School of Chemistry and Environment, Jiaying University, Meizhou, 514015, China.
Environ Sci Pollut Res Int. 2018 Sep;25(26):26069-26078. doi: 10.1007/s11356-018-2585-y. Epub 2018 Jul 3.
Photolysis of the widely used beta-blocker propranolol (PRO) was investigated in the presence of fulvic acid (FA) and inorganic ions under simulated solar irradiation. PRO undergoes direct photolysis proceeding mainly via degradation of the triplet excited state, PRO*. FA and inorganic ions inhibited photolysis of PRO in the order of FA > Fe > Cl > Ca > Mg > NO > K. An antagonistic effect between FA and inorganic ions toward the suppression of PRO photolysis was exhibited. The binding behaviors of PRO, FA, and inorganic ions were examined through fluorescence quenching experiments, which showed that inorganic ions affected the binding between FA and PRO through competing for the binding sites of FA or PRO. The correlation analysis demonstrated a positive correlation between the binding constant (K) of FA-PRO and the inhibition rate of FA on PRO photolysis. The observed rate constants of photolysis (k) have opposite correlations with the concentration of singlet oxygen (O). These findings strongly suggest that inorganic ions decrease the inhibition effect of FA on PRO photolysis via restraining the complexation of FA-PRO and production of O.
在模拟太阳光照射下，研究了富里酸（FA）和无机离子存在下，广泛使用的β受体阻滞剂普萘洛尔（PRO）的光解。PRO 主要通过三重态激发态 PRO*的降解进行直接光解。FA、无机离子对 PRO 光解的抑制作用顺序为 FA>Fe>Cl>Ca>Mg>NO>K。FA 和无机离子对 PRO 光解的抑制表现出拮抗作用。通过荧光猝灭实验研究了 PRO、FA 和无机离子的结合行为，结果表明，无机离子通过竞争 FA 或 PRO 的结合位点影响 FA 与 PRO 之间的结合。相关分析表明，FA-PRO 的结合常数（K）与 FA 对 PRO 光解抑制率之间呈正相关。光解的观测速率常数（k）与单线态氧（O）的浓度呈相反的相关性。这些发现强烈表明，无机离子通过抑制 FA-PRO 的络合和 O 的产生，降低了 FA 对 PRO 光解的抑制作用。
