抗癌藥物在水體環境中的光降解：環磷醯胺及5-氟尿嘧啶

Abstract

This work aimed to investigate the photodegradation of two widely used anticancer drugs, cyclophosphamide and 5-fluorouracil. Direct, indirect and surface water photolysis experiments were processed by sunlight simulator (Xenon–arc lamp, 765 W/m2, wavelength above 290 nm). Three precursors which generate photoreactive species including dissolved organic matter (DOM), nitrate and bicarbonate were studied individually and in combination in the indirect photolysis batch experiments. Four surface water samples were collected from the metropolitan area in northern Taiwan and were used to study the effect of different water matrices. Results show that cyclophosphamide does not undergo direct photolysis while 5-fluorouracil can be directly photodegraded with initial concentration from 5 to 500 μg/L, having corresponding half-lives 45.5 ± 5.1 to 74.9 ± 17.8 hours. DOM, nitrate and bicarbonate demonstrated to be important factors for cyclophosphamide and 5-fluorouracil photodegradation. Produced by the three precursors, the hydroxyl radical (•OH) and singlet oxygen (1O2) can both react with cyclophosphamide and 5-fluorouracil, but triplet excited states of dissolved organic matter (3DOM*) and carbonate radical (•CO3-) can only react with 5-fluorouracil. Althought the matrices were quite complex in the four surface water samples, their overall photodegradation rate were consistent with the conclusion of the indirect photolysis batch experiments, it indicates that the selected three precursors are the major materials affecting the photodegradation in the aquatic environments.The half-lives of cyclophosphamide and 5-fluorouracil in JingMei River sample were 50.1 ± 0.5 and 9.2 ± 0.7 hours, indicating that cyclophosphamide is more persistent. This possibly explains its high occurrence in the nature aquatic environments.