Urtica dioica L. (Urticaceae)
Note that Urtica urens L. has been referred to as Dwarf nettle.
Nettle Leaf (British Ph 2009, European Ph 2008); Stinging Nettle (The United States Ph 32).
Nettle root contains sterols including beta-sitosterol, and lignans, such as pinoresinol, secoisolariciresinol, dehydroconiferyl alcohol and neo-olivil. The triterpenes, oleanolic acid and ursolic acid, and their derivatives, and a lectin mixture known as Urtica dioica agglutinin (UDA) are also present. Root extracts may be standardised to its content of beta-sitosterol, scopoletin and amino acids (The United States Ph 32).
The leaves contain flavonoids, mainly kaempferol, isorhamnetin and quercetin glycosides, and caffeic acid derivatives. Extracts may be standardised to caffeoylmalic acid and chlorogenic acid expressed as chlorogenic acid (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4). Note that histamine, formic acid, acetylcholine, acetic acid and 5-hydroxytryptamine, which form the ‘sting’ when the fresh leaf is touched, are denatured during drying and processing.
Use and indications
The root is used mainly to treat benign prostatic hyperplasia in men, and difficulties in passing urine. There is some pharmacological evidence to support this use, but clinical evidence is equivocal and further trials are required. Leaf extracts have been used for treating allergies. Whole nettle extracts have been shown to have anti-inflammatory activity and may improve symptoms of osteoarthritis.