title: Quinolones and their N-oxides as inhibitors of photosystem II and the cytochrome b(6)/f-complex.
abstract: 4(1H)-quinolones (2-alkyl- (1), 2-alkyl-3-methyl- (2), 2-methyl-3-alkyl- (3), 1-hydroxy-2-methyl-3-alkyl- (4) and 1-hydroxy-2-alkyl- (5)) with n-alkyl side chains varying from C(5) to C(17) have been synthesized and tested for biological activity in photosystem II and the cytochrome b(6)/f-complex. In photosystem II, quinolones 1 and 2 showed only moderate activity, whereas 3<5<4 (increasing activity) were potent inhibitors. Displacement experiments with [(14)C]atrazine indicated that the quinolones share an identical binding site with other photosystem II commercial herbicides. In the cytochrome b(6)/f-complex, only 3<4 showed enhanced activity. Maximal inhibitory potency was achieved at a carbon chain length of 12-14 A. Further increase of the chain length decreased activity. In a quantitative structure-activity relationship inhibitory activity in photosystem II and the cytochrome b(6)/f-complex could be correlated to the physicochemical parameters lipophilicity pi and/or to STERIMOL L.
authors.affiliation: Lehrstuhl Biochemie der Pflanzen, Ruhr-Universität, Bochum, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Reil
authors.forename: G
authors.initials: G
authors.lastname: Höfle
authors.forename: W
authors.initials: W
authors.lastname: Draber
authors.forename: W
authors.initials: W
authors.lastname: Oettmeier
mesh_terms: D001665:Binding Sites; D003573:Cytochrome b Group / Q000737:chemistry*; D045346:Cytochrome b6f Complex; D004579:Electron Transport / Q000187:drug effects; D015394:Molecular Structure; D045322:Photosynthetic Reaction Center Complex Proteins / Q000037:antagonists & inhibitors*; D045332:Photosystem II Protein Complex; D015363:Quinolones / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D003573:Cytochrome b Group; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D015363:Quinolones; D045346:Cytochrome b6f Complex