Discovery of Novel Anti-cryptosporidial Activities From Natural Products by in vitro High-Throughput Phenotypic Screening.

Zi Jin,Guan Zhu,Haili Zhang,Jingbo Ma

doi:10.3389/fmicb.2019.01999

Zi Jin, Guan Zhu + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2019.01999

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Abstract

Cryptosporidium parvum is a globally distributed zoonotic protozoan parasite of both medical and veterinary importance. Nitazoxanide is the only FDA-approved drug to treat cryptosporidiosis in immunocompetent people, but it is not fully effective. There is no drug approved by FDA for use in immunocompromised patients or in animals. In the present study, we conducted phenotypic screening of 800 nature products with defined chemical structures for potential novel activity against the growth of C. parvum in vitro. We identified a large number of compounds showing low to sub-micromolar anti-cryptosporidial activity, and fully characterized 16 top hits for anti-parasitic efficacies in vitro [EC50 values from 0.122 to 3.940 μM, cytotoxicity (TC50) values from 6.31 to >100 μm] and their safety margins. Among them, 11 compounds were derived from plants with EC50 values from 0.267 to 3.940 μM [i.e., cedrelone, deoxysappanone B 7,4′-dimethyl ether (Deox B 7,4), tanshinone IIA, baicalein, deoxysappanone B 7,3′-dimethyl ether acetate, daunorubicin, dihydrogambogic acid, deacetylgedunin, deacetoxy-7-oxogedunin, dihydrotanshinone I, 2,3,4′-trihydroxy-4-methoxybenzophenone, and 3-deoxo-3beta-hydroxy-mexicanolide 16-enol ether]. Three compounds with sub-micromolar EC50 values (i.e., cedrelone, Deox B 7,4, and baicalein) were further investigated for their effectiveness on various parasite developmental stages in vitro. Cedrelone and baicalein were more effective than Dexo B 7,4 when treating parasite for shorter periods of time, but all three compounds could kill the parasite irreversibly. These findings provide us a large selection of new structures derived from natural products to be explored for developing anti-cryptosporidial therapeutics.

Highlights

Cryptosporidium parvum (Phylum Apicomplexa) is a zoonotic protozoan parasite causing cryptosporidiosis in humans and animals
No drugs are FDA-approved for treating cryptosporidiosis in animals in the United States, while nitazoxanide (NTZ) is the only drug approved by FDA for treating cryptosporidial infection in immunocompetent human patients, but not in people with compromised immunity (Bailey and Erramouspe, 2004; Rossignol et al, 2006; Abubakar et al, 2007; Amadi et al, 2009; Chavez and White, 2018)
In primary screening at 10 μM, we have observed a wide range of activity of the 800 natural products on the growth of C. parvum in vitro (Figure 1 and Supplementary Table S1)

Summary

Introduction

Cryptosporidium parvum (Phylum Apicomplexa) is a zoonotic protozoan parasite causing cryptosporidiosis in humans and animals. Cryptosporidium is one of the top agents causing diarrhea and associated with stunted growth and increased fatality in children (Molbak et al, 1997; Checkley et al, 1998; Mondal et al, 2009; Kotloff et al, 2013; Mmbaga and Houpt, 2017). It is an important water-borne and foodborne pathogen, frequently causing cryptosporidiosis outbreaks around world. No drugs are FDA-approved for treating cryptosporidiosis in animals in the United States, while nitazoxanide (NTZ) is the only drug approved by FDA for treating cryptosporidial infection in immunocompetent human patients, but not in people with compromised immunity (Bailey and Erramouspe, 2004; Rossignol et al, 2006; Abubakar et al, 2007; Amadi et al, 2009; Chavez and White, 2018)

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