Paracoccidioides: perfil proteômico após exposição à argentilactona, avaliação da inibição por argentilactona sobre isocitrato liase e padronização do método de micro-ensaio para as enzimas do ciclo do glioxilato
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2014-03-14
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Universidade Federal de Goiás
Resumo
Dimorphic fungi of the genus Paracoccidioides spp. are etiologic agent of
paracoccidioidomycosis (PCM), a human systemic mycosis with high incidence in
Brazil. Due to the toxicity of existing drugs, the long treatment and resistant isolates, the
search for new therapies has become relevant. In this study, we verified the activity
argentilactone, extracted the essential oil of Hyptis ovalifolia and its derivatives against
Paracoccidioides. The results showed a dose- dependent inhibition of argentilactone
fungus in yeast cells, as well as during dimorphism. Inhibition of cell growth was higher
than in the presence of acetate than glucose. Argentilactone also been shown to inhibit
the native enzyme isocitrate lyase Paracoccidioides (PbICL) and recombinant
(PbICLr). The greatest inhibition was observed in the presence of acetate, a condition in
which the enzyme is demonstrably more active than glucose. In silico analysis showed
that argentilactone binds to the catalytic site of PbICL. The micro-assays for PbICLr
and malate synthase (PbMLSr) were standardized, allowing the search for inhibiting
compounds on a large scale. A global analysis of Paracoccidioides proteomic profile in
response to argentilactone allowed visualization of metabolic adaptation of the fungus
to the compound. Important metabolic pathways were suppressed explaining the strong
action of the compound on fungal growth and viability. In this study, alternative
metabolic pathways adopted by the fungus were elucidated resulting in a better
understanding of the mode of action of the compound. It was also evaluated the
cytotoxicity and DNA damage caused by argentilactone in human cells, MRC5 and
A549, concluding that it occurs in a dose-dependent manner. Thus, it is concluded that
argentilactone is a candidate prototype antifungal for the treatment of PCM.
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PRADO, R. S. Paracoccidioides: perfil proteômico após exposição à argentilactona, avaliação da inibição por argentilactona sobre isocitrato liase e padronização do método de micro-ensaio para as enzimas do ciclo do glioxilato. 2014. 191 f. Tese (Doutorado em Medicina Tropical e Saúde Publica) - Universidade Federal de Goiás, Goiânia, 2014.