Metabolite in vitro

Figure 5.40 Product-ion spectrum of the (M + H)+ ion (m/z 614) of Indinavir with the proposed origins of the ions observed. Reprinted by permission of Elsevier Science from Identification of in vitro metabolites of Indinavir by Intelligent Automated LC-MS/MS (INTAMS) utilizing triple-quadrupole tandem mass spectrometry , by Yu, X., Cui, D. and Davis, M. R., Journal of the American Society for Mass Spectrometry, Vol. 10, pp. 175-183, Copyright 1999 by the American Society for Mass Spectrometry.

Duverger-Van Bogaert M, Lambotte-Vandepaer M, de Meester C, et al. 1981b. Effect of several factors on the liver extract mediated mutagenicity of acrylonitrile and identification of four new in vitro metabolites. Toxicol Lett 7 311-319. 

Estimating the amount of a metabolite when an authentic reference standard is not available is still a challenge. Yu et al.191 described a procedure that uses the results of an in vitro metabolite identification based on a test compound that produces 14C-labelled metabolites essentially the 14C-labelled metabolites are used to provide a correction factor for the MS response when assaying samples that contain the same metabolite in a study that did not use the 14C-labelled test compound. Flop192 described another novel approach for metabolite quantitation based on the observation that the MS responses for most compounds are very similar to responses from nanospray ESI. Valaskovic et al.193 also reported equimolar MS responses for multiple compounds when the flow rate to the nanospray ESI source was set to about 10 nl/min. It is too soon to know whether these intriguing findings can be readily applied to discovery metabolite identification studies. 

Juhl, K., Blum, K. Witte, I. (1989) The in vitro metabolites of 2,4.6-trichlorophenol and their DNA strand breaking properties. Chem.-biol. Interact., 69, 333-344... 

Hop, C. E., Tiller, P. R., and Romanyshyn, L. (2002). In vitro metabolite identification using fast gradient high performance liquid chromatography combined with tandem mass spectrometry. Rapid Commun. Mass Spectrom. 16 212-219. 

Figure 4.2. Separation of in vitro metabolites of dextromethorphan with HPLC vs. UPLC (bottom panel desmethyl-dextromethorphan (m/z 258) middle panel desmethyl-dextromethor-phan-glucuronide (m/z 434) top panel di-desmethyl-dextromethorphan-glucuronide (m/z 420) where S/N PtP = peak-to-peak signal-to-noise ratio).

Lin, G., Chu, K.-W., Damani, L. A., Hawes, E. M. Identification of lactams as in vitro metabolites of piperidine-type phenothiazine antipsychotic drugs. J. Pharmacol. Biomed. Anal. 1996,14, 727-738. 

Yu, X. Cui, D. Davis, M. R. 1999. Identification of in vitro metabolites of indinavir by intelligent automated LC-MS/MS (INTAMS) utilizing triple quadrupole tandem mass spectrometry. /. Am. Soc. Mass Spectrom., 10, 175-183. 

Chen H, Chen Y, Du P, Han F (2007) Structural elucidation of in vivo and in vitro metabolites of anisodine by liquid chromatography-mass spectrometry. J Pharm Biomed Anal 44 773-778... 

Generally based on shared in vitro metabolite profile with humans. Pharmacologic activity is a secondary consideration. Rodent and nonrodent species are easily identified. 

K. E. Zhang, B. Hee, C. A. Lee, B. Liang, and B. C. M. Potts, Liquid chromatography-mass spectrometry and liquid chromatography-NMR characterization of in vitro metabolites of a potent and irreversible peptidomimetic inhibitor of rhinovirus 3C protease. Drug Metab. Dispos. 29 (2001), 729-734. 

TOF and Q-TOF instraments are freqnently applied in metabolism studies. The identity of the epothilone B metabolites fonnd by precnrsor-ion analysis (Figure 10.5, Ch. 10.4.2) was confirmed using accnrate-mass determination on a LC-TOF-MS instmment [29]. Some other examples are the characterization of metabolites of moclobemide and remikiren [32], the identification of ketobemidone Phase-I and Phase-II metabolites [33], and the identification of in vitro metabolites of ethoxidine [34]. The nse of a five-channel multiplexed ESI interface (four chaimels for parallel LC-MS and one channel for lock-mass componnd infusion) on a Q-TOF instrument was recently described to speed np metabolite identification and to enhance the efficient nse of the costly instrument [35]. 

D.J. Foltz, J. Castro-Perez, P. Riley, J.R. Entwisle, T.R. Baker, Narrow-bore sample trapping and LC combined with Q-TOF-MS for ultrasensitive identification of in vivo and in vitro metabolites, J. Chromatogr. B, 825 (2005) 144. 

Positive and negative ion current traces om PPINICI analysis of in vitro metabolites... 

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