Phosphatase inhibitors BVT-948 and alexidine dihydrochloride inhibit sexual development of the malaria parasite Plasmodium berghei

BACKGROUND: With the emergence of resistance to front-line antimalarials, there is an urgent need to develop new medicines, including those targeting sexual development. This study aimed to assess the activity of a panel of phosphatase inhibitors against the sexual development of Plasmodium berghei and evaluate their potential as transmission-blocking agents. METHODS: Twenty-five compounds were screened for transmission-blocking activity in vitro using the P. berghei ookinete culture assay. The inhibitory effects on male gametogenesis, gamete-ookinete, and zygote-ookinete formation were evaluated. The transmission-blocking activity of two compounds was evaluated using an in vivo mosquito feeding assay. Their cytotoxic effects were assessed on the human cell line HepG2. RESULTS: Twelve compounds inhibited P. berghei ookinete formation with an IC(50) < 10 μM. Two compounds, BVT-948 and alexidine dihydrochloride, significantly inhibited different developmental stages from gametogenesis through ookinete maturation. They also showed a substantial in vivo transmission-blocking activity by the mosquito feeding assay. CONCLUSIONS: Some phosphatase inhibitors effectively inhibited Plasmodium sexual development and exhibited evident transmission-blocking activity, suggesting that phosphatases are valid targets for antimalarial development.