English: Prostrate knotweed, wireweed, knotgrass

Hindi: Machoti, anjawar

Sanskrit: Nasomali

The generic name comes from the Latin word aviculus, a diminutive of 'avis' meaning 'bird', because a large number of small birds feed on the seeds. The plant is used as a fodder for sheep and goats and also yields a dye rather like indigo.

Habitat

It is native to Europe, Russia and parts of Asia up to an altitude of 3600 m.

Botanical description

It is an annual herb with both erect and prostrate branches, reaching about 60 cm high and with tough fibrous roots (Plate 49). The leaves are narrowly lanceolate or elliptical, up to 1 cm long with lanceolate stipules. The flowers are green, edged with white or red, and present in axillary clusters. The nutlets are ovoid and minutely edged.

Parts used

Whole plant, leaves.

Traditional and modern use

A decoction of the herb is given in dysentery, diarrhoea, bronchitis, diabetes, jaundice and malaria. It is particularly useful for bleeding disorders including menorrhagia, haematuria and bleeding piles and has been used as an anodyne, antiseptic, diuretic, vermifuge and tonic. It is less often used for eczema, gonorrhoea and vaginitis.

Ethnoveterinary usage

Leaves are used in cuts, bruises and sores. It is also used in urinary complaints, problems of polyurea, diarrhoea and dysentery.

Major chemical constituents
Flavonoids and anthocyanins

Avicularin, catechin, delphinidin, hyperin, myricetin, quercetin, quercitrin, quercetin -3-arabinoside, rutin, astra gal in are present.

Polyphenolics and anthraquinones

Oxymethyl anthraquinone, polygonic acid, salicylic acid, tannic acid, fuglanin, betmidin and a lignan glycoside have been isolated.

Medicinal and pharmacological activities

Antifibrotic activity: The antifibrotic effect of a methanolic extract has been studied. Liver fibrosis was induced by a bile duct ligation and scission (BOLlS) operation. In BOLlS rats, the levels of aspartate transaminase (AST), alanine transaminase (AL T), alkaline phosphatase (ALP), total bilirubin in serum and hydroxyproline content in liver were dramatically increased. Rats treated with extract showed reduction in all the liver enzymes and the liver hydroxyproline content of the treated group was reduced to 40% that ofthe BOLlS control group. The morphological characteristics of fibrotic liver were also improved in the extract-treated BOLlS group.

Antimicrobial activity: An aqueous extract showed antifungal activity in vitro. Oermatophytes were inoculated on Sabouraud's dextrose agar medium containing different concentrations of the extract. After 2 weeks, growth of some strains of Trichophyton rubrum, T. mentagrophytes and Microsporum canis were completely inhibited by the extract and a moderate inhibitory effect was observed for other strains. The efficacy of P. aviculare extract was tested against gingivitis using 60 male dentistry students between the ages of 18 and 25 years, over a period of 2 weeks. These students used the extract (1 mg/ml) as an oral rinse twice daily and the O'Leary Plaque Index and the Loe and Silness Gingivitis Index were recorded at baseline (day 0) in all the subjects. The antibacterial and antiinflammatory effects of the extract were evaluated and the results showed that the extract in the oral rinse significantly decreased gingivitis from day 0 to day 14. However, a significant increase in dental plaque was observed during the same period although the consistency of this plaque permitted its mechanical flushing easily.

Antiinflammatory activity: Polygonum aviculare was found to inhibit prostaglandin biosynthesis and platelet-activating factor (PAP) induced in vitro.

Hepatoprotective and lipid peroxidation activity: A crude fraction consisting primarily of flavonoid glucosides inhibited the lipid peroxidation of rat liver in vitro. It decreased liver enzymes including GOT and GPT, and the thiobarbituric acid value compared to the control, suggesting strong protective action against hepatotoxicity induced by carbon tetrachloride.

Hypotensive and anticoagulant activity: Extracts of the aerial parts were hypotensive in dogs, cats and rabbits and showed anticoagulant activity in sheep blood.

Safety profile

The LOso of a 50% ethanolic extract of aerial parts was 500 mg/kg (IP in rats).7 Overdosage has been observed in farm animals. Six horses died and one was slaughtered after grazing on farms cultivating P. aviculare. The animals showed recumbency, hyperaesthesia and circulatory collapse. However, the plant accumulates nitrites and this may have caused the toxicity.