scholarly journals The inhibitory effects in vitro of phenothiazines and other drugs on lipid-peroxidation systems in rat liver microsomes, and their relationship to the liver necrosis produced by carbon tetrachloride

1968 ◽  
Vol 106 (1) ◽  
pp. 155-160 ◽  
Author(s):  
T F Slater
Keyword(s):  
Lipid Peroxidation ◽  
Carbon Tetrachloride ◽  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes ◽  
Protective Agent ◽  
Liver Necrosis ◽  
Inhibitory Effects

1. The effects of several phenothiazine derivatives on lipid-peroxidation systems in rat liver microsomes were studied and the results are considered in relation to the hepatotoxic action of carbon tetrachloride. 2. The lipid-peroxidation system coupled to NADPH2 oxidation and stimulated by an ADP–Fe2+ mixture is strongly inhibited in vitro by promethazine (50% inhibition at 29μm). Chlorpromazine and Stelazine also inhibit the peroxidation system but are less effective than promethazine. 3. The effects of promethazine on three other systems involving oxygen uptake (sulphite oxidation, orcinol oxidation and mitochondrial succinate oxidation) were also studied. Promethazine does not inhibit these systems to the same extent as it does the NADPH2–ADP–Fe2+ lipid-peroxidation system. 4. Promethazine also produces an inhibition of the NADPH2–ADP–Fe2+ system in liver microsomes after administration in vivo. It is concluded that the inhibition involves the interaction of the drug (or a metabolite of it) with the microsomal electron-transport chain. 5. Several other compounds known to protect the rat against liver necrosis after the administration of carbon tetrachloride were tested for inhibitory action on the NADPH2–ADP–Fe2+ system. No clear correlation was observed between effectiveness in vivo as a protective agent and inhibitory effects on the NADPH2–ADP–Fe2+ system in vitro. 6. Promethazine was found to inhibit the stimulation of lipid peroxidation produced in rat liver microsomes by low concentrations of carbon tetrachloride. This effect occurs at a concentration similar to that observed in vivo after administration of a normal clinical dose.

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).

Inhibitory Effect of Resveratrol on the Pharmacokinetics of Ticagrelor in Vivo and Vitro

2021 ◽  
Author(s):  
Peng Wang ◽  
Xiao-Xia Hu ◽  
Ying-hui Li ◽  
Nan-Yong Gao ◽  
Guo-quan Chen ◽  
...  
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
In Vitro Study ◽  
Inhibitory Effect ◽  
Control Group ◽  
Rat Liver Microsomes ◽  
Sprague Dawley ◽  
Group B

This study was to evaluate the effect of resveratrol on the pharmacokinetics of ticagrelor in rats and the metabolism of ticagrelor in human CYP3A4 and liver microsomes. Eighteen Sprague-Dawley rats were randomly divided into three groups: group A (control group), group B (50mg/kg resveratrol), and group C (150mg/kg resveratrol ). After 30 minutes administration of resveratrol, a single dose of ticagrelor (18mg/kg) was administered orally. The vitro experiment was performed to examine the influence of resveratrol on ticagrelor metabolism in CYP3A4*1, human, and rat liver microsomes. Serial biological samples were assayed by validated UHPLC-MS/MS methods. In vivo study, the AUC and Cmax of ticagrelor in group B and C appeared to be significantly higher than the control group, while Vz/F and CLz/F of ticagrelor in group B and C were significantly decreased. In vitro study, resveratrol exhibited an inhibitory effect on CYP3A4*1, human and rat liver microsomes. The IC50 values of resveratrol were 56.75μM，69.07μM and 14.22μM, respectively. Our results indicated that resveratrol had a inhibitory effect on the metabolism of ticagrelor in vitro and vivo. It should be paid more attention to the clinical combination of resveratrol with ticagrelor and ticagrelor plasma concentration should be monitored to avoid the occurrence of adverse reaction.

scholarly journals Inhibition of microsomal lipid peroxidation by glutathione and glutathione transferases B and AA. Role of endogenous phospholipase A2

1984 ◽  
Vol 220 (1) ◽  
pp. 243-252 ◽  
Author(s):  
K H Tan ◽  
D J Meyer ◽  
J Belin ◽  
B Ketterer
Keyword(s):  
Lipid Peroxidation ◽  
Phospholipase A2 ◽  
Rat Liver ◽  
Inhibitory Activity ◽  
Liver Microsomes ◽  
Supernatant Fraction ◽  
Rat Liver Microsomes ◽  
Microsomal Lipid Peroxidation ◽  
Soluble Supernatant

Lipid peroxidation in vitro in rat liver microsomes (microsomal fractions) initiated by ADP-Fe3+ and NADPH was inhibited by the rat liver soluble supernatant fraction. When this fraction was subjected to frontal-elution chromatography, most, if not all, of its inhibitory activity could be accounted for by the combined effects of two fractions, one containing Se-dependent glutathione (GSH) peroxidase activity and the other the GSH transferases. In the latter fraction, GSH transferases B and AA, but not GSH transferases A and C, possessed inhibitory activity. GSH transferase B replaced the soluble supernatant fraction as an effective inhibitor of lipid peroxidation in vitro. If the microsomes were pretreated with the phospholipase A2 inhibitor p-bromophenacyl bromide, neither the soluble supernatant fraction nor GSH transferase B inhibited lipid peroxidation in vitro. Similarly, if all microsomal enzymes were heat-inactivated and lipid peroxidation was initiated with FeCl3/sodium ascorbate neither the soluble supernatant fraction nor GSH transferase B caused inhibition, but in both cases inhibition could be restored by the addition of porcine pancreatic phospholipase A2 to the incubation. It is concluded that the inhibition of microsomal lipid peroxidation in vitro requires the consecutive action of phospholipase A2, which releases fatty acyl hydroperoxides from peroxidized phospholipids, and GSH peroxidases, which reduce them. The GSH peroxidases involved are the Se-dependent GSH peroxidase and the Se-independent GSH peroxidases GSH transferases B and AA.

scholarly journals Inhibition and Induction by Poziotinib of Different Rat Cytochrome P450 Enzymes In Vivo and in an In Vitro Cocktail Method

2021 ◽  
Vol 11 ◽  
Author(s):  
Jinhui Wang ◽  
Feifei Chen ◽  
Hui Jiang ◽  
Jia Xu ◽  
Deru Meng ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Rat Liver ◽  
Clinical Investigation ◽  
Liver Microsomes ◽  
Pharmacokinetic Parameters ◽  
Rat Liver Microsomes ◽  
Cytochrome P450 Enzymes ◽  
Significant Difference

Poziotinib is an orally active, irreversible, pan-HER tyrosine kinase inhibitor used to treat non-small cell lung cancer, breast cancer, and gastric cancer. Poziotinib is currently under clinical investigation, and understanding its drug-drug interactions is extremely important for its future development and clinical application. The cocktail method is most suitable for evaluating the activity of cytochrome P450 enzymes (CYPs). As poziotinib is partially metabolized by CYPs, cocktail probes are used to study the interaction between drugs metabolized by each CYP subtype. Midazolam, bupropion, dextromethorphan, tolbutamide, chlorzoxazone, phenacetin, and their metabolites were used to examine the effects of poziotinib on the activity of cyp1a2, 2b1, 2d1, 2c11, 2e1, and 3a1/2, respectively. The in vitro experiment was carried out by using rat liver microsomes (RLMs), whereas the in vivo experiment involved the comparison of the pharmacokinetic parameters of the probes after co-administration with poziotinib to rats to those of control rats treated with only probes. UPLC-MS/MS was used to detect the probes and their metabolites in rat plasma and rat liver microsomes. The in vitro results revealed that the half-maximal inhibitory concentration values of bupropion and tolbutamide in RLMs were 8.79 and 20.17 μM, respectively, indicating that poziotinib showed varying degrees of inhibition toward cyp2b1 and cyp2c11. Poziotinib was a competitive inhibitor of cyp2b1 and cyp2c11, with Ki values of 16.18 and 17.66 μM, respectively. No time- or concentration-dependence of inhibition by poziotinib was observed toward cyp2b1 and cyp2c11 in RLMs. Additionally, no obvious inhibitory effects were observed on the activity of cyp1a2, cyp2d1, cyp2e1, and cyp3a1/2. In vivo analysis revealed that bupropion, tolbutamide, phenacetin, and chlorzoxazone showed significantly different pharmacokinetic parameters after administration (p < 0.05); there was no significant difference in the pharmacokinetic parameters of dextromethorphan and midazolam. These results show that poziotinib inhibited cyp2b1 and cyp2c11, but induced cyp1a2 and cyp2e1 in rats. Thus, poziotinib inhibited cyp2b1 and cyp2c11 activity in rats, suggesting the possibility of interactions between poziotinib and these CYP substrates and the need for caution when combining them in clinical settings.

scholarly journals Contribution of metabolites to carbon tetrachloride-induced hepatotoxicity in rat liver microsomes in vitro.

Eisei kagaku ◽  
1987 ◽  
Vol 33 (6) ◽  
pp. 394-404
Author(s):  
YASUYOSHI SAYATO ◽  
KATSUHIKO NAKAMURO ◽  
SHIGEYUKI USUI
Keyword(s):  
Carbon Tetrachloride ◽  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes

scholarly journals Effects of neurotropin on rat liver microsomes and lysosomes, and in vitro lipid peroxidation.

1985 ◽  
Vol 33 (2) ◽  
pp. 810-817
Author(s):  
TARO OGISO ◽  
MASAHIRO IWAKI ◽  
EIJI TAMAKI ◽  
KAZUTOSHI MORIKAWA ◽  
YURIKO NAKAOKA
Keyword(s):  
Lipid Peroxidation ◽  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes
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