Sterol methyltransferase a target for anti-amoeba therapy: towards transition state analog and suicide substrate drug design

Kidane, Medhanie E.; Vanderloop, Boden H.; Zhou, Wenxu; Thomas, Crista D.; Ramos, Emilio; Singha, Ujjal K.; Chaudhuri, Minu; Nes, W. David

doi:10.1194/jlr.m079418

Cited by 22 publications

(55 citation statements)

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“…Structure-based drug design as a strategy is limited, since only a handful of proteins have been crystallized and structurally 378 investigated as potential therapeutic targets. These include genes involved in shikimate, histidine, and steroid 379 biosynthesis, and more recently, glucose metabolism 48,[54][55][56][57][58] . As a eukaryotic organism, these amoebae share common 380 functional pathways with humans in which unwanted side effects can result due to the required effective concentrations 381 needed from the current treatments used (e.g.…”

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confidence: 99%

Discovery of repurposing drug candidates for the treatment of diseases caused by pathogenic free-living amoebae

Rice¹,

Colon

Chen

et al. 2020

Preprint

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33Diseases caused by pathogenic free-living amoebae include primary amoebic meningoencephalitis (Naegleria 34 fowleri), granulomatous amoebic encephalitis (Acanthamoeba spp.), Acanthamoeba keratitis, and Balamuthia amoebic 35 encephalitis (Balamuthia mandrillaris). Each of these are difficult to treat and have high morbidity and mortality rates 36 due to lack of effective therapeutics. In pursuit of repurposing drugs for chemotherapies, we conducted a high throughput 37 phenotypic screen of 12,000 compounds from the Calibr ReFRAME library. We discovered a total of 58 potent inhibitors 38 (IC 50 <1 M) against N. fowleri (n=19), A. castellanii (n=12), and B. mandrillaris (n=27) plus an additional 90 micromolar 39 inhibitors. Of these, 113 inhibitors have never been reported to have activity against Naegleria, Acanthamoeba or 40 Balamuthia. Rapid onset of action is important for new anti-amoeba drugs and we identified 19 compounds that inhibit 41 N. fowleri in vitro within 24 hours (halofuginone, NVP-HSP990, fumagillin, bardoxolone, belaronib, and BPH-942, 42 solithromycin, nitracrine, quisinostat, pabinostat, pracinostat, dacinostat, fimepinostat, sanguinarium, radicicol, 43 acriflavine, REP3132, BC-3205 and PF-4287881). These compounds inhibit N. fowleri in vitro faster than any of the 44 drugs currently used for chemotherapy. The results of these studies demonstrate the utility of phenotypic screens for 45 discovery of new drugs for pathogenic free-living amoebae, including Acanthamoeba for the first time. Given that many 46 of the repurposed drugs have known mechanisms of action, these compounds can be used to validate new targets for 47 structure-based drug design. 48 49 Author Summary 50 Free-living amoebae (FLA) are ubiquitous in soil and freshwater and most are non-pathogenic to people; 51 however, three different pathogenic FLA have been found to cause severe, most often fatal diseases in humans. Due to 52 poor detection and inadequate treatment options available for pathogenic FLA, the fatality rates are still > 90% for the 53 diseases caused by Balamuthia mandrillaris, Naegleria fowleri, and Acanthamoeba spp. With hundreds of cases in the 54 United States and many more cases reported worldwide, there is still an urgent clinical need for effective diagnosis and 55 specific treatments discovered against these opportunistic parasites. Drug repurposing is a powerful approach for drug-56 discovery because it significantly improves the discovery time, reduces the amount of resources, and decreases costs 57 required to advance lead candidate drugs of interest into the clinic. This is extremely helpful for neglected diseases 58 including pathogenic FLA where there is a need for new active therapies with limited budgets. This report addresses the 59 discovery of new active drugs with potential for repurposing, multiple new drug classes that inhibit pathogenic FLA, and 60 numerous putative drug targets that can be used as tools for further investigation and structure-based drug design. 61 7 . Naegleria, being ther...

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Discovery of repurposing drug candidates for the treatment of diseases caused by pathogenic free-living amoebae

Rice¹,

Colon

Chen

et al. 2020

Preprint

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“…EL was recently reported as an inhibitor of Acanthamoeba spp. trophozoite growth with an IC 50 value of 7 nM, and in this study, EL yielded 20-fold higher inhibition compared to the reference drug voriconazole [ 90 ]. EL exhibited tight biding against both 24- and 28-SMT with K i values of around 9 nM [ 90 ].…”

Section: 24-smt Inhibitorsmentioning

confidence: 83%

“…trophozoite growth with an IC 50 value of 7 nM, and in this study, EL yielded 20-fold higher inhibition compared to the reference drug voriconazole [ 90 ]. EL exhibited tight biding against both 24- and 28-SMT with K i values of around 9 nM [ 90 ]. EL ( 41 ) can readily be synthesized directly from unprotected lanosterol with an excess of iodine azide and the addition of LAH ( Figure 22 ) [ 91 ].…”

Section: 24-smt Inhibitorsmentioning

confidence: 83%

“…26,27-Dehydrolanosterol (DHL; 43 ) was reported as an inhibitor of Acanthamoeba spp. trophozoite growth, with an IC 50 value of 6 μM making it a much weaker binder in comparison to EL (IC 50 of 7 nM) [ 90 ]. DHL is metabolized to a favorable substrate, which irreversibly inhibits Tb -24SMT, and the ED 50 values of DHL incubated with procyclic or bloodstream forms of T. brucei are 10 and 20 μM, respectively [ 97 ].…”

Section: 24-smt Inhibitorsmentioning

confidence: 99%

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Synthesis and Biological Activity of Sterol 14α-Demethylase and Sterol C24-Methyltransferase Inhibitors

Leaver

2018

Molecules

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Sterol 14α-demethylase (SDM) is essential for sterol biosynthesis and is the primary molecular target for clinical and agricultural antifungals. SDM has been demonstrated to be a valid drug target for antiprotozoal therapies, and much research has been focused on using SDM inhibitors to treat neglected tropical diseases such as human African trypanosomiasis (HAT), Chagas disease, and leishmaniasis. Sterol C24-methyltransferase (24-SMT) introduces the C24-methyl group of ergosterol and is an enzyme found in pathogenic fungi and protozoa but is absent from animals. This difference in sterol metabolism has the potential to be exploited in the development of selective drugs that specifically target 24-SMT of invasive fungi or protozoa without adversely affecting the human or animal host. The synthesis and biological activity of SDM and 24-SMT inhibitors are reviewed herein.

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“…SBDD has been discussed by several authors throughout the amoeba literature as an attractive method of designing selective enzymatic inhibitors that would specifically target the parasite over the human host 11 . Given how frequently this strategy is discussed, it is surprising that only a small number of laboratories have actually tested this methodology in practice against pathogenic FLA. Sterol biosynthesis has been the most attractive target since parasites utilize ergosterol over cholesterol for making cell plasma membranes with distinct host biosynthetic differences that could be selectively targeted [12][13][14] . Glucose metabolism is essential for parasitic cell viability.…”

Section: Introductionmentioning

confidence: 99%

The transcriptome ofBalamuthia mandrillaristrophozoites for structure-based drug design

Phan

Rice

Craig

et al. 2020

Preprint

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AbstractBalamuthia mandrillaris, a pathogenic free-living amoeba (FLA), causes cutaneous skin lesions as well as the brain-eating disease: Balamuthia granulomatous amoebic encephalitis (GAE). These diseases, and diseases caused by other pathogenic FLA, Naegleria fowleri or Acanthamoeba species, are minimally studied from a drug discovery perspective; few targets have been validated or characterized at the molecular level, and little is known about the biochemical pathways necessary for parasite survival. Chemotherapies for CNS disease caused by B. mandrillaris require vast improvement. Current therapeutics are limited to a small number of drugs that were previously discovered in the last century through in vitro testing or identified after use in the small pool of surviving reports.Using our recently published methodology to identify potentially useful therapeutics, we screened a collection of 85 compounds that have previously been reported to have antiparasitic activity. We identified 59 compounds that impacted growth at concentrations below 220 μM. Since there is no fully annotated genome or proteome, we used RNA-Seq to reconstruct the transcriptome of B. mandrillaris and locate the coding sequences of the specific genes potentially targeted by the compounds identified to inhibit trophozoite growth. We determined the sequence of 17 of these target genes and obtained expression clones for 15 that we validated by direct sequencing.

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Sterol methyltransferase a target for anti-amoeba therapy: towards transition state analog and suicide substrate drug design

Cited by 22 publications

References 40 publications

Discovery of repurposing drug candidates for the treatment of diseases caused by pathogenic free-living amoebae

Discovery of repurposing drug candidates for the treatment of diseases caused by pathogenic free-living amoebae

Synthesis and Biological Activity of Sterol 14α-Demethylase and Sterol C24-Methyltransferase Inhibitors

The transcriptome ofBalamuthia mandrillaristrophozoites for structure-based drug design

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