E. Reil et al., Quinolones and their N-oxides as inhibitors of photosystem II and the cytochrome b(6)/f-complex, BBA-BIOENER, 1506(2), 2001, pp. 127-132
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 experi
ments with [C-14]atrazine indicated that the quinolones share an identical
binding site with other photosystem II commercial herbicides. In the cytoch
rome b(6)/f-complex, only 3 < 4 showed enhanced activity. Maximal inhibitor
y potency was achieved at a carbon chain length of 12-14 <Angstrom>(.) Furt
her increase of the chain length decreased activity. In a quantitative stru
cture-activity relationship inhibitory activity in photosystem II and the c
ytochrome b(6)/f-complex could be correlated to the physicochemical paramet
ers lipophilicity ir and/ or to STERIMOL L. (C) 2001 Elsevier Science B.V.
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