Current leishmaniasis drug discovery.

Leishmaniasis is a complex protozoan infectious disease and, associated with malnutrition, poor health services and unavailability of prophylactic control measures, neglected populations are particularly affected. Current drug regimens are outdated and associated with some drawbacks, such as cytotoxicity and resistance, and the development of novel, efficacious and less toxic drug regimens is urgently required. In addition, leishmanial pathogenesis is not well established or understood, and a prophylactic vaccine is an unfulfilled goal. Human kinetoplastid protozoan infections, including leishmaniasis, have been neglected for many years, and in an attempt to overcome this situation, some new drug targets were recently identified, enabling the development of new drugs and vaccines. Compounds from new drug classes have also shown excellent antileishmanial activities, some of the most promising ones included in clinical trials, and could be a hope to control the disease burden of this endemic disease in the near future. In this review, we discuss the limitations of current control methods, explore the wide range of compounds that are being screened and identified as antileishmanial drug prototypes, summarize the advances in identifying new drug targets aiming at innovative treatments and explore the state-of-art vaccine development field, including immunomodulation strategies.

Synthesis of PJOV56, a new quinoxalinyl-hydrazone derivative able to induce autophagy and apoptosis in colorectal cancer cells, and related compounds.

Quinoxaline derivatives are reported as antineoplastic agents against a variety of human cancer cell lines, with some compounds being submitted to clinical trials. In this work, we report the synthesis, characterization and cytotoxicity potential of a new series of quinoxalinyl-hydrazones. The most cytotoxic compound was (E)-2-[2-(2-pyridin-2-ylmethylene)hydrazinyl]quinoxaline (PJOV56) that presented a time-dependent effect against HCT-116 cells. After 48 h of incubation, PJOV56 was able to induce autophagy and apoptosis of HCT-116 cells, mediated by upregulation of Beclin 1, upregulation of LC3A/B II and activation of caspase 7. Apoptosis was induced along with G0/G1 cell cycle arrest at the highest concentration of PJOV56 (6.0 µM). Thus, PJOV56 showed a dose-dependent mode of action related to induction of autophagy and apoptosis in HCT-116 cells.

Response of preantral follicles exposed to quinoxaline: A new compound with anticancer potential.

The culture of preantral follicles as an in vitro model to evaluate the toxicity of new anticancer drug has being established. Therefore, the aim of this study was to evaluate the effect of quinoxaline derivative the 2 2- (XYZC 6H 3 -CH=N-NH)-quinoxaline, 1 (QX) on caprine preantral follicles. We evaluate the follicular morphology and activation, proliferation and apoptosis of granulosa cells and finally the protein (ABCB1) and genes expression (cyclin/Cdks), respectively involved in multidrug resistance and cell cycle progression. Ovarian fragments containing primordial and developing follicles were exposed (in vitro culture) to different concentrations of QX (QX1.5, QX3.0 or QX6.0 µM/mL) during 6 days. To evaluate the effect of QX, the ovarian tissue was exposed to Paclitaxel 0.1 µg/mL (PTX - negative control) or in culture media without QX (MEM). At the end of exposure time, we realized that the QX (all concentrations) increased (P < .05) the normal morphology of preantral follicles compared to control (not treated ovarian tissue) or MEM. However, QX6.0 showed a enhanced (P < .05) on follicular activation (burnout) and apoptosis than QX1.5 and QX3.0. Expression of ABCB1 was similar between QX1.5 and QX6.0 and both were lower than control, MEM and PTX. Interestingly, the apoptosis rate in QX3.0 was similar to control and MEM and lower then QX1.5; QX6.0 and PTX. We conclude that quinoxaline may be a promising chemotherapeutic agent, however, other concentrations within a defined range (2-5.5 µM) could be widely investigated.

Antibiofilm Potential of Arenecarbaldehyde 2-Pyridinylhydrazone Derivatives Against Acinetobacter baumannii.

In the last 15 years, Acinetobacter baumannii has received special attention, mainly due to several resistance mechanisms and high rates of morbimortality. The ability to form biofilms contributes to the persistence of this microorganism in the hospital environment and facilitates the occurrence of nosocomial infections. Several studies have highlighted the pharmacological relevance of pyridines in the treatment and control of infectious diseases and others have related the anti-A. baumannii potential of hydrazine derivatives. Considering this scenario, we aimed to evaluate the antimicrobial and antibiofilm activity of 10 pyridinylhydrazone compounds against A. baumannii. The minimum inhibitory concentration of the compounds was determined by broth microdilution method and the antibiofilm activity was evaluated by inhibition and destruction biofilm assays. In addition, the cytotoxicity of the compounds in the J774A.1 cell line was also evaluated, and the selectivity index was calculated. Among the 10 pyridine compounds, the compounds B and D were able to inhibit the formation of biofilms and destroy bacterial biofilms even in a concentration of 12.5 µg/mL. Thus, the pyridine compounds evaluated can be a scaffold for the development of new substances with antimicrobial and antibiofilm activity.

Synthesis, biological activity, and mechanism of action of new 2-pyrimidinyl hydrazone and N-acylhydrazone derivatives, a potent and new classes of antileishmanial agents.

In this work, we report the antileishmanial activity of 15 compounds based on 2-pyrimidinyl hydrazone and N-acylhydrazone derivatives, being 13 new compounds. All compounds were tested against promastigotes and Leishmania amazonensis-GFP amastigotes, as well as murine macrophages. Besides, studies about the mechanism of action of the best antileishmanial compounds and in silico physicochemical and pharmacokinetic properties were performed. Studies about the mechanism of action of representative compounds of each class showed slight differences in mode of action and both are able to cause mitochondrial depolarization and increase of intracellular ROS levels. Through computational tool and further analysis of the physicochemical and pharmacokinetic parameters, the results indicating good oral bioavailability. These results confirm the potential of 2-pyrimidinyl derivatives as lead compounds in antileishmanial drug discovery.

Synthesis and antitubercular activity of new L-serinyl hydrazone derivatives.

A series of 32 L-serinyl hydrazone derivatives have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv, being also evaluated their cell viabilities in non infected and infected macrophages with Mycobacterium bovis Bacillus Calmette-Guerin (BCG). The compounds 8c, 8e, 8h and 8i, were non-cytotoxic and exhibited an important minimum inhibitory concentration (MIC) activity between 25 and 100 µg/mL, which can be compared with that of the tuberculostatic drug D-cicloserine (5-20 µg/mL).

Synthesis and biological aspects of mycolic acids: an important target against Mycobacterium tuberculosis.

Mycolic acids are an important class of compounds, basically found in the cell walls of a group of bacteria known as mycolata taxon, exemplified by the most famous bacteria of this group, the Mycobacterium tuberculosis (M. tb.), the agent responsible for the disease known as tuberculosis (TB). Mycolic acids are important for the survival of M. tb. For example, they are able to help fight against hydrophobic drugs and dehydration, and also allow this bacterium to be more effective in the host's immune system by growing inside macrophages. Due to the importance of the mycolic acids for maintenance of the integrity of the mycobacterial cell wall, these compounds become attractive cellular targets for the development of novel drugs against TB. In this context, the aim of this article is to highlight the importance of mycolic acids in drug discovery.