Characterization of intracellular metabolites of axenic amastigotes of Leishmania donovani by H-1 NMR spectroscopy

The intracellular metabolites of long-term in vitro cultured axenic amastig otes of Leishmania donovani (strain Dd8) were determined and compared with those of promastigotes and intracellular amastigotes, employing proton NMR spectroscopy. The presence of two new metabolites, i.e. betaine and beta-hy droxybutyrate were reported. Betaine was detected in all the three stages b eing highest in the promastigotes while beta-hydroxybutyrate could be detec ted only in promastigotes and axenic amastigotes. Among other metabolites, succinate and valine were found in higher quantities in intracellular amast igotes and axenic amastigotes than in promastigotes. Acetoacetate was prese nt only in axenic and intracellular amastigotes. The comparative metabolite profile of different parasite forms reveals that axenic amastigotes seem t o represent an intermediate stage between promastigotes and intracellular a mastigotes in spite of their strong resemblance to intracellular amastigote s in morphology, infectivity, biochemical studies and even in the manifesta tion of amastigote specific A2 protein. (C) 1999 Elsevier Science B.V. All rights reserved.