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

The inhibitory activity of 11 anilides of 2-alkylsulfanylpyridine-4-carboxy lic acids (R = SC3H7, SC5H11, SCH2C6H5, S-iC(4)H(9); substituents in the an ilide moiety: 2'-OH, T-OH, 5'-Cl, 3'-Br, 4'-Br, 3'-CF3, 5'-CF3) on oxygen e volution rate (OER) in freshwater algae Chlorella vulgaris has been investi gated. The IC50 values in the investigated set varied in the range from 47. 7 mu mol dm(-3) (R = SC3H7, Y = X-2 = H, X-1 = 4'-Br) to 474.1 mu mol dm(-3 ) (R = SCH2C6H5, Y = 2'-OH, X-1 = X-2 = H). The dependence of photosynthesi s-inhibiting activity upon the lipophilicity of the substituents showed a q uasi-parabolic course indicating that for the OER-inhibiting activity in Ch lorella vulgaris the lipophilicity of the compound is determining.