Development of Anthraquinone Derivatives as Ectonucleoside Triphosphate Diphosphohydrolase (NTPDase) Inhibitors With Selectivity for NTPDase2 and NTPDase3

Younis Baqi,Amelie Fiene,Enas M Malik,Laura Schäkel,Julie Pelletier,Christa E Müller,Mahmoud Rashed,Jean Sévigny

doi:10.3389/fphar.2020.01282

Abstract

Ectonucleoside triphosphate diphosphohydrolases (NTPDases) catalyze the hydrolysis of nucleoside tri- and di-phosphates to mono-phosphates. The products are subsequently hydrolyzed by ecto-5′-nucleotidase (ecto-5′-NT) to nucleosides. NTPDase inhibitors have potential as novel drugs, e.g., for the treatment of inflammation, neurodegenerative diseases, and cancer. In this context, a series of anthraquinone derivatives structurally related to the anthraquinone dye reactive blue-2 (RB-2) was synthesized and evaluated as inhibitors of human NTPDases utilizing a malachite green assay. We identified several potent and selective inhibitors of human NTPDase2 and -3. Among the most potent NTPDase2 inhibitors were 1-amino-4-(9-phenanthrylamino)-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (20, PSB-16131, IC50 of 539 nM) and 1-amino-4-(3-chloro-4-phenylsulfanyl)phenylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (48, PSB-2020, IC50 of 551 nM). The most potent NTPDase3 inhibitors were 1-amino-4-[3-(4,6-dichlorotriazin-2-ylamino)-4-sulfophenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (42, PSB-1011, IC50 of 390 nM) and 1-amino-4-(3-carboxy-4-hydroxyphenylamino)-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (33, PSB-2046, IC50 of 723 nM). The best NTPDase2 inhibitor 20 showed a non-competitive inhibition type, while the NTPDase3 inhibitor 42 behaved as a mixed-type inhibitor. These potent compounds were found to be selective vs. other NTPDases. They will be useful tools for studying the roles of NTPDase2 and -3 in physiology and under pathological conditions.

Highlights

Ectonucleotidases are membrane-bound metalloenzymes that affect extracellular nucleotide and nucleoside levels by catalyzing the hydrolysis of nucleotides to the corresponding nucleosides releasing inorganic phosphate or diphosphate (Dou et al, 2018; Le et al, 2019; Vuerich et al, 2019)
We investigated the structure-activity relationships (SARs) of this class of NTPDase inhibitors with the goal to improve their inhibitory potency and subtype-selectivity, in particular with the aim to obtain potent NTPDase2- selective inhibitors
In a study published in 2010, we reported the first SARs of anthraquinone derivatives as inhibitors of rat ecto-5’-nucleotidase (CD73) (Baqi et al, 2010)

Summary

Introduction

Ectonucleotidases are membrane-bound metalloenzymes that affect extracellular nucleotide and nucleoside levels by catalyzing the hydrolysis of nucleotides to the corresponding nucleosides releasing inorganic phosphate or diphosphate (Dou et al, 2018; Le et al, 2019; Vuerich et al, 2019). There are four major subfamilies of ectonucleotidases: the ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), the ectonucleotide pyrophosphatases/phosphodiesterases (NPPs), the alkaline phosphatases (APs), and the ecto-5′-nucleotidase (ecto-5′-NT, CD73) (Bonan, 2012; Al-Rashida and Iqbal, 2015; Baqi, 2015; Fiene et al, 2016; Le et al, 2019). There may be a massive increase in extracellular ATP concentrations causing proinflammatory immune responses via P2X and P2Y receptors. ATP can be hydrolyzed by NTPDases, or at very high concentrations by APs, via ADP to AMP. The resulting AMP can eventually be hydrolyzed by ecto-5’-NT yielding adenosine, which induces antiinflammatory effects via activation of P1 (adenosine) receptors (King et al, 2006; Burnstock, 2018; Antonioli et al, 2019; Müller et al, 2020)

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Conclusion