The occurrence of two hepatic microsomal sites for amobarbital hydroxylation

1983 ◽  
Vol 61 (1) ◽  
pp. 67-71 ◽  
Author(s):  
P. A. Reilly ◽  
B. K. Tang ◽  
D. J. Stewart ◽  
W. Kalow
Keyword(s):  
Rat Liver ◽  
Human Liver ◽  
Liver Microsomes ◽  
Isolated Hepatocytes ◽  
Rat Liver Microsomes ◽  
Low Velocity ◽  
Whole Cells ◽  
High Affinity ◽  
High Affinity Site

Amobarbital metabolism in human liver and in rat liver, lung, kidney, and small intestine was measured in vitro using thin-layer chromatography (TLC) for separation of metabolites generated from incubation with [2-14C]amobarbital. Formation of 3′-hydroxyamobarbital (C-OH) occurred primarily in the liver. The kinetics of C-OH formation by rat liver microsomes or isolated hepatocytes could be described by a Michaelis–Menten model incorporating two metabolic sites, one characterized by high-affinity and low-velocity constants (Km = 0.054 ± 0.012 mM, Vmax = 16.89 ± 4.27 nmol C-OH∙g liver−1∙min−1), the other by low-affinity and high-velocity (Km = 0.679 ± 0.097 mM, Vmax = 66.0 ± 5.41 nmol C-OH∙g liver−1∙min−1). The kinetic parameters of the high-affinity site differed significantly between whole cells and homogenates. Pretreatment with phenobarbital for 3 days induced only the high-affinity site. Quantitation of C-OH formation in four human liver samples from several sources showed that metabolism may conform to the two-site model observed in rat liver.

Comparative Metabolism Study of Five Protoberberine Alkaloids in Liver Microsomes from Rat, Rhesus Monkey, and Human

Planta Medica ◽  
2017 ◽  
Vol 83 (16) ◽  
pp. 1281-1288 ◽  
Author(s):  
Yan Li ◽  
Yanyan Zhou ◽  
Nan Si ◽  
Lingyu Han ◽  
Wei Ren ◽  
...  
Keyword(s):  
Rhesus Monkey ◽  
Rat Liver ◽  
Human Liver ◽  
Metabolic Profile ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Rat Liver Microsomes ◽  
Protoberberine Alkaloids ◽  
First Time

AbstractProtoberberine alkaloids including berberine, palmatine, jatrorrhizine, coptisine, and epiberberine are major components in many medicinal plants. They have been widely used for the treatment of cancer, inflammation, diabetes, depression, hypertension, and various infectious areas. However, the metabolism of five protoberberine alkaloids among different species has not been clarified previously. In order to elaborate on the in vitro metabolism of them, a comparative analysis of their metabolic profile in rat, rhesus monkey, and human liver microsomes was carried out using ultrahigh-performance liquid chromatography coupled with a high-resolution linear trap quadrupole-Orbitrap mass spectrometer (UHPLC-electrospray ionization-Orbitrap MS) for the first time. Each metabolite was identified and semiquantified by its accurate mass data and peak area. Fifteen metabolites were characterized based on accurate MS/MS spectra and the proposed MS/MS fragmentation pathways including demethylation, hydroxylation, and methyl reduction. Among them, the content of berberine metabolites in human liver microsomes was similar with those in rhesus monkey liver microsomes, whereas berberine in rat liver microsomes showed no demethylation metabolites and the content of metabolites showed significant differences with that in human liver microsomes. On the contrary, the metabolism of palmatine in rat liver microsomes resembled that in human liver microsomes. The content of jatrorrhizine metabolites presented obvious differences in all species. The HR-ESI-MS/MS fragmentation behavior of protoberberine alkaloids and their metabolic profile in rat, rhesus monkey, and human liver microsomes were investigated for the first time. The results demonstrated that the biotransformation characteristics of protoberberine alkaloids among different species had similarities as well differences that would be beneficial for us to better understand the pharmacological activities of protoberberine alkaloids.

scholarly journals Nontargeted Metabolomics by High-Resolution Mass Spectrometry to Study the In Vitro Metabolism of a Dual Inverse Agonist of Estrogen-Related Receptors β and γ, DN203368

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 776
Author(s):  
Sin-Eun Kim ◽  
Seung-Bae Ji ◽  
Euihyeon Kim ◽  
Minseon Jeong ◽  
Jina Kim ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Human Liver ◽  
High Resolution Mass Spectrometry ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Rat Liver Microsomes ◽  
High Resolution Mass ◽  
Resolution Mass

DN203368 ((E)-3-[1-(4-[4-isopropylpiperazine-1-yl]phenyl) 3-methyl-2-phenylbut-1-en-1-yl] phenol) is a 4-hydroxy tamoxifen analog that is a dual inverse agonist of estrogen-related receptor β/γ (ERRβ/γ). ERRγ is an orphan nuclear receptor that plays an important role in development and homeostasis and holds potential as a novel therapeutic target in metabolic diseases such as diabetes mellitus, obesity, and cancer. ERRβ is also one of the orphan nuclear receptors critical for many biological processes, such as development. We investigated the in vitro metabolism of DN203368 by conventional and metabolomic approaches using high-resolution mass spectrometry. The compound (100 μM) was incubated with rat and human liver microsomes in the presence of NADPH. In the metabolomic approach, the m/z value and retention time information obtained from the sample and heat-inactivated control group were statistically evaluated using principal component analysis and orthogonal partial least-squares discriminant analysis. Significant features responsible for group separation were then identified using tandem mass spectra. Seven metabolites of DN203368 were identified in rat liver microsomes and the metabolic pathways include hydroxylation (M1-3), N-oxidation (M4), N-deisopropylation (M5), N,N-dealkylation (M6), and oxidation and dehydrogenation (M7). Only five metabolites (M2, M3, and M5-M7) were detected in human liver microsomes. In the conventional approach using extracted ion monitoring for values of mass increase or decrease by known metabolic reactions, only five metabolites (M1-M5) were found in rat liver microsomes, whereas three metabolites (M2, M3, and M5) were found in human liver microsomes. This study revealed that nontargeted metabolomics combined with high-resolution mass spectrometry and multivariate analysis could be a more efficient tool for drug metabolite identification than the conventional approach. These results might also be useful for understanding the pharmacokinetics and metabolism of DN203368 in animals and humans.

In vitro metabolism in Sprague–Dawley rat liver microsomes of forsythoside A in different compositions of Shuang–Huang–Lian

Fitoterapia ◽  
2011 ◽  
Vol 82 (8) ◽  
pp. 1222-1230 ◽  
Author(s):  
Wei Zhou ◽  
Liu-qing Di ◽  
Jin-jun Shan ◽  
Xiao-lin Bi ◽  
Le-tian Chen ◽  
...  
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
In Vitro Metabolism ◽  
Rat Liver Microsomes ◽  
Sprague Dawley ◽  
Sprague Dawley Rat

scholarly journals In Vitro Characterization of Borneol Metabolites by GC--MS Upon Incubation with Rat Liver Microsomes

2008 ◽  
Vol 46 (5) ◽  
pp. 419-423 ◽  
Author(s):  
R. Zhang ◽  
C.-h. Liu ◽  
T.-l. Huang ◽  
N.-s. Wang ◽  
S.-q. Mi
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes ◽  
In Vitro Characterization

In Vitro Metabolism of E2, G2: Novel Bile Acid-Coupling Camptothecin Analogues, in Rat Liver Microsomes

2021 ◽  
Vol 16 ◽  
Author(s):  
Xiangli Zhang ◽  
Qin Shen ◽  
Yi Wang ◽  
Leilei Zhou ◽  
Qi Weng ◽  
...  
Keyword(s):  
Bile Acid ◽  
Phase I ◽  
Rat Liver ◽  
Deoxycholic Acid ◽  
Liver Microsomes ◽  
Intrinsic Clearance ◽  
Rat Liver Microsomes ◽  
Camptothecin Analogues

Background: E2 (Camptothecin - 20 (S) - O- glycine - deoxycholic acid), and G2 (Camptothecin - 20 (S) - O - acetate - deoxycholic acid) are two novel bile acid-derived camptothecin analogues by introducing deoxycholic acid in 20-position of CPT(camptothecin) with greater anticancer activity and lower systematic toxicity in vivo. Objective: We aimed to investigate the metabolism of E2 and G2 by Rat Liver Microsomes (RLM). Methods: Phase Ⅰ and Phase Ⅱ metabolism of E2 and G2 in rat liver microsomes were performed respectively, and the mixed incubation of phase I and phase Ⅱ metabolism of E2 and G2 was also processed. Metabolites were identified by liquid chromatographic/mass spectrometry. Results: The results showed that phase I metabolism was the major biotransformation route for both E2 and G2. The isoenzyme involved in their metabolism had some difference. The intrinsic clearance of G2 was 174.7mL/min. mg protein, more than three times of that of E2 (51.3 mL/min . mg protein), indicating a greater metabolism stability of E2. 10 metabolites of E2 and 14 metabolites of G2 were detected, including phase I metabolites (mainly via hydroxylations and hydrolysis) and their further glucuronidation products. Conclusion: These findings suggested that E2 and G2 have similar biotransformation pathways except some difference in the hydrolysis ability of the ester bond and amino bond from the parent compounds, which may result in the diversity of their metabolism stability and responsible CYPs(Cytochrome P450 proteins).

Induction of a high affinity nitrosamine demethylase in rat liver microsomes by acetone and isopropanol

1983 ◽  
Vol 44 (3) ◽  
pp. 247-260 ◽  
Author(s):  
Yityoong Yong Tu ◽  
Renxiu Peng ◽  
Zee-Fen Chang ◽  
Chung S. Yang
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes ◽  
High Affinity
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