Photosynthesis-Inhibiting efficiency of 4-chloro-2-(chlorophenylcarbamoyl)phenyl alkylcarbamates.

A series of photosynthetic electron transport (PET) inhibitors from the group of salicylanilide alkylcarbamates was investigated. The compounds were analyzed using RP-HPLC to determine lipophilicity, and their PET inhibition was determined in spinach (Spinacia oleracea L.) chloroplasts. The site of action of the studied compounds is situated at the donor site of photosystem 2 (PS 2). Compounds substituted by chlorine in C'-3 and C'-4 of the aniline ring and the optimal length of the alkyl chain pentyl-heptyl in the carbamate moiety provided the most active PET inhibitors (IC(50) inhibition <10 μmol/L). Disubstitution in C'-3,4 by chlorine caused significant PET inhibiting activity decrease. Nevertheless, for all three series of C'-3, C'-4, C'-3,4 compounds, the dependence of PET activity on lipophilicity showed to be quasi-parabolic.