Inhibition of human liver cytochrome P450 by star fruit juice

J Pharm Pharm Sci. 2007;10(4):496-503. doi: 10.18433/j30593.


Purpose: To examine the inhibitory effects of star fruit (Averrhoa carambola) juice towards seven major cytochrome P450 (CYP) isoforms and NADPH-cytochrome P450 reductase (CPR).

Methods: The inhibitory effects of star fruit juice (0.5 to 5%, v/v) against the activities of seven CYP isoforms including CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2D6, CYP2E1, CYP3A4 and CPR were examined in human liver microsomes. To identify time-dependent inhibition, star fruit juice (2.5%, v/v) was preincubated with microsomes and a NADPH-generating system for 0-15 min, and then the extent of inhibition towards seven CYP isoforms were examined.

Results: Star fruit juice (5.0%, v/v) was found to inhibit all the activities of CYP isoforms tested by more than 70%. Based on the half inhibition values (%, v/v), the inhibitory effects towards different CYP isoforms were in the following order: CYP2A6 (0.9) > CYP1A2 (1.4) > CYP2D6 (1.6) > CYP2E1 (2.0) > CYP2C8 (2.2) > CYP2C9 (3.0) > CYP3A4 (3.2). Time-dependent inhibition was not observed towards any of the tested CYP isoforms. In addition, star fruit juice was found not to inhibit the activity of CPR.

Conclusions: Star fruit juice inhibited the seven CYP isoforms tested, with the strongest inhibitory effect against CYP2A6 and the least towards CYP3A4.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Beverages*
  • Cytochrome P-450 Enzyme Inhibitors*
  • Cytochrome P-450 Enzyme System / metabolism
  • Enzyme Inhibitors / isolation & purification
  • Enzyme Inhibitors / pharmacology
  • Fruit / chemistry
  • Fruit / physiology*
  • Humans
  • Magnoliopsida / chemistry
  • Magnoliopsida / physiology*
  • Male
  • Microsomes, Liver / drug effects
  • Microsomes, Liver / enzymology*
  • Plant Extracts / isolation & purification
  • Plant Extracts / pharmacology


  • Cytochrome P-450 Enzyme Inhibitors
  • Enzyme Inhibitors
  • Plant Extracts
  • Cytochrome P-450 Enzyme System