NIS - libdoc.who.int - World Health Organization

WHO monographs on medicinal plants commonly used in the Newly Independent States (NIS)
Antispasmodic activity
A 95% ethanol extract of Herba Polygoni avicularis had antispasmodic
activity against barium-induced contractions at a concentration of 100 µg/
ml in the isolated guinea-pig ileum (67). Hexane, ethyl acetate, and n-
butanol extracts of Herba Polygoni avicularis were screened for potential
vasorelaxant activity using isolated rat aorta. Hexane and n-butanol extracts
exhibited distinctive vasorelaxant activity. The activity disappeared
on removal of the functional endothelium or following pretreatment of
the aortic tissues with N-nitro-l-arginine methyl ester, which is an inhibitor
of nitric oxide synthase. These findings suggest that Herba Polygoni
avicularis relaxes vascular smooth muscle via an endothelium-dependent
nitric oxide mechanism (68).
Insect repellent activity
A 95% ethanol extract of dried Herba Polygoni avicularis, at a concentration
of 1 g/l, was tested externally in hamsters as an insect repellent. The
extract, at a dose of 2.5 µg/cm 2 , had insect repellent activity against the
sand fly, Lutzomyia longipalpis, a major vector of leishmaniasis in South
America (69).
Toxicology
The LD 50
of a 50% ethanol extract of the aerial parts of Polygoni avicularis
administered by the intraperitoneal route in rats was determined to
be 500 mg/kg bw (70). Tests with a 10% infusion, decoction (1:4), aqueous
extract (1:50) and an ethanol extract of the leaves were conducted in
mice, cats, rabbits and dogs. The minimal lethal dose for cats and rabbits
was determined to be 20 ml/kg for the infusion or decoction, and 2 ml/kg
for the aqueous extract, when administered intravenously. For mice, the
minimal lethal dose was determined to be 0.2 ml (about 10 ml/kg) for the
aqueous extract, when administered intraperitoneally. Intravenous injections
lowered blood pressure in cats, rabbits and dogs. The most potent
preparations were the aqueous and ethanol extracts (71).
Clinical pharmacology
The effectiveness of a natural extract of Polygonum aviculare was assessed
in 60 students (18–25 years old). Over a period of 2 weeks they used the
extract (1 mg/ml) in an oral rinse twice daily. The O’Leary Plaque Index
and the Loe and Silness Gingivitis Index were recorded at baseline in all
the subjects. The result showed that the extract decreased gingivitis from
day 0 ( x” height = “11” width = “13” ≥ 1.056) to day 14 ( x” height =
“11” width = “13” ≥ 1.011) (p ≤ 0.05). The researchers concluded that the
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