Search results for "Rhodesain"
showing 10 items of 12 documents
Identification of Plakortide E from the Caribbean Sponge Plakortis halichondroides as a Trypanocidal Protease Inhibitor using Bioactivity-Guided Frac…
2014
In this paper, we report new protease inhibitory activity of plakortide E towards cathepsins and cathepsin-like parasitic proteases. We further report on its anti-parasitic activity against Trypanosoma brucei with an IC50 value of 5 mu M and without cytotoxic effects against J774.1 macrophages at 100 mu M concentration. Plakortide E was isolated from the sponge Plakortis halichondroides using enzyme assay-guided fractionation and identified by NMR spectroscopy and mass spectrometry. Furthermore, enzyme kinetic studies confirmed plakortide E as a non-competitive, slowly-binding, reversible inhibitor of rhodesain.
Dipeptidyl Enoates As Potent Rhodesain Inhibitors That Display a Dual Mode of Action
2015
Dipeptidyl enoates were prepared through a high-yielding two-step synthetic route. They have a dipeptidic structure with a 4-oxoenoate moiety as a warhead with multiple reactive sites. Dipeptidyl enoates were screened against rhodesain and human cathepsins B and L, and were found to be potent and selective inhibitors of rhodesain. Among them (S,E)-ethyl 5-((S)-2-{[(benzyloxy)carbonyl]amino}-3-phenylpropanamido)-7-methyl-4-oxooct-2-enoate (6) was the most potent, with an IC50 value of 16.4 nm and kinact/Ki=1.6×106 m−1 s−1 against rhodesain. These dipeptidyl enoates display a reversible mode of inhibition at very low concentrations and an irreversible mode at higher concentrations. Inhibition…
Drug combination studies of curcumin and genistein against rhodesain of Trypanosoma brucei rhodesiense
2018
Curcumin and genistein are two natural products obtained from Curcuma longa L. and soybeans, endowed with many biological properties. Within the last years they were shown to possess also a promising antitrypanosomal activity. In the present paper, we investigated the activity of both curcumin and genistein against rhodesain, the main cysteine protease of Trypanosoma brucei rhodesiense; drug combination studies, according to Chou and Talalay method, allowed us to demonstrate a potent synergistic effect for the combination curcumin-genistein. As a matter of fact, with our experiments we observed that the combination index of curcumin-genistein is < 1 for the reduction from 10 to 90% of rhode…
Synthesis and biological evaluation of novel peptidomimetics as rhodesain inhibitors
2016
Novel rhodesain inhibitors were developed by combining an enantiomerically pure 3-bromoisoxazoline warhead with a 1,4-benzodiazepine scaffold as specific recognition moiety. All compounds were proven to inhibit rhodesain with Ki values in the low-micromolar range. Their activity towards rhodesain was found to be coupled to an in vitro antitrypanosomal activity, with IC50 values ranging from the mid-micromolar to a low-micromolar value for the most active rhodesain inhibitor (R,S,S)-3. All compounds showed a good selectivity against the target enzyme since all of them were proven to be poor inhibitors of human cathepsin L. Novel rhodesain inhibitors were developed by combining an enantiomeri…
Development of novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation.
2015
Novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation were developed; some of them possess K(i) values in the micromolar range. We studied the structure-activity relationship of these derivatives and we performed docking studies, which allowed us to find out the key interactions established by the inhibitors with the target enzyme. Biological results indicate that the nature of the P2 and P3 substituents and their binding to the S2/S3 pockets is strictly interdependent.
The discovery of novel antitrypanosomal 4-phenyl-6-(pyridin-3-yl)pyrimidines
2021
Human African trypanosomiasis, or sleeping sickness, is a neglected tropical disease caused by Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense which seriously affects human health in Africa. Current therapies present limitations in their application, parasite resistance, or require further clinical investigation for wider use. Our work herein describes the design and syntheses of novel antitrypanosomal 4-phenyl-6-(pyridin-3-yl)pyrimidines, with compound 13, the 4-(2-methoxyphenyl)-6-(pyridine-3-yl)pyrimidin-2-amine demonstrating an IC50 value of 0.38 μM and a promising off-target ADME-Tox profile in vitro. In silico molecular target investigations showed rhodesain to be a pu…
Peptidyl Vinyl Ketone Irreversible Inhibitors of Rhodesain: Modifications of the P2 Fragment.
2020
In this paper, we report the design, synthesis and biological investigation of a series of peptidyl vinyl ketones obtained by modifying the P2 fragment of previously reported highly potent inhibitors of rhodesain, the main cysteine protease of Trypanosoma brucei rhodesiense. Investigation of the structure-activity relationship led us to identify new rhodesain inhibitors endowed with an improved selectivity profile (a selectivity index of up to 22 000 towards the target enzyme), and/or an improved antitrypanosomal activity in the sub-micromolar range.
Dipeptidyl Nitroalkenes as Potent Reversible Inhibitors of Cysteine Proteases Rhodesain and Cruzain.
2016
Dipeptidyl nitroalkenes are potent reversible inhibitors of cysteine proteases. Inhibitor 11 resulted to be the most potent one with Ki values of 0.49 and 0.44 nM against rhodesain and cruzain, respectively. According to enzymatic dilution and dialysis experiments, as well as computational and NMR studies, dipeptidyl nitroalkenes are tightly binding covalent reversible inhibitors. We thank Fundacion Española para la Ciencia y la Tecnología (Fecyt) and Generalitat Valenciana (AICO/2016/32) for financial support. T S. and B.E. thank the DFG (Deutsche Forschungsgemeinschaft) in the framework of the SFB630 for financial support. We thank Universitat Jaume I for technical suppport and funding. U…
Development of rhodesain inhibitors with a 3-bromoisoxazoline warhead
2013
Novel rhodesain inhibitors were obtained by combining an enantiomerically pure 3-bromoisoxazoline warhead with a specific peptidomimetic recognition moiety. All derivatives behaved as inhibitors of rhodesain, with low micromolar Ki values. Their activity against the enzyme was found to be paralleled by an in vitro antitrypanosomal activity, with IC50 values in the mid-micromolar range. Notably, a preference for parasitic over human proteases, specifically cathepsins B and L, was observed.
Development of Novel Benzodiazepine-Based Peptidomimetics as Inhibitors of Rhodesain from Trypanosoma brucei rhodesiense.
2020
Starting from the reversible rhodesain inhibitors 1 a-c, which have Ki values towards the target protease in the low-micromolar range, we have designed a series of peptidomimetics, 2 a-g, that contain a benzodiazepine scaffold as a β-turn mimetic; they are characterized by a specific peptide sequence for the inhibition of rhodesain. Considering that irreversible inhibition is strongly desirable in the case of a parasitic target, a vinyl ester moiety acting as Michael-acceptor was introduced as the warhead; this portion was functionalized in order to evaluate the size of corresponding enzyme pocket that could accommodate this substituent. With this investigation, we identified an irreversibl…