Spectrophotometric assay of the interaction of Plasmodium berghei infected erythrocyte lysates and neutral red.

In order to reveal by absorption spectrophotometry the redox differences between the Plasmodium berghei infected erythrocyte lysates (MEL) and the healthy ones (HEL) we studied their interaction with the neutral red (NR) redox dye. The variation of the dye absorption intensity at 540 nm as a function of the hemoglobin content of the samples was attributed to the redox potential variation of the different hemoglobin aggregates formed in the samples containing different hemoglobin quantities. By short term treatment of the lysates with ascorbic acid in the presence of NR, great redox reactivity difference was proved between MEL and HEL as revealed by absorption and explained by the initial higher oxidation state of the Hb iron in MEL than in HEL.