ABSTRACT
S(2) complex has been reported to have a direct antileishmanial effect. The possibility that the direct antileishmanial effect may be due to inhibition of key enzymes involved in glucose metabolism and/ or enzymes associated with virulence was investigated. Cell pellets were prepared from cultures of both axenic amastigotes and promastigotes of Leishmania major (MHOM/IQ/93/MRC6) and L. tropica (MHOM/IQ/93/MRC2). S(2) complex, at various concentrations, was added to the enzyme extracts prepared from the pellets. Results show that in the Embden-Meyerhof pathway, both hexokinase and glucose-phosphate isomerase but not fructophosphokinase were dose dependently inhibited. In the hexose-monophosphate shunt both glucose-6-phosphate dehydrogenase and ribose-5-phosphate isomerase were dose dependently inhibited. Malic dehydrogenase and malic enzyme from the citric-acid cycle were both dose dependently inhibited but succinate dehydrogenase from the same pathway was not inhibited. Both enzymes associated with virulence (protease and acid phosphatase), showed activation rather than inhibition at higher doses of S(2) complex. Thus, the direct antileishmanial effect of S(2) complex may result, partially or entirely, from the inhibition of enzymes that are necessary for the parasites' carbohydrate metabolism.
Subject(s)
Antiprotozoal Agents/pharmacology , Ascorbic Acid/pharmacology , Copper/pharmacology , Immunologic Factors/pharmacology , Leishmania major/enzymology , Leishmania tropica/enzymology , Niacinamide/pharmacology , Acid Phosphatase/drug effects , Acid Phosphatase/metabolism , Aldose-Ketose Isomerases/antagonists & inhibitors , Animals , Citric Acid Cycle/drug effects , Dose-Response Relationship, Drug , Enzyme Activation/drug effects , Glucose-6-Phosphate Isomerase/antagonists & inhibitors , Glucosephosphate Dehydrogenase/antagonists & inhibitors , Glycolysis/drug effects , Hexokinase/antagonists & inhibitors , Leishmania major/drug effects , Leishmania major/pathogenicity , Leishmania tropica/drug effects , Leishmania tropica/pathogenicity , Malate Dehydrogenase/antagonists & inhibitors , Pentose Phosphate Pathway/drug effects , Peptide Hydrolases/drug effects , Peptide Hydrolases/metabolism , VirulenceABSTRACT
This study was undertaken to try to determine the possible anti-leishmanial activity of S2-Complex, an organic complex of copper chloride, ascorbic acid, and nicotinamide. The promastigotes, axenic amastigotes, and intracellular amastigotes of both Leishmania major and Leishmania tropica were incubated with different concentrations of S2-Complex. The EC50 for each form was calculated. Results show that all forms of the parasites were dose dependently inhibited by S2-Complex. The promastigotes of both parasites were the most resistant with highest EC50 followed by axenic amastigotes. While intracellular amastigotes were the most sensitive with the lowest EC50. These results indicate that S2-Complex has a direct anti-leishmanial effect. When mice were treated with S2-Complex or BCG for four days before harvesting the macrophages, and the macrophages infected with both L. major and L. tropica, they showed increased phagocytosis and increased parasite killing. The results of S2-Complex were not statistically different from the immunomodulating agent BCG. These results indicate that S2-Complex has an immunomodulating effect in addition to the direct anti-leishmanial effect.
