Relationship between the physicochemical parameters and biological activity of sulfosuccinic and ester surfactants

The effect of 11 sulfosuccinic acid ester surfactants on the abiotrophic developmental forms of the asexual spores of Plasmopara halstedii was determined. The strength and the selectivity of the effect was separated by the spectral mapping technique and the relationship between the biological activities and physicochemical parameters of anionic surfactants was elucidated by stepwise regression analysis. It was established that the plasma‐lemma of cell wall less zoospores showed the highest and the resting zoosporangia the lowest average sensitivity toward the surfactants. The biological efficacy of surfactants was highly different the di‐n‐octyl ester being the most effective. Calculations proved that both the stregth and selectivity of the biological activity mainly depends on the lipophilicity of the molecule and, to a lesser extent, on the electronic parameters.