In Vitro and In Vivo Characterization of Reactive Intermediates of Corynoline

Abstract

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 dicatechol. 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.

Metabolism‐based herb–drug interaction of Corydalis Bungeanae Herba with berberine in vitro and in vivo in rats

“…Meanwhile, the mean t 1/2 of CRL after oral administration of BER for 7 days was significantly shortened from 0.671 to 0.447 h. Our early study demonstrated that CRL was metabolized to three oxidative products both in vitro and in vivo . The oxidative metabolites included two mono‐catechols (M1 and M2), and one bis ‐catechol (M3), as shown in Scheme (Mao et al, ). Naturally, levels of the three oxidative metabolites of CRL were also monitored for the two groups (Figure b–d).…”

“…Our early study demonstrated that multiple CYP enzymes, including CYPs1A2, 2C9, 2C19, 2D6 and 3A4 (rCYPs1A2, 2C12, 2C13, 2D2, and 3A1), were involved in the metabolism of CRL (Mao et al, ). We examined the activities of these enzymes in animals after 7 days of pretreatment with BER.…”

“…The capacity for a drug to modify CYP enzyme activities is routinely evaluated by determining the effect of the drug on probe reactions in vitro that represent the activity of specific CYP enzymes (Yuan, Madani, Wei, Reynolds, & Huang, ). Previous studies showed that five CYPs – CYPs1A2, 2C9, 2C19, 2D6 and 3A4 (rCYPs1A2, 2C12, 2C13, 2D2, and 3A1) – mainly participated in the metabolism of CRL (Mao et al, ). Thus, the metabolic rates of the five corresponding probe substrates were evaluated in microsomes obtained from animals after treatment with BER.…”

“…Our early study demonstrated that multiple CYP enzymes, including CYPs1A2, 2C9, 2C19, 2D6 and 3A4 (rCYPs1A2, 2C12, 2C13, 2D2, and 3A1), were involved in the metabolism of CRL (Mao et al, 2015).…”

“…Further research demonstrated elevations of mRNA levels and protein expression of CYPs1A2 and 3A4 in animals given BER (Cui et al, ). Multiple CYP enzymes were involved in the metabolism of CRL and BER (Guo et al, ; Mao, Peng, & Zheng, ). This led us to hypothesize that pre‐administration of BER and its original herb may change the pharmacokinetic behavior of CRL in C. bungeanae , owing to the alteration of activity and expression of CYP enzymes mediated by BER, which may cause serious adverse effects or significant efficacy loss of CRL and CRL‐containing herbal medicines.…”