Design, Synthesis and Evaluation of Resveratrol Analogues as Novel NQO2 Inhibitors

  • Asma Belgath

Student thesis: Phd


NRH: quinone oxidoreducatase (NQO2) is FAD-dependent flavoprotein which reduces quinone compounds to generate hydroquinones and reactive oxygen species (ROS). ROS have a deleterious effect on cellular components and body tissues which is implicated in many diseases such as cancer, neurodegenerative, stroke and diabetes. In this study, resveratrol, a known inhibitor of NQO2, was used as the lead compound. Two scaffolds were designed by replacing the double bond in resveratrol. This was achieved by docking of compounds into the NQO2 active site which predicted that the 3-aryisoquinolinone and benzothiazole scaffolds have high calculated affinities for NQO2. The 3-aryisoquinolinones were synthesized by reaction of o-toluamide derivatives with either n-butyllithium or lithium diisopropylamide. Five compound classes of the benzothiazole scaffold were synthesised (3,5-dimethoxy, 2,4-dimethoxy, 2,5-dimethoxy, 3,4-dimethoxy and 3,4,5-trimethoxy benzothiazoles) using a Jacobsen synthesis, the key precursors being benzoic acid and N-aniline derivatives. The inhibition of the NQO2 enzyme by the benzothiazoles and 3-aryisoquinolinones were evaluated. All of the 3-aryisoquinolinones were inactive, whereas the benzothiazole analogues showed a range of inhibition of enzyme activity. Hydroxyl, methoxy and trifluoromethyl-substituted 3,5-dimethoxybenzothiazoles were the most active compounds with nano-molar IC50 values. The 2,4-, 3,4- and most of the 2,5-substituted benzothiazoles inhibited NQO2 enzyme activity at micro-molar concentrations. Most of the 3,4,5-trimethoxybenzothiazoles inhibited NQO2 at nano-molar concentration. Cellular toxicity assays of substituted 3-aryisoquinolones in breast, liver and NCI cancer cell lines showed a substantial difference in cell toxicity with the meta substituted, analogues being 10-fold more potent than compounds with a para substituent. Compare analysis of 6-fluoro-3-(3-fluorophenyl)isoquinolin-1(2H)-one 159 against the NCI databases compounds gave a good correlation coefficient to some synthetic NCI database compounds, known to have tubulin binding effects. Preliminary mechanism of action studies showed that the meta-substituted isoquinolinones did not intercalate DNA and did not inhibit the enzyme tankyrase-1.
Date of Award1 Aug 2018
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorSally Freeman (Supervisor), Ian Stratford (Supervisor), Roger Whitehead (Supervisor), Costas Demonacos (Supervisor) & Karen Nolan (Supervisor)

Cite this