Kinetic Control of Complexity in Multiple Dynamic Libraries.

Multiple dynamic libraries of compounds are generated when more than one reversible reaction comes into play. Commonly, two or more orthogonal reversible reactions are used, leading to non-communicating dynamic libraries which share no building blocks. Only a few examples of communicating libraries have been reported, and in all those cases, building blocks are reversibly exchanged from one library to the other, constituting an antiparallel dynamic covalent system. Herein we report that communication between two different dynamic libraries through an irreversible process is also possible. Indeed, alkyl amines cancel the dynamic regime on the nucleophilic substitution of tetrazines, generating kinetically inert compounds. Interestingly, such amine can be part of another dynamic library, an imine-amine exchange. Thus, both libraries are interconnected with each other by an irreversible process which leads to kinetically inert structures that contain parts from both libraries, causing a collapse of the complexity. Additionally, a latent irreversible intercommunication could be developed. In such a way, a stable molecular system with specific host-guest and fluorescence properties, could be irreversibly transformed when the right stimulus was applied, triggering the cancellation of the original supramolecular and luminescent properties and the emergence of new ones.

Acrylonitrile derivatives: In vitro activity and mechanism of cell death induction against Trypanosoma cruzi and Leishmania amazonensis.

Leishmaniasis and Chagas disease are parasitic infections that affect millions of people worldwide, producing thousands of deaths per year. The current treatments against these pathologies are not totally effective and produce some side effects in the patients. Acrylonitrile derivatives are a group of compounds that have shown activity against these two diseases. In this work, four novels synthetic acrylonitriles were evaluated against the intracellular form and extracellular forms of L. amazonensis and T. cruzi. The compounds 2 and 3 demonstrate to have good selectivity indexes against both parasites, specifically the compound 3 against the amastigote form (SI = 6 against L. amazonensis and SI = 7.4 against T. cruzi). In addition, the parasites treated with these two compounds demonstrate to produce a programmed cell death, since they were positive for the events studied related to this type of death, including chromatin condensation, accumulation of reactive oxygen species and alteration of the mitochondrial membrane potential. In conclusion, this work confirms that acrylonitriles is a source of possible new compounds against kinetoplastids, however, more studies are needed to corroborate this activity.

Synthesis, biological and computational evaluation of novel cyanomethyl vinyl ether derivatives.

This work explores the biological evaluation of novel cyanomethyl vinyl ether derivatives as antiproliferative agents. Tubulin, crucial to microtubule structure and function, is a target for cancer therapies. In vitro cytotoxicity assessments revealed significant activity in SKOV3 ovarian carcinoma cells and A549 lung carcinoma cells. Structure-Activity Relationship (SAR) analysis indicated that the E isomer and specific substitutions influenced the biological activity. Computational assays predicted favorable ADME properties, highlighting potential as anticancerous agents. Molecular docking studies demonstrated that compound 12E, with the E geometry of the double bond and fused polyaromatic rings such as phenanthrene, has robust interaction with tubulin, suggesting enhanced stability due to diverse amino acid interactions. Comparative spatial distributions with colchicine further indicated potential mechanistic similarities.

Amoebicidal effect of synthetic indoles against Acanthamoeba spp.: a study of cell death.

Organic and synthetic chemistry plays a crucial role in drug discovery fields. Moreover, chemical modifications of available molecules to enhance their efficacy, selectivity and safety have been considered as an attractive approach for the development of new bioactive agents. Indoles, a versatile group of natural heterocyclic compounds, have been widely used in pharmaceutical industry due to their broad spectrum of activities including antimicrobial, antitumoral and anti-inflammatory among others. Herein, we report the amoebicidal activity of different indole analogs on Acanthamoeba castellanii Neff. Among the 40 tested derivatives, eight molecules were able to inhibit this protistan parasite. The structure-activity relationship (SAR) analysis of their anti-Acanthamoeba activity would suggest that a carboxylation of C-3 position and the incorporation of halogen as chlorine/fluorine would enhance their biological profile, presumably by increasing their lipophilicity and therefore their ability to cross the cell membrane. Fluorescence image base system was used to investigate the effect of indole 6o c-6 on the cytoskeleton network and various programmed cell death features. We were able to highlight that the methyl 6-chloro-1H-indole-3-carboxylate could induce program cell death by the mitochondrial dysfunction.

In vitro activity and mechanism of cell death induction of cyanomethyl vinyl ethers derivatives against Trypanosoma cruzi.

Chagas disease causes a problematic pathology that can lead to megacolon and heart disease, and can even cause the death of the patient. Current therapies for this disease are the same as they were 50 years ago, are not fully effective and have strong side effects. The lack of a safe and effective therapy makes it necessary to search for new, less toxic and totally effective compounds against this parasite. In this work, the antichagasic activity of 46 novel cyanomethyl vinyl ether derivatives was studied. In addition, to elucidate the type of cell death that these compounds produce in parasites, several events related to programmed cell death were studied. The results highlight four more selective compounds, E63, E64, E74 and E83, which also appear to trigger programmed cell death, and are therefore postulated as good candidates to use in future therapeutics for Chagas disease.

Cyanomethyl Vinyl Ethers Against Naegleria fowleri.

Naegleria fowleri is a pathogenic amoeba that causes a fulminant and rapidly progressive disease affecting the central nervous system called primary amoebic meningoencephalitis (PAM). Moreover, the disease is fatal in more than 97% of the reported cases, mostly affecting children and young people after practicing aquatic activities in nontreated fresh and warm water bodies contaminated with these amoebae. Currently, the treatment of primary amoebic meningoencephalitis is based on a combination of different antibiotics and antifungals, which are not entirely effective and lead to numerous side effects. In the recent years, research against PAM is focused on the search of novel, less toxic, and fully effective antiamoebic agents. Previous studies have reported the activity of cyano-substituted molecules in different protozoa. Therefore, the activity of 46 novel synthetic cyanomethyl vinyl ethers (QOET-51 to QOET-96) against two type strains of N. fowleri (ATCC 30808 and ATCC 30215) was determined. The data showed that QOET-51, QOET-59, QOET-64, QOET-67, QOET-72, QOET-77, and QOET-79 were the most active molecules. In fact, the selectivity index (CC50/IC50) was sixfold higher when compared to the activities of the drugs of reference. In addition, the mechanism of action of these compounds was studied, with the aim to demonstrate the induction of a programmed cell death process in N. fowleri.

Dynamic Hydroxyl-Yne Reaction with Phenols.

Dynamic Covalent Chemistry (DCvC) has gained increasing importance in supramolecular chemistry and materials science. Herein we prove the dynamic nature of the exchange between phenols and vinyl ethers. Exchange is fast at room temperature and under mild conditions. The equilibrium constants and the electronic effect of the phenol substituents were calculated. This novel incorporation to the DCvC toolbox could be quite useful, and as a proof it was used for the synthesis of a responsive molecular cage.

Isobenzofuran-1(3H)-one derivatives: Amoebicidal activity and program cell death in Acanthamoeba castellanii Neff.

The genus Acanthamoeba is characterized by being a group of ubiquitous and free-living amoebae that inhabit a variety of environments. Generally, human infections by this parasite are associated with Acanthamoeba keratitis, especially in contact lens wearers, and with chronic but fatal granulomatous amoebic meningoencephalitis. Current treatments used for eradication of amoeba from infection sites represent a challenge for pharmacotherapy, due to the lack of effective treatment and the amoebae highly resistant to anti-amoebic drugs. In this study, we describe the results of the assessment of the IC50 of 10 isobenzofuran-1(3H)-one derivatives (QOET) against four Acanthamoeba strains. The compounds QOET-3 and QOET-9 were the selected derivatives with the lowest IC50 in A. castellanii Neff trophozoites (73.71 ± 0.25 and 69.99 ± 15.32 µM, respectively). Interestingly, analysis of the compound effects on the cell apoptosis-like features showed that both active molecules triggered programmed cell death (PCD) in A. castellanii Neff. The results obtained in this study highlights that isobenzofuranone derivatives could represent an interesting source for developing novel antiamoebic drugs.

In vitro activity and cell death mechanism induced by acrylonitrile derivatives against Leishmania amazonensis.

Leishmaniasis produces approximately-one million of new cases annually, making it one of the most important tropical diseases. As current treatments are not fully effective and are toxic, it is necessary to develop new therapies that are more effective and less toxic, and cause a controlled cell death, with which we can avoid the immunological problems caused by necrosis. In this work 32 acrylonitriles were studied in vitro against Leishmania amazonensis. Three compounds Q20 (12.41), Q29 (11.2) and Q31 (11.56) had better selectivity than the reference compound, miltefosine (11.14) against promastigotes of these parasites, for this reason they were selected to determine their mechanism of action to know the cell death type of they produce. The results of the mechanisms of action show that these three acrylonitriles tested produce chromatin condensation, decreased mitochondrial membrane potential, altered plasma permeability and production of reactive oxygen species. All these characteristic events seem to indicate programmed cell death. Therefore, this study demonstrates the activity of acrylonitriles derivatives as possible leishmanicidal agents.

The therapeutic potential of novel isobenzofuranones against Naegleria fowleri.

The Free-Living Amoeba species, Naegleria fowleri is the causative agent of a lethal encephalitis known as Primary Amoebic Encephalitis (PAM). Moreover, most of the reported cases are often related to swimming and/or diving in aquatic environments. In addition, the current therapeutic options against PAM are not fully effective and hence, there is an urgent need to develop novel therapeutic agents against this disease. Previously isobenzofuranones compounds have been reported to present antiprotozoal and antifungal activity among others. However, to the best of our knowledge, these molecules have not been previously tested against N. fowleri. Therefore, the aim of this study was to evaluate the activity of 14 novel isobenzofuranones against this pathogenic amoeba. The most active and less toxic molecules, were assayed in order to check induction of Programmed Cell Death (PCD) in the treated amoebae. The obtained results showed that these molecules were able to eliminate N. fowleri trophozoites and also induced PCD. Therefore, the tested isobenzofuranones could be potential therapeutic candidates for the treatment of PAM.

In Vitro Antiviral Activity of Tyrosinase from Mushroom Agaricus bisporus against Hepatitis C Virus.

Tyrosinases from a commercial Agaricus bisporus protein extract and directly isolated from white mushrooms were purified in order to obtaining the well-known tyrosinase from A. bisporus (TyrAB) of 45 kDa and a newly discovered 50 kDa tyrosinase isoform (Tyr50 kDa), and tested showing high antiviral activity against the hepatitis C virus for the first time. Cell toxicity and antiviral activity of tyrosinases were determined in cultured Huh 5-2 liver tumor cells transfected with a replicon system (a plasmid that includes all non-structural hepatitis C virus proteins and replicates autonomously). TyrAB was able to inhibit the replication of the hepatitis C virus without inducing toxicity in liver cells. In addition, the post-translational isoform Tyr50 kDa showed higher antiviral capacity than the former (up to 10 times greater), also exhibiting 10 times higher activity than the commercial drug Ribavirin®. This antiviral activity was directly proportional to the enzymatic activity of tyrosinases, as no antiviral capacity was observed in the inactive form of the enzymes. The tyrosinases approach could represent a new antiviral inhibition mechanism, through a plausible catalytic mechanism of selective hydroxylation of the key role of tyrosine residues in viral proteases.

Acrylonitrile Derivatives against Trypanosoma cruzi: In Vitro Activity and Programmed Cell Death Study.

The neglected infection known as Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, results in more than 7000 deaths per year, with an increasing number of cases in non-endemic areas such as Europe or the United States. Moreover, with the current available therapy, only two compounds which are active against the acute phase of the disease are readily available. In addition, these therapeutic agents display multiple undesired side effects such as high toxicity, they are expensive, the treatment is lengthy and the resistant strain has emerged. Therefore, there is a need to find new compounds against Chagas disease which should be active against the parasite but also cause low toxicity to the patients. In the present work, the activity of novel acrylonitriles against Trypanosoma cruzi was evaluated as well as the analysis of the physiological events induced in the treated parasites related to the cell death process. Hence, the characteristic features of an apoptosis-like process such as chromatin condensation and mitochondrial membrane potential, among others, were studied. From the 32 compounds tested against the epimastigote stage of T. cruzi, 11 were selected based on their selectivity index to determine if these compounds were able to induce programmed cell death (PCD) in the treated parasites. Furthermore, acrylonitriles Q5, Q7, Q19, Q27 and Q29 were shown to trigger physiological events related in the PCD. Therefore, this study highlights the therapeutic potential of acrylonitriles as novel trypanocidal agents.

Cyanovinylation of Aldehydes: Organocatalytic Multicomponent Synthesis of Conjugated Cyanomethyl Vinyl Ethers.

A novel organocatalytic multicomponent cyanovinylation of aldehydes was designed for the synthesis of conjugated cyanomethyl vinyl ethers. The reaction was implemented for the synthesis of a 3-substituted 3-(cyanomethoxy)acrylates, using aldehydes as substrates, acetone cyanohydrin as the cyanide anion source, and methyl propiolate as the source of the vinyl component. The multicomponent reaction is catalyzed by N-methyl morpholine (2.5 mol%) to deliver the 3-(cyanomethoxy)acrylates in excellent yields and with preponderance of the E-isomer. The multicomponent reaction manifold is highly tolerant to the structure and composition of the aldehyde (aliphatic, aromatic, heteroaromatics), and it is instrumentally simple (one batch, open atmospheres), economic (2.5 mol% catalyst, stoichiometric reagents), environmentally friendly (no toxic waste), and sustainable (easy scalability).

Short and Modular Synthesis of Substituted 2-Aminopyrroles.

We herein describe a simple and metal-free domino methodology to synthesize 2-aminopyrroles from alkynyl vinyl hydrazides. The domino reaction involves a novel propargylic 3,4-diaza-Cope rearrangement and a tandem isomerization/5-exo-dig N-cyclization reaction. By using this approach, a number of 2-aminopyrroles with diverse substituents have been prepared.

A General and Scalable Synthesis of Polysubstituted Indoles.

A consecutive 2-step synthesis of N-unprotected polysubstituted indoles bearing an electron-withdrawing group at the C-3 position from readily available nitroarenes is reported. The protocol is based on the [3,3]-sigmatropic rearrangement of N-oxyenamines generated by the DABCO-catalyzed reaction of N-arylhydroxylamines and conjugated terminal alkynes, and delivers indoles endowed with a wide array of substitution patterns and topologies.

The enzyme-induced formation of iron hybrid nanostructures with different morphologies.

A new synthesis method for tailor-made iron-hybrid nanoparticles has been carried out for the first time using enzymes, which directly induce the formation of inorganic iron species. The role of the protein was critical for the formation and morphology of the iron nanostructures and, depending on the enzyme, by simple mixing with ammonium iron(ii) sulfate at room temperature and under air, it was possible to obtain, for the first time, well stabilized superparamagnetic iron and iron oxide nanorods, nanosheets and nanorings or even completely amorphous non-magnetic iron structures in the protein network. These iron nanostructure-enzyme hybrids showed excellent results as heterogeneous catalysts in organic chemistry (chemoselective hydrogenation and C-C bonding formation) and environmental remediation processes.

Short and modular synthesis of tetraarylsalicylaldehydes.

In this study, we describe a novel strategy that allows the obtention of all 15 possible substitution geometries of perarylated salicylaldehydes with total control of the regioselectivity. This strategy entitles the formation of the salicylaldehyde core via a Claisen rearrangement of propargyl vinyl ethers, followed by bromination and Pd-catalyzed aryl-aryl cross-coupling reactions.

Catalytic Hydrocyanation of Activated Terminal Alkynes.

A universal, practical and scalable organocatalytic hydrocyanation manifold to provide ß-substituted acrylonitriles bearing an electron-withdrawing functionality has been implemented. The catalytic manifold operates under the reactivity generation principle "a good nucleophile generates a strong base", and it uses 1,4-diazabicyclo[2.2.2]octane (DABCO) as the catalyst, activated terminal alkynes as substrates and acetone cyanohydrin as the cyanide source. The acrylonitriles obtained as E,Z mixtures are straightforwardly resolved by simple flash chromatography delivering the pure isomers in preparative amounts.

Recent Advances in the Synthesis of 2H-Pyrans.

In this review, we discuss the nature of the different physicochemical factors affecting the valence isomerism between 2H-pyrans (2HPs) and 1-oxatrienes, and we describe the most versatile synthetic methods reported in recent literature to access to 2HPs, with the only exception of 2HPs fused to aromatic rings (i.e., 2H-chromenes), which are not included in this review.

A Focused Library of NO-Donor Compounds with Potent Antiproliferative Activity Based on Green Multicomponent Reactions.

Cancer is the second leading cause of death worldwide. Herein, a strategy to quickly and efficiently identify novel lead compounds to develop anticancer agents, using green multicomponent reactions followed by antiproliferative activity and structure-activity relationship studies, is described. A second-generation focused library of nitric oxide-releasing compounds was prepared by microwave-assisted Passerini and Ugi reactions. Nearly all compounds displayed potent antiproliferative activities against a panel of human solid tumor cell lines, with 1-phenyl-1-[(tert-butylamino)carbonyl]methyl 3-[(3-phenylsulfonyl-[1,2,5]oxadiazol-4-yl N2 -oxide)oxy]benzoate (4 k) and N-[1-(tert-butylaminocarbonyl)-1-phenylmethyl]-N-(4-methylphenyl)-3-(3-phenylsulfonyl-[1,2,5]oxadiazol-4-yl N2 -oxide)oxyphenyl carboxamide (6 d) exhibiting the strongest activity on SW1573 lung cell line (GI50 =110 and 21 nm) with selectivity indices of 70 and 470, respectively. Preliminary mechanistic studies suggest a relationship between NO release and antiproliferative activity. Our strategy allowed the rapid identification of at least two molecules as future candidates for the development of potent antitumor drugs.