Page 226 - Pharmacognosy 2 PG303

Pharmacognosy-2 (PG303) Level 2 Clinical Pharmacy-Pharm D

8- Two layers of tegumentary tissue from the rhizome in surface view

9- Endodermis in tangential longitudinal view.
10- Bordered pitted vessels with associated xylem parenchyma from the stem base.
11- Parenchyma in longitudinal view.

12- Part of a group of sclereids from the rhizome.

13- Parts of fibers from the stem base.

Tests for purity
Powdered valerian contains no Ca OX crystals and no foreign starch granules.

Alcohol (60%)-soluble extractives, not less than 15% (European) and 25% (Indian).
Deteriorated Valerian: Mix about 1.0 gm of the alcoholic (60%) extractives,
accurately weighed, with 25 ml of neutral alcohol (60%). The liquid requires not
more than 20 ml of 0.1 N KOH for complete neutralization, using phenolphthalein
T.S. as indicator, equivalent to not more than 4% of free acids calculated as
isovaleric acid. Each ml of 0.1 N KOH is equivalent to 0.0102 gm of isovaleric
acid.

Constituents
The drug contains 0.3-0.7% essential oil, the composition of which varies

considerably according to the source. Usually, bornyl acetate is the main constituent,
but other sesquiterpenes are always present. Carefully dried roots, i.e., roots dried
below 40°C (pharmacopeial requirement), contain 0.5-2.0% valepotriates (valeriana
epoxy-triester), bicyclic monoterpenes (iridoids). The composition of the
valepotriate mixture differs greatly according to the variety, but quantitatively
valtrate and isovaltrate generally dominate. There are also small amounts of
didrovaltrate and glycoside valerosidatum.

Valerenic and acetoxy-valerenic acids (ca. 0.08-0.3%) are characteristic
constituents of the official drug. They don't occur in other Valeriana species.
Valerian root contains very small amounts (0.01-0.05°/o) of alkaloids e.g.,
valerianine and a-methyl-pyrryl-ketone.

Uses
When Thies discovered the valepotrates, it was thought that genuine active

constituents had been found. These compounds, however, are not present in
infusions and tinctures, but rather their degradation products (the so-called
baldrinals) which are probably responsible (at least in part) for the sedative action.
The essential oil is also important regarding the sedative effect of the drug. Hence

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