METHODS: Diabetic rats were randomly assigned to four groups, with six rats in each group. Group 1 was administered distilled water. Group 2 was administered V. amygdalina aqueous leaf extract alone. Group 3 was administered metformin alone. Group 4 was co-administered V. amygdalina extract plus metformin. Blood was collected at predetermined intervals, and plasma metformin levels were measured with liquid chromatography. The area under the curve (AUC0-t), maximum plasma concentration (Cmax), time to reach Cmax (Tmax), half-life (t1/2), and clearance (CL), were calculated based on noncompartment analysis. The effect of the extract on CYP2C9, CYP3A4, and UGT activities was determined using a Fluorometric Screening Kit.
RESULTS: The combined treatment altered the pharmacokinetic parameters of metformin. The Tmax increased from 90±0.18 min to 180±0.13 min and the Cmax, increased from 0.91±0.32 μg/mL to 2.153±0.28 μg/mL. Additionally, the AUC(0-t) increased from 118.25±1.37 μg min mL-1 to 301.006±1.96 μg min mL-1 and the t1/2 increased from 34.69±0.61 min to 101.321±0.55 min. However, the CL rate was decreased. The extract inhibited CYP3A4 and CYP2C9 enzyme activities.
CONCLUSIONS: The alteration of pharmacokinetic parameters by the extract suggests potential herb-drug interactions.
METHODS: The quantification of the bioactive compounds was conducted using ultra-high-performance liquid chromatography multiple reactions monitoring tandem mass spectrometry (UHPLC-MS/MS-MRM) technique. The effect of the extract on CYP2C9 and CYP3A4 activities was determined using a fluorometric screening kit according to the manufacturer's instructions.
RESULTS: The three bioactive compounds were detected and quantified in the aqueous leaf extract. Results showed that the content of luteolin-7-O-glucuronide (47 μg/mg) was the highest followed by luteolin-7-O-glucoside (3.5 μg/mg) and 1,5-O-dicaffeoylquinic acid (1.07 μg/mg). The extract showed an inhibitory effect on CYP3A4 and CYP2C9 enzyme activities in control and diabetic rats.
CONCLUSIONS: The UHPLC-MS/MS-MRM method is sensitive and reliable for the quality control of V. amygdalina leaf extract. The inhibitory effect of the extract suggests that concomitant use of V. amygdalina leaf preparations with conventional drugs metabolized and eliminated from the body by CYP3A4 and CYP2C9 enzymes may lead to possible interaction.