Figure 3.

St. John's wort extracts and hyperforin induce CYP3A4 expression in human hepatocytes. Northern blot analysis was performed with total RNA (10 μg) prepared from primary cultures of human hepatocytes treated for 30 h with extracts prepared from three different commercial preparations of St. John's wort [extract 1, Nature's Way (9 μg/ml); extract 2, Nature's Plus (75 μg/ml); extract 3, Solaray (7 μg/ml)], 1 μM hyperforin, or vehicle alone (0.1% ethanol). The blot was probed sequentially with ³²P-labeled fragments of CYP3A4 and β-actin.