Enzyme kinetics of psoralen and isopsoralen in rat and human liver microsomes
10.3867/j.issn.1000-3002.2015.06.008
- VernacularTitle:补骨脂素和异补骨脂素在大鼠和人肝微粒体的酶促动力学
- Author:
Haiying YANG
;
Yuhuan ZHONG
;
Lin CHEN
;
Hua LI
;
Xiaomei ZHUANG
- Publication Type:Journal Article
- Keywords:
psoralen;
isopsoralen;
liver microsomes;
cytochrome P-450 enzyme system;
pharma-cokinetics
- From:
Chinese Journal of Pharmacology and Toxicology
2015;(6):924-930
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE To investigate and compare the enzyme kinetic characters of psoralen (PRN)and isopsoralen(IPRN)in rat and human liver microsomes. METHODS PRN and IPRN in liver microsomes incubates were determined using LC-MS/MS. The enzyme kinetic and metabolic stability of PRN and IPRN were investigated by employing the optimized rat and human liver microsomes incubations. The Vmax and Km values were calculated using the nonlinear regression method. RESULTS The quanti?tative method showed good linearity within the range of 0.1-50.0 μmol · L-1 and was suitable for the assay in biological samples. The in vitro elimination was linear with the substrate concentrations lower than 1 μmol,the protein concentration within 0.5 g · L-1,and the incubation time within 40 min. The t1/2 values of PRN and IPRN in rat and human liver microsomes were 74.5,95.0,74.5 and 173.3 min, respectively. The Vmax values of PRN in rat and human liver microsomes were(1.140±0.080)μmol·min-1·g-1 protein,(0.620±0.060)μmol·min-1·g-1 protein,while Km values of PRN in rat and human liver microsomes were (12.9 ± 0.3)μmol · L- 1,(7.4 ± 1.3)μmol · L- 1,respectively. The Vmax values of IPRN in rat and human liver microsomes were(0.251±0.012)and(0.103±0.014)μmol·min-1·g-1 protein,while Km values of IPRN in rat and human liver microsomes were (3.0 ± 0.4)μmol · L-1,(3.4 ± 0.7)μmol · L-1,respectively. CONCLUSION The enzyme kinetic characters and metabolic stability of PRN and IPRN show species and chemical structures related differences. Interestingly,the metabolic eliminations of PRN and IPRN are similar in rats. However,the metabolic elimination of IPRN in humans involved in CYP enzymes may be much slower than that of PRN.
