Effects of Guanxinning injection on rat cytochrome P450 isoforms activities in vivo and in vitro

Evaluation of the impact of vindoline, an active components of Catharanthus roseus, on rat hepatic cytochrome P450 enzymes by using a cocktail of probe drugs

The objection of this study was to investigate the effects of vindoline(VDL) on the cytochrome P450 (CYP 450) isoforms (CYP1A2, 2B, 2C11, 2D1 and 3A) in rats. Firstly, the rats were randomly divided into VDL pretreatment group and blank group, each group had six rats. VDL pretreatment group was administrated VDL (20 mg·kg-1) by oral gavage for fifteen days consecutively, and the equivalent CMC-Na solution without VDL was given to the blank group by gavage. Secondly, a cocktail of caffeine, bupropion, diclofenac, dextromethorphan and midazolam was then administered on the sixteenth day. Finally, blood samples were collected at the specified time point, and the plasma concentration of the probe drug was determined by UHPLC-QTOF-MS/MS. The effects of VDL on the activity of these CYP enzymes in rats were evaluated by pharmacokinetic parameters. VDL pretreatment group compared with the blank group, accelerated the metabolism of diclofenac, and weakened the metabolism of caffeine. These results suggested that VDL could induce the activity of CYP2C11, and inhibits the activity of CYP1A2, but had no significant effects on CYP2B, CYP2D1 and CYP3A. The results in this study can provide beneficial information for the later clinical application of VDL.

Effects of Vindoline on rat cytochrome P450 isoforms activities in vitro

A specific ultra-high performance liquid chromatography/quadrupole time-of-flightmass spectrometry (UHPLC-Q-TOF-MS/MS) method has been described for the simultaneous determination of the metabolites of tacrine, bupropion, diclofenac, dextromethorphan and midazolam, which are the five probe drugs of the five cytochrome P450 (CYP450) isoforms CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A4. The inhibition degree is determined by calculating IC50. The chromatographic separation was performed on a C18 column with a mobile phase consisted of 0.1% formic acid and acetonitrile. The mass spectrometric analysis was conducted in a positive electrospray ionization mode. IC50 values of CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A were 113.4 μmol·L^-1 , 83.78 μmol·L^-1 , 22.50 μmol·L^-1 , 9.081 μmol·L^-1 and 52.76 μmol·L^-1 , respectively. The in vitro results demonstrated that vindoline could inhibit CYP2D1 activity in rats, and weak inhibitory effect on CYP2C11 and CYP3A, but had no obvious effects on CYP1A2 and CYP2B.

Enzyme Activity of Natural Products on Cytochrome P450

Drug-metabolizing enzymes, particularly the cytochrome P450 (CYP450) monooxygenases, play a pivotal role in pharmacokinetics. CYP450 enzymes can be affected by various xenobiotic substrates, which will eventually be responsible for most metabolism-based herb–herb or herb–drug interactions, usually involving competition with another drug for the same enzyme binding site. Compounds from herbal or natural products are involved in many scenarios in the context of such interactions. These interactions are decisive both in drug discovery regarding the synergistic effects, and drug application regarding unwanted side effects. Herein, this review was conducted as a comprehensive compilation of the effects of herbal ingredients on CYP450 enzymes. Nearly 500 publications reporting botanicals’ effects on CYP450s were collected and analyzed. The countries focusing on this topic were summarized, the identified herbal ingredients affecting enzyme activity of CYP450s, as well as methods identifying the inhibitory/inducing effects were reviewed. Inhibitory effects of botanicals on CYP450 enzymes may contribute to synergistic effects, such as herbal formulae/prescriptions, or lead to therapeutic failure, or even increase concentrations of conventional medicines causing serious adverse events. Conducting this review may help in metabolism-based drug combination discovery, and in the evaluation of the safety profile of natural products used therapeutically.

Characterization of chemical components in the Guanxinning injection by liquid chromatography-mass spectrometry

Guanxinning injection (GXNI) is widely used in the treatments of cerebral thrombosis, cerebral hemorrhage, sequela, coronary disease, stenocardia, arrhythmia, and so on. For the herbal injections, more components should be characterized and quantified as much as possible to guarantee the drug safety. However, large numbers of the chemical constituents in the GXNI still remain unknown. In this study, ultrahigh performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry (UHPLC-Q Orbitrap HRMS), in combination of nuclear magnetic resonance (NMR), was used to identify the components in GXNI, which led to the identification of 194 compounds. With the aid of solvent partition, more phthalides, diterpenoid quinines, and salvianolic acids were tentatively identified, and minor compounds with the other structural types were also detected. The structural diversity of phthalides and diterpenoid quinones were revealed by the structural network, and six phthalides and 13 diterpenoid quinones were further detected in GXNI with the help of the characteristic fragmentation pattern and structural network. In addition, NMR also revealed the presence of a series of primary metabolites in the GXNI, which could be used as a complimentary approach for the rapid identification of the chemical components in the traditional Chinese medicines (TCM). However, the unknown NMR signals of GXNI needed to be further identified to guarantee the drug safety.