Malaria is a neglected tropical disease that remains a leading cause of morbidity and mortality among the world’s poorest populations. In 2015, 91 tropical and sub-tropical countries are endemic for this infectious disease. Pregnant women and children are the most sensitive to this infection and, in 2015, 429 000 people died. Among the five species of Plasmodium responsible for human malaria, P. falciparum is the parasite which causes the most serious form of the disease. More recent efforts focused on the development of antimalarial vaccines and since 2006, World Health Organization (WHO) recommends artemisinin-based combination therapies (ACTs). In drugs resistance areas, several antimalarial drugs, such as aminoaryl-alcohol (mefloquine (MQ), lumefantrine (LM)), are currently used in combination with artemisinin derivatives. However, the emergence of multi-drug-resistant parasites decreases efficacy of ACTs. Thus, the design of new active compounds on Plasmodium-resistant strains is urgently.

We have previously developed an asymmetric synthesis to prepare 4-aminoquinoline-methanol enantiomers (AQM) as MQ analogs. They were active on nanomolar range against Pf3D7 (chloroquine-sensitive) and PfW2 (chloroquine-resistant) P. falciparum strains. Interestingly, (S)-enantiomers displayed an activity increased by 2 to 15-fold as compared to their (R)-counterparts. Currently their mechanisms of actions are not totally clear and remain to be explored.

In continuation of our work, we are interested now to study the change of heterocycle (fluorene vs quinoline) on the antimalarial activity. We focus on the design and the preparation of novel asymmetric 2,4,7-trisusbtituted fluorenes, new aminofluorène-methanol derivatives (AFM) as LM analogs. The evaluation of their antiplasmodial activities against P. falciparum and their corresponding cytotoxicities proved the interest of this pharmacophore with activities on nanomolar range against Pf3D7 and PfW2. We will present here the access and the biological results on these AFMs.

Despite the fact that the percentage of methicillin-resistant Staphylococcus aureus is slowly decreasing in Europe [1], new compounds for fighting bacterial infections are still needed. Biofilm-associated infections, which are a significant cause of mortality, are also considered a serious problem [2]. Derivatives of cinnamic acid have been investigated for a long time due to their wide spectrum of biological activities, such as antibacterial, antiviral, antidiabetic, anxiolytic and anti-inflammatory [3].

Based on these facts, a series of 16 ring-substituted N-arylcinnamamides was synthetized and investigated for their antibacterial activity against S. aureus ATCC 29213 and 3 methicillin-resistant isolates. The microtitration dilution method was used for the determination of minimum inhibitory concentration (MIC). In addition, the most potent compounds were studied for their synergetic effect with clinically used antibacterial chemotherapeutics and ability to inhibit and degrade staphylococcal biofilm; in addition, the dynamics of their antibacterial activity was characterized.

(2E)-N-[3,5-bis(Trifluoromethyl)phenyl]-3-phenylprop-2-enamide and (2E)-3-phenyl-N-[3-(trifluoromethyl)phenyl]prop-2-enamide showed the highest activities (MICs = 22.27 and 27.47 µM, respectively) against all four staphylococcal strains. These compounds showed an activity against biofilm formation of S. aureus ATCC 29213 in concentrations close to MICs, but no degradative effect on mature biofilm was observed. Both compounds showed abilities to increase the activity of clinically used antibiotics with different mechanisms of action (vancomycin, ciprofloxacin and tetracycline). In time-kill studies, a decrease of colony-forming units (CFU/mL) of >99% was observed after 8 h from the beginning of incubation.

This contribution was supported by grant No. UK/229/2018 of the Comenius University in Bratislava, grants FaF UK/9/2018 and FaF UK/37/2018 of the Faculty of Pharmacy of Comenius University in Bratislava and partially by SANOFI-AVENTIS Pharma Slovakia, s.r.o.

1. HEUER, O. et al. Antimicrobial resistance surveillance in Europe: annual report of the European Antimicrobial Resistance Surveillance Network (EARS-Net). European Centre for Disease Prevention and Control (ECDC), 2010.
2. SON, J.S. et al. Antibacterial and biofilm removal activity of a podoviridae Staphylococcus aureus bacteriophage SAP-2 and a derived recombinant cell-wall-degrading enzyme. Microbiol. Biotechnol. 2010. 86, 1439-1449.
3. POSPISILOVA, S. et al. Synthesis and spectrum of biological activities of novel N‑arylcinnamamides. J. Mol. Sci. 2018, 19, 2318.

In addition of the protein coding information viral RNA genomes code functional information in structurally conserved units termed functional RNA domains. These RNA domains play essential roles in the viral cycle. Members of the Flaviviridae family are responsible of important worldwide human diseases (e.g. hepatitis C, dengue, zika, west Nile fever, among others). Their genome consists in a (+) single stranded RNA molecule, which contains numerous highly structurally conserved RNA domains. They represent a good model to study and characterize the functional roles of RNA domains in the regulation of essential viral processes (e.g. translation, replication). Understanding the molecular mechanisms behind their function is essential to understand the viral infective cycle. Interfering with the function of the genomic RNA domains offers a potential means of developing antiviral strategies. Nucleic acids tools and in particular aptamers are good candidates for targeting structural RNA domains. Besides its potential as therapeutics, aptamers also provides an excellent means for investigating the functionality of RNA domains in viral genomes.

Tuberculosis is regarded as one of the deadliest diseases in the world. In 2017, 10 million people were affected by tuberculosis and 1.7 million died because of it¹.
Tuberculosis is a bacterial infection caused by some bacteria from the genus Mycobacterium, such as Mycobacterium tuberculosis. Some bacterial strains are multi-resistant or extensively-resistant against classical antibiotics. Consequently, there is a necessity to set up new strategies to prevent the spread of antibiotic resistant mycobacteria.
Only two antitubercular compounds have been commercialized during the last 40 years: bedaquiline in 2012² and delamanid in 2014. That emphasizes the lack of therapeutic options available to cure tuberculosis.

Quinoline core is present in some antitubercular compounds.
Indeed, bedaquiline is a diarylquinoline, which acts by inhibiting selectively the mycobacterial ATP synthase, an enzyme required for the energetic metabolism of the cell. The stereochemistry is particularly important in this selectivity as the (1R, 2S) enantiomer is 630 times more active than the (1S, 2R) enantiomer.
Mefloquine is a quinoline used as antimalarial compound but this molecule shows also antimycobacterial properties. Indeed, mefloquine can inhibit ATP synthase of Streptococcus pneumoniae³.
The objectives of this work are designing, synthesizing, and evaluating new antitubercular compounds as quinoline derivatives (AQM). These molecules are expected to inhibit mycobacterial ATP synthase in order to fight latent forms of mycobacteria.
The previous works of the research team⁴ have allowed to identify a lead compound which shows an MIC of 2 µM against M. tuberculosis Mtb_H37Rv strain. A pharmacomodulation of this lead compound will be shown here.
Twenty two molecules have been synthesized through an asymmetric synthetic route in 5 steps with an average yield from 14 to 47 %. These molecules have been tested in vitro, against M. avium and M. xenopi and have shown interesting biological activity with a MIC between 18 µM and more than 72 µM.

1. WHO, Global tuberculosis report 2017.
2. Haagsma AC, Abdillahi-Ibrahim R, et al. Antimicrob Agents Chemother. 2009, 53, 1290-1292.
3. Martin-Galiano AJ, Gorgojo B, Kunin CM, de la Campa AG. Antimicrob Agents Chemother. 2002, 46, 1680-1697.
4. Jonet, A. Dassonville-Klimpt, P. Sonnet, C. Mullié. J. of Antibiotics, 2013, 66, 683-686.

Resistance to antibiotics is an emerging phenomenon and a major medical problem. The resistance of Gram-negative bacteria such as Pseudomonas aeruginosa and the Burkholderia group to conventional antibiotics leads to therapeutic failure and requires new antibiotic therapies. The use of iron transport systems is a promising strategy to overcome this phenomenon. These TonB-dependent receptors, essential for the survival of microorganisms, allow specific recognition of ferric siderophore complexes in order to transport iron within bacteria¹. Bacteria, according to their kind, express different types of receptors that allow them to recognize their endogenous siderophores but also xenosiderophores. Pseudomonas aeruginosa and Burkholderia pseudomallei in particular possess FptA receptors allowing the recognition of pyochelin.² These specific systems may allow the introduction of antibacterial agents by forming antibiotic-siderophore conjugates or toxic complexes such as gallium complexes, in the bacteria to kill it. Siderophores have three types of chelating function: catechols, hydroxamates and hydroxy-carboxylates. Previous work in the laboratory has shown that piperazine 1,4-dicatechol structures (MPPS0225) could be recognized by Pseudomonas aeruginosa strains. In order to further investigate this piperazine platform, we have synthesized iron chelators bearing 3-hydroxypyridin-4-ones and 1,3-dihydroxypyridin-4-one ligands. At the same time, we were interested in the synthesis of a more complex 2,5-dioxopiperazine platform, part of the rhodotorulic acid (RA), a natural siderophore produced by Rhodotorula pilimanae showing an interesting iron affinity (pFe = 21,8). Two RA synthesis strategies will be developed as well as the corresponding 3,6-disubstituted analogs. Through the synthesis of these chelators, we would like to study the influence, on the iron complexation, of: i) the nitrogen platform (piperazine or dioxopiperazine), ii) the presence of stereogenic centers (3,6-disubstituted dioxopiperazine vs 1,4 -disubstituted piperazines) and iii) the nature of the iron ligands (hydroxypyridinone vs catechol). An evaluation of the siderophore-like potential and a measurement of the complexing force will be carried out.

We would like to thank the DGA and the Haut de France region for their financial support.

References

1. Miethke M.; Marahiel MA. Microbiology and Molecular Biology Reviews. 2007, 71, 413-451.
2. Butt AT.; Thomas MS. Frontiers in Cellular and Infection Microbiology. 2017, 7.

The search for therapeutic inhibitors of specific kinases has been developed in the last three decades as a major approach to discover new drugs . Our group is focused on the regulation of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A), a conserved eukaryotic kinase that belongs to the DYRK family and the CMGC group, which includes cyclin-dependent kinases (CDKs), mitogen-activated protein kinases (MAP kinases), glycogen synthase kinases (GSK), and Ccd2-like kinases (CLKs). Five years ago, a series of tricyclic aminopyrimidine derivatives was synthesized and evaluated on DYRK1A and DYRK1B.

A fragment-growing approach was performed using a novel in silico tool that drills down through, to evaluate hundreds of thousands fragments extracted from co-crystallized kinase/inhibitor complexes. Addition of aromatic fragments on C2 seemed to increase the interaction with the hinge region.

Efficient metal catalyzed C–H arylation of 8-alkyl-thiazolo[5,4-f]-quinazolin-9-ones was explored for SAR studies. Application of this powerful chemical tool at the last stage of the synthesis of kinase inhibitors allowed the synthesis of arrays of molecules inspired by fragment-growing studies generated by molecular modeling calculations. Among the potentially active compounds designed through this strategy, FC162 (Cc) exhibits nanomolar IC50 values against some kinases, and is the best candidate for development as a DYRK kinase inhibitor.

Aims: Neurodegenerative disorders prevalence is growing due to life expectancy increase, thus the passage signs of time are clearly visible in the brain. Oxidative stress is a factor that contributes to the organic defenses imbalance, producing free radicals, brain-aging progression and various degenerative diseases. Macromolecules oxidative damage increases with age, leading to a progressive decline in cell and tissue function. Antioxidants reduce these free radicals formation or react with them by neutralizing them. Euterpe oleracea Martius, popularly known as açaí, is rich in α-tocopherol, fibers, lipids, polyphenols and mineral ions. Believes that polyphenols high content, among which flavonoids, confers to açaí fruits a variety of health promoting effects, including anti-inflammatory, immunomodulatory, antinociceptive and antioxidant properties. The present study aims to analyze, in silico, flavonoids physicochemical, pharmacokinetic and toxicological properties present in Euterpe oleracea Martius.

Place and Duration of Study: Pharmaceutical and Medicinal Chemistry Laboratory (PharMedChem) at Amapá Federal University (UNIFAP), Macapá, Brazil, between December 2017 and January 2018.

Methodology: Initially, selected 16 molecules present in Euterpe oleracea Martius, divided into açaí pulp and oil. The physicochemical properties of the flavonoids were analyzed by the rule of 5, pharmacokinetic properties in the QikProp module of the Schrödinger software and the toxicity profile using the DEREK program.

Results: Among physical-chemical properties, the flavonoid compounds catechin, epicatechin, luteolin, chrisoeriol, taxifolin, apigenin, dihydrocaempferol, isovitexin and vitexin presented good oral bioavailability. In pharmacokinetic properties, the molecules catechin, epicatechin, isovitexin, luteolin, chrisoeriol, taxifolina and isorhamnetina rutinosídeo presented the best results and high human oral absorption. In toxicological properties prediction the compounds presented good results, except for the isorhamnetina rutinoside and rutin compounds that presented alert about the mutagenicity for hydroxynaphthalene or derivative.

Conclusion: Catechin, chrysoerythol and taxifolin flavonoids presented the best results, but other computational and experimental methods are needed to identify these compounds biological activity.

Abstract

Introduction

Lichens have a very important role in both human and animal nutrition, as well as in the pharmaceutical industry and traditional medicine (1). Lichens synthesize a large number of secondary metabolites and most of these metabolites are unique to the lichen. The extracts of the lichens and their secondary metabolites exhibit a broad spectrum of biological activity (2).

Material and methods

Lichens were collected at the site of the eastern slope of the mountain Kopaonik on the territory of the Republic of Serbia. Extraction was performed with methanol using the Soxhlet apparatus. The phytochemical analysis of the methanol extract of lichen Pleurosticta acetabulum was carried out by high-performance liquid chromatography (HPLC). The antioxidant activity of the lichen extract was evaluated by measuring the total anti-oxidative capacity, reducing capacity, inhibition lipid peroxidation and scavenging capacity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl (OH) radicals. To determine total phenols and flavonoids, we used spectrophotometric methods (3). In vitro anticancer activity on HeLa S3 adenocarcinoma cervix and LS174 human colon adenocarcinoma cells line was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (4).

Results

Salazinic acid (retention time± standard deviation: t_R =1.56 ± 0.20), norstictic acid (t_R=2.70 ± 0.10), protocetraric (t_R=3.24 ± 0.20) acid and evernic acid (t_R=5.08 ± 0.10) were identified from methanol extract of lichen P. acetabulum. As a result of the antioxidant activity, methanol extract of P. acetabulum had moderate free radical DPPH scavenging activity (half-maximum inhibitory concentration IC₅₀ = 48.52 µg/mL), OH radical scavenging activity ( IC₅₀ = 163.83 µg/mL) and inhibition lipid peroxidation (IC₅₀= 74.30±1.48). Measured values of absorbance for reducing power varied from 0.25 to 0.018. The value of total antioxidant capacity was 74.29 mg AA/g (equivalents of ascorbic acid per g of dry extract). The contents of total phenols and flavonoids in the lichen extract were 73.45 mg GA/g (mg equivalents of gallic acid per g of dry extract) and 15.42 mg RU/g (mg equivalents of routine per g of dry extract), respectively. Cytotoxic activity (based on the IC₅₀ values) ranged from 39.17±5.54 µg/mL to >200 µg/mL after 24 h and 72 h treatment of extract.

Conclusion

The present study provides data for supporting the use of P. acetabulum extract as natural antioxidant agents and confirms that this extract represents a significant source of phenolic compounds.

REFERENCES

1. Romagni JG., Dayan F. (2002). Structural diversity of lichen metabolites and their potential use. Advances in Microbial Toxin Research and Its Biotechnological Exploitation, 12:151-169.
2. Müller K. (2001). Pharmaceutically relevant metabolites from lichens. Applied Microbiology and Biotechnology, 56(1-2):9-16.
3. Manojlovic N. T., Vasiljevic PJ., Maskovic PZ., Juskovic M., & Bogdanovic-Dusanovic, G. (2012). Chemical composition, antioxidant, and antimicrobial activities of lichen Umbilicaria cylindrica (L.) Delise (Umbilicariaceae). Evidence-based Complementary and Alternative Medicine, Article ID 452431.
4. Mosmann, T. (1983). Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. Journal of Immunological Methods, 65(1-2), 55-63.

In recent years, the clinical and scientific interest in antibiotics known as polymyxin has increased greatly due to the large number of reports of multiresistant Gram-negative bacteria, among them Pseudomonas aeruginosa. This work aimed to investigate proteins responsible for resistance to polymyxins encoded in P. aeruginosa genomes using in silico tools. To do so, Escherichia coli MCR1 protein was used as bait. Sequences with similarities to MCR1 encoded in P. aeruginosa genomes were analyzed for physico-chemical properties including, theoretical molecular, isoelectric point, instability index, aliphatic index and hydropation index, secondary structures and protein domain. 31 Protein isoforms (EptA) more likely to confer resistance to polymyxin present in P. aeruginosa were determined. These proteins are between 465 and 521 amino acids in length. Molecular masses between 52.06 - 57.58 kDa, isoelectric point between 5.83 to 8.06, instability index between 60.33 to 66.42, aliphatic index between 99.980 to 107.39 and the hydropathy index between -0.038 to 0.037. These proteins belong to the DUF1705 superfamily with a Bit-score between 592,806 and 608,599. In conclusion the results evidenced the high degree of similarity between P. aeruginosa EpTAs including amino acids number, molecular mass, isoelectric point, instability index, aliphatic and hydrophobicity index, as well as secondary structures and protein domain with other proteins that confer resistance to polymyxins present in Gram-negative bacterial species of clinical interest. However, further studies are needed to identify the actual contribution of EptAs in P. aeruginosa species.

Histone deacetylase 6 (HDAC6) catalyses the removal of acetyl groups from the lysine residues of a series of non-histone proteins, e.g., α-tubulin, Hsp90 and cortactin. The design of selective inhibitors of HDAC6 is related with important outcomes in the oncological, immunological and neurological fields. Herein, we describe the design, synthesis and pharmacological evaluation of a series of N-acylhydrazones (NAH) designed from the trichostatin A as HDAC6 inhibitors. The use of the phenyl linker in the design of the compounds led to HDAC6 selectivity among the HDAC family. Para-substituted phenyl-hydroxamic acids presented a more potent inhibition of HDAC6 than their meta-substituted analogs. The N- and C- methylation of the NAH framework attached to para-substituted phenyl-hydroxamic unit was evaluated and the compound LASSBio-1911 was identified as a potent and selective HDAC6 inhibitor (IC₅₀ = 15 nM). In the next step, we evaluated the influence of the cap group. We found that the use of different aromatic and heteroaromatic rings did not influence the inhibition of HDAC6. Some of these compounds were able to reduce significantly cell migration, corroborating their inhibitory profile against HDAC6. On the other hand, an analysis of their antiproliferative activity against different tumor cell lines showed that they can induce cell cycle arrest or induce apoptosis through caspase 3/7 activation, with particular relevance for hepatocellular carcinoma (HepG2) cells.

References

Rodrigues, D. A.; Ferreira-Silva, G. A.; Ferreira, A. C.; Fernandes, R. A.; Kwee, J. K.; Sant'Anna, C. M.; Ionta, M.; Fraga, C. A. M. J. Med. Chem., 2016, 59, 655-706.

Rodrigues, D. A.; Thota, S.; Fraga, C. A. M. Mini-Rev. Med. Chem., 2016, 16, 1175-1184.

Pinheiro, P. S. M.; Rodrigues, D. A.; Sant'Anna, C. M. R.; Fraga, C. A. M. Int. J. Quantum Chem., 2018;e25720.