Synthesis and Biological Evaluation of Coumarin-Based Inhibitors of NAD(P)H: Quinone Oxidoreductase-1 (NQO1)

Abstract

The synthesis is reported here of two novel series of inhibitors of human NAD(P)H quinone oxidoreductase-1 (NQO1), an enzyme overexpressed in several types of tumor cell. The first series comprises substituted symmetric dicoumarol analogues; the second series contains hybrid compounds where one 4-hydroxycoumarin system is replaced by a different aromatic moiety. Several compounds show equivalent or improved NQO1 inhibition over dicoumarol, both in the presence and in the absence of added protein. Further, correlation is demonstrated between the ability of these agents to inhibit NQO1 and computed binding affinity. We have solved the crystal structure of NQO1 complexed to a hybrid compound and find good agreement with the in silico model. For both MIA PaCa-2 pancreatic tumor cells and HCT116 colon cancer cells, dicoumarol shows the greatest toxicity of all compounds. Thus, we provide a computational, synthetic, and biological platform to generate competitive NQO1 inhibitors with superior pharmacological properties to dicoumarol. This will allow a more definitive study of NQO1 activity in cells, in particular, its drug activating/detoxifying properties and ability to modulate oncoprotein stability.

Dicoumarol: A Drug which Hits at Least Two Very Different Targets in Vitamin K Metabolism

“…In general the asymmetric series had greater aqueous solubility compared to dicoumarol. Three of the symmetrical analogues had higher affinity for NQO1 than dicoumarol (Scheme 5) [105]. One of the 29 inhibitors was co-crystallised with NQO1 and the resulting structure (PDB: 3JSX) compared to the docked model; the experimental and theoretical structures of the complex were in good agreement, further validating the structure-based drug design approach in this case [105].…”

“…The availability of several high resolution crystal structures of NQO1 makes such a strategy viable [77,90,[104][105][106]. Of particular interest is the structure with dicoumarol bound (PDB: 2F1O; Figure 4) [90].…”

“…A series of 29 symmetrical and asymmetrical analogues of dicoumarol were synthesised and tested for their ability to inhibit NQO1 [105]. In general the asymmetric series had greater aqueous solubility compared to dicoumarol.…”

“…Three of the symmetrical analogues had higher affinity for NQO1 than dicoumarol (Scheme 5) [105]. One of the 29 inhibitors was co-crystallised with NQO1 and the resulting structure (PDB: 3JSX) compared to the docked model; the experimental and theoretical structures of the complex were in good agreement, further validating the structure-based drug design approach in this case [105]. These novel compounds inhibited NQO1 in colon, lung and pancreatic cancer cell lines and the degree of cellular inhibition broadly correlated with the in vitro affinity [116].…”

Insilico Drug Design and Molecular Docking Studies of Novel Coumarin Derivatives as Anti-Cancer Agents

“…It is a cytosolic reductase and is upregulated in many human cancers compared to adjacent normal tissues [9]. Dicoumarol and series of 4-hydroxycoumarin derivatives have been reported to inhibit overexpressed NAD(P)H dehydrogenase (quinone) 1 (NQO1) in many cancer cells [10]. Epidermal growth factor receptor (EGFR), a member of ERBb family of tyrosine kinase of Rtk and, is associated with pathogenesis and development of different types of cancers [11,12].…”