Effect of Some Benzonitrile Esters on the K+ Uptake of Wheat Seedlings: Quantitative Structure-Activity Relationships

The effect of 15 benzonitrile esters on potassium uptake of excised roots of wheat (Triticum aestivum L. cv. F 481) seedlings was determined. The pI50 values were correlated with the lipophilicity of compounds determined by reversed-phase thin-layer chromatography. Calculations proved that lipophilicity alone did not explain the biological activity of the compounds. After introducing a sterical parameter for the presence of a second ring structure in the molecule, very good correlation was found between the biological activity as dependent, and lipophilicity and sterical parameter as independent variables. Our results suggest that hydrophobic interactions may exert a considerable influence on the biological activity. The presence of a second ring structure in the molecule decreases the effectivity, stressing the importance of sterical parameters.