**Acknowledgements**

**Figure 5.** Heme biosynthesis of malaria parasites. The enzymes in the pathway are localized in the mitochondrion, api‐

Our recent study resolved this issue: in the presence of ferrous ion, ALA efficiently inhibited the *in vitro* growth of *Plasmodium* even without light exposure [94]. Because there was a previous report on protection from malaria by elevated zinc protoporphyrin, which binds to heme crystals to inhibit further crystallization to form hemozoin [95], we first investigated effects of metal ions on growth inhibition by ALA using an *in vitro* culture system of *P. falciparum*. Our results showed that treatment with 10 μM sodium ferrous citrate (SFC) and 0.2 mM ALA increased the growth inhibition to more than 50% when compared with that of 0.2 mM ALA alone. Notably, no other metal ions (e.g., zinc, lead, and copper) had such a syner‐

Next, to determine heme intermediate, we analyzed the cell extract of the parasite using HPLC. The extract contained three major intermediates: coproporphyrin I, coproporphyrin III (CPIII), and PPIX. Unlike in cancer cells, CPIII was majorly accumulated in the apicoplast. Although

gistic effect, indicating that only ferrous compounds are synergistic with ALA.

coplast, and cytosol [89-91].

28 An Overview of Tropical Diseases

We would like to thank Y. Koyama for the helpful discussion.This work was supported by a Grant-in-aid for Scientific Research (no. 26253025) from the Japanese Society for the Promotion of Science. We also acknowledge the support of the Science and Technology Research Promo‐ tion Program for Agriculture, Forestry, Fisheries and Food Industry and JST/ JICA, SATREPS (Science and Technology Research Partnership for Sustainable Development) (no. 10000284).
