Structure elucidation of aplidine metabolites formed <i>in vitro</i> by human liver microsomes using triple quadrupole mass spectrometry

Brandon, Esther; Ooijen, Ronald D. van; Sparidans, Rolf W.; Lázaro, Luis López; Heck, Albert J. R.; Beijnen, Jos H.; Schellens, Jan H.M.

doi:10.1002/jms.863

Cited by 20 publications

(17 citation statements)

References 11 publications

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“…It is interesting to note that a CYP3A-mediated carbon-carbon bond cleavage (metabolite V) was found in TPV metabolism in both the mouse and HLM. This type of carbon-carbon cleavage was reported by Brandon et al (2005Brandon et al ( , 2006, but the mechanism underlying this type of carbon-carbon cleavage is not clear.…”

Section: Et Almentioning

confidence: 70%

Metabolism-Mediated Drug Interactions Associated with Ritonavir-Boosted Tipranavir in Mice

Li¹,

Wang²,

Guo³

et al. 2010

Drug Metab Dispos

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ABSTRACT:Tipranavir (TPV) is the first nonpeptidic protease inhibitor used for the treatment of drug-resistant HIV infection. Clinically, TPV is coadministered with ritonavir (RTV) to boost blood concentrations and increase therapeutic efficacy. The mechanism of metabolismmediated drug interactions associated with RTV-boosted TPV is not fully understood. In the current study, TPV metabolism was investigated in mice using a metabolomic approach. TPV and its metabolites were found in the feces of mice but not in the urine. Principal component analysis of the feces metabolome uncovered eight TPV metabolites, including three monohydroxylated, three desaturated, one dealkylated, and one dihydroxylated. In vitro study using human liver microsomes recapitulated five TPV metabolites, all of which were suppressed by RTV. CYP3A4 was identified as the primary enzyme contributing to the formation of four TPV metabolites (metabolites II, IV, V, and VI), including an unusual dealkylated product arising from carbon-carbon bond cleavage. Multiple cytochromes P450 (2C19, 2D6, and 3A4) contributed to the formation of a monohydroxylated metabolite (metabolite III). In vivo, RTV cotreatment significantly inhibited eight TPV metabolic pathways. In summary, metabolomic analysis revealed two known and six novel TPV metabolites in mice, all of which were suppressed by RTV. The current study provides solid evidence that the RTV-mediated boosting of TPV is due to the modulation of P450-dependent metabolism.Tipranavir (TPV) is a nonpeptidic HIV protease inhibitor (PI) displaying high enzymatic inhibition and potent antiviral activity. TPV was approved by the Food and Drug Administration in 2005 and extended for pediatric use in 2008. TPV exhibits a different therapeutic profile from that of other currently available PIs, rendering it a potential option for treatment-experienced patients with resistance to multiple PIs (Pham, 2005;Courter et al., 2008). Systematic bioavailability of TPV is low. Clinically, TPV is administered orally twice daily and must be given in combination with low-dose ritonavir (RTV) to boost TPV bioavailability (Cahn et al., 2006). RTV was originally developed as an HIV protease inhibitor. It is now rarely used for its antiviral activity, but it is used as a cytochrome P450 (P450) inhibitor to boost other PIs (Kempf et al., 1997;Hsu et al., 1998). In a phase I clinical trial with healthy adult volunteers, it was noted that coadministration of TPV and RTV (TPV/r) resulted in a significant increase in steady-state TPV trough concentrations compared with TPV at a steady state alone. The means of the TPV trough concentrations were above a preliminary target threshold with most of the RTV-boosted doses. Without the RTV coadministration, none of the TPV-alone doses exceeded the threshold .The mechanism of drug-drug interactions associated with RTVboosted TPV is not fully understood. An in vitro study with human liver microsomes (HLM) suggested that CYP3A4 is the predominant enzyme involved in TPV metabolism. RTV strongly ...

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Section: Et Almentioning

confidence: 70%

Metabolism-Mediated Drug Interactions Associated with Ritonavir-Boosted Tipranavir in Mice

Li¹,

Wang²,

Guo³

et al. 2010

Drug Metab Dispos

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“…1) [10]. The metabolites apli-da and apli-h were immediately converted further to apli-da/h if the aplidine concentration was below 10 µg/ml.…”

Section: Biotransformation Of Aplidine In Pooled Human Liver Microsomesmentioning

confidence: 99%

“…The chromatographic assay with diode array detection was previously described by Brandon et al [10]. The percentage metabolised was calculated by dividing aplidine peak areas (sum of both conformations) of the incubation with microsomes and NRS (degradation and metabolism) by the areas of the incubation without microsomes and with NRS (degradation only).…”

Section: Analysis Of Aplidine and Metabolitesmentioning

confidence: 99%

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In vitro characterization of the human biotransformation pathways of aplidine, a novel marine anti-cancer drug

et al. 2006

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Aplidine is a potent marine anti-cancer drug and is currently being investigated in phase II clinical trials. However, the enzymes involved in the biotransformation of aplidine and thus its pharmacokinetics are not known yet. To assess the biotransformation pathways of aplidine and their potential implications for human pharmacology and toxicology, the in vitro metabolism of aplidine was characterized using incubations with human plasma, liver preparations, cytochrome P450 (CYP) and uridine diphosphoglucuronosyl transferase (UGT) supersomes in combination with HPLC analysis and cytotoxicity assays with cell lines. Aplidine was metabolised by carboxyl esterases in human plasma. Using CYP supersomes and liver microsomes, it was shown that aplidine was metabolised mainly by CYP3A4 and also by CYP2A6, 2E1 and 4A11. Four metabolites were observed after incubation with human liver microsomes, one formed by CYP2A6 (C-demethylation) and three by CYP3A4 (hydroxylation and/or C-dealkylation). No conjugation was observed in human liver S9 fraction. However, the aplidine metabolites formed by CYP were further conjugated by the phase II enzymes UGT, GST and SULT. In accordance with the findings in microsomes and CYP supersomes, a significant effect of specific CYP2A6, 2E1, 3A4 and 4A11 inhibitors on the cytotoxicity of aplidine in Hep G2 and IGROV-1 cells could be observed. These results provide evidence that CYP3A4 has a major role in metabolising aplidine in vitro with additional involvement of CYP2A6, 2E1, and 4A11. Further, the metabolites formed by CYPs can be conjugated by UGT, SULT and GST. These findings could help interpret the in vivo pharmacokinetics of aplidine.

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“…This solves the problem of a nonspecific ring opening of a cyclic molecule during the protonation/dissociation process. 179 In addition, specificity enhancement in cyclic structure opening can also be induced by cationization 180 or chemical reaction. 181,182 Enzyme digestion 183 has not found widespread use owing to the distinct resistance of cyclic peptides to proteases.…”

Section: Mass Spectrometry Of Cyclic Peptidesmentioning

confidence: 99%

Nonribosomal cyclic peptides: specific markers of fungal infections

Jegorov¹,

Hajdúch

Šulc

et al. 2006

J. Mass Spectrom.

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Some cyclic peptides and depsipeptides are synthesized in microorganisms by large multienzymes called nonribosomal peptide synthetases. The structures of peptide products originating in this way are complex and diverse and are microorganism-specific. This work proposes the use of fungal cyclic peptides and depsipeptides as extremely specific markers of fungal infections. Since a reliable molecular tool for diagnosing fungal infections at an early stage is still missing, we present mass spectrometry as a new, modern, broadband (with respect to fungal strain) and specific tool for clinical mycologists. More than 40 different fungal species can be rapidly characterized according to specific families of cyclic peptides, and in some cases, a particular fungal strain can be identified on the basis of its cyclopeptide profile. This paper is also aimed at initiating discussion on the biological role of these secondary metabolites, especially of those synthesized by medically important strains. Proven cytotoxic, anti-inflammatory or immunosuppressive activities of some cyclic peptides indicate that these molecules may contribute to the synergistic array of fungal virulence factors and support microbial invasion during fungal infection. In addition to an overview on recent mass spectrometric protocols for cyclic peptide sequencing, the structures of new peptides from Paecilomyces and Pseudallescheria are presented.

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Structure elucidation of aplidine metabolites formed in vitro by human liver microsomes using triple quadrupole mass spectrometry

Cited by 20 publications

References 11 publications

Metabolism-Mediated Drug Interactions Associated with Ritonavir-Boosted Tipranavir in Mice

Metabolism-Mediated Drug Interactions Associated with Ritonavir-Boosted Tipranavir in Mice

In vitro characterization of the human biotransformation pathways of aplidine, a novel marine anti-cancer drug

Nonribosomal cyclic peptides: specific markers of fungal infections

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