Exploiting the furo[2,3-b]pyridine core against multidrug-resistant Mycobacterium tuberculosis.

Identification of new antibiotics suitable for the treatment of tuberculosis is required. In addition to selectivity, it is necessary to find new antibiotics that are effective when the tuberculous mycobacteria are resistant to the available therapies. The furo[2,3-b]pyridine core offers potential for this application. Herein, we have described the screening of our in-house library of furopyridines against Mycobacterium tuberculosis and identified a promising selective bioactive compound against different drug-resistant strains of this mycobacteria. The library of compounds was prepared by a CH amination reaction using mild and metal-free conditions, increasing the available information about the reactivity of furo[2,3-b]pyridine core through this reaction.

Lapachol biotransformation by filamentous fungi yields bioactive quinone derivatives and lapachol-stimulated secondary metabolites.

Lapachol is a natural naphthoquinone with a range of biological effects, including anticancer activity. Microbial transformations of lapachol can lead to the formation of new biologically active compounds. In addition, fungi can produce secondary metabolites that are also important for drug discovery. The goal of this study was to evaluate the ability of filamentous fungi to biotransform lapachol into biologically active compounds and identify secondary metabolites produced in the presence of lapachol. Seven out of nine strains of filamentous fungi tested exhibited the ability to biotransform or biodegrade lapachol. The bioactive derivatives norlapachol and isolapachol were identified among biotransformation products. Moreover, lapachol stimulated the production of pyrrolo-[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) and phenol-2,4-bis-(1,1-dimethylethyl), secondary metabolites already known to have antimicrobial and antioxidant activities. These results open the perspective of using these strains of filamentous fungi for lapachol biotransformation and efficient production of several biologically active compounds.

Arene-Ligand-Free Ruthenium(II/III) Manifold for meta-C-H Alkylation: Remote Purine Diversification.

meta-Selective C-H alkylations of bioactive purine derivatives were accomplished by versatile ruthenium catalysis. Thus, the arene-ligand-free complex [Ru(OAc)2 (PPh3 )2 ] enabled remote C-H functionalizations with ample scope and excellent levels of chemo- and positional selectivities. Detailed experimental and computational mechanistic studies provided strong support for a facile C-H activation within a ruthenium(II/III) manifold.

Charting the Chemical Reactivity Space of 2,3-Substituted Furo[2,3-b]pyridines Synthesized via the Heterocyclization of Pyridine-N-oxide Derivatives.

A concise strategy for the synthesis of 2,3-substituted furo[2,3-b]pyridines is described. Mild, metal-free conditions were successfully applied to produce a range of 2-(alkyl or aryl)-3-ethylcarboxylate-furo[2,3-b]pyridines in yields of 50-91%. Then, the chemical reactivity of this heterocyclic framework was explored to develop straightforward methods for its functionalization. The pyridine moiety reactivity was successfully explored by C-H amination and borylation reactions, although C-H fluorination and radical C-H arylation processes were not as efficient. In addition, while the furopyridine core proved stable under basic conditions, the ring-opening reaction of the furan moiety with hydrazine generated a valuable new pyridine-dihydropyrazolone scaffold.

In vivo antimalarial activity of novel 2-hydroxy-3-anilino-1,4-naphthoquinones obtained by epoxide ring-opening reaction.

1,4-Naphthoquinone derivatives are known to have relevant activities against several parasites. Among the treatment options for malaria, atovaquone, a 1,4-naphthoquinone derivative, is widely applied in the treatment and prophylaxis of such disease. Based on the structure simplification of atovaquone, we designed and synthesized four novel naphthoquinoidal derivatives. The compounds were obtained by the underexplored epoxide-opening reaction of 1,4-naphthoquinone using aniline derivatives as nucleophiles. The antiplasmodial activity of the synthesized compounds was performed in vivo using Peter's 4days suppression test. Significant parasitemia reduction and increased survival were observed for some of the compounds.

Synthesis and Structure-Activity Relationships of Imidazopyridine/Pyrimidine- and Furopyridine-Based Anti-infective Agents against Trypanosomiases.

Neglected tropical diseases remain among the most critical public health concerns in Africa and South America. The drug treatments for these diseases are limited, which invariably leads to fatal cases. Hence, there is an urgent need for new antitrypanosomal drugs. To address this issue, a large number of diverse heterocyclic compounds were prepared. Straightforward synthetic approaches tolerated pre-functionalized structures, giving rise to a structurally diverse set of analogs. We report on a set of 57 heterocyclic compounds with selective activity potential against kinetoplastid parasites. In general, 29 and 19 compounds of the total set could be defined as active against Trypanosoma cruzi and T. brucei brucei, respectively (antitrypanosomal activities <10 µM). The present work discusses the structure-activity relationships of new fused-ring scaffolds based on imidazopyridine/pyrimidine and furopyridine cores. This library of compounds shows significant potential for anti-trypanosomiases drug discovery.

Adult and yearling pampas deer stags (Ozotoceros bezoarticus) display mild reproductive seasonal patterns with maximum values in autumn.

The pampas deer is an endangered species, from which reproductive biology little is known. We aimed to describe and compare the reproductive seasonal patterns of adult and yearling pampas deer stags throughout the year, including morphological traits, testosterone concentration, sperm morphology and cryoresistance pattern changes. Six adult (AS) and five yearling (YS) stags were captured with anesthetic darts once in winter, spring, summer and autumn to study morphological variables, serum testosterone and semen. Adult males were heavier, their neck girth tended to be greater and their testosterone concentration was higher than in YS. Animals were heavier in summer and autumn. Neck girth and testosterone concentration were greater in autumn. Scrotal circumference, testicular volume and gonado-somatic index varied with seasons, decreasing from winter to spring, increasing in summer and remaining in greater values in autumn. Sperm quality had maximum values from summer to winter. However, the cryoresistance ratio of motility score was greater in spring. In conclusion, in the captivity conditions, pampas deer stags seems to present a light seasonal reproductive pattern, with maximum testis size, testosterone secretion and fresh semen quality in autumn. Nevertheless, sperm cryoresistance ratio seemed to remain stable along the year. Although YS were still growing, they achieved similar semen quality than AS.

Ligand-based design, synthesis and biochemical evaluation of potent and selective inhibitors of Schistosoma mansoni dihydroorotate dehydrogenase.

Schistosomiasis ranks second only to malaria as the most common parasitic disease worldwide. 700 million people are at risk and 240 million are already infected. Praziquantel is the anthelmintic of choice but decreasing efficacy has already been documented. In this work, we exploited the inhibition of Schistosoma mansoni dihydroorotate dehydrogenase (SmDHODH) as a strategy to develop new therapeutics to fight schistosomiasis. A series of quinones (atovaquone derivatives and precursors) was evaluated regarding potency and selectivity against both SmDHODH and human DHODH. The best compound identified is 17 (2-hydroxy-3-isopentylnaphthalene-1,4-dione) with IC50 = 23 ±â€¯4 nM and selectivity index of 30.83. Some of the new compounds are useful pharmacological tools and represent new lead structures for further optimization.

Poly-ε-caprolactone based nanoparticles for delivery of genistein in melanoma treatment

We developed poly-ε-caprolactone (PCL)-based nanoparticles containing D-α-tocopherol polyethylene glycol-1000 succinate (TPGS) or Poloxamer 407 as stabilizers to efficiently encapsulate genistein (GN). Two formulations, referred to as PNTPGS and PNPol, were prepared using nanoprecipitation. They were characterized by size and PDI distribution, zeta potential, nanoparticle tracking analysis (NTA), GN association (AE%), infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC). PNTPGS-GN exhibited a particle size of 141.2 nm, a PDI of 0.189, a zeta potential of -32.9 mV, and an AE% of 77.95%. PNPol-GN had a size of 146.3 nm, a better PDI than PNTPGS-GN (0.150), a less negative zeta potential (-21.0 mV), and an AE% of 68.73%. Thermal and spectrometric analyses indicated that no new compounds were formed, and there was no incompatibility detected in the formulations. Cellular studies revealed that Poloxamer 407 conferred less toxicity to PCL nanoparticles. However, the percentage of uptake decreased compared to the use of TPGS, which exhibited almost 80% cellular uptake. This study contributes to the investigation of stabilizers capable of conferring stability to PCL nanoparticles efficiently encapsulating GN. Thus, the PCL nanoparticle proposed here is an innovative nanomedicine for melanoma therapy and represents a strong candidate for specific pre-clinical and in vivo studie

In vitro evaluation of folate-modified PLGA nanoparticles containing paclitaxel for ovarian cancer therapy.

Ovarian cancer is the most lethal gynecological cancer of female reproductive system. In order to improve the survival rate, some modifications on nanoparticles surfaces have been investigated to promote active targeting of drugs into tumor microenvironment. The aim of this study was the development and characterization of folate-modified (PN-PCX-FA) and unmodified PLGA nanoparticles (PN-PCX) containing paclitaxel for ovarian cancer treatment. Nanocarriers were produced using nanoprecipitation technique and characterized by mean particle diameter (MPD), polydispersity index (PDI), zeta potential (ZP), encapsulation efficiency (EE), DSC, FTIR, in vitro cytotoxicity and cellular uptake. PN-PCX and PN-PCX-FA showed MPD < 150 nm and PDI < 0.2 with high EE (about 90%). Cytotoxicity assays in SKOV-3 cells demonstrated the ability of both formulations to cause cellular damage. PCX encapsulated in PN-PCX-FA at 1 nM showed higher cytotoxicity than PN-PCX. Folate-modified nanoparticles showed a 3.6-fold higher cellular uptake than unmodified nanoparticles. PN-PCX-FA is a promising system to improve safety and efficacy of ovarian cancer treatment. Further in vivo studies are necessary to prove PN-PCX-FA potential.

Serial collection method of dog saliva: Effects of different chemical stimulants on behaviour, volume and saliva composition.

The objective of this study was to evaluate different chemical stimulants with different flavours such as acids (citric and acetic), sweet (sucrose) and salty (sodium chloride) applied to cotton rolls and compare their effects on the volume, pH and protein concentrations of the saliva collected and the behaviour of dogs during sampling management. As an additional objective, serum cortisol concentrations of saliva samples obtained with or without citric acid and with or without previous pH adjustment were compared. Five clinically healthy were randomly assigned to one of 5 treatments with cottons with different substances: 1) control, 2) citric acid, 3) acetic acid, 4) sodium chloride, 5) sucrose. Each dog received one treatment per day, and in 5 days, all dogs were tested with the five treatments. On each day, cottons were applied to dogs at times 0, 20, 40, 60 and 80 minutes. The cottons with citric acid generated more volume than the rest of the treatments (p<0.0001), and sodium chloride generated more volume than the control and acetic acid (p≤0.03). Cottons with citric acid generated lower pH of saliva than the rest of the treatments (p<0.0001). Cottons with acetic acid generated lower pH than control, sodium chloride and sucrose (p<0.0001). There were no differences in cortisol concentrations between the control samples and those obtained with citric acid, nor between these same samples with and without pH adjusted with buffer. The concentration of proteins in saliva and excitement degree did not change with treatment. Citric acid was more palatable than the rest of the treatments (p<0.0001). Sodium chloride and sucrose were more palatable than control (p<0.05). In conclusion, citric acid was the chemical stimulant that generated greater volume of saliva and greater palatability in dogs. Although the pH of the saliva obtained with citric acid was clearly acidic, its acidic pH did not affect the determination of cortisol by chemiluminescence or RIA. Sodium chloride and sucrose allowed to obtain high volumes of saliva and were more palatable than the control, which can be other interesting options to obtain saliva in case of not being able to use citric acid.

Novel benzophenone-3 derivatives with promising potential as UV filters: Relationship between structure, photoprotective potential and phototoxicity.

Benzophenone-3 (BP-3) is a UV filter with absorption at the UVB and UVA wavelengths which has not been extensively studied in experiments involving its absorbing effects and toxicity. We synthetized four BP-3 derivatives and characterized their photoprotective potential by UV absorption and photodegradation, their phototoxicity potential by 3T3 Neutral Red Uptake (3T3 NRU PT) and their photoreactivity by the reactive oxygen species (ROS) assay. The UV absorption, photodegradation, phototoxicity and photoreactivity of the four BP-3 derivatives (BP-3 carbonate, BP-3 carbazole, BP-3 phenylamine and BP-3 methoxy-phenylamine) were evaluated and compared to those of BP-3. Results showed that all derivatives were photostable, except BP-3 carbonate, which did not absorb in the UVA range. BP-3 phenylamine and BP-3 methoxy-phenylamine were considered non-phototoxic and weakly photoreactive in the ROS assay, while the carbazole derivative was considered phototoxic and non-photoreactive due to its rigid structure. The UV spectra of BP-3 carbonate, BP-3 phenylamine and BP-3 methoxy-phenylamine showed the influence of hydrogen bonding on their UV absorption. Based on these results, we concluded that BP-3 phenylamine and BP-3 methoxy-phenylamine could be promising UVA filters.

Cytotoxicity, hemolysis and in vivo acute toxicity of 2-hydroxy-3-anilino-1,4-naphthoquinone derivatives.

The 1,4-naphthoquinones, important members of the family of quinones are used as both crude extracts and as compound manipulated by the pharmaceutical industry. They have gained great emphasis by presenting different pharmacological properties as antibacterial, antiviral, antiprotozoal and anthelmintic, and has antitumor activity. Our aim was to evaluate the cytotoxicity, hemolytic activity and in vivo acute toxicity of three derivatives of 2-hydroxy-1,4-naphthoquinones. The cell viability in vitro against RAW Cell Line displayed IC50 ranging of 483.5-2044.8 µM, whereas in primary culture tests using murine macrophages, IC50 were 315.8-1408.0 µM for naphthoquinones derivatives 4a and 4c respectively, besides no hemolysis was observed at the dose tested. The in vivo acute toxicity assays exhibited a significant safety margin indicated by a lack of systemic and behavioral toxicity up to 300 mg/kg, and at a dose of 1000 mg/kg the derivatives not triggering signs of toxicity although the compound 4a have promoted hepatic steatosis and hyperemia in kidney tissue. Thereby, these modifications decrease the toxicity of the tested derivatives naphthoquinones, providing a high potential for the development of news drugs.