title: Profiling the NIH Small Molecule Repository for compounds that generate H2O2 by redox cycling in reducing environments.
abstract: We have screened the Library of Pharmacologically Active Compounds (LOPAC) and the National Institutes of Health (NIH) Small Molecule Repository (SMR) libraries in a horseradish peroxidase-phenol red (HRP-PR) H2O2 detection assay to identify redox cycling compounds (RCCs) capable of generating H2O2 in buffers containing dithiothreitol (DTT). Two RCCs were identified in the LOPAC set, the ortho-naphthoquinone beta-lapachone and the para-naphthoquinone NSC 95397. Thirty-seven (0.02%) concentration-dependent RCCs were identified from 195,826 compounds in the NIH SMR library; 3 singleton structures, 9 ortho-quinones, 2 para-quinones, 4 pyrimidotriazinediones, 15 arylsulfonamides, 2 nitrothiophene-2-carboxylates, and 2 tolyl hydrazides. Sixty percent of the ortho-quinones and 80% of the pyrimidotriazinediones in the library were confirmed as RCCs. In contrast, only 3.9% of the para-quinones were confirmed as RCCs. Fifteen of the 251 arylsulfonamides in the library were confirmed as RCCs, and since we screened 17,868 compounds with a sulfonamide functional group we conclude that the redox cycling activity of the arylsulfonamide RCCs is due to peripheral reactive enone, aromatic, or heterocyclic functions. Cross-target queries of the University of Pittsburgh Drug Discovery Institute (UPDDI) and PubChem databases revealed that the RCCs exhibited promiscuous bioactivity profiles and have populated both screening databases with significantly higher numbers of active flags than non-RCCs. RCCs were promiscuously active against protein targets known to be susceptible to oxidation, but were also active in cell growth inhibition assays, and against other targets thought to be insensitive to oxidation. Profiling compound libraries or the hits from screening campaigns in the HRP-PR H(2)O(2) detection assay significantly reduce the timelines and resources required to identify and eliminate promiscuous nuisance RCCs from the candidates for lead optimization.
authors.affiliation: Pittsburgh Molecular Library Screening Center, Drug Discovery Institute, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Karina M
authors.initials: KM
authors.lastname: Soares
authors.forename: Nicole
authors.initials: N
authors.lastname: Blackmon
authors.forename: Tong Ying
authors.initials: TY
authors.lastname: Shun
authors.forename: Sunita N
authors.initials: SN
authors.lastname: Shinde
authors.forename: Harold K
authors.initials: HK
authors.lastname: Takyi
authors.forename: Peter
authors.initials: P
authors.lastname: Wipf
authors.forename: John S
authors.initials: JS
authors.lastname: Lazo
authors.forename: Paul A
authors.initials: PA
authors.lastname: Johnston
mesh_terms: D016000:Cluster Analysis; D055808:Drug Discovery; D004353:Drug Evaluation, Preclinical; D004777:Environment; D006735:Horseradish Peroxidase / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007202:Indicators and Reagents; D015233:Models, Statistical; D009316:National Institutes of Health (U.S.); D010084:Oxidation-Reduction; D010637:Phenolsulfonphthalein; D054852:Small Molecule Libraries; D013329:Structure-Activity Relationship; D014481:United States
chemical_list: D007202:Indicators and Reagents; D054852:Small Molecule Libraries; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D010637:Phenolsulfonphthalein