Potential herb-drug interaction risk of thymoquinone and phenytoin

Physcion inhibition of CYP2C9, 2D6 and 3A4 in human liver microsomes

CONTEXT

The effect of the active ingredients in traditional Chinese medicines on the activity of cytochrome P450 enzymes (CYP450s) is a critical factor that should be considered in TCM prescriptions. Physcion, the major active ingredient of Rheum spp. (Polygonaceae), possesses wide pharmacological activities.

OBJECTIVES

The effect of physcion on CYP450 activity was investigated to provide a theoretical basis for use.

MATERIALS AND METHODS

The experiments were conducted in pooled human liver microsomes (HLMs). The activity of CYP450 isoforms was evaluated with corresponding substrates and probe reactions. Blank HLMs were set as negative controls, and typical inhibitors were employed as positive controls. The inhibition model was fitted with Lineweaver Burk plots. The concentration (0, 2.5, 5, 10, 25, 50 and 100 μM physcion) and time-dependent (0, 5, 10, 15 and 30 min) effects of physcion were also assessed.

RESULTS

Physcion suppressed CYP2C9, 2D6 and 3A4 in a concentration-dependent manner with IC50 values of 7.44, 17.84 and 13.50 μM, respectively. The inhibition of CYP2C9 and 2D6 was competitive with the Ki values of 3.69 and 8.66 μM, respectively. The inhibition of CYP3A4 was non-competitive with a Ki value of 6.70 μM. Additionally, only the inhibition of CYP3A4 was time-dependent with the KI and Kinact parameters of 3.10 μM-1 and 0.049 min-1, respectively.

CONCLUSIONS

The inhibition of CYP450s by physcion should be considered in its clinical prescription, and the study design can be employed to evaluate the interaction of CYP450s with other herbs.

Rehmannioside A inhibits the activity of CYP3A4, 2C9 and 2D6 in vitro

To assess the effect of Rehmannioside A on CYP450s activity and to estimate its inhibitory properties.The effect of Rehmannioside A on the activity of major CYP450s in human liver microsomes (HLMs) was assessed with the corresponding substrates and marker reactions, and compared with a blank control and the respective inhibitors. Suppression of CYP3A4, 2C9 and 2D6 was assessed by the dose-dependent assay and fitted with non-competitive or competitive inhibition models. The inhibition of CYP3A4 was determined in a time-dependent manner.Rehmannioside A suppressed the activity of CYP3A4, 2C9, and 2D6 with IC50 values of 10.08, 12.62, and 16.43 μM, respectively. Suppression of CYP3A4 was fitted to a non-competitive model with Ki value of 5.08 μM, whereas CYP2C9 and 2D6 were fitted to a competitive model with Ki values of 6.25 and 8.14 μM. Additionally, the inhibitory effect on CYP3A4 was time-dependent with KI value of 8.47 μM-1 and a Kinact of 0.048 min-1.In vitro suppression of CYP3A, 2C9 and 2D6 by Rehmannioside A indicated that Rehmannioside A or its source herbs may interact with drugs metabolised by these CYP450s, which could guide the clinical application.

Effect of tubeimoside I on the activity of cytochrome P450 enzymes in human liver microsomes

This study assessed the effect of tubeimoside I on CYP1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 to reveal the potential of tubeimoside I to induce drug-drug interaction.The evaluation of cytochromes P450 enzyme (CYP) activity was performed in pooled human liver microsomes with probing substrates of CYP1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4. Typical inhibitors were employed as positive controls and the effect of 0, 2.5, 5, 10, 25, 50, and 100 μM tubeimoside I was investigated.The activity of CYP2D6, 2E1, and 3A4 was significantly inhibited by tubeimoside I with the IC50 values of 10.34, 11.58, and 9.74 μM, respectively. The inhibition of CYP2D6 and 2E1 was competitive with the Ki value of 5.66 and 5.29 μM, respectively. While the inhibition of CYP3A4 was non-competitive with the Ki value of 4.87 μM. Moreover, the inhibition of CYP3A4 was time-dependent with the KI and Kinact values of 0.635 μM-1 and 0.0373 min-1, respectively.Tubeimoside I served as a competitive inhibitor of CYP2D6 and 2E1 exerting weak inhibition and a non-competitive inhibitor of CYP3A4 exerting moderate inhibition.

Treating Epilepsy with Natural Products: Nonsense or Possibility?

Epilepsy is a neurological disease characterized by recurrent seizures that can lead to uncontrollable muscle twitching, changes in sensitivity to sensory perceptions, and disorders of consciousness. Although modern medicine has effective antiepileptic drugs, the need for accessible and cost-effective medication is urgent, and products derived from plants could offer a solution. For this review, we have focused on natural compounds that have shown anticonvulsant activity in in vivo models of epilepsy at relevant doses. In some cases, the effects have been confirmed by clinical data. The results of our search are summarized in tables according to their molecular targets. We have critically evaluated the data we present, identified the most promising therapeutic candidates, and discussed these in the text. Their perspectives are supported by both pharmacokinetic properties and potential interactions. This review is intended to serve as a basis for future research into epilepsy and related disorders.