title: Combinatorial synthesis of novel and potent inhibitors of NADH:ubiquinone oxidoreductase.
abstract: BACKGROUND
  NADH:ubiquinone oxidoreductase (complex I) is the first of three large enzyme complexes located in the cell's inner mitochondrial membrane which form the electron transport chain that carries electrons from NADH to molecular oxygen during oxidative phosphorylation. There is significant interest in developing small molecule inhibitors of this enzyme for use as biological probes, insecticides and potential chemopreventive/chemotherapeutic agents. Herein we describe the application of novel natural product-like libraries to the discovery of a family of potent benzopyran-based inhibitors.
  
  
  RESULTS
  Initially a combinatorial library of benzopyrans, modeled after natural products, was synthesized using a solid phase cycloloading strategy. Screening of this diversity oriented library for inhibitory potency against NADH:ubiquinone oxidoreductase activity in vitro using bovine heart electron transport particles provided several lead compounds which were further refined through a series of focused libraries.
  
  
  CONCLUSIONS
  Using this combinatorial library approach, a family of potent 2,2-dimethylbenzopyran-based inhibitors was developed with IC(50) values in the range of 18-55 nM. Cell-based assays revealed that these inhibitors were rather non-cytotoxic in the MCF-7 cell line; however, they were quite cytostatic in a panel of cancer cell lines suggesting their potential as chemotherapeutic/chemopreventive candidates.
authors.affiliation: Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: K
authors.initials: K
authors.lastname: Nicolaou
authors.forename: J
authors.initials: J
authors.lastname: Pfefferkorn
authors.forename: F
authors.initials: F
authors.lastname: Schuler
authors.forename: A
authors.initials: A
authors.lastname: Roecker
authors.forename: G
authors.initials: G
authors.lastname: Cao
authors.forename: J
authors.initials: J
authors.lastname: Casida
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001578:Benzopyrans / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D020650:Combinatorial Chemistry Techniques; D042967:Electron Transport Complex I; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D008929:Mitochondria, Heart / Q000201:enzymology; D008958:Models, Molecular; D015394:Molecular Structure; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I