Characterization of in vitro metabolites of deoxypodophyllotoxin in human and rat liver microsomes using liquid chromatography/tandem mass spectrometry

Abstract

The in vitro metabolism of deoxypodophyllotoxin (DPT), a medicinal herbal product isolated from Anthriscus sylvestris (Apiaceae), was investigated in rats and human microsomes and human recombinant cDNA-expressed CYPs. The incubation of DPT with pooled human microsomes in the presence of NADPH generated five metabolites while its incubation with dexamethasone (Dex)-induced rat liver resulted in seven metabolites (M1-M7) with major metabolic reactions including mono-hydroxylation, O-demethylation and demethylenation. Reasonable structures of the seven metabolites of DPT could be proposed, based on the electrospray tandem mass spectra. Chemical inhibition by ketoconazole and metabolism studies with human recombinant cDNA-expressed CYPs indicated that CYP 3A4 and 2C19 are the major CYP isozymes in the metabolism of DPT in human liver microsomes.

Mechanism-Based Inhibition of CYP3A4 by Podophyllotoxin: Aging of an Intermediate Is Important for in Vitro/in Vivo Correlations

“…The released carbene is unstable and would react with water to ultimately produce catechol. 39, 40 An additional pathway leads to the formation of the inactive P420 ( k 6 ) from the enzyme-inhibitor complex (EI), which degrades to an unknown product ( k 7 ). The estimated parameters (with their respective standard deviations) are presented in Table 1 for both CYP3A4 baculosomes and HLM, whereas two representative fittings for CYP3A4 baculosomes and HLM are shown in Figures 4a and 4b, respectively.…”

Quality Evaluation of Juniperus rigida Sieb. et Zucc. Based on Phenolic Profiles, Bioactivity, and HPLC Fingerprint Combined with Chemometrics

“…Chemical and pharmacological research on J. rigida has led to the discovery of bioactive components, such as flavonoids and phenolic compounds that potentially contribute to its antioxidant activity (Robards et al, 1999; Woo et al, 2011; Taviano et al, 2013). Moreover, lignans and flavonoids from J. rigida , such as catechin, podophyllotoxin, and amentoflavone, exert strong biological effects, including anti-inflammatory, anticancer, and antiviral activities (Lee et al, 2008; Gordien et al, 2009; Ryu et al, 2010; Lesjak et al, 2011, 2013, 2014; Jeong et al, 2012). …”

Identification of Metabolites of N-(5-Benzoyl-2-(4-(2-Methoxyphenyl)piperazin-1-yl)thiazol-4-yl)pivalamide Including CYP3A4-Mediated C-Demethylation in Human Liver Microsomes with High-Resolution/High-Accuracy Tandem Mass

“…The inhibitory effects of known P450 isoform-selective inhibitors and the metabolism of KRO-105714 were evaluated to determine the P450 isoforms involved in the metabolic pathway. Well characterized P450-selective inhibitors-i.e., a-naphthoflavone for CYP1A2 (1 and 5 mM), tranylcypromine for CYP2A6 (1 and 5 mM), quercetin for CYP2C8 (5 and 20 mM), fluconazole for CYP2C9 (5 and 10 mM), ticlopidine for CYP2C19 (2 and 10 mM), quinidine for CYP2D6 (10 and 50 mM), diethyldithiocarbamate for CYP2E1 (20 and 100 mM), and ketoconazole for CYP3A4 (2 and 10 mM)-were incubated with KRO-105714 (Newton et al, 1995;Ko et al, 2000;Lee et al, 2008;Khojasteh et al, 2011). Incubations were performed with P450-selective inhibitor, pooled HLMs (1 mg/ml) and KR-105714 (50 mM).…”