Inhibition of oxygen evolution rate in freshwater algae Chlorella vulgaris by some anilides of substituted pyridine-4-carboxylic acids

The inhibitory activity of 11 anilides of 2-alkylsulfanylpyridine-4-carboxylic acids (R = SC(3)H(7), SC(5)H(11), SCH(2)C(6)H(5), S-iC(4)H(9); substituents in the anilide moiety: 2'-OH, T-OH, 5'-Cl, 3'-Br, 4'-Br, 3'-CF(3), 5'-CF(3)) on oxygen evolution rate (OER) in freshwater algae Chlorella vulgaris has been investigated. The IC(50) values in the investigated set varied in the range from 47.7 mu mol dm(-3) (R = SC(3)H(7), Y = X(2) = H, X(1) = 4'-Br) to 474.1 mu mol dm(-3) (R = SCH(2)C(6)H(5), Y = 2'-OH, X(1) = X(2) = H). The dependence of photosynthesis-inhibiting activity upon the lipophilicity of the substituents showed a quasi-parabolic course indicating that for the OER-inhibiting activity in Chlorella vulgaris the lipophilicity of the compound is determining.