Contents of hypericin and pseudohypericin in five commercial products of St John's wort (Hypericum perforatum)



Hypericin and pseudohypericin are the two major dianthrones of St John's wort (SJW, Hypericum perforatum) that are reported to have antidepressant and antiviral effects. In this study we used methanol extracts of five commercial SJW products to determine the two congeners using a modified reverse phase HPLC method with gradient elution. One SJW product is specified by the manufacturer to contain 340 µg hypericin per tablet (170 mg extract), while the other four products are specified to contain 900 µg hypericin per tablet (300 mg); none of the products is claimed to contain pseudohypericin. Our results showed that the actual contents of hypericin in these products ranged from 1.7 to 38.5% of the claimed amounts. However, the amounts of pseudohypericin were in general much higher than those of hypericin. When hypericin and pseudohypericin were combined as total hypericin, the four products that supposedly contain 900 µg per tablet were found to contain 26, 484, 587 and 615 µg total hypericin per tablet, or 2.9, 53.8, 65.2 and 68.3% of the claimed hypericin contents respectively. The product which supposedly contains 340 µg hypericin per tablet was found to contain 388 µg total hypericin per tablet, or 114% of the claimed hypericin content. The relatively low hypericin contents measured in these products are not a result of losses during extraction, because the two congeners had high recoveries (93.7 and 94.3% for hypericin and pseudohypericin respectively) when added before methanolic extraction to an SJW product with known amounts of the two congeners. Thus our results show that the commercial SJW products vary greatly in their amounts of total hypericin and that pseudohypericin, rather than hypericin, is the major hypericin in these products. Copyright © 2004 Society of Chemical Industry