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EFFECTS OF INDIVIDUAL GINSENOSIDES, GINKGOLIDES AND FLAVONOIDS ON CYP2C19 AND CYP2D6 ACTIVITY IN HUMAN LIVER MICROSOMES

Authors


Dr Nu He, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Room 345, 720 Westview Drive SW, Atlanta, GA 30310–1458, USA. Email: nhe@msm.edu

SUMMARY

  • 1The effects of four individual ginsenosides (Rb1, Rb2, Rc and Rd), two ginkgolides (A and B) and one flavonoid (quercetin) on CYP2C19-dependent S-mephenytoin 4¢-hydroxylation and CYP2D6-mediated bufuralol 1¢-hydroxylation were evaluated in human liver microsomes.
  • 2Increasing concentrations of each test compound were added to microsomal incubation mixtures containing a well-characterized marker substrate (S-mephenytoin for CYP2C19 or bufuralol for CYP2D6) to determine their IC50 values (compound concentration yielding 50% inhibition of a marker enzyme activity), which were estimated by graphical inspection.
  • 3For CYP2C19, the IC50 values were 46, 46 and 62 mmol/L for ginsenoside Rd, quercetin and ginsenoside Rb2, respectively, whereas only ginsenoside Rd had an IC50 value of 57 mmol/L for CYP2D6.
  • 4The data suggest that the tested compounds are not likely to inhibit the metabolism of the concurrent use of a given drug whose primary route of elimination is through CYP2C19 or CYP2D6.

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