Figure 7. Targeting blood-stage Plasmodium parasites by chemiluminescence-based photodynamic therapy (CL-PDT).
(A) Schematic depiction of a CL-PDT mechanism for targeting blood-stage malaria. (B) Effect of 100 µM ALA, 750 µM luminol (lum), 50 µM 4-iodophenol (ph), 50 µM SA and their combination (all 0.25% DMSO) on the growth of asynchronous 3D7 parasites. (C) Effect of 100 µM ALA, 750 µM luminol, 0.5 nM dihydroartemisinin (DHA), 50 µM SA and their combination (all 0.25% DMSO) on the growth of asynchronous 3D7 parasites. Parasite media was changed twice daily, and parasitemia increases were fit to an exponential growth equation.
Figure 7—figure supplement 1. Spectral compatibility of luminol and PPIX.
(A) Overlay of normalized absorbance spectrum of PPIX (black) and chemiluminescence spectrum of luminol (red). (B) Chemiluminescence of luminol (solid red) is attenuated in the presence of PPIX (solid black), giving rise to a difference spectrum (dashed black) that is similar to the absorbance spectrum of PPIX in the spectral region that overlaps luminol chemiluminescence. Solutions contained 25 mM luminol in 100 mM NaOH (aq), 0.5% (wt/vol) ammonium persulfate, and/or 70 µM PPIX.
Figure 7—figure supplement 2. Effect of combinatorial ALA, luminol, and 4-iodophenol treatment on parasite growth.
(A) Luminol concentrations as high as 750 µM (in 0.2% DMSO) have no effect on 3D7 parasite growth over 48 hr. (B) Effect of 750 µM luminol, 100 µM ALA, and their combination (all in 0.2% DMSO) on the growth of asynchronous 3D7 parasites. (C) Concentration dependence of growth inhibition of 3D7 parasites by 4-iodophenol (in 0.2% DMSO) over 48 hr. (D) Effect of 100 µM ALA, 50 µM 4-iodophenol, and their combination (all in 0.2% DMSO) on the growth of asynchronous 3D7 parasites.
Figure 7—figure supplement 3. Giemsa-stained blood smear of 3D7 parasite culture after 3 days of treatment in 100 µM ALA, 750 µM luminol, and 50 µM 4-iodophenol.
Arrows point to dead parasite remnants.
Figure 7—figure supplement 4. Efficacy of CL-PDT with drug-resistant parasites.
Effect of 100 µM ALA, 750 µM luminol, 50 µM 4-iodophenol, 50 µM SA (all 0.2% DMSO) and their combination on the growth of asynchronous (A) Dd2 parasites or (B) Kelch-13 I543T (MRA-1241) parasites.
Figure 7—figure supplement 5. Concentration dependence of growth inhibition of 3D7 parasites by DHA over 48 hr (in 0.2% DMSO).
Figure 7—figure supplement 6. Effect of 500 pM DHA, 100 µM ALA, and their combination (all in 0.2% DMSO) on the growth of asynchronous 3D7 parasites.
