Acute Photoinduced Toxicity Of Anthraquinones To The Crustacean Daphnia Magna And QSAR

Anthraquinones are an important industrial material, and it is reported that some anthraquinones have photosensitization activity. Thus there compounds, discharged into aqueous system, may take place photochemistry reaction after absorb visible light, and lead to have a great risk for aqueous ecology systems. Daphnia magna have been used word-wide as a standard test organism for ecotoxicological evaluation of contamination.The thesis study the acute toxicity of 20 anthraquinones to Daphnia magna under two different light/dark cycles, 14 (light): 10 h (dark), and sole dark. Furthermore, their photoinduced toxicity to Daphnia magna and the effects of two solubilizing agents on the photoinduced toxicity was investigated. Based on toxicity data, a quantitative structure-activity relationship (QSAR) was obtained. The mechanism of the photoinduced toxicity was also discussed. The results indicated that seven compounds were not toxic. 1,2-Dihydroxyanthraquinone and 1,4-dihydroxyanthraquinone were subject to photomodification under the daylight fluorescent lamp. The photoinduced toxicity of the tested eleven anthraquinones to Daphnia magna was enhanced due to photosensitization. The two co-solvents, dimethylsulfoxide and acetone, did not affect the photoinduced toxicity of the compounds. The photoinduced toxicity of the anthraquinones depended on the number, position and electron-donating ability of the substituent groups to the parent structure of anthraquinone. The gap between the energy of the highest occupied molecular orbital and the lowest unoccupied molecular orbital can be used as an indicator of the potential photoinduced toxicity of anthraquinones to Daphnia magna. Q_cum² of the final models of the toxicity of the tested eleven anthraquinones to Daphnia magna, were higher than 0.902, indicating that the models have good predictive ability and robustness. The main factors governing photoinduced toxicity of the anthraquinone are molecular polarity, the ability of electron transition and the largest negative net atomic charges.