Toxicity of anilines to Photobacterium phosphoreum and the quantitative structure-activity relationship

The acute toxicity of 13 anilines to Photobacterium phosphoreum at different pH(pH 5.0, 7.0 and 9.0) are determined by taking 15 min-EC_(50) as indicator which means the concentration value causing a 50% inhibion of bio-luminescence after 15 minutes. The quantitative structure-activity relationship is studied by applying two physico-chemical parameters logP and pK_(a). The mechanism of toxicity of anilines to Photobacterium phosphoreum is also investigated. The results show that the toxicity of anilines to Photobacterium phosphoreum increases with the rise of pH. This phenomenon is relevant to the ionization degree of anilines at different pH. At the same pH, the toxicity of anilines is differing with the variety, the number and the substitution position of substituent group. Anilines belong to polar narcotic compounds. Its toxicity to Photobacterium phosphoreum is mainly electrophilic. The toxicity can be described by logP in combination with pK_(a).