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Eur J Med Chem. 2018 Sep 5;157:115-126. doi: 10.1016/j.ejmech.2018.07.064. Epub 2018 Aug 1.

8-Aryl-6-chloro-3-nitro-2-(phenylsulfonylmethyl)imidazo[1,2-a]pyridines as potent antitrypanosomatid molecules bioactivated by type 1 nitroreductases.

Author information

1
Aix Marseille Univ, CNRS, ICR UMR 7273, Equipe Pharmaco-Chimie Radicalaire, FAC PHARM, 27 Boulevard Jean Moulin, CS30064, 13385, Marseille Cedex 05, France.
2
Université de Limoges, UMR Inserm 1094, Neuroépidémiologie Tropicale, Faculté de Pharmacie, 2 rue du Dr Marcland, 87025, Limoges, France.
3
LCC-CNRS Université de Toulouse, CNRS, UPS, Toulouse, France.
4
IHU Méditerranée Infection, Aix-Marseille Univ, UMR VITROME, 19-21 Boulevard Jean Moulin, 13005, Marseille, France.
5
UMR 152 PHARMA-DEV, Université de Toulouse, IRD, UPS, Toulouse, France.
6
University of Dundee, School of Life Sciences, Division of Biological Chemistry and Drug Discovery, Dow Street, Dundee, DD1 5EH, Scotland, United Kingdom.
7
LCC-CNRS Université de Toulouse, CNRS, UPS, Toulouse, France. Electronic address: pierre.verhaeghe@univ-tlse3.fr.
8
Aix Marseille Univ, CNRS, ICR UMR 7273, Equipe Pharmaco-Chimie Radicalaire, FAC PHARM, 27 Boulevard Jean Moulin, CS30064, 13385, Marseille Cedex 05, France. Electronic address: patrice.vanelle@univ-amu.fr.

Abstract

Based on a previously identified antileishmanial 6,8-dibromo-3-nitroimidazo[1,2-a]pyridine derivative, a Suzuki-Miyaura coupling reaction at position 8 of the scaffold was studied and optimized from a 8-bromo-6-chloro-3-nitroimidazo[1,2-a]pyridine substrate. Twenty-one original derivatives were prepared, screened in vitro for activity against L. infantum axenic amastigotes and T. brucei brucei trypomastigotes and evaluated for their cytotoxicity on the HepG2 human cell line. Thus, 7 antileishmanial hit compounds were identified, displaying IC50 values in the 1.1-3 μM range. Compounds 13 and 23, the 2 most selective molecules (SI = >18 or >17) were additionally tested on both the promastigote and intramacrophage amastigote stages of L. donovani. The two molecules presented a good activity (IC50 = 1.2-1.3 μM) on the promastigote stage but only molecule 23, bearing a 4-pyridinyl substituent at position 8, was active on the intracellular amastigote stage, with a good IC50 value (2.3 μM), slightly lower than the one of miltefosine (IC50 = 4.3 μM). The antiparasitic screening also revealed 8 antitrypanosomal hit compounds, including 14 and 20, 2 very active (IC50 = 0.04-0.16 μM) and selective (SI = >313 to 550) molecules toward T. brucei brucei, in comparison with drug-candidate fexinidazole (IC50 = 0.6 & SI > 333) or reference drugs suramin and eflornithine (respective IC50 = 0.03 and 13.3 μM). Introducing an aryl moiety at position 8 of the scaffold quite significantly increased the antitrypanosomal activity of the pharmacophore. Antikinetoplastid molecules 13, 14, 20 and 23 were assessed for bioactivation by parasitic nitroreductases (either in L. donovani or in T. brucei brucei), using genetically modified parasite strains that over-express NTRs: all these molecules are substrates of type 1 nitroreductases (NTR1), such as those that are responsible for the bioactivation of fexinidazole. Reduction potentials measured for these 4 hit compounds were higher than that of fexinidazole (-0.83 V), ranging from -0.70 to -0.64 V.

KEYWORDS:

HepG2 cytotoxicity; Imidazo[1,2-a]pyridine; In vitro activity; Leishmania; Nitroheterocycles; Nitroreductases; Redox potentials; SARs; Suzuki-Miyaura cross-coupling reaction; Trypanosoma

PMID:
30092366
DOI:
10.1016/j.ejmech.2018.07.064
[Indexed for MEDLINE]

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