Cryptosporidium spp. are gastrointestinal opportunistic protozoan parasites that infect humans, domestic animals, and wild animals all over the world. Cryptosporidiosis is the second leading infectious diarrheal disease in infants less than 5 years old. Cryptosporidiosis is a common zoonotic disease associated with diarrhea in infants and immunocompromised individuals. Consequently, cryptosporidiosis is considered a serious economic, veterinary, and medical concern. The treatment options for cryptosporidiosis are limited. To address this problem, we screened a natural product library containing 87 compounds of Traditional Chinese Medicines for anti-Cryptosporidium compounds that could serve as novel drug leads and therapeutic targets against C. parvum. To examine the anti-Cryptosporidium activity and half-maximal inhibitory doses (EC50) of these compounds, we performed in vitro assays (Cryptosporidium growth inhibition assay and host cell viability assay) and in vivo experiments in mice. In these assays, the C. parvum HNJ-1 strain was used. Four of the 87 compounds (alisol-A, alisol-B, atropine sulfate, and bufotalin) showed strong anti-Cryptosporidium activity in vitro (EC50 values = 122.9±6.7, 79.58±13.8, 253.5±30.3, and 63.43±18.7 nM, respectively), and minimum host cell cytotoxicity (cell survival > 95%). Furthermore, atropine sulfate (200 mg/kg) and bufotalin (0.1 mg/kg) also showed in vivo inhibitory effects. Our findings demonstrate that atropine sulfate and bufotalin are effective against C. parvum infection both in vitro and in vivo. These compounds may, therefore, represent promising novel anti-Cryptosporidium drug leads for future medications against cryptosporidiosis.
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