title: A small library of synthetic di-substituted 1, 4-naphthoquinones induces ROS-mediated cell death in murine fibroblasts.
abstract: Synthesis of compound libraries and their concurrent assessment as selective reagents for probing and modulating biological function continues to be an active area of chemical biology. Microwave-assisted solid-phase Dötz benzannulation reactions have been used to inexpensively synthesize 2, 3-disubstituted-1, 4-naphthoquinone derivatives. Herein, we report the biological testing of a small library of such compounds using a murine fibroblast cell line (L929). Assessment of cellular viability identified three categories of cytotoxic compounds: no toxicity, low/intermediate toxicity and high toxicity. Increased levels of Annexin-V-positive staining and of caspase 3 activity confirmed that low, intermediate, and highly toxic compounds promote cell death. The compounds varied in their ability to induce mitochondrial depolarization and formation of reactive oxygen species (ROS). Both cytotoxic and non-cytotoxic compounds triggered mitochondrial depolarization, while one highly cytotoxic compound did not. In addition, all cytotoxic compounds promoted increased intracellular ROS but the cells were only partially protected from compound-induced apoptosis when in the presence of superoxide dismutase, catalase, or ascorbic acid suggesting utilization of additional pro-death mechanisms. In summary, nine of twelve (75%) 1, 4-naphthoquinone synthetic compounds were cytotoxic. Although the mitochondria did not appear to be a central target for induction of cell death, all of the cytotoxic compounds induced ROS formation. Thus, the data demonstrate that the synthesis regime effectively created cytotoxic compounds highlighting the potential use of the regime and its products for the identification of biologically relevant reagents.
authors.affiliation: Dept. of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America; Border Biomedical Research Center, University of Texas at El Paso, El Paso, Texas, United States of America.
authors.forename: Oscar
authors.initials: O
authors.lastname: Ramirez
authors.affiliation: Dept. of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Motta-Mena
authors.affiliation: Dept. of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America.
authors.forename: Amanda
authors.initials: A
authors.lastname: Cordova
authors.forename: Abril
authors.initials: A
authors.lastname: Estrada
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Li
authors.forename: Luis
authors.initials: L
authors.lastname: Martinez
authors.affiliation: Dept. of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America; Border Biomedical Research Center, University of Texas at El Paso, El Paso, Texas, United States of America.
authors.forename: Kristine M
authors.initials: KM
authors.lastname: Garza
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D004789:Enzyme Activation; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D009285:Naphthoquinones / Q000737:chemistry / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D054852:Small Molecule Libraries; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D009285:Naphthoquinones; D017382:Reactive Oxygen Species; D054852:Small Molecule Libraries; D002374:Catalase; D013482:Superoxide Dismutase; D053148:Caspase 3