The Structure-Activity Relationship For Ecological Effects Of Alkyl Phenols

Alkyl phenols, which are regarded as environmental endocrine disruptors, can activate breast cancer cells and are helpful to cancer cells' growth. Biodegradation is one of their maining degradating processes in the environment. Research on their biodegradation is of great significance to wasted water treatment and ecological risk assessment. In this article, alkyl phenols were selected as the test chemicals. Based on their 96hEC50 values determined on the inhibition of Scenedesmus obliques for the lack of algal acute toxicity data at present, the biodegradation kinetics and bioaccumulation of alkyl phenols, viz. phenol, o-cresol, m-cresol, 4-ethylphenol, 4-octylphenol by Tolypothrix, were studied and compared for the first time. Experimental results showed that the degradation rate mainly depended on Tolypothrix density and initial chemicals' concentrations of the five chemicals,and decreased with MW and the number of substituted carbon atoms. With low initial chemicals' concentrations of the chemicals, the kinetic constant K was mainly associated with the rate of Tolypothrix growth, r, and was linear with MW; Within 5 days, BCF values of chemicals changed with 3 stages (increased, decreased and increased, except 4-octylphenol). The average BCF increased with KOW. Moreover, the Promethean QSBR study was carried between the biodegradation data logK obtained by experiments and the chemicals' structure parameters, viz. logKOW,,△Hf and μ. The results showed that chemicals' transportation process into alga body determined the biodegradation rates and steric parameters were dominant factors governing the biodegradability of alkyl phenols, the influence of △Hf and electronic effect parameter μ,Ehomo on the final biodegradation products shouldn't be ignored. Finally, for the first time, the QSARs between the DNA damage of little mice's spleen cell by 12 phenols and molecular structure parameters,viz. KOW, MR, Ehomo, qH+, etc., were established. The results showed that the DNA damage by phenols was correlated well with the logarithm of octanol/water partition coefficient (logKOW) and molecular refractivity MR.