title: In vitro sodium nitroprusside-mediated toxicity towards Leishmania amazonensis promastigotes and axenic amastigotes.
abstract: Leishmania parasites survive despite exposure to the toxic nitrosative oxidants during phagocytosis by the host cell. In this work, the authors investigated comparatively the resistance of Leishmania amazonensis promastigotes and axenic amastigotes to a relatively strong nitrosating agent that acts as a nitric oxide (NO) donor, sodium nitroprusside (SNP). Results demonstrate that SNP is able to decrease, in vitro, the number of L. amazonensis promastigotes and axenic amastigotes in a dose-dependent maner. Promastigotes, cultured in the presence of 0.25, 0.5, and 1 mmol L(-1) SNP for 24 h showed about 75% growth inhibition, and 97-100% when the cultures were treated with >2 mmol L(-1) SNP. In contrast, when axenic amastigotes were growing in the presence of 0.25-8 mM SNP added to the culture medium, 50% was the maximum of growth inhibition observed. Treated promastigotes presented reduced motility and became round in shape further confirming the leishmanicidal activity of SNP. On the other hand, axenic amastigotes, besides being much more resistant to SNP-mediated cytotoxicity, did not show marked morphological alteration when incubated for 24 h, until 8 mM concentrations of this nitrosating agent were used. The cytotoxicity toward L. amazonensis was attenuated by reduced glutathione (GSH), supporting the view that SNP-mediated toxicity triggered multiple oxidative mechanisms, including oxidation of thiols groups and metal-independent oxidation of biomolecules to free radical intermediates.
authors: Oswaldo Cruz Institute, Oswaldo Cruz Foundation-FIOCRUZ, Rio de Janeiro, Brazil. genestra@ioc.fiocruz.br
authors: Marcelo
authors: M
authors: Genestra
authors: Rômulo José
authors: RJ
authors: Soares-Bezerra
authors: Liliane
authors: L
authors: Gomes-Silva
authors: Daniela Leite
authors: DL
authors: Fabrino
authors: Thiago
authors: T
authors: Bellato-Santos
authors: Denise Barçante
authors: DB
authors: Castro-Pinto
authors: Marilene Marcuzzo
authors: MM
authors: Canto-Cavalheiro
authors: Leonor L
authors: LL
authors: Leon
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000494:pharmacology; D007894:Leishmania mexicana / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D008018:Life Cycle Stages / Q000187:drug effects*; D020030:Nitric Oxide Donors / Q000633:toxicity; D009573:Nitrites / Q000032:analysis / Q000378:metabolism; D009599:Nitroprusside / Q000633:toxicity*
chemical_list: D017077:Culture Media, Conditioned; D020030:Nitric Oxide Donors; D009573:Nitrites; D009599:Nitroprusside; D001119:Arginase; D005978:Glutathione