Abstract
Hypericum perforatum (St. John’s wort) is a fivepetalled, yellow-flowered perennial weed common to the United States, Europe, and Asia. Small, dark red dots on the petals contain hypericin, one of many compounds found in this plant. Hypericum contains numerous biologically active constituents, including hypericin and its derivatives, hyperforin, flavonoids (hyperoside, rutin, quercetin, etc.), catechin, epicatechin, procyanidin B2, amino acid derivatives (melatonin, GABA), and essential oils.