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Keywords:

  • CYP2C19;
  • CYP2D6;
  • ginkgolides;
  • ginsenosides;
  • herb–drug interactions;
  • human liver microsome;
  • quercetin

SUMMARY

  • 1
    The 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.
  • 2
    Increasing 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.
  • 3
    For 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.
  • 4
    The 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.