Abstract
Kinetoplast DNA (kDNA) bearing unusual mitochondrion of trypanosomatid parasites offers a new paradigm in chemotherapy modality. Topoisomerase II of Leishmania donovani (LdTopII), a key enzyme associated with kDNA replication, is emerging as a potential drug target. However, mode of action of LdTopII targeted compounds in the parasites at sub-cellular level remains largely unknown. Previously, we reported that an isobenzofuranone derivative, namely 3,5-bis(4-chlorophenyl)-7-hydroxyisobenzofuran-1(3H)-one (JVPH3), targets LdTopII and induces apoptosis-like cell death in L. donovani. Here, we elucidate the phenotypic changes and the events occurring at sub-cellular level caused by JVPH3 in L. donovani. In addition, we have evaluated the cytotoxicity and ultrastructural alterations caused by JVPH3 in two brazilian trypanosomatid pathogens viz. L. amazonensis and Trypanosoma cruzi. Despite killing these parasites, JVPH3 caused significantly different phenotypes in L. donovani and L. amazonensis. More than 90% population of parasites showed altered morphology. Mitochondrion was a major target organelle subsequently causing kinetoplast network disorganization in Leishmania. Altered mitochondrial architecture was evident in 75–80% Leishmania population being investigated. Quantification of mitochondrial function using JC-1 fluorophore to measure a possible mitochondrial membrane depolarization further confirmed the mitochondrion as an essential target of the JVPH3 corroborating with the phenotype observed by electron microscopy. However, the impact of JVPH3 was lesser on T. cruzi than Leishmania. The molecule caused mitochondrial alteration in 40% population of the epimastigotes being investigated. To our knowledge, this is the first report to evaluate the proliferation pattern and ultrastructural alterations caused in Brazilian kinetoplastid pathogens by a synthetic LdTopII inhibitor previously established to have promising in vivo activity against Indian strain of L. donovani.
Highlights
Trypanosomatid infection accounts for an alarming death tally in the continents of Asia, South America and Africa
In an earlier study in 2014, we reported the synthesis of an isobenzofuranone derivative, namely 3,5-bis(4chlorophenyl)-7-hydroxyisobenzofuran-1(3H)-one (JVPH3)[4] where we established that JVPH3 is a synthetic catalytic inhibitor of LdTopII and effective to reduce the L. donovani parasite burden in an experimental model of visceral leishmaniasis (VL)
Since trypanosomatid parasites share structural similarities in their kinetoplast DNA (kDNA) network and have a common mechanism for kDNA replication[5], we were interested to evaluate the effect of JVPH3 in Brazilian pathogens viz. L. amazonensis and Trypanosoma cruzi as well as to use the molecule JVPH3 as a model topoisomerase II inhibitor to study ultrastructural alterations caused in kinetoplastid parasites
Summary
Trypanosomatid infection accounts for an alarming death tally in the continents of Asia, South America and Africa. Trypanosomatid parasites possess an unusual mitochondrion which contains a structurally complex DNA known as kinetoplast DNA (kDNA) This is a planar network of maxicircles and minicircles catenated together. Our laboratory has been engaged to explore topoisomerase II of Leishmania donovani (LdTopII) as a drug target for anti-leishmanial therapeutics It is essential as well as interesting to study the effect of topoisomerase II inhibition within the parasite. Since trypanosomatid parasites share structural similarities in their kDNA network and have a common mechanism for kDNA replication[5], we were interested to evaluate the effect of JVPH3 in Brazilian pathogens viz. L_amazonensis and Trypanosoma cruzi as well as to use the molecule JVPH3 as a model topoisomerase II inhibitor to study ultrastructural alterations caused in kinetoplastid parasites. This report establishes the events occurring at sub-cellular level of three kinetoplastid pathogens by a parasite topoisomerase II targeted compound for the first time
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