Species difference in the inhibition of pentobarbital metabolism by empenthrin

Nrf2 Antioxidative System is Involved in Cytochrome P450 Gene Expression and Activity: A Delay in Pentobarbital Metabolism in Nrf2-Deficient Mice

NF-E2-related factor 2 (Nrf2) is a transcriptional regulator of biologic defense proteins, such as antioxidant proteins and phase II detoxification enzymes. Cytochrome P450 (P450) enzymes have been shown to regulate phase I metabolism of various drugs and are partially regulated by Nrf2; however, the influence of Nrf2 on drug pharmacokinetics is not known. Here, we showed that Nrf2 depletion prolonged the effect of pentobarbital, a sleep-promoting drug. Pretreatment with phenobarbital, a P450 inducer, shortens the sleeping time associated with pentobarbital-induced sedation in wild-type (WT) mice; however, this effect was not observed in Nrf2^-/- mice. Furthermore, the blood pentobarbital concentration was higher in Nrf2^-/- mice than in WT mice at 30-60 minutes, and the phenobarbital-induced enhancement of its clearance was attenuated in Nrf2^-/- mice compared with WT mice. Total P450 content was decreased in Nrf2^-/- mouse livers, and the phenobarbital-induced increase in P450 content was lower in Nrf2^-/- mice than WT mice. Cyp1a2, Cyp2a5, Cyp2c29, and Cyp2e1 gene expression levels under physiologic conditions and Cyp1a2, Cyp2a5, and Cyp2b10 gene expression levels under phenobarbital-treated conditions were lower in Nrf2^-/- mice compared with WT mice. Additionally, pentobarbital metabolism in liver microsomes was attenuated by Nrf2 depletion. Taken together, these findings suggested that Nrf2 influenced pentobarbital pharmacokinetics through the regulation of drug metabolism and P450 gene expression. Thus, Nrf2-mediated regulation of P450 may contribute to the biologic defense against increased reactive oxygen species production. SIGNIFICANCE STATEMENT: NF-E2-related factor 2 (Nrf2) plays a critical role in the cellular defense against oxidative stress. Nrf2^-/- mice with reduced ability to eliminate reactive oxygen species (ROS) showed a significant delay in emergence from pentobarbital-induced sleep, which was associated with decreased P450 activities and gene expression. Our findings provide that Nrf2 dysfunction or ROS that exceed a threshold level of the eliminating ability of the Nrf2 system may reduce P450 activity.

Pharmacological and toxicological study of a chemical-standardized ethanol extract of the branches and leaves from Eysenhardtia polystachya (Ortega) Sarg. (Fabaceae)

Eysenhardtia polystachya is used for the empirical treatment of cancer, infections, diarrhea, inflammation, and pain. This study identified, using GC-MS, the main chemical components in an ethanol extract of E. polystachya branches and leaves (EPE) and tested its cytotoxic, antimicrobial, anti-diarrheal, anti-inflammatory, and antinociceptive effects. The in vitro and in vivo toxicity of EPE was evaluated using the comet assay in human peripheral blood mononuclear cells (PBMC) and the acute toxicity test in mice, respectively. The cytotoxic and the antimicrobial effects were performed using the MTT assay and the minimum inhibitory concentration (MIC) test, respectively. The levels of pro-inflammatory mediators in LPS-stimulated macrophages were measured to evaluate the in vitro anti-inflammatory effects of EPE. The antidiarrheal (castor oil test, small intestine transit, and castor oil-induced enteropooling), and anti-inflammatory activities (TPA and carrageenan) of EPE were also performed. The antinociceptive actions of EPE were carried out with the following tests: acetic acid, formalin, and hot plate. The hypnotic and locomotor effects were analyzed using pentobarbital and a rotarod system, respectively. The main component in EPE was D-pinitol (26.93%). The antidiarrheal and antinociceptive effects of D-pinitol were also evaluated. EPE showed low in vitro toxicity (DNA damage in PBMC at concentrations higher than 200 µg/ml), and low in vivo toxicity (LD₅₀ > 2000 mg/kg i.p. and p.o.). Furthermore, EPE lacked cytotoxic activity (IC₅₀ > 300 µg/ml) on human cancer cells, but showed good antimicrobial effects in E. coli (MIC=1.56 µg/ml) and S. aureus (MIC = 0.78 µg/ml). In multi-drug resistant microorganisms, EPE showed MIC> 100 µg/ml. EPE exerted in vitro anti-inflammatory effects, mainly, by the decrease in the production of H₂O₂ (IC₅₀ = 43.9 ± 3.8 µg/ml), and IL-6 (73.3 ± 6.9 µg/ml). EPE (ED₅₀ =7.5 ± 0.9 mg/kg) and D-pinitol (ED₅₀ = 0.1 ± 0.03 mg/kg) showed antidiarrheal activity, and antinociceptive effects in the acetic acid test with ED₅₀ = 117 ± 14.5 mg/kg for EPE and 33 ± 3.2 mg/kg for D-pinitol. EPE showed also antinociceptive activity in the phase 2 of the formalin test (ED₅₀ = 48.9 ± 3.9 mg/kg), without inducing hypnotic effects or altering the locomotor activity in mice. The results here presented corroborate the folk medicinal use of Eysenhardtia polystachya in the treatment of infections, diarrhea, inflammation, and pain. D-pinitol, the main metabolite of EPE, showed antinociceptive and antidiarrheal effects with similar potency compared to standard drugs.

Interaction between different extracts of Hypericum perforatum L. from Serbia and pentobarbital, diazepam and paracetamol

Herb-drug interactions are an important safety concern and this study was conducted regarding the interaction between the natural top-selling antidepressant remedy Hypericum perforatum (Hypericaceae) and conventional drugs. This study examined the influence of acute pretreatment with different extracts of Hypericum perforatum from Serbia on pentobarbital-induced sleeping time, impairment of motor coordination caused by diazepam and paracetamol pharmacokinetics in mice. Ethanolic extract, aqueous extract, infusion, tablet and capsule of Hypericum perforatum were used in this experiment. The profile of Hypericum perforatum extracts as well as paracetamol plasma concentration was determined using RP-HPLC analysis. By quantitative HPLC analysis of active principles, it has been proven that Hypericum perforatum ethanolic extract has the largest content of naphtodianthrones: hypericin (57.77 µg/mL) and pseudohypericin (155.38 µg/mL). Pretreatment with ethanolic extract of Hypericum perforatum potentiated the hypnotic effect of pentobarbital and impairment of motor coordination caused by diazepam to the greatest extent and also increased paracetamol plasma concentration in comparison to the control group. These results were in correlation with naphtodianthrone concentrations. The obtained results have shown a considerable influence of Hypericum perforatum on pentobarbital and diazepam pharmacodynamics and paracetamol pharmacokinetics.

Moduratory effect of Thai traditional medicine (Yahom Tultavai) on hepatic cytochrome P450 enzymes and pentobarbital-induced sleeping in mice

Yahom Tultavai is a Thai traditional medicine that has been widely used for the treatment of nausea, vomiting, dizziness and weakness in aged-people, especially. Its formula contains several medicinal plants, and one of them is Kaempferia galanga L., which has ethyl-p-methoxycinnamate (EPMC) as its major compound. Recently, several herbs and traditional medicines have been reported to demonstrate herbal-drug interaction with conventional medicines. This study aims to investigate the effect of Yahom Tultavai extracts on hepatic cytochrome P450 enzymes and pentobarbital-induced sleeping in mice. Three extracts of Yahom Tultavai, using dichloromethane, methanol and distilled water as solvents were orally administered for 28 days prior to determine CYP1A1, CYP1A2, CYP2B, CYP2E1 and CYP3A4 activities. All three extracts significantly inhibited CYP1A1, CYP1A2 and CYP 2E1 activities, but only dichloromethane extract enhanced CYP2B activity. In addition, all three extracts had no effect on CYP3A4 activity. As an indicator for metabolic drug interaction, pentobarbital-induced sleeping time was decreased in connection with the induction of CYP2B activity between 7 and 28 days of dichloromethane extract and EPMC-treated animals when compared to control. In conclusion, Yahom Tultavai extracts affected hepatic microsomal CYP enzyme activities and reduced pentobarbital-induced sleeping time in mice. The results suggest that Yahom Tultavai may potentially cause herbal and conventional drug interaction, which can affect the clinical implication of drug action. Therefore, the co-administration of Yahom Tultavai with certain drugs should be carefully considered.

The influence of essential oil of aniseed (Pimpinella anisum, L.) on drug effects on the central nervous system

Anise (Pimpinella anisum L.; Apiaceae) and its essential oil have been widely used in folk medicine, pharmacy and food industry. Since there are some data about the impact of anise on functions of central nervous system (CNS), the issue of possible interactions with drugs acting in CNS should be considered. This survey aimed to examine the influence of aniseed essential oil (EO) intake on the effects of drugs that act in CNS. The chemical profile of essential oil determined by GC-MS revealed as the main components: trans-anethole (88.49%), γ-himachalene (3.13%), cis-isoeugenol (1.99%), and linalool (1.79%). The effects of codeine, diazepam, midazolam, pentobarbital, imipramine and fluoxetine were tested in mice after 5days of peroral pretreatment with human equivalent dose of aniseed EO (0.3mg/kg). The intake of EO led to significant increase of analgesic effect of codeine. The motor impairment caused by midazolam was enhanced in the group treated by EO. The application of diazepam decreased the number and percentage of entries in open arm in elevated maze plus test in the group pretreated with EO indicating augmented effect of drug on motor activity. EO pretreatment caused significant shortage of pentobarbital induced sleeping time when compared to control. The decrease in antidepressant effect of imipramine and fluoxetine was diminished by the pretreatment with aniseed EO. Based on the results of this study we conclude that concomitant intake of aniseed EO preparations and drugs that act on CNS should be avoided due to potential herb-drug interactions, which also need further clinical confirmation.