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AL-471, the leading exponent of a class of potent HIV and enterovirus A71 (EV-A71) entry inhibitors discovered in our research group, contains four l-tryptophan (Trp) units bearing an aromatic isophthalic acid directly attached to the C2 position of each indole ring. Starting from AL-471, we (i) replaced l-Trp with d-Trp, (ii) inserted a flexible linker between C2 and the isophthalic acid, and (iii) substituted a nonaromatic carboxylic acid for the terminal isophthalic acid. Truncated analogues lacking the Trp motif were also synthesized. Our findings indicate that the antiviral activity seems to be largely independent of the stereochemistry (l- or d-) of the Trp fragment and also that both the Trp unit and the distal isophthalic moiety are essential for antiviral activity. The most potent derivative, 23 (AL-534), with the C2 shortest alkyl urea linkage (three methylenes), showed subnanomolar potency against different EV-71 clinical isolates. This finding was only observed before with the early dendrimer prototype AL-385 (12 l-Trp units) but remained unprecedented for the reduced-size prototype AL-471. Molecular modeling showed the feasibility of high-affinity binding of the novel l-Trp-decorated branches of 23 (AL-534) to an alternative site on the VP1 protein that harbors significant sequence variation among EV-71 strains.

There is a clear need for novel antiviral concepts to control SARS-CoV-2 infection. Based on the promising anti-coronavirus activity observed for a class of 1,4,4-trisubstituted piperidines, we here conducted a detailed analysis of the structure–activity relationship of these structurally unique inhibitors. Despite the presence of five points of diversity, the synthesis of an extensive series of analogues was readily achieved by Ugi four-component reaction from commercially available reagents. After evaluating 63 analogues against human coronavirus 229E, four of the best molecules were selected and shown to have micromolar activity against SARS-CoV-2. Since the action point was situated post virus entry and lying at the stage of viral polyprotein processing and the start of RNA synthesis, enzymatic assays were performed with CoV proteins involved in these processes. While no inhibition was observed for SARS-CoV-2 nsp12-nsp7-nsp8 polymerase, nsp14 N7-methyltransferase and nsp16/nsp10 2’-O-methyltransferase, nor the nsp3 papain-like protease, the compounds clearly inhibited the nsp5 main protease (Mpro). Although the inhibitory activity was quite modest, the plausibility of binding to the catalytic site of Mpro was established by in silico studies. Therefore, the 1,4,4-trisubstituted piperidines appear to represent a novel class of non-covalent CoV Mpro inhibitors that warrants further optimization and development.

We have recently described a novel family of compounds of reduced size and dual anti-HIV and anti-EV71 ac- tivity that encompasses tripodal and tetrapodal derivatives. The tripodal prototype, AL-470, has a nitro group at the focal point of the central scaffold and three attached tryptophan residues, each of which bearing an iso- phthaloyl moiety at the C2 position of the indole ring. A nitro to amino substitution has allowed us now to introduce a chemically addressable functionality to perform further structural modifications consisting of both direct and linker-mediated attachment of several aromatic groups, including the fluorescent dye Alexa Fluor 647 and the antibody-recruiting 2,4-dinitrophenyl motif. Some of the derivatives turned out to be more potent and selective than AL-470 against HIV-1, HIV-2 and EV-A71. The fluorescent probe demonstrated a specific tropism for intestines and lungs, two important niches for the human microbiome in health and disease

N-methylation of the triazole moiety present in our recently described triazole-phenyl-thiazole dimerization disruptors of Leishmania infantum trypanothione disulfide reductase (LiTryR) led to a new class of potent in- hibitors that target different binding sites on this enzyme. Subtle structural changes among representative library members modified their mechanism of action, switching from models of classical competitive inhibition to time- dependent mixed noncompetitive inhibition. X-ray crystallography and molecular modeling results provided a rationale for this distinct behavior. The remarkable potency and selectivity improvements, particularly against intracellular amastigotes, of the LiTryR dimerization disruptors 4c and 4d reveal that they could be exploited as leishmanicidal agents. Of note, L. infantum promastigotes treated with 4c significantly reduced their low- molecular-weight thiol content, thus providing additional evidence that LiTryR is the main target of this novel compound.

Unprecedented 3D hexa-adducts of [60]fullerene peripherally decorated with twelve tryptophan (Trp) or tyrosine (Tyr) residues have been synthesized. Studies on the antiviral activity of these novel compounds against HIV and EV71 reveal that they are much more potent against HIV and equally active against EV71 than the previously described dendrimer prototypes AL-385 and AL-463, which possess the same number of Trp/Tyr residues on the periphery but attached to a smaller and more flexible pentaerythritol core. These results demonstrate the relevance of the globular 3D presentation of the peripheral groups (Trp/Tyr) as well as the length of the spacer connecting them to the central core to interact with the viral envelopes, particularly in the case of HIV, and support the hypothesis that [60]fullerene can be an alternative and attractive biocompatible carbon-based scaffold for this type of highly symmetrical dendrimers. In addition, the functionalized fullerenes here described, which display twelve peripheral negatively charged indole moieties on their globular surface, define a new and versatile class of compounds with a promising potential in biomedical applications.

Here we highlight a sound and unique work reported by Chen and co-workers entitled “HIV-1 fusion inhibitors targeting the membrane-proximal external region of Env spikes” (Xiao et al., Nat. Chem. Biol. 2020, 16, 529). In this article, the authors identify, by means of a clever antibody-guided strategy, several small molecules as fusion inhibitors of HIV-1 replication acting at the membrane proximal external region (MPER) of the HIV-1 envelope (Env) spike. MPER, which was previously recognized as a vaccine target, emerges as a novel druggable target for the discovery of HIV-1 fusion inhibitors. The compounds (exemplified by dequalinium and dequalinium-inspired analogues) prevent the conformational changes of Env from the prefusion species to the intermediate states required for membrane fusion. This work not only paves the way to novel, specific and useful anti-HIV-1 inhibitors, but also discloses new therapeutic strategies against other infectious diseases.

The nuclear export receptor exportin-1 (XPO1, CRM1) mediates the nuclear export of proteins that contain a leucine-rich nuclear export signal (NES) towards the cytoplasm. XPO1 is considered a relevant target in different human diseases, particularly in hematological malignancies, tumor resistance, inflammation, neurodegeneration and viral infections. Thus, its pharmacological inhibition is of significant therapeutic interest. The best inhibitors described so far (leptomycin B and SINE compounds) interact with XPO1 through a covalent interaction with Cys528 located in the NES-binding cleft of XPO1. Based on the well-established feature of chalcone derivatives to react with thiol groups via hetero-Michael addition reactions, we have synthesized two series of chalcones. Their capacity to react with thiol groups was tested by incubation with GSH to afford the hetero-Michael adducts that evolved backwards to the initial chalcone through a retro-Michael reaction, supporting that the covalent interaction with thiols could be reversible. The chalcone derivatives were evaluated in antiproliferative assays against a panel of cancer cell lines and as XPO1 inhibitors, and a good correlation was observed with the results obtained in both assays. Moreover, no inhibition of the cargo export was observed when the two prototype chalcones 9 and 10 were tested against a XPO1-mutated Jurkat cell line (XPO1C528S), highlighting the importance of the Cys at the NES-binding cleft for inhibition. Finally, their interaction at the molecular level at the NES-binding cleft was studied by applying the computational tool CovDoc.

Inhibition of Leishmania infantum trypanothione disulfide reductase (LiTryR) by disruption of its homodimeric interface has proved to be an alternative and unexploited strategy in the search for novel antileishmanial agents. Proof of concept was first obtained by peptides and peptidomimetics. Building on previously reported dimerization disruptors containing an imidazole-phenyl-thiazole scaffold, we now report a new 1,2,3-triazole-based chemotype that yields noncompetitive, slow-binding inhibitors of LiTryR. Several compounds bearing (poly)aromatic substituents dramatically improve the ability to disrupt LiTryR dimerization relative to reference imidazoles. Molecular modeling studies identified an almost unexplored hydrophobic region at the interfacial domain as the putative binding site for these compounds. A subsequent structure-based design led to a symmetrical triazole analogue that displayed even more potent inhibitory activity over LiTryR and enhanced leishmanicidal activity. Remarkably, several of these novel triazole-bearing compounds were able to kill both extracellular and intracellular parasites in cell cultures.

Trypanothione disulfide reductase (TryR) is an essential homodimeric enzyme of trypanosomatid parasites that has been validated as a drug target to fight human infections. Using peptides and peptidomimetics, we previously obtained proof of concept that disrupting protein–protein interactions at the dimer interface of Leishmania infantum TryR (LiTryR) offered an innovative and so far unexploited opportunity for the development of novel antileishmanial agents. Now, we show that linking our previous peptide prototype TRL38 to selected hydrophobic moieties provides a novel series of small-molecule–peptide conjugates that behave as good inhibitors of both LiTryR activity and dimerization.

We have recently described a new generation of potent human immunodeficiency virus (HIV) and EV-A71 entry inhibitors. The prototypes contain three or four tryptophan (Trp) residues bearing an isophthalic acid moiety at the C2 position of each side-chain indole ring. This work is now extended by both shifting the position of the isophthalic acid to C7 and synthesizing doubly arylated C2/C7 derivatives. The most potent derivative (50% effective concentration (EC50) HIV-1, 6 nM; EC50 EV-A71, 40 nM), 33 (AL-518), is a C2/C7 doubly arylated tetrapodal compound. Its superior anti-HIV potency with respect to the previous C2- arylated prototype is in consonance with its higher affinity for the viral gp120. 33 (AL-518) showed comparable antiviral activities against X4 and R5 HIV-1 strains and seems to interact with the tip and base of the gp120 V3 loop. Taken together, these findings support the interest in 33 (AL-518) as a useful new prototype for anti-HIV/EV71 drug development.

Here, we report a class of tryptophan trimers and tetramers that inhibit (at low micromolar range) dengue and Zika virus infection in vitro. These compounds (AL family) have three or four peripheral tryptophan moieties directly linked to a central scaffold through their amino groups; thus, their carboxylic acid groups are free and exposed to the periphery. Structure-activity relationship (SAR) studies demonstrated that the presence of extra phenyl rings with substituents other than COOH at the N1 or C2 position of the indole side chain is a requisite for the antiviral activity against both viruses. The molecules showed potent antiviral activity, with low cytotoxicity, when evaluated on different cell lines. Moreover, they were active against laboratory and clinical strains of all four serotypes of dengue virus as well as a selected group of Zika virus strains. Additional mechanistic studies performed with the two most potent compounds (AL439 and AL440) demonstrated an interaction with the viral envelope glycoprotein (domain III) of dengue 2 virus, preventing virus attachment to the host cell membrane. Since no antiviral agent is approved at the moment against these two flaviviruses, further pharmacokinetic studies with these molecules are needed for their development as future therapeutic/prophylactic drugs.

Currently, there are only three FDA-approved drugs that inhibit human immunodeficiency virus (HIV) entry-fusion into host cells. The situation is even worse for enterovirus EV71 infection for which no antiviral therapies are available. We describe here the discovery of potent entry dual inhibitors of HIV and EV71. These compounds contain in their structure three or four tryptophan (Trp) residues linked to a central scaffold. Critical for anti-HIV/EV71 activity is the presence of extra phenyl rings, bearing one or two carboxylates, at the C2 position of the indole ring of each Trp residue. The most potent derivatives, 22 and 30, inhibit early steps of the replicative cycles of HIV-1 and EV-A71 by interacting with their respective viral surfaces (glycoprotein gp120 of HIV and the fivefold axis of the EV-A71 capsid). The high potency, low toxicity, facile chemical synthesis, and great opportunities for chemical optimization make them useful prototypes for future medicinal chemistry studies.

The present invention refers to new compounds useful in the treatment of leishmaniasis and, more particularly, to a series of 5-6-5 triazole-phenyl-thiazole heterocycles capable of inhibiting both activity and dimerization of L. infantum Try R in enzymatic assays at low micromolar concentrations and endowed with potent in vitro activity against promastigote and amastigote forms of Leishmania which indicates a good permeability across the plasma membrane ofthe parasites

Se describen nuevos inhibidores de fusión dirigidos a la Hemaglutinina del virus influenza

We have previously reported a new class of dendrimers with tryptophan (Trp) residues on the surface that show dual antiviral activities against HIV and enterovirus EV71. The prototype compound of this family is a derivative of pentaerythritol with 12 peripheral Trp groups and trivalent spacer arms. Here a novel series of dendrimers with divalent and tetravalent branched arms, instead of the trivalent ones present on the prototype, has been synthesized and its activity against HIV, EV71 and a panel of 16 different viruses and other pathogens has been determined. Convergent or divergent approaches have been used for the synthesis of these compounds. Our findings demonstrate that only compounds with tetravalent branched arms showed the same anti-HIV and anti-EV71 activity of the prototype (low micromolar) and even gain significant antiviral activity against new pathogens such as HSV-2, adenovirus-2, human corona virus and respiratory syncytial virus, being the first members of the Trp dendrimer family that showed activity against those viruses. As the prototype, these compounds also showed low-nanomolar activity against a representative EV71 clinical isolate. Experimental work carried on to determine the mode of action of the most potent IIa, containing tetravalent branched arms, demonstrated that it interacts with the viral envelopes of HIV, EV71 and HSV-2 and thus may prevent virus attachment to the host cell. These results support the interest of this new series of Trp dendrimers and qualify them as useful prototypes for the development of novel inhibitors of viral entry with broad antiviral spectrum.

Microtubule targeting agents represent a very active arena in the development of anticancer agents. In particular, compounds binding at the colchicine site in tubulin are being deeply studied, and the structural information recently available on this binding site allows structure-directed design of new ligands. Structural comparison of our recently reported high resolution X-Ray structure of the cyclohexanedione derivative TUB075 bound to tubulin and the tubulin-DAMA-colchicine complex has revealed a conformational change in the aT5 loop. By a grid-based computational analysis of the tubulinDAMA-colchicine binding site, we have identified a new favourable binding area in the colchicine-site that was unexplored by our lead TUB075. Thus, based on a structure-guided design, new cyclohexanedione derivatives have been synthesized and tested for tubulin binding and in cellular assays. As a result, we have identified diphenyl ether derivatives with IC50 values around 10e40 nM against three different tumor cell lines and affinity constants for tubulin similar to that of colchicine around 107 M 1 . As expected, they halted the cell cycle progression at G2/M phase at concentrations as low as 0.08 mM.

Los virus son los agentes etiológicos responsables de muchas enfermedades en humanos que van desde leves (p. ej. resfriado común) a letales (p. ej. la viruela, el SIDA, etc). Asimismo, los virus juegan un papel importante en el desarrollo de ciertos tipos de cáncer. Actualmente, se conocen más de 219 especies de virus capaces de infectar seres humanos. Algunos de estos virus son responsables de importantes infecciones virales: como el virus de inmunodeficiencia humana (VIH-1) responsable del SIDA (37-40 millones de personas infectadas en el mundo); el virus influenza que causa cerca de 250.000-500.000 muertes anuales; el virus de la hepatitis B y el virus de la hepatitis C (VHB y VHC) con 240 y 140 millones de personas infectadas, respectivamente; el virus herpes simplex (VHS) causante de neumonía, encefalitis, meningitis, lesiones genitales, etc; el virus varicela zóster (VVZ) y el citomegalovirus humano (CMVH), ambos pertenecientes a la familia de los virus herpes, responsables de graves enfermedades en pacientes inmunodeprimidos. Las enfermedades virales (re)emergentes suponen una amenaza para la humanidad. En un mundo globalizado como en el que vivimos, una infección viral que aparece en un lugar distinto y remoto a su entorno natural, puede ser fácilmente diseminada a otras partes del mundo y como consecuencia se pueden originar brotes virulentos de dimensiones difíciles de predecir. La mayoría de las enfermedades virales (re)emergentes están causadas por virus ARN que en general muestran una alta capacidad de mutación comparada con la de los virus ADN..., Viruses are the aetiological agents of several human diseases ranging from mild (i.e. commond cold) to lethal (i.e. smallpox, AIDS, etc.). Moreover, they also play an important role in the development of some kinds of cancers. There are more than 219 known species of viruses capable of infecting humans. Some examples of these viruses, responsible the most important viral infections, include Human immunodeficeincy virus (HIV-1) responsible of AIDS (37-40 million people infected around the world); Influenza viruses that cause among 250.000-500.000 deads anually; Hepatitis B and Hepatitis C Viruses (HBV and HCV) with approximately 240 and 140 million people infected, respectively; Herpes simplex viruses (HSV) causing several serious diseases as pneumonia, encephalitis, meningitis, genital lessions etc.; Virus varicella zoster (VZV) and Human citomegalovirus (HCMV), both belonging to the herpesvirus family, causing serious diseases in immunosuppressed patients. (Re)emerging viral diseases are serious threats to humanity. In a globalized world a viral infection that appears in a remote site is rapidly spread to other parts of the world and as a consequence may originate virulent pandemias of dimensions difficult to predict. Most of the (re)emerging viral diseases are caused by RNA viruses (with a higher rate of mutation and thus of adaptation than DNA viruses). Currently there are a limited number of antivirals to treat a limited number of diseases caused by viruses, therefore there is an urgent need for the discovery of new wide-spectrum antivirals that may act to a common target of different viruses. The viruses use the celular machinery for the replication, for the synthesis of their nucleic acids and for the transcription of the genomic information. Viral polymerases play a key role in the replication of the viral genoma. In particular, catallyze the synthesis of nucleic acids...

Microtubules, made of ¿ß¿tubulin heterodimers, are the key components of the cytoskeleton and play a crucial role in many cellular processes, such as cell motility, morphogenesis and mitosis.[1] Interference with microtubule dynamics induces cell cycle arrest during mitosis and triggers cell death. Compounds that interact with tubulin, especially those binding at the colchicine domain, have been deeply investigated as anticancer drugs due to their dual mechanism of action as antimitotics and as vascular disrupting agents.[2,3] Our research group has recently described a new family of colchicine¿domain binders, based on a cyclohexanedione skeleton, with potent antiproliferative activity against tumor and endothelial cells.[4] Moreover, to gain insight into the binding mode of these cyclohexanediones, we have determined the crystal structure of ¿ß¿tubulin in complex with our hit compound (TUB075). Based on this detailed information and by applying the affinity maps program cGRILL, a structurebased synthesis of new cyclohexanedione derivatives has been accomplished with the objective of improving their affinity for tubulin and their antitumor activity. Following this approach, we have obtained new compounds with potent antiproliferative activity against tumor and endothelial cells (IC50=8¿31 nM) and with the highest Kb value reported for compounds binding at the colchicine site in tubulin. Additional studies have shown that they arrest cell cycle at G2/M and disrupt a network of endothelial cells. Moreover they keep antiproliferative activity against cell lines overexpressing P¿gp, further supporting the potential of these compounds.

Synthetic nucleosides, designed to mimic naturally occurring nucleosides, are important antiviral and anticancer chemotherapeutic agents. However, nucleosides are not active as such and need to be metabolized, step by step, to their corresponding active nucleoside triphosphates (NTPs). This is mediated by phosphorylating enzymes, mainly host cellular kinases with strong specificity for their substrates; in many cases, this specificity prevents efficient conversion into the NTPs. To circumvent this metabolic handicap, successful nucleo(s/t)ide prodrugs have been developed as a valuable concept in the design of effective drugs. The unique concept of the TriPPPro approach, developed by Chris Meier and colleagues, is a powerful tool for the intracellular delivery of active NTPs, bypassing all the phosphorylation steps required by nucleosides to yield the active NTP metabolites. This concept is illustrated herein with general examples.

HIV infection still has a serious health and socio-economical impact and is one of the primary causes of morbidity and mortality all over the world. HIV infection and the AIDS pandemic are still matters of great concern, especially in less developed countries where the access to highly active antiretroviral therapy (HAART) is limited. Patient compliance is another serious drawback. Nowadays, HAART is the treatment of choice although it is not the panacea. Despite the fact that it suppresses viral replication at undetectable viral loads and prevents progression of HIV infection into AIDS HAART has several pitfalls, namely, long-term side-effects, drug resistance development, emergence of drug-resistant viruses, low compliance and the intolerance of some patients to these drugs. Moreover, another serious health concern is the event of co-infection with more than one pathogen at the same time (e.g. HIV and HCV, HBV, herpes viruses, etc). Currently, the multi-target drug approach has become an exciting strategy to address complex diseases and overcome drug resistance development. Such multifunctional molecules combine in their structure pharmacophores that may simultaneously interfere with multiple targets and their use may eventually be more safe and efficacious than that involving a mixture of separate molecules because of avoidance or delay of drug resistance, lower incidence of unwanted drug-drug interactions and improved compliance. In this review we focus on multifunctional molecules with dual activity against different targets of the HIV life cycle or able to block replication, not only of HIV but also of other viruses that are often co-pathogens of HIV. The different approaches are documented by selected examples.

Cationic and non-peptide small molecules containing a total of six positive charges arranged on one side and a long aliphatic tail on the other have been synthesized and tested against Gram-positive and Gram-negative bacteria. The positive charges have been contributed by two aminophenol residues. These molecules have showed remarkable antimicrobial activity against Gram-positive bacteria including multidrug-resistant strains. Our structure–activity relationship studies demonstrated the importance of the length and flexibility of the hydrophobic tail for the antimicrobial activity. Importantly, these compounds are non-toxic to eukaryotic cells at the concentration affecting growth in bacteria, reflecting an acceptable margin of safety. The small size and easy synthetic accessibility of our molecules can be of interest for the further development of novel antimicrobials against Gram-positive bacterial pathogens, including multidrug-resistant strains.

We have recently described a new class of dendrimers with tryptophan (Trp) on the surface that show dual antiviral activities against HIV and EV71 enterovirus. The prototype compound of this family is a pentaerythritol derivative with 12 Trps on the periphery. Here we complete the structure-activity relationship studies of this family to identify key features that might be significant for the antiviral activity. With this aim, novel dendrimers containing different amino acids (aromatic and non-aromatic), tryptamine (a “decarboxylated” analogue of Trp) and N-methyl Trp on the periphery have been prepared. Dendrimer with N-Methyl Trp was the most active against HIV-1 and HIV-2 while dendrimer with tyrosine was endowed with the most potent antiviral activity against EV71. This tyrosine dendrimer proved to inhibit a large panel of EV71 clinical isolates (belonging to different clusters) in the low nanomolar/high picomolar range. In addition, a new synthetic procedure (convergent approach) has been developed for the synthesis of the prototype and some other dendrimers. This convergent approach proved more efficient (higher yields, easier purification) than the divergent approach previously reported., Ministerio de Economía, Comercio y Empresa (España), KU Leuven, Belgian Interuniversity Attraction Poles, China Scholarship Council, Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

Los virus son los agentes etiológicos responsables de muchas enfermedades en humanos que van desde leves (p. ej. resfriado común) a letales (p. ej. la viruela, el SIDA, etc). Asimismo, los virus juegan un papel importante en el desarrollo de ciertos tipos de cáncer. Actualmente, se conocen más de 219 especies de virus capaces de infectar seres humanos. Algunos de estos virus son responsables de importantes infecciones virales: como el virus de inmunodeficiencia humana (VIH-1) responsable del SIDA (37-40 millones de personas infectadas en el mundo); el virus influenza que causa cerca de 250.000-500.000 muertes anuales; el virus de la hepatitis B y el virus de la hepatitis C (VHB y VHC) con 240 y 140 millones de personas infectadas, respectivamente; el virus herpes simplex (VHS) causante de neumonía, encefalitis, meningitis, lesiones genitales, etc; el virus varicela zóster (VVZ) y el citomegalovirus humano (CMVH), ambos pertenecientes a la familia de los virus herpes, responsables de graves enfermedades en pacientes inmunodeprimidos. Las enfermedades virales (re)emergentes suponen una amenaza para la humanidad. En un mundo globalizado como en el que vivimos, una infección viral que aparece en un lugar distinto y remoto a su entorno natural, puede ser fácilmente diseminada a otras partes del mundo y como consecuencia se pueden originar brotes virulentos de dimensiones difíciles de predecir. La mayoría de las enfermedades virales (re)emergentes están causadas por virus ARN que en general muestran una alta capacidad de mutación comparada con la de los virus ADN...

A series of 9-mer and 13-mer amide-bridged cyclic peptides derived from the linear prototype Ac-PKIIQSVGIS-Nle-K-Nle-NH (Toro et al. ChemBioChem 2013) has been designed and synthesized by introduction of the lactam between amino acid side chains that are separated by one helical turn (i, i+4). All of these compounds were tested in vitro as both dimerization and enzyme inhibitors of Leishmania infantum trypanothione reductase (Li-TryR). Three of the 13-mer cyclic peptide derivatives (3, 4 and 6) inhibited the oxidoreductase activity of Li-TryR in the low micromolar range and they also disrupted enzyme dimerization. Cyclic analogues 3 and 4 were more resistant to proteases than was the linear prototype. Furthermore, the most potent TryR inhibitors in the linear and cyclic series displayed potent in vitro activity against Leishmania infantum upon conjugation with cationic cell-penetrating peptides. To date, these conjugated peptides can be considered the first example of TryR dimerization inhibitors that are active in cell culture.

We have recently described a new class of dendrimers with tryptophan (Trp) on the surface that show dual antiviral activities against HIV and EV71 enterovirus. The prototype compound of this family is a pentaerythritol derivative with 12 Trps on the periphery. Here we complete the structure-activity relationship studies of this family to identify key features that might be significant for the antiviral activity. With this aim, novel dendrimers containing different amino acids (aromatic and non-aromatic), tryptamine (a “decarboxylated” analogue of Trp) and N-methyl Trp on the periphery have been prepared. Dendrimer with N-Methyl Trp was the most active against HIV-1 and HIV-2 while dendrimer with tyrosine was endowed with the most potent antiviral activity against EV71. This tyrosine dendrimer proved to inhibit a large panel of EV71 clinical isolates (belonging to different clusters) in the low nanomolar/high picomolar range. In addition, a new synthetic procedure (convergent approach) has been developed for the synthesis of the prototype and some other dendrimers. This convergent approach proved more efficient (higher yields, easier purification) than the divergent approach previously reported.

We investigated the microtubule-destabilizing, vascular-targeting, anti-tumor and anti-metastatic activities of a new series of chalcones, whose prototype compound is (E)-3-(3’’-amino-4’’-methoxyphenyl)-1-(5’-methoxy-3’,4’-methylendioxyphenyl)- 2-methylprop-2-en-1-one (TUB091). X-ray crystallography showed that these chalcones bind to the colchicine site of tubulin and therefore prevent the curved-tostraight structural transition of tubulin, which is required for microtubule formation. Accordingly, TUB091 inhibited cancer and endothelial cell growth, induced G2/M phase arrest and apoptosis at 1-10 nM. In addition, TUB091 displayed vascular disrupting effects in vitro and in the chicken chorioallantoic membrane (CAM) assay at low nanomolar concentrations. A water-soluble L-Lys-L-Pro derivative of TUB091 (i.e. TUB099) showed potent antitumor activity in melanoma and breast cancer xenograft models by causing rapid intratumoral vascular shutdown and massive tumor necrosis. TUB099 also displayed anti-metastatic activity similar to that of combretastatin A4-phosphate. Our data indicate that this novel class of chalcones represents interesting lead molecules for the design of vascular disrupting agents (VDAs). Moreover, we provide evidence that our prodrug approach may be valuable for the development of anti-cancer drugs.

Tryptophan dendrimers that inhibit HIV replication by binding to the HIV envelope glycoproteins gp120 and gp41 have unexpectedly also proven to be potent, specific, and selective inhibitors of the replication of the unrelated enterovirus A71. Dendrimer 12, a consensus compound that was synthesized on the basis of the structure-activity relationship analysis of this series, is 3-fold more potent against the BrCr lab strain and, surprisingly, inhibits a large panel of clinical isolates in the low-nanomolar/high-picomolar range.

El proceso de entrada fusión del virus de la Inmunodeficiencia Humana VIH en la célula huésped constituye una diana terapéutica de gran interés. Este proceso está mediado por las glicoproteínas, gp120 y gp41, de la envoltura viral que interactúan con los receptores celulares CD4 situados en la superficie de los linfocitos T. La glicoproteína gp120 es el primer punto de contacto con la célula huésped. Gp120 está densamente glicosilada, aproximadamente el 50 por ciento de su peso molecular se debe a los carbohidratos que presenta. Dichos carbohidratos actúan como un escudo protector que esconde al virus del sistema inmune del huésped. Algunas lectinas, proteínas que se unen a carbohidratos, muestran una potente actividad anti VIH. Las lectinas previenen la entrada del VIH en la célula debido a la interacción que establecen con los glicanos de la glicoproteína gp120 viral. Además, ante la presión de dichas lectinas se seleccionan cepas de virus resistentes en las que se eliminan o modifican los glicanos de la gp120. Debido a su naturaleza proteica y a su elevado peso molecular, las lectinas no presentan propiedades farmacocinéticas adecuadas. Sería interesante disponer de compuestos de naturaleza no peptídica con un mecanismo similar al de las lectinas. Dichos compuestos podrían actuar impidiendo la interacción de la glicoproteína gp120 con los carbohidratos de la cubierta y, seleccionando cepas de virus resistentes en las que parte del escudo protector desaparecería dejando los epítopos inmunogénicos expuestos, facilitando la respuesta inmune del huésped. Para el diseño, síntesis y evaluación bilológica de los compuestos recogidos en esta tesis se ha tenido en cuenta que: i la interacción que establecen las lectinas con los carbohidratos son débiles y de baja afinidad, ii las lectinas para aumentar la afinidad y especificidad en el reconocimiento establecen múltiples interacciones con el oligosacárido con el que interaccionan; iii las interacciones proteína carbohidra

In the search of novel enzyme-based prodrug approaches to improve pharmacological properties of therapeutic drugs such as solubility and bioavailability, dipeptidyl-peptidase IV (DPP IV, also termed as CD26) enzyme activity provides a previously unexplored successful prodrug strategy. This review covers key aspects of the enzyme useful for the design of CD26-directed prodrugs. The proof-of-concept of this prodrug technology is provided for amine-containing agents by directly linking appropriate di- (or oligo)peptide moieties to a free amino group of a non-peptidic drug through an amide bond which is specifically hydrolized by DPP IV/CD26. Special emphasis is also made in discussing the design and synthesis of more elaborated tripartite prodrug systems, for further extension of the strategy to hydroxy-containing drugs. The application of this technology to improve water solubility and oral bioavailability of prominent examples of antiviral nucleosides is highlighted.

we describe a class of unconventional nucleosides (methyloxynucleosides) that combine unconventional nucleobases such as substituted aminopyrimidines, aminopurines, or aminotriazines with unusual sugars in their structures. The allitollyl or altritollyl derivatives were pursued as ribonucleoside mimics, whereas the tetrahydrofuran analogues were pursued as their dideoxynucleoside analogues. The compounds showed poor, if any, activity against a broad range of RNA and DNA viruses, including human immunodeficiency virus (HIV). This inactivity may be due to lack of an efficient metabolic conversion into their corresponding 5′-triphosphates and poor affinity for their target enzymes (DNA/RNA polymerases). Several compounds showed cytostatic activity against proliferating human CD4+ T-lymphocyte CEM cells and against several other tumor cell lines, including murine leukemia L1210 and human prostate PC3, kidney CAKI-1, and cervical carcinoma HeLa cells. A few compounds were inhibitory to Moloney murine sarcoma virus (MSV) in C3H/3T3 cell cultures, with the 2,6-diaminotri-O-benzyl-D-allitolyl- and -D-altritolyl pyrimidine analogues being the most potent among them. This series of unconventional nucleosides may represent a novel family of potential antiproliferative agents.

The glycoprotein gp120 of the HIV-1 viral envelope has a high content in mannose residues, particularly ¿-1,2-mannose oligomers. Compounds that interact with these high-mannose type glycans may disturb the interaction between gp120 and its (co)receptors and are considered potential anti-HIV agents. Previously, we demonstrated that a tripodal receptor (1), with a central scaffold of 1,3,5-triethylbenzene substituted with three 2,3,4-trihydroxybenzoyl groups, selectively recognizes ¿-1,2-mannose polysaccharides. Here we present additional studies to determine the anti-HIV-1 activity and the mechanism of antiviral activity of this compound. Our studies indicate that 1 shows anti-HIV-1 activity in the low micromolar range and has pronounced gp120 binding and HIV-1 integrase inhibitory capacity. However, gp120 binding rather than integrase inhibition seems to be the primary mechanism of antiviral activity of 1.