In Vitro and In Vivo Activities of 2,3-Diarylsubstituted Quinoxaline Derivatives against Leishmania amazonensis

Abstract

Leishmaniasis is endemic in 98 countries and territories worldwide. The therapies available for leishmaniasis have serious side effects, thus prompting the search for new therapies. The present study investigated the antileishmanial activities of 2,3-diarylsubstituted quinoxaline derivatives against Leishmania amazonensis. The antiproliferative activities of 6,7-dichloro-2,3-diphenylquinoxaline (LSPN329) and 2,3-di-(4-methoxyphenyl)-quinoxaline (LSPN331) against promastigotes and intracellular amastigotes were assessed, and the cytotoxicities of LSPN329 and LSPN331 were determined. Morphological and ultrastructural alterations were examined by electron microscopy, and biochemical alterations, reflected by the mitochondrial membrane potential (⌬⌿m), mitochondrial superoxide anion (O 2 · ؊ ) concentration, the intracellular ATP concentration, cell volume, the level of phosphatidylserine exposure on the cell membrane, cell membrane integrity, and lipid inclusions, were evaluated. In vivo antileishmanial activity was evaluated in a murine cutaneous leishmaniasis model. Compounds LSPN329 and LSPN331 showed significant selectivity for promastigotes and intracellular amastigotes and low cytotoxicity. In promastigotes, ultrastructural alterations were observed, including an increase in lipid inclusions, concentric membranes, and intense mitochondrial swelling, which were associated with hyperpolarization of ⌬⌿m, an increase in the O 2 · ؊ concentration, decreased intracellular ATP levels, and a decrease in cell volume. Phosphatidylserine exposure and DNA fragmentation were not observed. The cellular membrane remained intact after treatment. Thus, the multifactorial response that was responsible for the cellular collapse of promastigotes was based on intense mitochondrial alterations. BALB/c mice treated with LSPN329 or LSPN331 showed a significant decrease in lesion thickness in the infected footpad. Therefore, the antileishmanial activity and mitochondrial mechanism of action of LSPN329 and LSPN331 and the decrease in lesion thickness in vivo brought about by LSPN329 and LSPN331 make them potential candidates for new drug development for the treatment of leishmaniasis.

Induction of Early Autophagic Process on Leishmania amazonensis by Synergistic Effect of Miltefosine and Innovative Semi-synthetic Thiosemicarbazone

“…After centrifugation, a suspension of 5 × 10 5 macrophages in RPMI was placed on glass coverslips in 24-wells microplate and incubated during 2 h, at 37°C and 5% CO 2 atmosphere, for cellular adhesion. After this period, the wells were washed and the macrophages were infected with L. amazonensis promastigotes in stationary phase (5–6 days) at a ratio of 7 parasites/1 mammalian cell, during 4 h, at 34°C and 5% CO 2 tension and then, the tested compounds were added during 48 h ( Kaplum et al, 2016 ). At the end of this period, the glass coverslips were subject to fixation with methanol during 10 min and stained with 10% Giemsa stain (GIBCO KaryoMax ® Giemsa), for 40 min.…”

N-acetyl-cysteine inhibits liver oxidative stress markers in BALB/c mice infected with Leishmania amazonensis

“…Leishmania parasite resides within macrophages and can cause inhibition of mitochondrial respiratory activity, inactivation of peroxidases, increased susceptibility to oxidant damage, inhibition of glycolysis, S-nitrosylation, ADP-ribosylation, tyrosine nitration of proteins, disruption of Fe-S clusters, zinc fingers or heme groups and peroxidation of membrane lipids ( Mauel & Ransijn 1997 ). The therapies available for leishmaniasis have serious side effects causing high toxicity if using at long periods ( de Menezes et al 2015 , Kaplum et al 2016) . Currently there is no vaccine available for prevention of Leishmania parasites for human use.…”

Acyclic Sesquiterpenes from the Fruit Pericarp of Sapindus saponaria Induce Ultrastructural Alterations and Cell Death in Leishmania amazonensis

“…Antileishmanial activity assays against intracellular amastigote forms were performed according to methods described by Kaplum et al [ 16 ]. Briefly, peritoneal macrophages were isolated from BALB/c mice by washing the peritoneal cavity with cold phosphate-buffered saline (PBS) supplemented with 3% FBS (protocol number 029/2014 approved by the Ethical Committee of the State University of Maringa).…”