[Determination of trigonelline by HPLC and study on its pharmacokinetics].

Aim: To develop a sensitive and specific HPLC method for determination of trigonelline in rabbit plasma, and study the pharmacokinetics in rabbit.

Methods: After ig of fenugreek extract and i.v. of trigonelline in rabbit, the biological samples could be well purified after precipitation of protein with methanol and acetonitrile. Asahipak NH2P-50 column was used, the mobile phase consisted of acetonitrile-water (90:10) at a flow-rate of 1.2 mL.min-1, and detection wavelength was set at UV 265 nm. The column temperature is 30 degrees C.

Results: The calibration curve was linear in the range from 0.98 mg.L-1 to 31.28 mg.L-1, with r = 0.9986, the detection limit of this method was 50 micrograms.L-1. The concentration-time curves of trigonelline in rabbits after ig and i.v. administration were shown to fit one-compartment and two-compartment open model, respectively. The main parameters after ig of fenugreek extract were as follow: T1/2(Ka) was 0.9 h, T1/2(Ke) was 2.2 h, V was 0.64 L.kg-1, AUC was 1.93 mg.min.L-1. The main parameters after i.v. of trigonelline were as follows: T1/2 alpha was 10.8 min, T1/2 beta was 44.0 min, K21 was 0.044 min-1, K10 was 0.026 min-1, K12 was 0.017 min-1, AUC was 931.0 mg.min.L-1.

Conclusion: Trigonelline showed a middle rate of absorption and fast rate of elimination in rabbit. Meanwhile, the method is simple, accurate, with a good reproducibility, and it provide a basic method for the investigation of trigonelline and fenugreek pharmacokinetics.