Metabolic Activation of the Indoloquinazoline Alkaloids Evodiamine and Rutaecarpine by Human Liver Microsomes: Dehydrogenation and Inactivation of Cytochrome P450 3A4

Abstract

Evodiamine and rutaecarpine are the main active indoloquinazoline alkaloids of the herbal medicine Evodia rutaecarpa, which is widely used for the treatment of hypertension, abdominal pain, angina pectoris, gastrointestinal disorder, and headache. Immunosuppressive effects and acute toxicity were reported in mice treated with evodiamine and rutaecarpine. Although the mechanism remains unknown, it is proposed that metabolic activation of the indoloquinazoline alkaloids and subsequent covalent binding of reactive metabolites to cellular proteins play a causative role. Liquid chromatography-tandem mass spectrometry analysis of incubations containing evodiamine and NADPH-supplemented microsomes in the presence of glutathione (GSH) revealed formation of a major GSH conjugate which was subsequently indentified as a benzylic thioether adduct on the C-8 position of evodiamine by NMR analysis. Several other GSH conjugates were also detected, including conjugates of oxidized and demethylated metabolites of evodiamine. Similar GSH conjugates were formed in incubations with rutaecarpine. These findings are consistent with a bioactivation sequence involving initial cytochrome P450-catalyzed dehydrogenation of the 3-alkylindole moiety in evodiamine and rutaecarpine to an electrophile 3-methyleneindolenine. Formation of the evodiamine and rutaecarpine GSH conjugates was primarily catalyzed by heterologously expressed recombinant CYP3A4 and, to a lesser extent, CYP1A2 and CYP2D6, respectively. It was found that the 3-methyleneindolenine or another reactive intermediate was a mechanism-based inactivator of CYP3A4, with inactivation parameters K I = 29 mM and k inact = 0.029 minute 21, respectively. In summary, these findings are of significance in understanding the bioactivation mechanisms of indoloquinazoline alkaloids, and dehydrogenation of evodiamine and rutaecarpine may cause toxicities through formation of electrophilic intermediates and lead to drug-drug interactions mainly via CYP3A4 inactivation.

Effects of Evodiamine on the Pharmacokinetics of Dapoxetine and Its Metabolite Desmethyl Dapoxetine in Rats

“…Therefore, the increased bioavailability of oral dapoxetine by evodiamine may be due to the inhibition of CYP3A4-mediated metabolism. These results are consistent with the report in that evodiamine was primarily catalyzed by heterologously expressed recombinant CYP3A4 [9]. …”

“…In addition, the anti-tumor properties of evodiamine have drawn much attention, and growing evidences demonstrated that evodiamine showed potential anti-tumor activity through inhibiting proliferation, inducing apoptosis and reducing invasion and metastasis of various tumor cells [5,6,7]. Recently, drug metabolizing enzymes involved in the metabolism of evodiamine were investigated, including CYP3A4, CYP2C9 and CYP1A2 [8,9]. …”

In vitro and in vivo metabolic activation of berbamine to quinone methide intermediate

“…The quinone methide intermediate reacted with thiols via Michael addition by three mechanisms, including 1,2‐, 1,4‐, or 1,6‐addition. The observed fragment m/z 607 of M3 was derived from the loss of the NAC moiety, implying the presence of benzylic thioether motif rather than phenyl thioether in this NAC adduct . Based on the MS/MS data of M3, our previous dauricine work and literatures, we proposed that the nucleophile attacked the exocyclic methylene via 1,6‐addition to form benzylic thioether conjugate.…”

Investigating the molecular and aggregated states of a drug molecule rutaecarpine using spectroscopy, microscopy, crystallography and computational studies

“…1 The quinazoline skeleton (Chart 1) present in rutaecarpine is of huge pharmacological importance. [3][4][5][6] Even though many synthetic procedures have been reported in literature to synthesize rutaecarpine and its analogues, [4][5][6][7] studies aiming at understanding the influence of the microenvironment of such molecules on their biological activity are still a topic of interest. [3][4][5][6] Even though many synthetic procedures have been reported in literature to synthesize rutaecarpine and its analogues, [4][5][6][7] studies aiming at understanding the influence of the microenvironment of such molecules on their biological activity are still a topic of interest.…”