Electrochemistry combined with mass spectrometry (EC–MS) is an emerging analytical technique in the imitation of oxidative drug metabolism at the early stages of new drug development. Here, we present the benefits of electrochemical oxidation by square-wave potential pulses for the oxidation of lidocaine, a test drug compound, on a platinum electrode. Lidocaine was oxidized at constant potential and by square-wave potential pulses with different cycle times, and the reaction products were analyzed by liquid chromatography–mass spectrometry [LC–MS(/MS)]. Application of constant potentials of up to +5.0 V resulted in relatively low yields of N-dealkylation and 4-hydroxylation products, while oxidation by square-wave potential pulses generated up to 50 times more of the 4-hydroxylation product at cycle times between 0.2 and 12 s (estimated yield of 10%). The highest yield of the N-dealkylation product was obtained at cycle times shorter than 0.2 s. Tuning of the cycle time is thus an important parameter to modulate the selectivity of electrochemical oxidation reactions. The N-oxidation product was only obtained by electrochemical oxidation under air atmosphere due to reaction with electrogenerated hydrogen peroxide. Square-wave potential pulses may also be applicable to modulate the selectivity of electrochemical reactions with other drug compounds in order to generate oxidation products with greater selectivity and higher yield based on the optimization of cycle times and potentials. This considerably widens the scope of direct electrochemistry-based oxidation reactions for the imitation of in vivo oxidative drug metabolism.
电
化学结合质谱法(
EC-MS)是一种新兴的分析技术,用于在新药开发的早期阶段模拟药物的氧化代谢。在此,我们介绍了方波电位脉冲电
化学氧化法在
铂电极上氧化
利多卡因(一种测试药物化合物)的优势。
利多卡因在恒定电位和不同周期时间的方波电位脉冲下被氧化,反应产物通过
液相色谱-质谱法[LC-MS(/MS)]进行分析。使用高达 +5.0 V 的恒定电位时,N-脱烷基化和
4-羟基化产物的产率相对较低,而使用方波电位脉冲进行氧化时,在 0.2 至 12 秒的周期时间内,
4-羟基化产物的产率最高可达 50 倍(估计产率为 10%)。因此,调整周期时间是调节电
化学氧化反应选择性的一个重要参数。由于与电生
过氧化氢发生反应,只有在空气环境下进行电
化学氧化才能获得 N-氧化产物。方波电位脉冲也可用于调节其他药物化合物电
化学反应的选择性,以便在优化循环时间和电位的基础上生成选择性更强、产率更高的氧化产物。这大大拓宽了基于电
化学的直接氧化反应的范围,可用于模仿体内药物的氧化代谢。