Alternative oxidase inhibitors as antiparasitic agents against scuticociliatosis.
Philasterides dicentrarchi causes a severe disease in turbot, and at present there are no drugs available to treat infected fish. We have previously demonstrated that, in addition to the classical respiratory pathway, P. dicentrarchi possesses an alternative mitochondrial respiratory pathway that is cyanide-insensitive and salicylhydroxamic acid (SHAM)-sensitive. In this study, we found that during the initial phase of growth in normoxia, ciliate respiration is sensitive to the natural polyphenol resveratrol (RESV) and to Antimycin A (AMA). However, under hypoxic conditions, the parasite utilizes AMA-insensitive respiration, which is completely inhibited by RESV and by the antioxidant propyl gallate (PG), an alternative oxidase (AOX) inhibitor. PG caused significantly dose-dependent inhibition of the in vitro growth of the parasite under normoxia and hypoxia and an over-expression of heat shock proteins of the Hsp70 subfamily. RESV and PG may affect the protective role of the AOX against mitochondrial oxidative stress, leading to an impaired mitochondrial membrane potential and mitochondrial dysfunction, which the parasite attempts to neutralize by increasing the expression of Hsp70. In view of the antiparasitic effects induced by AOX inhibitors and the absence of AOX in their host, this enzyme constitutes a potential target for the development of new drugs against scuticociliatosis.
Department of Microbiology and Parasitology, Laboratory of Parasitology, Institute of Research and Food Analysis,University of Santiago de Compostela,Spain.
Natalia
N
Mallo
Department of Cell Biology and Ecology, Faculty of Biology,University of Santiago de Compostela,Spain.
Jesús
J
Lamas
Department of Microbiology and Parasitology, Laboratory of Parasitology, Institute of Research and Food Analysis,University of Santiago de Compostela,Spain.
José M
JM
Leiro
D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D000977:Antiparasitic Agents / Q000494:pharmacology*; D019069:Cell Respiration / Q000187:drug effects; D005412:Flatfishes / Q000469:parasitology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors*; D016802:Oligohymenophorea / Q000187:drug effects / Q000201:enzymology*; D018384:Oxidative Stress / Q000187:drug effects; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D010940:Plant Proteins / Q000037:antagonists & inhibitors*; D011435:Propyl Gallate / Q000494:pharmacology*; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology; D000099188:Alternative Oxidase
D000968:Antimycin A; D000975:Antioxidants; D000977:Antiparasitic Agents; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D011435:Propyl Gallate; D000077185:Resveratrol; D013267:Stilbenes; D000099188:Alternative Oxidase