St. John’s wort is a very common and widespread perennial herbaceous plant. It grows wild in Italy and in mountainous areas of central Europe, Africa, North America and northern Asia. The plant is from 20 to 90 cm (8 to 35 in.) high, has an erect stem, opposite oval-shaped leaves and golden-yellow flowers grouped in clusters. It flowers from June to September. The essential oil is little known. The oil can be prepared by steam distillation in very low yields. The parts used are the flowering tops, leaves and caulis. St. John’s wort has a balsamic odor and an aromatic taste.
Phenylpropanes, flavonol derivatives, biflavones, proanthocyanidins, xanthones, phloroglucinols, some amino acids, naphthodianthrones and essential oil constituents are the natural plant products known from the crude drug of Hypericum perfora-tum.* Flavonoids, such as quercetin, kaempferol, luteolin, amentoflavone, glycosides rutin and hyperoside, have been identified in
the plant. The herb contains vitamin C (0.13%), myrcene, tannin (~10%), α-pinene, alkaloids, ocimene and xanthone derivatives.
The essence can be dextro- or levorotatory, depending on the origin, and contains α-pinene. The dried product contains hypericin.
The best-known components of the plant are anthraquinone derivatives hypericin (0.02 to 2.5%, red pigment) and pseudohypericin.
Essential oil contains 2-methyloctane (16.4%), α-pinene (10.6%), dodecanol (5%), nonane (3.4%), undecane (3.2%), 3-methyl nonane
(3.2%), isoundecane (3.1%), 6-methyl-5-hepten-2-one (2.1%) (CoE, 2000).
