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A. J. Cariello, G. F. P. Souza, A. S. Foronda, M. C. Z. Yu, M. G. Oliveira, A. L. Höfling-Lima; In vitro Activity of S-nitrosothiols Against trophozoite of Acanthamoeba castellanii. Invest. Ophthalmol. Vis. Sci. 2008;49(13):506. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the potential in vitro microbicidal activity of three nitric oxide (NO) donors: two primary S-nitrosothiols (S-nitrosoglutathione, GSNO and S-nitroso-N-acetylcysteine, SNAC) and sodium nitroprusside (SNP), against Acanthamoeba Castellanii trophozoites.
Trophozoites of Acanthamoeba castellanii strain (ATCC 30011) were incubated in 96-well sterile tissue culture plates with GSNO or SNAC or SNP in three different concentrations: 100, 500 and 1000 µmolar. Control well received sterile distilled water in place of drug dilutions. After 3, 8 and 24 h of incubation, cellular viability was assessed in a single blinded trypan blue exclusion assay. The numbers of unstained (living) and stained (dead) trophozoites were counted in a Fuchs-Rosenthal haemacytometer using a phase contrast microscope. Cultures were tested in three independent experiments run in duplicates.
GSNO and SNAC exhibited a time and concentration-dependent amoebicidal activity (p<0.01). After 3 h, GSNO at the concentrations of 500 and 1000 µmolar killed 80.3 % and 89.9 % of trophozoites, and this activity was increased to 97.6 and 100 %, after 24 h, respectively. On the other hand, after 3 h, SNAC at the concentrations of 500 and 1000 µmolar, killed 7.8 % and 81.3 % of trophozoites, and this activity was increased to 51.9 and 95.9 %, after 24 h, respectively. However, neither GSNO nor SNAC displayed amoebicidal activities at the concentration 100 µmolar. Cultures incubated with SNP in the concentration range used, were not different from control. In all cases, there was not difference between the duplicate experiments or among the three independent experiments.
GSNO and SNAC have strong concentration and time-dependent amoebicidal activity against trophozoite of Acanthamoeba Catellanii in vitro, whereas SNP have no amoebicidal acticity in the same incubation conditions. These results suggest that the amoebicidal effect of NO may depend on NO lability in different NO donors and that primary S-nitrosothiols have potential to be used as therapeutic agents against Acanthamoeba.
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