title: Development of a functional assay to detect inhibitors of Plasmodium falciparum glutathione reductase utilizing liquid chromatography-mass spectrometry.
abstract: Plasmodium falciparum (Pf) like most other organisms, has a sophisticated antioxidant system, part of which includes glutathione reductase (GR). GR works by recycling toxic glutathione disulfide to glutathione, thereby reducing reactive oxygen species and making a form of glutathione (GSH) the parasite can use. Inhibition of this enzyme in Pf impedes parasite growth. In addition, it has been confirmed that PfGR is not identical to human GR. Thus, PfGR is an excellent target for antimalarial drug development. A functional assay utilizing liquid chromatography-mass spectrometry was developed to specifically identify and evaluate inhibitors of PfGR. Using recombinant PfGR enzyme and 1,4-naphthoquinone (1) as a reference compound and 4-nitrobenzothiadiazole (2) and methylene blue (3) as additional compounds, we quantified the concentration of GSH produced compared with a control to determine the inhibitory effect of these compounds. Our results coincide with that presented in literature: compounds 1-3 inhibit PfGR with IC50 values of 2.71, 8.38, and 19.23 µm, respectively. Good precision for this assay was exhibited by low values of intraday and interday coefficient of variation (3.1 and 2.4%, respectively). Thus, this assay can be used to screen for other potential inhibitors of PfGR quickly and accurately.
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA.
authors.forename: Lexi
authors.initials: L
authors.lastname: Burkard
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Scheuermann
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA.
authors.forename: Johayra
authors.initials: J
authors.lastname: Simithy
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA.
authors.forename: Angela I
authors.initials: AI
authors.lastname: Calderón
mesh_terms: D000962:Antimalarials / Q000737:chemistry / Q000494:pharmacology; D002853:Chromatography, Liquid / Q000379:methods*; D057075:Enzyme Assays / Q000379:methods*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism*; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000469:parasitology; D013058:Mass Spectrometry / Q000379:methods; D008751:Methylene Blue / Q000737:chemistry / Q000494:pharmacology; D009285:Naphthoquinones / Q000737:chemistry / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology*; D015203:Reproducibility of Results; D013830:Thiadiazoles / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000962:Antimalarials; D004791:Enzyme Inhibitors; D009285:Naphthoquinones; D013830:Thiadiazoles; C015700:benzo-1,2,3-thiadiazole; D005980:Glutathione Reductase; D005978:Glutathione; C035342:1,4-naphthoquinone; D008751:Methylene Blue
keywords: LC-MS; Plasmodium falciparum; enzyme activity assay; glutathione; glutathione reductase