Bian Xu (Polygoni Avicularis Herba)

What Is Bian Xu

Bian Xu commonly known as Polygoni Avicularis Herba is the aerial part of Polygonum aviculare, which is an annual herb belonging to the family Polygonaceae. It is a relatively practical and common Chinese herbal medicine, which first appeared in in the late Western Han Dynasty (around 100 BCE).

There are about 162 species of Polygonum and they are widely distributed all over the world. Among them, some species can be used as ornamental plants, and some species can be made into diuretics.

Polygonum aviculare also called Prostrate knotweed or Common knotgrass is a common summer annual weed. They like cool and moist environments. They grow well in organic-rich loam soil.

They often grow in fields or wetlands below 4,200 meters above sea level. They are native to Eurasia and North America and are now widely distributed in temperate regions of the world. Their seedlings and young leaves are traditional wild vegetables in some Asian countries and can also be used as animal feed.

Polygonum aviculare

In the summer, when the leaves of the Polygonum aviculare are in full bloom, people gather them, remove their roots and impurities, wash them with water, cut them into pieces, dry them in the sun, and make them into Chinese herbal medicines.

Bian Xu contains kaempferol, quercetin, myricetin, luteolin, tetra-O-methylscutellarein, 5,7-dihydroxy-6-methoxyflavane, 5,7-dimethoxy-4′-hydroxyflavane, aromadendrin, betmidin, myricitrin, juglanin, avicularin, quercetrin, astragalin, quercetin-3-O-mannopyranoside, liquiritin, vitexin, isovitexin, hyperoside, caffeic acid, ferulic acid, sinapic acid, p-coumaric acid, vanillic acid, syringic acid, p-hydroxybenzoic acid, gallic acid, salicylic acid, oxalic acid, tachioside, isotachioside, syringaresinol, aviculin, umbelliferone, scopoletin, patriscabritine, 6-methoxyplumbagin, loliolide, oleanolic acid, β-sitosterol, β-daucosterol, α-camphor, linalool, camphene, polysaccharides, amino acids, and some trace elements.

Generally, the gray-green or brown-red, and tender Bian Xu with many leaves is preferred.

According to the Chinese Pharmacopoeia, the medicinal nature of Bian Xu is slightly cold, with a bitter taste. It has a certain therapeutic effect on the pathological changes of the bladder meridian.

In traditional Chinese medicine, it is often used to induce diuresis and relieve stranguria, kill insects and relieve itching, and treat scanty dark urine, difficulty and pain in micturition, urgent urination, frequent micturition, edema of lower limbs, jaundice due to damp-heat, cystitis, urethritis, glomerulonephritis, pyelonephritis, urinary system infection, nephritis, calculosis, hyperplasia of prostate, prostatitis, gingivitis, intestinal parasite infection, eczema, hemorrhoid, pruritus vulvae, leukorrhea, bacillary dysentery, and non insulin dependent diabetes mellitus.

There are about 50 kinds of traditional Chinese medicine prescriptions containing it, such as Qian Lie Tai Pian, Fu Fang Shi Wei Pian, and Shen Shi Tong Wan.


  • Anti-oxidation, scavenging DPPH free radicals and ABTS free radicals, reducing ferric tripyridyltriazine (Fe 3+ TPTZ) into ferrous tripyridyltriazine (Fe 2+ TPTZ) [1].
  • Inhibiting α-glucosidase activity, promoting glucose uptake in 3T3-L1 adipocytes, and lowering blood sugar.
  • Inducing diuresis and increasing urine output and Na+ and K+ excretion in experimental rats.
    Clearing damp-heat in the lower jiao, and treating stranguria due to heat, scanty dark urine, and urolithiasis.
  • Killing insects and treating abdominal pain and cyanotic complexion caused by Ascaris infection, enterobiasis, and ancylostomiasis.
  • Relieving itching and treating skin eczema, pruritus vulvae, and leukorrhea.
  • Intravenous administration of its infusion, decoction, or ethanolic extract to cats, rabbits, and dogs caused a transient drop in blood pressure.
  • Its flavonoid glycosides can relax the vasoconstriction induced by potassium chloride and phenylephrine in isolated rat thoracic aorta.
  • Its ethanol extract reduced body weight, serum lipid levels, and blood pressure, and decreased atherosclerotic plaque and adipocyte size in ApoE KO mice [2].
  • Its extract can inhibit the proliferation of MCF-7 cells and induce their apoptosis [3].
  • Its methanol extract reduced serum aspartate transaminase, alanine transaminase, alkaline phosphatase, and hydroxyproline levels in fibrotic rats induced by bile duct ligation and scission. These results indicate that it has an antifibrotic effect on fibrotic rats induced by bile duct ligation and scission [4].
  • Its chloroform extract has certain inhibitory effects on Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Salmonella paratyphi, Shigella flexneri, Staphylococcus aureus, Bacillus subitilis, Streptococcus pyogenes, Aspergillus flavus, Aspergillus fumigatus, and Aspergillus niger in vitro [5].
  • Studies have found that its methanol extract has a protective effect on experimental liver injury in rats induced by CCL4 or α-naphthyl isothiocyanate [6].
  • Studies have found that its ethanol extract inhibited body weight gain, reduced adipose tissue weight, adipocyte size, and lipogenic gene expression as well as serum triglyceride, leptin, and MDA levels in high-fat diet-induced obese mice. In addition, its ethanol extract inhibited 3T3-L1 adipocyte differentiation [7].


Side Effects

  • Overdose of it may cause adverse effects such as thirst, dry skin, deep sunken eyes, dizziness, tinnitus, soreness and weakness of the waist and knees, sternal rib pain, oliguria, or anuria.

Precautions and Warnings

  • The dosage of Bian Xu should be controlled at 9-15g.
  • It can be made into decoctions, pills, or lotions.
  • People who are allergic to Bian Xu should not take it.
  • Patients with spleen deficiency should not take it.
  • Patients with enuresis due to kidney deficiency should not take it.
  • Pregnant and breastfeeding women should take it under the guidance of a doctor.