Synthetic hydrazones: In silico studies and in vitro evaluation of the antileishmania potential.

Bioprospecting and synthesis of strategically designed molecules have been used in the search for drugs that can be in leishmaniasis. Hydrazones (HDZ) are promising compounds with extensive biological activities. The objective of this work was to perform in silico studies of hydrazones 1-5 and to evaluate their antileishmanial, cytotoxic and macrophage immunomodulatory potential in vitro. Hydrazones were subjected to prediction and molecular docking studies. Antileishmanial protocols on promastigotes and amastigotes of Leishmania amazonensis, cytotoxicity and macrophage immunomodulatory activity were performed. Hydrazones showed a good pharmacokinetic profile and hydrazone 3 and hydrazone 5 were classified as non-carcinogenic. Hydrazone 5 obtained the best conformation with trypanothione reductase. Hydrazone 1 and hydrazone 3 obtained the best mean inhibitory concentration (IC50) values for promastigotes, 4.4-61.96 µM and 8.0-58.75 µM, respectively. It also showed good activity on intramacrophagic amastigotes, with hydrazone 1 being the most active (IC50 = 6.79 µM) with selectivity index of 56. In cytotoxicity to macrophages hydrazone 3 was the most cytotoxic (CC50 = 256.3 ± 0,04 µM), while hydrazone 4 the least (CC50 = 1055.9 ± 0.03 µM). It can be concluded that the hydrazones revealed important pharmacokinetic and toxicological properties, in addition to antileishmania potential in reducing infection and infectivity in parasitized macrophages.

Antileishmania and immunomodulatory potential of cashew nut shell liquid and cardanol.

Conventional treatments for leishmaniasis have caused serious adverse effects, poor tolerance, development of resistant strains. Natural products have been investigated as potential therapeutic alternatives. The cashew nut shell liquid (CNSL) is a natural source of phenolic compounds with several biological activities, where cardanol (CN) is considered one of the most important and promising compounds. This study aimed to evaluate antileishmanial, cytotoxic and immunomodulatory activities of CNSL and CN. Both showed antileishmanial potential, with IC50 for CNSL and CN against Leishmania infantum: 148.12 and 56.74 µg/mL; against Leishmania braziliensis: 85.71 and 64.28 µg/mL; against Leishmania major: 153.56 and 122.31 µg/mL, respectively. The mean cytotoxic concentrations (CC50) of CNSL and CN were 37.51 and 31.44 µg/mL, respectively. CNSL and CN significantly reduced the percentage of infected macrophages, with a selectivity index (SI) >20 for CN. CNSL and cardanol caused an increase in phagocytic capacity and lysosomal volume. Survival rates of Zophobas morio larvae at doses of 3; 30 and 300 mg/kg were: 85%, 75% and 60% in contact with CNSL and 85%, 60% and 40% in contact with CN, respectively. There was a significant difference between the survival curves of larvae when treated with CN, demonstrating a significant acute toxicity for this substance. Additional investigations are needed to evaluate these substances in the in vivo experimental infection model.

Isopropyl Gallate, a Gallic Acid Derivative: In Silico and In Vitro Investigation of Its Effects on Leishmania major.

Isopropyl gallate (IPG) is a polyphenol obtained from alterations in the gallic acid molecule via acid catalysis with previously reported leishmanicidal and trypanocidal activities. The present study aims to evaluate in silico binding activity towards some targets for antileishmanial chemotherapy against Leishmania major species, and ADMET parameters for IPG, as well as in vitro antileishmanial and cytotoxic effects. Molecular docking was performed using AutoDockVina and BIOVIA Discovery Studio software, whereas in silico analysis used SwissADME, PreADMET and admetSAR software. In vitro antileishmanial activity on promastigotes and amastigotes of Leishmania major, cytotoxicity and macrophages activation were assessed. IPG exhibited affinity for pteridine reductase (PTR1; -8.2 kcal/mol) and oligopeptidase B (OPB; -8.0 kcal/mol) enzymes. ADMET assays demonstrated good lipophilicity, oral bioavailability, and skin permeability, as well as non-mutagenic, non-carcinogenic properties and low risk of cardiac toxicity for IPG. Moreover, IPG inhibited the in vitro growth of promastigotes (IC50 = 90.813 µM), presented significant activity against amastigotes (IC50 = 13.45 µM), promoted low cytotoxicity in macrophages (CC50 = 1260 µM), and increased phagocytic capacity. These results suggest IPG is more selectively toxic to the parasite than to mammalian cells. IPG demonstrated acceptable in silico pharmacokinetics parameters, and reduced infection and infectivity in parasitized macrophages, possibly involving macrophage activation pathways and inhibition of leishmania enzymes.

Synthesis and antileishmanial activity of naphthoquinone-based hybrids / Síntesis y actividad antileishmania de híbridos naftoquinónicos / Síntese e atividade antileishmania de híbridos naftoquinónicos

SUMMARY Introduction: Leishmaniasis is a disease caused by protozoa of the genus Leishmania and is considered endemic in 98 countries. Treatment with pentavalent antimonials has a high toxicity, which motivates the search for effective and less toxic drugs. α- and β-lapachones have shown different biological activities, including antiprotozoa. In recent studies, the isonicotinoylhydrazone and phthalazinylhydrazone groups were considered innovative in the development of antileishmania drugs. Molecular hybridization is a strategy for the rational development of new prototypes, where the main compound is produced through the appropriate binding of pharmacophoric subunits. Aims: To synthesize four hybrids of α- and β-lapachones, together with the isonicotinoylhydrazone and phthalazinylhydrazone groups and to determine the antileishmania activity against the promastigotic forms of L. amazonensis, L. infantum and L. major. Results: β-lapachone derivatives were more active against all tested leishmania species. βACIL (IC50 0.044μM) and βHDZ (IC50 0.023μM) showed 15-fold higher activity than amphotericin B. The high selectivity index exhibited by the compounds indicates greater safety for vertebrate host cells. Conclusion: The results of this work show that the hybrids βACIL and (3HDZ are promising molecules for the development of new antileishmania drugs.

RESUMEN Introducción: Leishmaniasis es una enfermedad causada por protozoos del género Leishmania y se considera endémica en 98 países. El tratamiento con antimoniales pentavalentes tiene una alta toxicidad, lo que motiva la búsqueda de fármacos eficaces y menos tóxico. α- y β-lapachones han mostrado diferentes actividades biológicas, incluido los antiprotozoarios. En estudios recientes, los grupos isonicotinoilhidra-zona y ftalazinilhidrazona se consideraron innovadores en el desarrollo de fármacos antileishmania. La hibridación molecular es una estrategia para el desarrollo racional de nuevos prototipos, donde el compuesto principal se produce a través de la unión apropiada de subunidades farmacofóricas. Objetivos: Sintetizar cuatro híbridos de α- y β-lapachones, junto con los grupos isonicotinoilhidrazona y ftalazinilhidrazona y determinar la actividad antileishmania frente a las formas promastigotas de L. amazonensis, L. infantum y L. major. Resultados: Los derivados de β-lapachone fueron más activos contra todas las especies de leishmania probadas. La βACIL (CI50 0,044μM) y βHDZ (CI50 0,023μM) mostraron actividad 15 veces mayor que la anfotericina B. El alto índice de selectividad que presentan los compuestos indica una mayor seguridad para las células huésped del vertebrado. Conclusión: Los resultados de este trabajo demuestran que los híbridos (ACIL y (HDZ son moléculas prometodoras para el desarrollo de nuevos fármacos antileishmania.

RESUMO Introdução: A leishmaniose é uma doença causada por protozoários do género Leishmania e é considerada endémica em 98 países. O tratamento com antimoniais pentavalentes apresenta alta toxicidade, o que motiva a pesquisa por medicamentos eficazes e menos tóxicos. α- e β-lapachones tém mostrado diferentes atividades biológicas, incluindo antiprotozoários. Em estudos recentes, os grupos isonicotinoilhi-drazona e ftalazinilhidrazona foram considerados inovadores no desenvolvimento de drogas antileishmania. A hibridização molecular é uma estratégia para o desenvolvimento racional de novos protótipos, onde o composto principal é produzido através da ligação apropriada de subunidades farmacofóricas. Objetivos: Sintetizar quatro híbridos de α- e β-lapachones, juntamente com os grupos isonicotinoil-hidra-zona e ftalazinilhidrazona e determinar a atividade antileishmania contra as formas promastigóticas de L. amazonensis, L. infantum e L. major. Resultados: Os derivados de β-lapachona foram mais ativos contra todas as espécies de leishmania testadas. BACIL (IC50 0,044 μM) e βHDZ (IC50 0,023 μM) apresentaram atividade 15 vezes maior do que a anfotericina B. O alto índice de seletividade dos compostos indica maior segurança para células hospedeiras de vertebrados. Conclusaõ: Os resultados deste trabalho mostram que os híbridos βACIL e βHDZ são moléculas promissoras para o desenvolvimento de novos fármacos antileishmania.

Limonene-carvacrol: A combination of monoterpenes with enhanced antileishmanial activity.

BACKGROUND: Leishmaniasis is a parasitosis with a wide incidence in developing countries. The drugs which are indicated for the treatment of this infection usually are able to promote high toxicity. PURPOSE: A combination of limonene and carvacrol, monoterpenes present in plants with antiparasitic activity may constitute an alternative for the treatment of these diseases. METHODS: In this study, the antileishmania activity against Leishmania major, cytotoxicity tests, assessment of synergism, parasite membrane damage tests as well as molecular docking and immunomodulatory activity of limonene-carvacrol (Lim-Car) combination were evaluated. RESULTS: The Lim-Car combination (5:0; 1:1; 1:4; 2:3; 3:2; 4:1 and 0:5) showed potential antileishmania activity, with mean inhibitory concentration (IC50) ranging from 5.8 to 19.0 µg.mL-1. They demonstrated mean cytotoxic concentration (CC50) ranging from 94.1 to 176.0 µg.mL-1, and did not show significant hemolytic effect. In the investigation of synergistic interaction, the 4:1 Lim-Car combination showed better fractional inhibitory concentration (FIC) index as well as better activity on amastigotes and IS. The samples caused considerable damage to the parasite membrane this monoterpene activity seems to be more related to Trypanothione Reductase (TryR) enzyme interaction, demonstrated in the molecular docking assay. In addition, the 4:1 Lim-Car combination stimulated macrophage activation, and showed at was the best association, with reduction of infection and infectivity of parasitized macrophages. CONCLUSION: The 4:1 Lim-Car combination appears to be a promising candidate as a monotherapeutic antileishmania agent.

Methods of macrophages activation and their modulation for the prospection of new antileishmania drugs: a review

Leishmaniasis are a group of parasitic zoonoses provoked by protozoa from Leishmania genus and belonging to the group of neglected tropical diseases. The search and development for new drugs is necessary not only to investigate the activity against only the parasite, but also to investigate the possible synergistic effect of new drugs with the immune response of the host. In the present review, macrophages are pointed out as potential targets of the investigation of new antileishmanial drugs, and some methodologies in order to assess their activation as response to Leishmania-infected cells are presented. Macrophages are an important role in the cellular immune response, since they are cells from mononuclear phagocytic system, the first line of defense of the host, against parasites from Leishmania genus. Phagocytic capacity, lysosomal activity, increase of nitric oxide and intracellular calcium levels are parameters regarding assessment of macrophages activation which allow them to be more hostile in order to solve the infection and lead the patient to cure. In this context, we bring 19 substances already investigated and that activate macrophages, what makes them promising in the antileishmanial treatment. Therefore, assessment of macrophages activation, are important tools for discovery of immunomodulatory compounds which have potential to act in synergism with host immune response. Such compounds might be promising as monotherapy in the treatment of leishmaniasis, as well as being used as adjuvants in vaccines and/or in combination with conventional drugs.