Browsing by Author "Nixon, Gemma L."
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- Endoperoxide carbonyl falcipain 2/3 inhibitor hybrids: toward combination chemotherapy of malaria through a single chemical entityPublication . Gibbons, Peter D.; Verissimo, Edite; Araujo, Nuna C. P.; Barton, Victoria; Nixon, Gemma L.; Amewu, Richard K.; Chadwick, J.; Stocks, Paul A.; Biagini, Giancarlo A.; Srivastava, Abhishek; Rosenthal, Philip J.; Gut, Jiri; Guedes, Rita C.; Moreira, Rui; Sharma, Raman; Berry, Neil; Cristiano, Maria Lurdes Santos; Shone, Alison E.; Ward, Stephen A.; O'Neill, Paul M.We extend our approach of combination chemotherapy through a single prodrug entity (O’Neill et al. Angew. Chem., Int. Ed. 2004, 43, 4193) by using a 1,2,4-trioxolane as a protease inhibitor carbonylmasking group. These molecules are designed to target the malaria parasite through two independent mechanisms of action: iron(II) decomposition releases the carbonyl protease inhibitor and potentially cytotoxic C-radical species in tandem. Using a proposed target “heme”, we also demonstrate heme alkylation/carbonyl inhibitor release and quantitatively measure endoperoxide turnover in parasitized red blood cells.
- Rational design, synthesis, and biological evaluation of heterocyclic quinolones targeting the respiratory chain of Mycobacterium tuberculosisPublication . Hong, W. David; Gibbons, Peter D.; Leung, Suet C.; Amewu, Richard; Stocks, Paul A.; Stachulski, Andrew; Horta, Pedro; Cristiano, Maria De Lurdes; Shone, Alison E.; Moss, Darren; Ardrey, Alison; Sharma, Raman; Warman, Ashley J.; Bedingfield, Paul T. P.; Fisher, Nicholas E.; Aljayyoussi, Ghaith; Mead, Sally; Caws, Maxine; Berry, Neil G.; Ward, Stephen A.; Biagini, Giancarlo A.; O'Neill, Paul M.; Nixon, Gemma L.A high-throughput screen (HTS) was undertaken against the respiratory chain dehydrogenase component, NADH:menaquinone oxidoreductase (Ndh) of Mycobacterium tuberculosis (Mtb). The 11000 compounds were selected for the HTS based on the known phenothiazine Ndh inhibitors, trifluoperazine and thioridazine. Combined HTS (11000 compounds) and in-house screening of a limited number of quinolones (50 compounds) identified similar to 100 hits and four distinct chemotypes, the most promising of which contained the quinolone core. Subsequent Mtb screening of the complete in-house quinolone library (350 compounds) identified a further similar to 90 hits across three quinolone subtemplates. Quinolones containing the amine-based side chain were selected as the pharmacophore for further modification, resulting in metabolically stable quinolones effective against multi drug resistant (MDR) Mtb. The lead compound, 42a (MTC420), displays acceptable antituberculosis activity (Mtb IC50 = 525 nM, Mtb Wayne IC50 = 76 nM, and MDR Mtb patient isolates IC50 = 140 nM) and favorable pharmacokinetic and toxicological profiles.