TABLE 6

IC50 values for the CYP3A inhibitory potential of selected inhibitory herbal supplements [horehound, St. John’s wort (SJW), and fruit juices], GFJ, cranberry juice (CBJ), and orange juice (OJ) in cryopreserved human enterocytes

The IC50 values are expressed as percent of the recommended oral dosage. The manufacturer of each of the herbal supplements is shown in parentheses. The results were derived from nonlinear regression analysis of plots of CYP3A activity (luciferin-IPA metabolism) vs. log conc. of each substance using the Graphpad Prism 8.0 software. The different brands are shown in parentheses.

CYP3A Inhibitory PotencyFruit JuiceHerbal Supplement
GFJCBJOJHorehound (Nature’s Answer)SJW (GNC)Valerian Root (Nature’s Way)
IC50 (%)3.9752.24>10045.0838.6714.26
IC50 (%) (95% likelihood)3.042–5.02831.29–121.8NA29.53–73.9023.25–78.7012.49–16.29
  • NA, not applicable.