NIS - libdoc.who.int - World Health Organization

Herba Bidentis
multicellular with a longitudinally striated cuticle. Secretion ducts filled
with dark red liquid, along veins and near the leaf edges. Flower: florets
with two opposing barbed, blunt-ended pappus spines from the top of
the ovary, and as long as the tubular corolla, consisting of a multicellular
column of cells about 200 µm in diameter including some vascular tissue,
with many thorn-like unicellular covering trichomes about 350 µm long
directed towards the pappus base. Pollen grains spherical, with a spiny
exine and three pores, about 30 µm in diameter (1, 23).
Powdered plant material
Green, brown-green or green-violet with a sprinkling of yellow. The
powder has the same microscopic characteristics as the entire leaf and
flower (see Microscopic characteristics) (1).
General identity tests
Macroscopic and microscopic examinations; thin-layer chromatography,
paper chromatography and chromatography–mass-spectroscopy for the
presence of flavonoids (1, 24); chemical tests for the presence of polysaccharides
(precipitation with ethanol and reduction of simple sugars results
after the acid hydrolysis of polysaccharides) (1).
Purity tests
Microbiological
Tests for specific microorganisms and microbial contamination limits are
as described in the WHO guidelines on quality control methods for medicinal
plants (25).
Chemical
The paper chromatogram (chromatography paper FN 12, Germany; n-
butanol-acetic acid-water (4:1:2); 16 hours; ultraviolet (UV) light, 360 nm)
shows two dark brown zones of flavonoids with Rf values of about 0.38
and 0.58. A dark-brown zone with an Rf value of about 0.75 should not
be present since it indicates the presence of flavonoids of Bidens cernua
L.) (1).
Foreign organic matter
Not more than 40% stems or their fragments; not more than 8% of
parts with non-characteristic colour of the plant material; not more than
3% of other foreign organic matter (fragments of non-toxic plants). For
cut drug: not more than 10% of fragments having a diameter more than
39