyltransferases and glycosidases. Here we propose a new approach to antiparasitic drug discovery that involves the use of carbohydrate-binding agents that bind specifically to cell-surface glycans, giving rise to cytotoxic events and parasite death. The potential and limitations of this strategy are addressed with a specific focus on the treatment of sleeping sickness.
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http://dx.doi.org/10.1016/j.pt.2017.06.009DOI Listing
October 2017

New prodrugs of two pyrimidine acyclic nucleoside phosphonates: Synthesis and antiviral activity.

Bioorg Med Chem 2017 09 6;25(17):4637-4648. Epub 2017 Jul 6.

Rega Institute for Medical Research, KU Leuven, Herestraat 49, Box 1043, B-3000 Leuven, Belgium. Electronic address:

New 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]pyrimidine (PMEO-DAPy) and 1-[2-(phosphonomethoxy)ethyl]-5-azacytosine (PME-5-azaC) prodrugs were prepared with a pro-moiety consisting of carbonyloxymethyl esters (POM, POC), alkoxyalkyl esters, amino acid phosphoramidates and/or tyrosine. The activity of the prodrugs was evaluated in vitro against different virus families. None of the synthesized prodrugs demonstrated activity against RNA viruses but some of them proved active against herpesviruses [including herpes simplex virus (HSV), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV)]. The bis(POC) and the bis(amino acid) phosphoramidate prodrugs of PMEO-DAPy inhibited herpesvirus replication at lower doses than the parent compound although the selectivity against HSV and VZV was only slightly improved compared to PMEO-DAPy. The mono-octadecyl ester of PME-5-azaC emerged as the most potent and selective PME-5-azaC prodrug against HSV, VZV and HCMV with EC's of 0.15-1.12µM while PME-5-azaC only had marginal anti-herpesvirus activity. Although the bis(hexadecylamido-l-tyrosyl) and the bis(POM) esters of PME-5-azaC were also very potent anti-herpesvirus drugs, these were less selective than the mono-octadecyl ester prodrug.
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http://dx.doi.org/10.1016/j.bmc.2017.06.046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7126465PMC
September 2017

A new four-component reaction involving the Michael addition and the Gewald reaction, leading to diverse biologically active 2-aminothiophenes.

Org Biomol Chem 2017 May;15(18):3892-3900

Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.

The Gewald three-component reaction yielding highly substituted 2-aminothiophene heterocycles has been known for a long time and holds an extraordinary potential in the pharmaceutical industry. Herein, we describe a four-component reaction initiated by the conjugate addition of different indole derivatives to α,β-unsaturated carbonyl compounds. This is followed by an in situ Gewald three-component reaction which results in the formation of a compound containing an indole and a 2-aminothiophene moiety separated by a methylene spacer. We also examined the impact of the use of other nucleophilic components such as pyrrole derivatives on this MG-4CR (Michael-Gewald four component reaction). All these synthesized compounds were tested for anti-proliferative activity and three of them showed activity in the nanomolar range.
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http://dx.doi.org/10.1039/c7ob00707hDOI Listing
May 2017

A Multitarget Approach toward the Development of 8-Substituted Purines for Photoprotection and Prevention of UV-Related Damage.

ChemMedChem 2017 05 3;12(10):760-769. Epub 2017 May 3.

Department of Life Sciences and Biotechnology, Master Course in Cosmetic Science and Technologies, University of Ferrara, via L. Borsari 46, 44121, Ferrara, Italy.

Ultraviolet (UV) light is the most abundant and significant modifiable risk factor for skin cancer and many other skin diseases such as early photo-aging. Across the solar radiation spectrum, UV light is the main cause behind skin problems. In the search for novel photoprotective compounds, a new series of 8-substituted purines were synthesized from commercially available 6-hydroxy-4,5-diaminopyrimidine hemisulfate or 4,5-diaminopyrimidine. All title compounds were investigated for their UV filtering, antioxidant, antifungal, and antiproliferative activities. For the photoprotection assays we used a diffuse transmittance technique to determine the sun protection factor (SPF) in vitro, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP) tests for evaluating the antioxidant activity of the more potent compounds. Among them, 8-(2,5-dihydroxyphenyl)-7H-purin-6-ol (compound 26) proved to be a good radical scavenger and is also endowed with broad-spectrum UVA filtering capabilities, suitable for further development as a protective molecule.
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http://dx.doi.org/10.1002/cmdc.201700137DOI Listing
May 2017

Guanine α-carboxy nucleoside phosphonate (G-α-CNP) shows a different inhibitory kinetic profile against the DNA polymerases of human immunodeficiency virus (HIV) and herpes viruses.

Biochem Pharmacol 2017 07 6;136:51-61. Epub 2017 Apr 6.

Department of Chemistry, Analytical and Biological Chemistry Research Facility, Synthesis and Solid State Pharmaceutical Centre, University College Cork, Ireland; School of Pharmacy, Analytical and Biological Chemistry Research Facility, Synthesis and Solid State Pharmaceutical Centre, University College Cork, Ireland.

α-Carboxy nucleoside phosphonates (α-CNPs) are modified nucleotides that represent a novel class of nucleotide-competing reverse transcriptase (RT) inhibitors (NcRTIs). They were designed to act directly against HIV-1 RT without the need for prior activation (phosphorylation). In this respect, they differ from the nucleoside or nucleotide RTIs [N(t)RTIs] that require conversion to their triphosphate forms before being inhibitory to HIV-1 RT. The guanine derivative (G-α-CNP) has now been synthesized and investigated for the first time. The (L)-(+)-enantiomer of G-α-CNP directly and competitively inhibits HIV-1 RT by interacting with the substrate active site of the enzyme. The (D)-(-)-enantiomer proved inactive against HIV-1 RT. In contrast, the (+)- and (-)-enantiomers of G-α-CNP inhibited herpes (i.e. HSV-1, HCMV) DNA polymerases in a non- or uncompetitive manner, strongly indicating interaction of the (L)-(+)- and the (D)-(-)-G-α-CNPs at a location different from the polymerase substrate active site of the herpes enzymes. Such entirely different inhibition profile of viral polymerases is unprecedented for a single antiviral drug molecule. Moreover, within the class of α-CNPs, subtle differences in their sensitivity to mutant HIV-1 RT enzymes were observed depending on the nature of the nucleobase in the α-CNP molecules. The unique properties of the α-CNPs make this class of compounds, including G-α-CNP, direct acting inhibitors of multiple viral DNA polymerases.
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http://dx.doi.org/10.1016/j.bcp.2017.04.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5557014PMC
July 2017

Pronounced anti-proliferative activity and tumor cell selectivity of 5-alkyl-2-amino-3-methylcarboxylate thiophenes.

Eur J Med Chem 2017 May 23;132:219-235. Epub 2017 Mar 23.

KU Leuven, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, B-3000 Leuven, Belgium. Electronic address:

5-(2-(4-Methoxyphenyl)ethyl)-2-amino-3-methylcarboxylate thiophene (TR560) is the prototype drug of a recently discovered novel class of tumor-selective compounds that preferentially inhibit the proliferation of specific tumor cell types (e.g. leukemia/lymphoma). Here, we further increased tumor selectivity by simplification of the molecule through replacing the 4-methoxyphenyl moiety by an alkyl chain. Several 2-amino-3-methylcarboxylate thiophene derivatives containing at C-5 an alkyl group consisting of at least 6 (hexyl) to 9 (nonyl) carbon units showed pronounced anti-proliferative activity in the mid-nanomolar range with 500- to 1000-fold tumor cell selectivity. The compounds preferentially inhibited the proliferation of T-lymphoma CEM and Molt/4, prostate PC-3, kidney Caki-1 and hepatoma Huh-7 tumor cells, but were virtually inactive against other tumor cell lines including B-lymphoma Raji and cervix carcinoma HeLa cells. The novel prototype drug 3j (containing a 5-heptyl chain) elicited a cytotoxic, rather than cytostatic activity, already after 4 h of exposure. The unusual tumor selectivity could not be explained by a differential uptake (or efflux) of the drug by sensitive versus resistant tumor cells. Exposure of a fluorescent derivative of 3j revealed pronounced uptake of the drug in the cytoplasm, no visible appearance in the nucleus, and a predominant localization in the endoplasmic reticulum. These observations may be helpful to narrow down the intracellular localization and identification of the molecular target of the 5-substituted thiophene derivatives.
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http://dx.doi.org/10.1016/j.ejmech.2017.03.044DOI Listing
May 2017

6-Benzylidene-2-[4-(pyridin-3-ylcarboxy)benzylidene]cyclohexanones: A novel cluster of tumour-selective cytotoxins.

Bioorg Med Chem Lett 2017 04 10;27(7):1611-1615. Epub 2017 Feb 10.

Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada. Electronic address:

Novel cytotoxins 3-5 containing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore are disclosed. The compounds in series 3 and 5 have the potential to liberate niacin which may reduce some of the side effects of antineoplastic compounds. 3a-c emerged as the most potent cytotoxic compounds with IC values in the low micromolar range against human Molt4/C8 and CEM CD T-lymphocytes as well as murine L1210 leukemia cells. QSAR studies revealed that cytotoxic potencies were negatively correlated with the magnitude of the Hammett sigma values of the aryl substituents. The compounds 3a-e displayed tumour-selective toxicity against human HL-60, HSC-2, HSC-3 and HSC-4 neoplasms as compared to human HGF, HPC and HPLF nonmalignant cells. A representative potent compound 3a caused PARP1 cleavage and G/G cell cycle arrest in HSC-2 cells. These compounds are well tolerated in mice at doses up to and including 300mg/kg of the compounds and no mortalities were noted after 4h. The stability studies undertaken did not reveal that a representative compound 3a underwent hydrolysis to the related phenol 2a. Some guidelines for further analog development of the novel esters 3 were made.
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http://dx.doi.org/10.1016/j.bmcl.2017.02.016DOI Listing
April 2017