Page 32 - Pharmacognosy 02-06203

St. John's Wort

Hypericum consists of the dried aerial parts of Hypericum perforatum, family Hypericaceae
gathered usually at the time of flowering or shortly before. Commercial extracts are standardized
on their naphthodianthrone content, expressed as hypericin.

Macroscopy:

The drug consists of green leaf fragments and stems, unopened buds and yellow flowers. Oil
glands are visible in the leaves as transparent areas, hence the specific name perforatum, and as
small black dots on the lower surface. The opposite, sessile leaves are 1.5– 4.0 cm in length,
elliptical to ovate in outline, glabrous with an entire margin. Pieces of hollow stem are cylindrical
with two faint ribs on either side.
The odour is distinct and the taste slightly sweet and astringent.

Microscopy:

The T.S. of the stem is roundish in outline with two conspicuous wings; a few rows of collenchyma
may occur inside the epidermis; reddish-brown secretory glands occur in the cortex; endodermis
conspicuous; xylem tissue occurs in a solid ring consisting of fibers and vessels alternating with
uniseriate medullary rays; pith of pitted parenchyma cells.

Constituents:

Hypericum contains a variety of constituents with biological activity.
Anthraquinones: Principally hypericin and pseudohypericin; also iso-hypericin and
emodinanthrone.
Prenylated phloroglucinol derivatives: Hyperforin, adhyperforin and furohyperforin. These
phloroglucinols constitute the principal components of the lipophilic extract of the plant and are
considered to be the most important active constituents regarding antibiotic and antidepressant
properties. Unfortunately, they are very prone to oxidative transformations.
Flavonoids:
Kaempferol, luteolin and quercetin, quercitrin, isoquercitrin and hyperoside. The biflavonoid
amentoflavone is confined principally to the flowers.

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