The mechanism behind the antileishmanial effect of zinc sulphate. II. Effects on the enzymes of the parasites.
When used in vitro, zinc sulphate has a direct antileishmanial effect. To see if this effect involved the inhibition of the parasites' enzymes, extracts of the promastigotes and axenic amastigotes of Leishmania major (MHOM/IQ/93/MRC6) and L. tropica (MHOM/IQ/93/MRC2) were prepared. Zinc sulphate, at various concentrations, was then added to samples of these extracts before the activities, in the samples, of certain key enzymes of the Embden-Meyerhof pathway, hexose-monophosphate shunt and citric-acid cycle, and of two enzymes associated with virulence (protease and acid phosphatase), were determined. The zinc was found to inhibit every enzyme investigated, usually in a dose-dependent manner. Thus the direct antileishmanial effect of zinc may result, partially or entirely, from the inhibition of enzymes that are necessary for the parasites' carbohydrate metabolism and virulence.
Al-Mulla Hummadi
Y M
YM
Department of Pharmacology, College of Medicine, University of Baghdad, P.O. Box 61208, Baghdad 12114, Iraq.
Al-Bashir
N M
NM
Najim
R A
RA
D019747:Aldose-Ketose Isomerases / Q000037:antagonists & inhibitors; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005956:Glucose-6-Phosphate Isomerase / Q000037:antagonists & inhibitors; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors; D006593:Hexokinase / Q000037:antagonists & inhibitors; D007891:Leishmania / Q000187:drug effects* / Q000201:enzymology; D018320:Leishmania major / Q000187:drug effects / Q000201:enzymology; D007895:Leishmania tropica / Q000187:drug effects / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000037:antagonists & inhibitors; D014774:Virulence; D019287:Zinc Sulfate / Q000494:pharmacology*
D000981:Antiprotozoal Agents; D004791:Enzyme Inhibitors; D019287:Zinc Sulfate; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D006593:Hexokinase; D019747:Aldose-Ketose Isomerases; C022548:ribosephosphate isomerase; D005956:Glucose-6-Phosphate Isomerase