NIS - libdoc.who.int - World Health Organization

WHO monographs on medicinal plants commonly used in the Newly Independent States (NIS)
(30 µl/disc) (52). An ointment from P. major leaves expressed antiyeast
activity against Candida albicans at a dose of 20.7 µg/g/agar plate (71).
The antibacterial effect of a pectin polysaccharide isolated from P. major
leaves was examined in inbred NIH/OlaHsd and Fox Chase SCID mice,
infected with Streptococcus pneumoniae serotype 6B. The pectin polysaccharide
was administered intraperitoneally (12 µg/animal) either once,
three days before challenge, or one to three times, 3–48 hours after challenge.
The number of bacteria in blood and the mouse survival rates were
recorded. Pre-challenge administration of the polysaccharide and also a
lipopolysaccharide (included as a control), provided a dose-dependent
protective effect against S. pneumoniae serotype 6B infection. However,
injection of pectic polysaccharide after establishment of the infection in
mice had no effect. These results demonstrate that the pectic polysaccharide
fraction from P. major protects against pneumococcal infection in
mice when administered systemically before challenge, and that the protective
effect is due to stimulation of the immune system (72).
Antiparasite activity
Weak antigiardiasis activity of a decoction of Plantago leaves at a concentration
of 60 mg/ml, was observed in vitro in a blinded study using trophozoites
of Giardia duodenalis incubated with the decoction. The viability of
trophozoites was determined using 3-[4,5-dimethylthiazol-2-il]-2,5-diphenyl
tetrazolium bromide (MTT), which is reduced to MTT-formazan
by the activity of live trophozoites. The reduced MTT was extracted and
measured by spectrophotometry at 570 nm. Negative (trophozoites without
extract) and positive controls (incubated with tinidazol) were also analysed.
Antigiardiasis activity of the decoction as determined by trophozoite
mortality was 76 ± 1.2% (73).
Antinociceptive effects
The antinociceptive effect of methanolic extracts of P. major leaves
(400 g/kg body weight (bw)) was studied in mice using the acetic acidinduced
writhing inhibition and tail-flick tests. Orally administered extract
inhibited the nociception to acetic acid-induced writhing with a
protection of 50.8–45.8% compared with controls. In the tail-flick test,
at a dose of 400 mg/kg bw, the extract significantly increased the latency
in response of the tail to thermal stimulation. At doses up to 2 g/kg bw,
the extracts did not cause any deaths or major signs of acute toxicity
(74). Intragastric administration of an aqueous extract of dried leaves of
P. major inhibited acetic acid-induced writhing in mice at a dose of 1 g/
kg bw (65).
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