title: NO donors inhibit Leishmania infantum cysteine proteinase activity.
abstract: Nitric oxide (NO) releasing drugs (e.g., glyceryl trinitrate) were successfully used in the treatment of cutaneous leishmaniasis in man. In the present study, the effect of NO donors on the catalytic activity of the cysteine proteinase from promastigotes of Leishmania infantum, an agent of Old World visceral and cutaneous leishmaniases, is reported. In particular, one equivalent of NO, released by the NO donors S-nitrosoglutathione, glyceryl trinitrate, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide, 3-morpholinosydnonimine, S-nitrosoacetylpenicillamine and sodium nitroprusside, inhibited one equivalent of the parasite cysteine proteinase. As expected, NO-deprived compounds did not affect the catalytic activity of the parasite cysteine proteinase. Furthermore, the absorption spectrum of the (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide-treated inactive L. infantum enzyme displayed a maximum in the 330-350 nm wavelength range. The reducing agents dithiothreitol and L-ascorbic acid completely prevented parasite cysteine proteinase inhibition by NO, fully restored the catalytic activity, and reversed the NO-induced absorption spectrum of the inactive enzyme. Moreover, S-nitrosoacetylpenicillamine displayed a leishmanicidal effect, inhibiting the cysteine proteinase activity in vivo. As expected, the NO-deprived compound N-acetylpenicillamine did not affect significantly the parasite viability and the enzyme activity in vivo. These data suggest that the L. infantum cysteine proteinase undergoes NO-mediated S-nitrosylation, thereby representing a possible mechanism of antiparasitic host defence.
authors.affiliation: Dipartimento di Biologia, Università "Roma Tre", Rome, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Salvati
authors.forename: M
authors.initials: M
authors.lastname: Mattu
authors.forename: M
authors.initials: M
authors.lastname: Colasanti
authors.forename: A
authors.initials: A
authors.lastname: Scalone
authors.forename: G
authors.initials: G
authors.lastname: Venturini
authors.forename: L
authors.initials: L
authors.lastname: Gradoni
authors.forename: P
authors.initials: P
authors.lastname: Ascenzi
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D007700:Kinetics; D018314:Leishmania infantum / Q000187:drug effects*; D007976:Leupeptins / Q000494:pharmacology; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009574:Nitro Compounds / Q000494:pharmacology; D005996:Nitroglycerin / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009603:Nitroso Compounds / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors*; D026422:S-Nitrosoglutathione
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; C093285:NOC 18; D020030:Nitric Oxide Donors; D009574:Nitro Compounds; D009603:Nitroso Compounds; D015800:Protozoan Proteins; C110881:S-nitro-N-acetylpenicillamine; D009599:Nitroprusside; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; C010005:N-acetylpenicillamine; C002385:linsidomine; C061872:FK 409; D008981:Molsidomine; D003546:Cysteine Endopeptidases; D005996:Nitroglycerin; D005978:Glutathione; D010396:Penicillamine; C032854:leupeptin; D001205:Ascorbic Acid; D004229:Dithiothreitol