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Coumarin–triazole hybrids went through antitumor activity screening, finding anti-breast cancer cell line MCF7 activity, besides antioxidant activity, mitochondrial membrane disruption and no DNA damage.

Abstract: The discovery of a new drug requires over a billion dollars and around 12 years of research efforts, and toxicity is the leading reason for the failure to approve candidate drugs. Many alternative methods have been validated to detect toxicity as early as possible to diminish the waste of resources and efforts in medicinal chemistry research, and in vivo alternative methods are especially valuable for the amount of information they can provide at little cost and in a short time. In this work, we present a review of the literature published between the years 2000 and 2021 on in vivo alternative methods of toxicity screening employed in medicinal chemistry, which we believe will be useful because, in addition to shortening the research time, these studies provide much additional information aside from the toxicity of drug candidate compounds. These in vivo models include zebrafish, Artemia salina, Galleria mellonella, Drosophila melanogaster, planarians, and Caenorhabditis elegans. The most published ones in the last decade were zebrafish, D. melanogaster, and C. elegans due to their reliability, ease, and cost-effectiveness in implementation and flexibility. Special attention is given to C. elegans because of its rising popularity, a wide range of uses, including toxicity screening, and active effects measurement, from antioxidant effects to anthelmintic and antimicrobial activities, and its fast and reliable results. Over time, C. elegans also became a viable high-throughput (HTS) automated drug screening option. Additionally, this manuscript lists briefly the other screening methods used for the initial toxicological analyses and the role of alternative in vivo methods in these scenarios, classifying them as in silico, in vitro and alternative in vivo models that have been receiving a growing increase in interest in recent years.

Dihydropyrimidinones (DHPMs) are heterocycles obtained by the multicomponent Biginelli reaction. Recently, new synthetic protocols have allowed us to explore functionalisation at less explored positions of DHPMs, such as the N1 position. In this context, a full literature survey of N1- substituted DHPMs was performed. We analysed 27 papers and identified 379 compounds with substituents at the N1 position, most of them with alkyl groups, and a total of 28% compounds with aromatic substituents attached at the N1 position. N1-substituted DHPMs were explored mainly due to their effects on cancer cell proliferation via numerous targets, such as kinesin Eg5, heat shock protein 70, heat shock protein 90, and the epidermal growth factor receptor. Similarity analyses were performed using the data of 379 DHPMs from different cheminformatic approaches, i.e., chemical property correlations, principal component analysis, similarity networks, and compound clustering.

The complexity of Chagas disease is still a challenge in endemic regions and an emergent public health problem in non-endemic countries. The causative agent of this neglected tropical disease, Trypanosoma cruzi, is mainly transmitted by triatomine vectors and possesses multiple epidemiologically important strains. Current chemotherapeutics are outdated and their limited efficacy is one of the major reasons for treatment discontinuation. In this context, the development of novel, safe and economically accessible antichagasic drugs is required. Various classes of heterocycles and natural compounds have been described as potential antichagasic scaffolds, and coumarins are no exception. These versatile compounds have a wide spectrum of biological activities, and numerous natural and synthetic coumarins have been reported with antichagasic potential. This review aims to discuss the available literature between 2001 and 2020 regarding natural and synthetic coumarins with anti- Trypanosoma cruzi activity. Moreover, some of the studies herein comprised are dedicated to the potential of coumarins to inhibit promising targets in Trypanosoma cruzi.

Leishmaniasis still stands as one of the most prevalent neglected tropical diseases in the least developed and emerging countries. The recommended therapeutic arsenal to treat leishmaniasis is characterized by several shortcomings, and resistance has already been reported. Hence, this dramatic background highlights the pressing need to develop novel, affordable, and safe antileishmanial drugs. Multiple classes of natural compounds have been reported to possess antileishmanial activity. Among these classes, iridoids stand out as a special type of monoterpenoids with diverse biological properties—including their antileishmanial potential. This review aims to discuss the available literature between 1991 and 2020 related to the antileishmanial activity of the iridoid class. Throughout the past decades, various investigations attributed antileishmanial action to assorted iridoid types, including inhibitory potential towards validated drug targets and immunomodulatory activity. The latter deserves special attention due to the ability of some iridoids to improve the host’s immune response against parasites. It opens the possibility of iridoids become adjuncts in leishmaniasis treatments by improving the efficacy of currently employed drugs. Furthermore, the present study intends to provide a convenient visual representation of which iridoids and Leishmania spp. species have been most investigated as a guide for further researches.

The practical two-step synthesis of 1-phenylthiourea is reported here as an undergraduate experiment for the organic synthesis laboratory. The reactions involved in 1-phenylthiourea preparation are very useful didactic examples to illustrate concepts relating to carbonyl substitution and addition, the effect of pH on solubility of organic compounds, and many laboratory techniques, such as isolation, purification, and product analysis. The products were purified through precipitation, which involves changing the pH value, followed by recrystallization. The products were identified by melting point and infrared and NMR spectroscopy.

The purinergic signaling has drawn attention from academia and more recently from pharmaceutical industries as a potential therapeutic route for cancer treatment, since ATP may act as chemotactic agent and possess in vitro antineoplastic activity. On the other way, adenosine, produced in extracellular medium by ecto-5'-NT, acts as immunosuppressor and is related to neoangiogenesis, vasculogenesis and evasion to the immune system. Consequently, inhibitors of ecto-5'-NT may prevent tumor progression, reducing adenosine concentrations, preventing escape from the host's immune system and slowing cancer's growth. This review aims to highlight important biochemical and structural features of ecto-5'NT, highlight its expression profile in normal and cancer cell lines detailing compounds which may act as expression regulators and to review the several classes of ecto-5'NT inhibitors developed in the past 12 years, in order to build a general structure-activity relationship model to guide further compound design.

The authors wish to thank the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001 for the fellowships and Conselho Nacional de Pesquisa Cientifica (CNPq, edital Universal) for the financial support grant n. 403075 2016-5. A series of novel thiourea and amide liquid crystals containing 5-membered isoxazoline and isoxazole rings were synthetized and the liquid crystal properties studied. Thioureas were obtained using a condensation reaction of benzoyl chlorides, arylamines and ammonium thiocyanate. The amides, on the other hand, were the byproduct of a quantitative reaction which used potassium cyanate as the starting material. Thiourea and amide derivatives were predominantly SmA mesophase inductors. A nematic mesophase was observed only for thioureas and amides containing an isoxazole ring. Additionaly, the liquid crystal behavior was also dependent on the relative position of nitrogen and oxygen atoms on the 5-membered heterocycle. publishersversion published

Background: Since the Monastrol discovery in 1999 as the first inhibitor of Eg5, functionalized dihydropyrimidinones/thiones (DHPMs) have emerged as prototypes for drug design in different targets. The present work aimed to evaluate the antifungal activity of a chemical library of DHPMs. Methods: The compounds were obtained employing Biginelli reaction. Their antifungal activities were assessed against C. neoformans and C. albicans. Results: The compounds 1-i and 1-k inhibited moderately the fungal growth of C. neoformans, with compound 2-k presenting MIC80 values of 62.5-125 µg·mL-1. Considering activity against C. albicans, the compounds 1-i and 1-n present an MIC50 value of 125-250 µg·mL-1. Conclusion: The changes performed in DHPM scaffold appear to be valuable for generating compounds with potential antifungal effect. Fil: De Azambuja, Gabriel Oliveira. Universidade Federal do Rio Grande do Sul; Brasil Fil: Svetaz, Laura Andrea. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina Fil: Goncalves, Itamar Luis. Universidade Federal do Rio Grande do Sul; Brasil Fil: Corbelini, Patricia Frasson. Universidade Federal do Rio Grande do Sul; Brasil Fil: von Poser, Gilsane Lino. Universidade Federal do Rio Grande do Sul; Brasil Fil: Kawano, Daniel Fabio. Universidade Estadual Do Campinas. Instituto de Química.; Brasil Fil: Zacchino, Susana Alicia Stella. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; Argentina Fil: Eifler Lima, Vera Lucia. Universidade Federal do Rio Grande do Sul; Brasil

Background Chagas disease (CD) is a tropical parasitic disease. Although the number of people infected is very high, the only drugs available to treat CD, nifurtimox (Nfx) and benznidazole, are highly toxic, particularly in the chronic stage of the disease. Coumarins are a large class of compounds that display a wide range of interesting biological properties, such as antiparasitic. Hence, the aim of this work is to find a good antitrypanosomal drug with less toxicity. The use of simple organism models has become increasingly attractive for planning and simplifying efficient drug discovery. Within these models, Caenorhabditis elegans has emerged as a convenient and versatile tool with significant advantages for the toxicological potential identification for new compounds. Methods Trypanocidal activity: Forty-two 4-methylamino-coumarins were assayed against the epimastigote form of Trypanosoma cruzi (Tulahuen 2 strain) by inhibitory concentration 50% (IC50). Toxicity assays: Lethal dose 50% (LD50) and Body Area were determined by Caenorhabditis elegans N2 strain (wild type) after acute exposure. Structure-activity relationship: A classificatory model was built using 3D descriptors. Results Two of these coumarins demonstrated near equipotency to Nifurtimox (IC50 = 5.0 ± 1 μM), with values of: 11 h (LaSOM 266), (IC50 = 6.4 ± 1 μM) and 11 g (LaSOM 231), (IC50 = 8.2 ± 2.3 μM). In C. elegans it was possible to observe that Nfx showed greater toxicity in both the LD50 assay and the evaluation of the development of worms. It is possible to observe that the efficacy between Nfx and the synthesized compounds (11 h and 11 g) are similar. On the other hand, the toxicity of Nfx is approximately three times higher than that of the compounds. Results from the QSAR-3D study indicate that the volume and hydrophobicity of the substituents have a significant impact on the trypanocidal activities for derivatives that cause more than 50% of inhibition. These results show that the C. elegans model is efficient for screening potentially toxic compounds. Conclusion Two coumarins (11 h and 11 g) showed activity against T. cruzi epimastigote similar to Nifurtimox, however with lower toxicity in both LD50 and development of C. elegans assays. These two compounds may be a feasible starting point for the development of new trypanocidal drugs.

Piperazine designer drugs are a group of synthetic drugs of abuse that have appeared on the illicit market since the second half of the 1990s. The most common derivatives are 1-benzylpiperazine (BZP), 1-(4-methoxyphenyl)piperazine (MeOPP) and 1-(3,4-methylenedioxybenzyl)piperazine (MDBP). They can be consumed as capsules, tablets, but also in powder or liquid forms. Generally, although less potent than amphetamines, piperazines have dopaminergic and serotonergic activities. The aim of this work was to evaluate the toxic effects of BZP, MeOPP and MDBP using Caenorhabditis elegans as in vivo model for acute toxicity, development, reproduction and behavior testing. The LC50 for BZP, MeOPP and MDBP were 52.21, 5.72 and 1.22 mm, respectively. All concentrations induced a significant decrease in the body surface of the worms, indicating developmental alterations, and decrease in the brood size. Worms exposed to piperazine designer drugs also presented a decrease in locomotor activity and mechanical sensitivity, suggesting the possible dysfunction of the nervous system. Neuronal damage was confirmed through the decrease in fluorescence of BY200 strains, indicating loss of dopaminergic transporters. In conclusion, we suggest that piperazine designer drugs lead to neuronal damage, which might be the underlying cause of the altered behavior observed in humans.

The discovery of a new drug requires over a billion dollars and around 12 years of research efforts, and toxicity is the leading reason for the failure to approve candidate drugs. Many alternative methods have been validated to detect toxicity as early as possible to diminish the waste of resources and efforts in medicinal chemistry research, and in vivo alternative methods are especially valuable for the amount of information they can provide at little cost and in a short time. In this work, we present a review of the literature published between the years 2000 and 2021 on in vivo alternative methods of toxicity screening employed in medicinal chemistry, which we believe will be useful because, in addition to shortening the research time, these studies provide much additional information aside from the toxicity of drug candidate compounds. These in vivo models include zebrafish, Artemia salina, Galleria mellonella, Drosophila melanogaster, planarians, and Caenorhabditis elegans. The most published ones in the last decade were zebrafish, D. melanogaster, and C. elegans due to their reliability, ease, and cost-effectiveness in implementation and flexibility. Special attention is given to C. elegans because of its rising popularity, a wide range of uses, including toxicity screening, and active effects measurement, from antioxidant effects to anthelmintic and antimicrobial activities, and its fast and reliable results. Over time, C. elegans also became a viable high-throughput (HTS) automated drug screening option. Additionally, this manuscript lists briefly the other screening methods used for the initial toxicological analyses and the role of alternative in vivo methods in these scenarios, classifying them as in silico, in vitro and alternative in vivo models that have been receiving a growing increase in interest in recent years.

Isoxazoline is a 5-membered heterocycle present in the active compounds of many commercial veterinary anti-ectoparasitic products. The molecular target of isoxazolines is the inhibition of GABA-gated chloride channels in insects. These facts have inspired the use of the isoxazoline scaffold in the design of novel insecticide compounds. The main strategies used for isoxazoline synthesis are either the 1,3-dipolar cycloaddition between a nitrile oxide and an alkene or the reaction between hydroxylamine and an α,β-unsaturated carbonyl compound. This review highlights the utilization of isoxazoline as insecticide: its mode of action, its commercial preparations and its consideration in the design of novel insecticides. Similarity analyses were performed with 235 isoxazoline derivatives in three different cheminformatic approaches - chemical property correlations, similarity network and compound clustering. The cheminformatic methodologies are interesting tools to use in evaluating the similarity between commercial isoxazolines and to clarify the main features explored within their derivatives.

Background: Dihydropyrimidin-2-thiones (DHPMs) are a class of heterocyclic compound which have been intensively investigated mainly due to their anticancer activity as kinesin Eg5 inhibitors. Materials & methods: A library of N1 aryl substituted DHPMs were tested against glioma and bladder cancer cell lines. Quantitative structure–activity relationship (QSAR) investigation was performed in order to identify key elements of DHPMs linked with their antiproliferative effect. The toxicity of most active compounds was investigated using Caenorhabditis elegans as the model. Results & conclusion: DHPMs 9, 13 and 17 have been identified as having improved activity against glioma and bladder cell lines as compared with monastrol. Flow cytometry investigations showed that the new compounds induce cell cycle arrest in phase G2/M and cell death by apoptosis. In addition, compound 13 was able to modulate the reactive oxygen species production in vivo in C. elegans. The biphenyl dihydropyrimidinthiones provided a safety profile in C. elegans.

Polar-terminated 3,5-diarylisoxazole liquid crystals (ILCs) were synthetized and characterized. ILCs are composed by rigid core 3,5-diarylisoxazol, alkyl chain and polar-terminated flexible spacer. Hydroxyl-, ketal- and 1,2-diol-terminated ILCs rendered smectic C and A mesophase, while bromine-terminated ILCs showed smectic A and B mesophase, for monosubstituted and linear ILCs. For branched alkyl chain monotropic SmA was detected and for disubstituted ILCs no mesophase was detected. Out-of-layer fluctuations (OLFs) are discussed based on X-ray diffraction date and textures. The OLFs are dependent on the bromine atom hardness, hydrogen bonding through collective actions and conformational effects at the interface between layers. Smectic translational order parameter (TOP) Σ was also obtained for orientated bromine- and hydroxyl-terminated ILCs and related it with OLFs. For 1,2-diol-terminated ILCs two SmC sublayers were founded, probably related to the intramolecular hydrogen bond favoring the 5-membered and 6-membered formation.

Although molecular dynamics encompasses several applications, studies focusing on biomolecular systems are central issues of this research area. Such simulations require the generation of trajectory files, which provide a path for the analysis and interpretation of results with biological significance. However, although several programs have been developed in Python language for the analyses of molecular dynamics (MD) trajectories, they usually require some knowledge of programming languages in order to write or run the scripts using command lines, which certainly hinders the access of MD simulations to many scientists with the necessary biological background to interpret their results. To ease the access to Python packages focusing on MD trajectory analyses, we built a user-friendly and easy-to-install graphical PyMOL interface. Geo-Measures integrates the PyMOL functionalities with MDTraj, a powerful library of trajectory analyses, allowing the users to access up to 14 different types of analyses. Two sample cases are reported here to demonstrate the use of Geo-Measures. In the first example, which involves the use a MD trajectory file of hemoglobin from the MoDEL MD bank, we exemplified the analyses of the following variables: root mean square deviation, radius of gyration, free energy landscape and principal component analysis. In the second case, we built a trajectory file for the ecto-5'-nucleotidase using the LiGRO program to study the carbon alpha pincer angles, to define the secondary structure of the proteins and to analyze the Modevectors. This user-friendly graphical PyMOL plugin, which can be used to generate several descriptive analyses for protein structures, is open source and can be downloaded at: https://pymolwiki.org/index.php/Geo_Measures_Plugin.

Background Melatonin has been described in the literature as a potent antioxidant. However, melatonin presents variable, low bioavailability and a short half-life. The use of polymeric nanoparticulated systems has been proposed for controlled release. Thus, the purpose of this study was to investigate the action of melatonin-loaded lipid-core nanocapsules (Mel-LNC) in the antioxidant system of Caenorhabditis elegans, and the possible protective effect of this formulation against lipid peroxidation caused by paraquat (PQ). Methods The suspensions were prepared by interfacial deposition of the polymer and were physiochemically characterized. C. elegans N2 wild type and transgenic worm CF1553, muls84 [sod-3p::gfp; rol6(su1006)] were obtained from the Caenorhabditis Genetics Center (CGC). The worms were divided into 5 groups: Control, PQ 0.5 mM, PQ 0.5 mM + Mel-LNC 10 μg/mL, PQ + unloaded lipid-core nanocapsules (LNC), and PQ + free melatonin (Mel) 10 μg/mL. The lipid peroxidation was assessed through thiobarbituric acid (TBARS) levels and the fluorescence levels of the transgenic worms expressing GFP were measured. Results The LNC and Mel-LNC presented a bluish-white liquid, with pH values of 5.56 and 5.69, respectively. The zeta potential was − 6.4 ± 0.6 and − 5.2 ± 0.2, respectively. The mean particle diameter was 205 ± 4 nm and 203 ± 3 nm, respectively. The total melatonin content was 0.967 mg/ml. The TBARS levels were significantly higher in the PQ group when compared to the control group (p p C. elegans from lipid peroxidation caused by PQ and this was not observed when free melatonin was used. Moreover, Mel-LNC increased the fluorescence intensity of the transgenic strain that encodes the antioxidant enzyme SOD-3, demonstrating a possible mechanism of protection from PQ-induced damage. Conclusion These findings demonstrated that melatonin, when associated with nanocapsules, had improved antioxidant properties and the protective activity against PQ-induced lipid peroxidation could be associated with the activation of antioxidant enzymes by Mel-LNC in C. elegans.

A multi-component synthesis of biphenyl dihydropyrimidin-2-thiones from 1-phenylthiourea, aldehydes and ketones or di-ketones has been demonstrated. The reaction proceeded well for aldehydes with electron donor or acceptor substituents under mild conditions.

Glioblastoma (GBM) is the most frequent and aggressive brain tumor in adults and the current treatments only have a modest effect on patient survival. Recent studies show that bozepinib (BZP), a purine derivative, has potential applications in cancer treatment. The aim of this study was to evaluate the effect of BZP against GBM cells, specially concerning the purinergic system. Thus, GBM cells (C6 and U138 cell lines) were treated with BZP and cell viability, cell cycle, and annexin/PI assays, and active caspase-3 measurements were carried out. Besides, the effect of BZP over the purinergic system was also evaluated in silico and in vitro. Finally, we evaluate the action of BZP against important markers related to cancer progression, such as Akt, NF-κB, and CD133. We demonstrate here that BZP reduces GBM cell viability (IC50 = 5.7 ± 0.3 µM and 12.7 ± 1.5 µM, in C6 and U138 cells, respectively), inducing cell death through caspase-dependent apoptosis, autophagosome formation, activation of NF-κB, without any change in cell cycle progression or on the Akt pathway. Also, BZP modulates the purinergic system, inducing an increase in CD39 enzyme expression and activity, while inhibiting CD73 activity and adenosine formation, without altering CD73 enzyme expression. Curiously, one cycle of treatment resulted in enrichment of GBM cells expressing NF-κB and CD133+, suggesting resistant cells selection. However, after another treatment round, the resistant cells were eliminated. Altogether, BZP presented in vitro anti-glioma activity, encouraging further in vivo studies in order to better understand its mechanism of action.

Doxazosin is an important drug used for treating hypertension and prostatic hyperplasia. An enantiomeric mixture (R)/(S) doxazosin mesylate was complete characterized by NMR and additionally FT-IR spectroscopy techniques. Were performed different NMR experiments, such as APT, HSQC, and HMBC in order to confirm the NMR signals assignments. All the hydrogens and the most of carbons atoms were assigned.

Malaria, a tropical parasitic disease caused by Plasmodium spp., continues to place a heavy social burden, with almost 200 million cases and more than 580,000 deaths per year. Plasmodium falciparum purine nucleoside phosphorylase (PfPNP) can be targeted for antimalarial drug design since its inhibition kills malaria parasites both in vitro and in vivo. Although the currently known inhibitors of PfPNP, immucillins, are orally available and of low toxicity to animals and humans, to the best of our knowledge, none of these compounds has entered clinical trials for the treatment of malaria. Using a pharmacophore-based virtual screening coupled to a consensual molecular docking approach, we identified 59 potential PfPNP inhibitors that are predicted to be orally absorbed in a Caco-2 cell model. Although most of these compounds are predicted to have high plasma protein binding levels, poor water solubility (except for compound 25) and CYP3A4 metabolic stability (except for 4, 7 and 8), four structures (4, 7, 8 and 25) remain as potential leads because of their plausible interaction with a specific hydrophobic pocket of PfPNP, which would confer them higher selectivity for PfPNP over human PNP. Additionally, both predicted Gibbs free energies for binding and molecular dynamics suggest that compound 4 may form a more stable complex with PfPNP than 5[Formula: see text]-methylthio-immucillin-H, a potent and selective inhibitor of PfPNP.

Aiming to recover fractions enriched with coumarins, the aerial parts of Pterocaulon balansae Chodat (Asteraceae) were subjected to supercritical fluid extraction (SFE) using CO2 as solvent under constant temperature (40 °C) and gradual pressure increments (90, 120, 150 and 200 bar). The yields of the coumarins in the extracts were calculated using high-performance liquid chromatography analyses, which allowed the identification of seven coumarins previously reported by our research group. Coumarin 7-((3,3-dimethyloxiran-2-yl)methoxy)-5,6-dimethoxy-2H-chromen-2-one was identified as the major component of all extracts but we also identified considerable amounts of other epoxy-substituted coumarins. The mild conditions provided by the supercritical CO2 extraction (SC-CO2 extraction) may considerably reduce the ring-opening of the epoxy groups in the coumarins from the aerial parts of P. balansae, when compared to the conventional extraction procedures.

Background: Guanine phosphoribosyltransferase (GPRT) is a very attractive target for the development of new drugs against G. lamblia because of its critical role in the synthesis of DNA and RNA. Herein we report the use of in silico approaches to identify potential G. lamblia GPRT inhibitors. Methods: Analyses of the binding site of the enzyme accomplished through the use of several methods allowed the construction of a pharmacophore model, which was screened against a database of commercial substances. The resulting retrieved compounds were then screened against GPRT by consensus docking with two different methods, and the top 10% scored compounds had their poses visually inspected. Root Mean Square Deviation (RMSD) values ≤ 2.0 Å were used to define a consensual pose while RMSD values between 2 and 3 Å defined a partial consensus. Main toxicity endpoints were predicted through substructural analyses. Results: From the 1,230 compounds retrieved in the pharmacophore-based screening, eleven had their binding modes consensually ascribed by the docking methods, suggesting a better selectivity for the parasite enzyme in comparison to the human counterpart by avoiding steric bumps with a flexible loop in the human enzyme binding site. One compound, ZINC38139588, was predicted to be totally devoid of toxicity, being perhaps the most promising of this series. Conclusion: Through rigorously validated docking protocols, we predicted the binding mode of these compounds in the GPRT binding site. The use of a consensus docking strategy yielded more reliable predictions of the binding modes to guide the future biological assays.

The neglected tropical disease leishmaniasis is still a major public health problem that affects millions of people worldwide. Related to poor-living conditions, this vector-borne disease presents multiple clinical manifestations - from asymptomatic to systemic conditions. The protozoans of the genus Leishmania are the etiologic agents transmitted through the bite of sandflies, the main vectors. Current pharmacological interventions are outdated and present several drawbacks, thus the search for new antileishmanial compounds is imperative. Medicinal chemists have been continuously investigating for new alternatives to combat leishmaniasis, and coumarins play a pivotal role in this search. Various biological properties have been described owing to coumarin's structural versatility combined with its unique features, including antileishmanial activity. The aim of this review is to highlight the most relevant studies between 1997 and 2020 and provide a guide for the development of new antileishmanial coumarins. Naturally occurring and synthetically designed coumarins are comprised in this review, along with a structure-activity relationship to provide an insight for further development of coumarins with antileishmanial activity.

Coumarins are important especialized metabolites that have potential application in different fields. For the purpose of obtaining fractions enriched with coumarins, extracts from the leaves and inflorescences of Pterocaulon lorentzii Malme (Asteraceae) were obtained by different methods and solvents, i.e. with water at 60 °C, with dichloromethane at room temperature (25 °C) and by means of supercritical CO2 (SC-CO2) extraction at 40 °C with gradual pressure increments (90, 120, 150, 200 and 300 bar). The coumarins content in the extracts was calculated using ultra-fast liquid chromatography analyses, which allowed the characterization of the coumarins. Sabandinol (5-(2′,3′-dihydroxy-3′-methylbutyloxy)-6,7-methylenedioxycoumarin) was the main coumarin found in the aqueous and dichlorometane extracts. The epoxy-derivative 5-(2′,3′-epoxy-3′-methylbutyloxy)-6,7-methylenedioxycoumarin was identified as the major component of all extracts obtained by SC-CO2. The SC-CO2 extract from the inflorescences proved to be richer in coumarins than the extract from the leaves. The results suggest that when the objective is to obtain epoxy-coumarins, the method of choice should be SC-CO2, as this technique was effective for preventing the ring-opening of the epoxy group.

For more than 40 years, the fluid mosaic model of cellular membranes has supported our vision of an inert lipid bilayer containing membrane protein receptors that are randomly hit by extracellular molecules to trigger intracellular signaling events. However, the notion that compartmentalized cholesterol- and sphingomyelin-rich membrane microdomains (known as lipid rafts) spatially arrange receptors and effectors to promote kinetically favorable interactions necessary for the signal transduction sounds much more realistic. Despite their assumed importance for the dynamics of ligand-receptor interactions, lipid rafts and biomembranes as a whole remain less explored than the other classes of biomolecules because of the higher variability and complexity of their membrane phases, which rarely provide the detailed atomic-level structural data in X-ray crystallography assays necessary for molecular modeling studies. The fact that some alkylphospholipids (e.g. edelfosine: 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) selectively induce the apoptotic death of cancer cells by recruiting Fas death receptors and the downstream signaling molecules into clusters of lipid rafts suggests these potential drug targets deserve a more in-depth investigation. Herein, we review the structure of lipid rafts, their role in apoptotic signaling pathways and their potential role as drug targets for the treatment of cancer.

Imidazoles and benzimidazoles are privileged heterocyclic bioactive compounds used with success in the clinical practice of innumerous diseases. Although there are many advancements in cancer therapy, microtubules remain as one of the few macromolecular targets validated for planning active anti-cancer compounds, and the design of drugs that modulate microtubule dynamics in unknown sites of tubulin is one of the goals of the medicinal chemistry. The discussion of the role of new and commercially available imidazole and benzimidazole derivatives as tubulin modulators is scattered throughout scientific literature, and indicates that these compounds have a tubulin modulation mechanism different from that of tubulin modulators clinically available, such as paclitaxel, docetaxel, vincristine and vinblastine. In fact, recent literature indicates that these derivatives inhibit microtubule formation binding to the colchicine site, present good pharmacokinetic properties and are capable of overcoming multidrug resistance in many cell lines. The understanding of the mechanisms involved in the imidazoles/benzimidazoles modulation of microtubule dynamics is very important to develop new strategies to overcome the resistance to anti-cancer drugs and to discover new biomarkers and targets for cancer chemotherapy.

Advances in, and dissemination of, computer technologies in the field of drug research now enable the use of molecular modeling tools to teach important concepts of drug design to chemistry and pharmacy students. A series of computer laboratories is described to introduce undergraduate students to commonly adopted in silico drug design methods, such as molecular geometry optimization, pharmacophore modeling, protein–ligand docking simulations, homology modeling, virtual screening, and pharmacokinetics/toxicity predictions. Freely available software and web servers are selected to compose this pedagogical resource, such that it can be easily implemented in any institution equipped with an Internet connection and Windows OS computers. This material is an illustration of a drug discovery pipeline, starting from the structure of known drugs to obtain novel bioactive compounds, and, therefore, is a valid pedagogical instrument for educating future professionals in the field of drug development.

Bladder cancer is one of the most prevalent malignancies of the genitourinary tract, and approximately 25% of patients develop superficial cancers with invasive and metastatic pathology. Coumarins and their derivatives have antiproliferative activity and induce apoptosis in several cancer cell lines. Due to the potential therapeutic applications of these compounds, a series of 4-methylcoumarins were synthesized to investigate the antitumor cytotoxic effect in the T24 and RT4 human bladder cancer cell lines. The microwave-assisted synthesis of the coumarinsvia Pechmann condensation with modifications at position 7 was performed with excellent yields (74–100%). The 7,8-dihydroxy-4-methyl-2-oxo-2H-chromene-5-carboxylic acid derivative (3c) exhibited greater cytotoxicity against T24 cells, which represent a more malignant cell line compared to RT4. In the T24 cells, cell cycle analysis revealed a large number of cells in the sub-G1 phase after treatment with 3c, which is indicative of apoptosis. Apoptotic death was confirmed by annexin V staining assay. Based on the chemical structures of the compounds, it is suggested that the 5-carboxycoumarin ring group has a positive influence on the cytotoxic activity. These results indicate that these new compounds are promising for further chemical modulation to discover a new antitumor agent.

Coumarins are considered to be privileged structures due to their broad range of biological properties, including anticoagulant, anti-neurodegenerative, antioxidant, anticancer and antimicrobial activities. These interesting properties of coumarins can be ascribed to the chemical attributes of the 2H-chromen-2-one core; its aromatic ring can establish a series of hydrophobic, π-π, CH-π and cation-π interactions, and the two oxygen atoms in the lactone ring may hydrogen-bond to a series of amino acid residues in different classes of enzymes and receptors. Additionally, the double bond in the lactone helps to make the entire system planar, allows charge delocalization between the carbonyl group of the lactone and the aromatic ring and confers the characteristic fluorescence of this class of compounds, which can be explained by their preventing the trans-cis transformation of the double bond under ultraviolet (UV) irradiation. It is the possibility of radical delocalization in the 2H-chromen-2-one nucleus that makes most of the coumarins good antioxidants by acting as free radical scavengers, although some coumarins (mainly hydroxycoumarins) may also prevent the formation of free radicals by chelating metal ions. In this review, we provide a systematic analysis of the most important aspects surrounding the development of coumarins as antioxidants. Our analysis includes the synthesis of some complex antioxidant coumarins, strategies for structural modification to improve their antioxidant activities, qualitative/ quantitative structure-antioxidant relationships studies and the main in vitro assays used to evaluate their antioxidant properties.

To speed up the drug-discovery process, molecular dynamics (MD) calculations performed in GROMACS can be coupled to docking simulations for the post-screening analyses of large compound libraries. This requires generating the topology of the ligands in different software, some basic knowledge of Linux command lines, and a certain familiarity in handling the output files. LiGRO-the python-based graphical interface introduced here-was designed to overcome these protein-ligand parameterization challenges by allowing the graphical (non command line-based) control of GROMACS (MD and analysis), ACPYPE (ligand topology builder) and PLIP (protein-binder interactions monitor)-programs that can be used together to fully perform and analyze the outputs of complex MD simulations (including energy minimization and NVT/NPT equilibration). By allowing the calculation of linear interaction energies in a simple and quick fashion, LiGRO can be used in the drug-discovery pipeline to select compounds with a better protein-binding interaction profile. The design of LiGRO allows researchers to freely download and modify the software, with the source code being available under the terms of a GPLv3 license from http://www.ufrgs.br/lasomfarmacia/ligro/ .

Background: Leishmaniasis reaches millions of people around the world. The control of the disease is difficult due to the restricted access to the diagnosis and medication, and low adherence to the treatment. Thus, more efficient drugs are needed and natural products are good alternatives. Iridoids, natural products with reported leishmanicidal activity, can be exploited for the development of anti- Leishmania drugs. The aim of this study was to isolate and to investigate the in vitro activity of iridoids against Leishmania amazonensis and to compare the activity in silico of these compounds with those reported as active against this parasite. Methods: Iridoids were isolated by chromatographic methods. The in vitro activity of asperuloside (1) and geniposide (2) from Escalonia bifida, galiridoside (3) from Angelonia integerrima and theveridoside (4) and ipolamiide (5) from Amphilophium crucigerum was investigated against promastigote forms of Leishmania amazonensis. Molecular modeling studies of 1-5 and iridoids cited as active against Leishmania spp. were performed. Results: Compounds 1-5 (5-100 µM) did not inhibit the parasite survival. Physicochemical parameters predicted for 1-5 did not show differences compared to those described in literature. The SAR and the pharmacophoric model confirmed the importance of maintaining the cyclopentane[C]pyran ring of the iridoid, of oxygen-linked substituents at the C1 and C6 positions and of bulky substituents attached to the iridoid ring to present leishmanicidal activity. Conclusion: The results obtained in this study indicate that iridoids are a promising group of secondary metabolites and should be further investigated in the search for new anti-Leishmania drugs.

Inhibition of mushroom tyrosinase was observed with synthetic dihydropyrano[3,2-b]chromenediones. Among them, DHPC04 displayed the most potent tyrosinase inhibitory activity with a Ki value of 4μM, comparable to the reference standard inhibitor kojic acid. A kinetic study suggested that these synthetic heterocyclic compounds behave as competitive inhibitors for the L-DOPA binding site of the enzyme. Furthermore, molecular modeling provided important insight into the mechanism of binding interactions with the tyrosinase copper active site.

The Biginelli reaction is an acid-catalyzed, three-component reaction between an aldehyde, a hydrogen methylene active compound, and urea (or its analogue) and constitutes a rapid and easy synthesis of highly functionalized heterocycles. Synthesis of ethyl 6-methyl-2-oxo-4-{4-[(1-phenyl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-1,2,3,4-tetrahydropyrimidine-5-carboxylate, identified by our laboratory code LaSOM® 293, was achieved using the Biginelli reaction as the key step, followed by the Huisgen 1,3-dipolar cycloaddition in a convergent four-step route. The product LaSOM® 293 was obtained with a yield of 84%.