Japanese Knotweed

Scientific Name(s): Polygonum cuspidatum Siebold & Zucc.
Common Name(s): Fleeceflower, Huzhang, Japanese bamboo, Japanese knotweed, Mexican bamboo

Medically reviewed by Drugs.com. Last updated on Dec 27, 2021.

Clinical Overview

Use

Huzhang (Japanese Knotweed) has been used in traditional Chinese medicine as well as in Japan and Korea for many years. Although used for various applications, few clinical studies validate claims and guidance regarding dosing or safety is limited.

For information specific to the activity of resveratrol, see Resveratrol.

Dosing

Clinical evidence on which to base dosing guidelines is limited. One clinical study used an oral extract of P. cuspidatum 200 mg containing resveratrol 40 mg over 6 weeks for anti-inflammatory effect.

Contraindications

Pregnancy.

Pregnancy/Lactation

Do not use. Avoid use during lactation because information is lacking.

Interactions

None well documented.

Adverse Reactions

Clinical evidence is limited.

Toxicology

Information is limited.

Scientific Family

• Polygonaceae (Buckwheat)

Botany

P. cuspidatum is a perennial plant growing to approximately 2 m tall. It has mucous hollow stems with reddish purple spots and ovate/elliptical deciduous leaves (5 to 12 cm by 4 to 9 cm). The male and female flowers occur on separate plants, and the fruits are black/brown, shiny, and ovoid. The plant is native to eastern Asia, including Japan, China, and Korea. It is cultivated in those countries and in the US, and is propagated by seeds or the root. Synonyms include Pleuropterus cuspidatus (Siebold & Zucc.) Moldenke, Fallopia japonica (Houtt.) Ronse Decr., Pleuropterus zuccarinii (Small) Small, Polygonum cuspidatum Siebold & Zucc. var. compactum (Hook. f.) L.H. Bailey, and Reynoutria japonica Houtt.

Because of the plant's spreading rhizomes, P. cuspidatum is grown commercially as a major source for resveratrol production (see Resveratrol monograph), while also being considered a noxious, invasive class B or C weed in certain US states.Chen 2013, Peng 2013, USDA 2013

History

At least 100 prescriptions using the root exist in the Pharmacopoeia of the People's Republic of China to treat bronchitis and cough, gonorrhea, inflammation, infection, jaundice, hyperlipidemia and hypertension, menopausal symptoms and amenorrhea, and skin burns. The root is used extensively in traditional medicine in China, Japan, and Korea, and the young plant parts are eaten as a vegetable. P. cuspidatum is a primary source of resveratrol, which is widely available in the United States as a botanical dietary supplement.Hao 2012, Li 2013, Peng 2013

Chemistry

Volatile essential oils are described for the leaves, but the roots are the main plant part used traditionally. Major constituent chemicals include quinines (eg, anthraquinone, naphthoquinone, phylloquinone) and emodin-type anthroquinones, stilbenes (eg, resveratrol, piceatannol polydatin), flavonoids (eg, quercetin, catechin, rutin), coumarins, lignans, and other compounds.Chen 2012, Du 2013, Hao 2012, Kirino 2012, Li 2013, Peng 2013, Piotrowska 2012, Shen 2011, Zhang 2012

Emodin and phsycion demonstrate anti-inflammatory effects.Shen 2011 The stilbene content, including resveratrol, resveratroloside, polydatin...