QUANTITATIVE-ANALYSIS OF THE ANTIMICROBIAL ACTIVITY AND MEMBRANE-PERTURBATION POTENCY OF ANTIFOULING PARASUBSTITUTED ALKYLPHENOLS

To better understand the antifouling action of para-substituted phenol ic compounds, the antimicrobial activity, which is known to be related to the antifouling activity, was examined with Trychophyton mentagrop hytes. The effect of phenolic compounds on mitochondrial swelling was also investigated to elucidate their membrane-perturbation action. The variation of each activity was quantitatively analyzed by a regressio n analysis, using hydrophobic substituent parameter pi. Each activity varied parabolically with increasing hydrophobicity of the para-substi tuent, the optimum pi value being ca. 3.5-4.0. The introduction of a b ulky substituent to the ortho position resulted in a drastic decrease in each activity. It is therefore likely that the antimicrobial activi ty is due to perturbation of the membrane structure. Considering the g ood correlation between the antifouling and antimicrobial activities o f para-substituted phenols, the antifouling activity is assumed to be related to perturbation of the membrane structure and/or function.