Nettle (Urtica dioica) is a plant used to treat the symptoms of seasonal allergies (including allergic rhinitis.) Tiny hairs under the leaves, containing formic acid and histamine, cause stinging when touched. The plant is called stinging nettles. It grows wild in Europe and the United States.
Nettle was found in this study to inhibit a number of inflammatory chemical factors. Nettle inhibits the production of histamine. Nettle inhibits the formation of prostaglandins by inhibiting the COX-1 and COX-2 inflammatory enzymes, which are responsible for allergic rhinitis.
The most active nettle bioactive chemicals include 4-shogaol, piperine, 8-dehydrogingerdione, deoxyharringtonine and carnosol. The white cells called mast cells release allergens which can be absorbed by tyrosine, an amino acid. A form of tyrosine is found in nettle. Shikimic acid is anti-inflammatory and is found in nettle.
CONCLUSION: Bioactive chemicals, such as phenolics, were found in nettle, which inhibit the inflammatory pathways which cause seasonal allergies. These chemicals include histamine pathways chemicals, cytokines, chemokines, COX-1 and 2, etc., associated with allergic rhinitis.
NOTE: Rhinitis is used to mean inflammation of the nasal passages and is one type of seasonal allergy. Shikimic acid, which is found in nettle and in the spice, star anise, has been used in Tamilflu, a pharmaceutical treatment for epidemic avian and swine flues.
Touching the underside of a nettle leaf will demonstrate the origin of the name stinging nettle. A sting, which persists, will be felt. The tiny hairs can be seen on the back of the leaves. Nettle tea is a general remedy for allergic symptoms.
Read about nettles, echinacea and hops as COX-2 inhibitors.
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