title: LQB-118, an orally active pterocarpanquinone, induces selective oxidative stress and apoptosis in Leishmania amazonensis.
abstract: OBJECTIVE
  The pterocarpanquinone LQB-118, previously demonstrated to be effective in vivo via oral delivery, was investigated for its mechanism in selective parasite killing.
  
  
  METHODS
  Oxidative stress in Leishmania amazonensis was analysed by evaluating reactive oxygen species (ROS) production (2',7'-dichlorodihydrofluorescein diacetate) and the loss of mitochondrial membrane potential (ΔΨm) using rhodamine, JC-1 and MitoCapture. Ultrastructural analysis was performed using transmission electron microscopy (TEM). DNA fragmentation was evaluated using terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL).
  
  
  RESULTS
  Treatment with LQB-118 induced ROS production in the promastigotes of L. amazonensis in a concentration-dependent manner for the first 4 h and was sustained for 24 h. TEM analysis revealed several alterations typical of apoptosis. Promastigotes presented a reduction of ΔΨm after 24 h of incubation with 2.5 μM (18.7%), 5 μM (63.7%) or 10 μM (70.7%) LQB-118. A sub-G0/G1 cell cycle phenotype was observed in 21%-83% of the promastigotes incubated with 1.25-10 μM LQB-118. Concentration-dependent DNA fragmentation was observed in promastigotes treated with 2.5-10 μM LQB-118, and selective DNA fragmentation was observed in intracellular amastigotes after 72 h with 2.5 μM treatment.
  
  
  CONCLUSIONS
  Our results suggest that LQB-118 selectively induces ROS-triggered and mitochondria-dependent apoptosis in this parasite.
authors.affiliation: Laboratório de Bioquímica de Tripanosomatídeos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
authors.forename: Grazielle Alves
authors.initials: GA
authors.lastname: Ribeiro
authors.forename: Edézio Ferreira
authors.initials: EF
authors.lastname: Cunha-Júnior
authors.forename: Roberta Olmo
authors.initials: RO
authors.lastname: Pinheiro
authors.forename: Silvia Amaral Gonçalves
authors.initials: SA
authors.lastname: da-Silva
authors.forename: Marilene Marcuzzo
authors.initials: MM
authors.lastname: Canto-Cavalheiro
authors.forename: Alcides José Monteiro
authors.initials: AJ
authors.lastname: da Silva
authors.forename: Paulo Roberto R
authors.initials: PR
authors.lastname: Costa
authors.forename: Chaquip Daher
authors.initials: CD
authors.lastname: Netto
authors.forename: Rossana C N
authors.initials: RC
authors.lastname: Melo
authors.forename: Elmo Eduardo
authors.initials: EE
authors.lastname: Almeida-Amaral
authors.forename: Eduardo Caio
authors.initials: EC
authors.lastname: Torres-Santos
mesh_terms: D000981:Antiprotozoal Agents / Q000494:pharmacology*; D017209:Apoptosis; D053938:DNA Fragmentation; D020287:In Situ Nick-End Labeling; D007891:Leishmania / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D009285:Naphthoquinones / Q000494:pharmacology*; D018384:Oxidative Stress; D036343:Pterocarpans / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000032:analysis
chemical_list: D000981:Antiprotozoal Agents; C569361:LQB 118; D009285:Naphthoquinones; D036343:Pterocarpans; D017382:Reactive Oxygen Species