Hydractinia echinata test system. II. SAR toxicity study of some anilide derivatives of Naphthol-AS type

The Hydractinia echinata Test-System. III: Structure-Toxicity Relationship Study of Some Azo-, Azo-Anilide, and Diazonium Salt Derivatives

“…Just as in case of the Naphthol-AS [9], the measured toxicity values, F(1+2+…)e could be higher than the individual values of the reaction products F(1), F(2) etc ., especially in the case of “strong” interactions. However, in this situation, one could not notice the additivity F(1+2+…)e > F(1+2+...)t (e = experimental; t = theoretical), as suggested by Backhaus [18] (Table 2).…”

“…Considering that toxicity is constant in a range of ±0.50 log units (Köln model), the measured toxicity values Mlog(1/MRC 50 ) are compared to the calculated average value Clog(1/MRC 50 ). The introduction of this parameter points out the “class isotoxicity” character of the tested derivatives, which is also noticed in the case of AS-naphthols [9].…”

“…For all the tested compounds, SUAD-subadditive toxicity values [9], e.g., (F(1 + 2+..)e < F(1 + 2+..)t, were found equal to zero. It is relevant to highlight the fact that none of the studied cases presented synergism, considering the individual toxicities of the metabolites.…”

“…In the case of the anilide group, its hydrolysis involves the formation of an oxyanionic intermediate during the rate determining step [9]. The electronic shift in the carbonyl oxygen’s direction, increases the C=O bond length from 1.2 Å (fundamental state) to 1.4 Å (transition state).…”

“…Most azo derivatives contain, beside the azo group, one or more amidic (anilidic) groups (chromophores). The hydrolysis of these compounds occurs enzymatically [8], like the naphthols AS’s hydrolysis [9], involving the formation of an oxyanionic intermediate during the rate-determining step.…”