W. Oettmeier et al., INHIBITION OF ELECTRON-TRANSPORT THROUGH THE Q(P) SITE IN CYTOCHROME B C(1) COMPLEXES BY ACRIDONES/, Biochimica et biophysica acta. Bioenergetics, 1188(1-2), 1994, pp. 125-130
4-substituted acridones (9-azaanthracen-10-ones) and, to an even highe
r extent, 2-substituted acridones were found to be efficient inhibitor
s of isolated cytochrome b/c(1) complexes from either beef heart or th
e photosynthetic bacterium Rhodospirillum rubrum. Inhibitory activity
in a Quantitative Structure-Activity Relationship (QSAR) could be corr
elated to physicochemical parameters like STERIMOLb sigma-Hammett and
lipophilicity pi. Maximal inhibitory potency for 2-alkylacridones was
achieved at a carbon chain length of 9-10 Angstrom. Oxidant-induced re
duction of cytochrome b established that 2-alkylacridones are inhibito
rs of the Q(p) rather than the Q(n) site.