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

Figures & data

Figure 1. Chemical structure of physcion.

Table 1. Reaction conditions of CYP450 isoforms tested, including maker reactions, incubation conditions and Km used in the inhibition study.

CYPs	Marker reactions	Substrate concentration (μM)	Protein concentration (mg/mL)	Incubation time (min)	Estimated Km (μM)	Inhibitors	Concentration of inhibitors (μM)
1A2	Phenacetin O-deethylation	40	0.2	30	48	Furafylline	10
2A6	Coumarin 7-hydroxylation	1.0	0.1	10	1.5	Tranylcypromine	10
2C8	Paclitaxel 6α-hydroxylation	10	0.5	30	16	Montelukast	5
2C9	Diclofenac 4’-hydroxylation	10	0.3	10	13	Sulphaphenazole	10
2C19	S-Mephenytoin 4-hydroxylation	100	0.2	40	105	Tranylcypromine	50
2D6	Dextromethorphan O-demethylation	25	0.25	20	4.8	Quinidine	10
2E1	Chlorzoxazone 6-hydroxylation	120	0.4	30	126	Clomethiazole	50
3A4	Testosterone 6β-hydroxylation	50	0.5	10	53	Ketoconazole	1

Figure 2. Effect of physcion on the major CYP450 isoforms (A) and its concentration-dependent manner in the inhibition of CYP2C9 (B), 2D6 (C) and 3A4 (D). ^****p < 0.0001 relative to the negative control. Negative control: blank treatment; physcion: treated with 100 μM physcion; positive control: treated with typical inhibitors (inhibitor types and concentrations are listed in Table 1).

Figure 3. The inhibition of CYP2C9 (A) and 2D6 (B) by physcion was best fitted with the competitive inhibition model by Lineweaver–Burk plot in the presence of 0, 2, 5, 10 and 15 μM physcion and the K_i values were 3.69 and 8.66 μM, respectively.

Figure 4. The inhibition of CYP3A4 by physcion was best fitted the non-competitive inhibition model by Lineweaver Burk plot in the presence of 0, 5, 10, 20 and 30 μM physcion (A) and the K_i value was 6.70 μM (B).

Figure 5. Only the inhibition of CYP3A4 showed a significant time-dependent manner (A), which was observed under various concentrations of physcion (B). The time-dependent K_I and K_inact parameters of CYP3A4 were obtained as 3.10 μM⁻¹ and 0.049 min⁻¹, respectively (C).

Data availability statement

The datasets used and/or analysed during this study are available from the corresponding author on reasonable request.