title: Hybrid ubiquinone: novel inhibitor of mitochondrial complex I.
abstract: We synthesized novel ubiquinone analogs by hybridizing the natural ubiquinone ring (2,3-dimethoxy-5-methyl-1,4-benzoquinone) and hydrophobic phenoxybenzamide unit, and named them hybrid ubiquinones (HUs). The HUs worked as electron transfer substrates with bovine heart mitochondrial succinate-ubiquinone oxidoreductase (complex II) and ubiquinol-cytochrome c oxidoreductase (complex III), but not with NADH-ubiquinone oxidoreductase (complex I). With complex I, they acted as inhibitors in a noncompetitive manner against exogenous short-chain ubiquinones irrespective of the presence of the natural ubiquinone ring. Elongation of the distance between the ubiquinone ring and the phenoxybenzamide unit did not recover the electron accepting activity. The structure/activity study showed that high structural specificity of the phenoxybenzamide moiety is required to act as a potent inhibitor of complex I. These findings indicate that binding of the HUs to complex I is mainly decided by some specific interaction of the phenoxybenzamide moiety with the enzyme. It is of interest that an analogous bulky and hydrophobic substructure can be commonly found in recently registered synthetic pesticides the action site of which is mitochondrial complex I.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kita-shirakawa, Sakyo-ku, 606-8502, Kyoto, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yabunaka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kenmochi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nakatogawa
authors.forename: Kimitoshi
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Hideto
authors.initials: H
authors.lastname: Miyoshi
mesh_terms: D000818:Animals; D002417:Cattle; D004579:Electron Transport; D042967:Electron Transport Complex I; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000378:metabolism; D008929:Mitochondria, Heart / Q000737:chemistry / Q000201:enzymology; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000378:metabolism; D009206:Myocardium / Q000737:chemistry / Q000166:cytology; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D010575:Pesticides / Q000737:chemistry; D013329:Structure-Activity Relationship; D013367:Submitochondrial Particles / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000378:metabolism; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D010575:Pesticides; D014451:Ubiquinone; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III