Corynoline is a 1,3-benzodioxole-containing isoquinoline alkaloid isolated from Corydalis bugeana Turcz., a traditional herbal medicine. Corynoline has reportedly demonstrated multiple pharmacologic properties. Previous studies have also shown that corynoline induced cytotoxicity and inhibited cytochrome P450 (CYP) enzymes, but the mechanisms of the adverse effects remain unknown. The major objective of the present study was to identify reactive metabolites of corynoline responsible for the cytotoxicity and enzyme inhibition. Three oxidative metabolites (M1–M3) were detected by liquid chromatography–tandem mass spectrometry in rat liver microsomal incubations after exposure to corynoline. M1 and M2 were two isomers of catechol derivatives, and M3 was a di-catechol. The M1–M3 metabolites were also observed in urine of rats given corynoline. A total of four N -acetylcysteine (NAC) conjugates (M4–M7) were detected in microsomes containing corynoline, NAC, and NADPH. Apparently, M4 and M5 were derived from M1, M6 resulted from M2, and M7 was a M3-derived NAC conjugate. This indicates that corynoline was bioactivated to ortho -quinone derivatives. No corynoline-derived NAC conjugates (M4–M7) were detected in urine of rats given corynoline; however, three corresponding cysteinylglycine conjugates (M8–M10) were observed instead. Recombinant P450 enzyme incubations demonstrated that the CYPs 2C9, 3A4, and 2C19 were mainly involved in metabolic activation of corynoline. The metabolism study facilitates the understanding of corynoline-induced cytotoxicity and P450 enzyme inhibition.
堇花碱是从一种传统草药 Corydalis bugeana Turcz.中分离出来的一种含有 1,3-苯并二恶茂的
异喹啉生物碱。据报道,Corynoline 具有多种药理特性。以前的研究也表明,堇草碱会诱发细胞毒性并抑制细胞色素 P450(CYP)酶,但其不良反应的机制仍不清楚。本研究的主要目的是找出导致细胞毒性和酶抑制作用的反应性代谢产物。通过
液相色谱-串联质谱法,在大鼠肝脏微粒体培养液中检测到了三种氧化代谢物(M1-M3)。M1 和 M2 是
儿茶酚衍
生物的两种异构体,M3 是二
儿茶酚。在服用了考来诺林的大鼠尿液中也观察到了 M1-M3 代谢物。在含有考来诺林、
NAC 和
NADPH 的微粒体中总共检测到四种 N -乙酰半胱
氨酸(
NAC)共轭物(
M4-M7)。显然,
M4 和 M5 来自 M1,M6 来自 M2,而 M7 则是 M3 衍生的
NAC 结合物。这表明噌啉被
生物活化为邻醌衍
生物。在服用了考来诺林的大鼠尿液中未检测到来源于考来诺林的
NAC 共轭物(
M4-M7),但却检测到了三种相应的半胱
氨酰甘
氨酸共轭物(M8-M10)。
重组 P450 酶培养结果表明,CYPs 2C9、3A4 和 2C19 主要参与了考来诺林的代谢活化。新陈代谢研究有助于理解由
紫堇灵诱导的细胞毒性和 P450 酶抑制作用。