Medically reviewed on April 16, 2018
Scientific Name(s): Alkanna tinctoria (L.) Tausch Family: Boraginaceae
Common Name(s): Alkanet , alkannawurzel (German), alkermeswurzel (German), Anchusa tinctoria , Dyers's Bugloss , henna , orchanet (English), racine d'alcanna (French), racine d'orcanette (French), radix anchusea (tinctoriae) (Latin), rote ochsenzungenwurzel (German), schminkwurzel (German)
Alkanna is an astringent and a source of red pigment used in cosmetics. It was traditionally used topically for the treatment of skin wounds and diseases. Orally, alkanna root has been used for diarrhea and gastric ulcers. Alkanna root has demonstrated radical scavenging activity, suggesting potential antiaging effects; however, clinical trial information is lacking.
No recent clinical data justify human dosage.
Contraindications have not been identified.
Documented adverse effects. Contains pyrrolizidine alkaloids. Avoid use.
The pyrrolizidine alkaloid components of alkanna root are substrates for the cytochrome P450 3A4 isoenzyme. Inducers of this isoenzyme, including rifampin, St. John's wort, and phenobarbital, may increase the conversion of pyrrolizidine alkaloids to toxic metabolites.
Alkanna root may cause acute liver failure, cirrhosis, pneumonitis, pulmonary hypertension, or heart failure.
Alkanna root may cause hepatic and/or lung toxicity because of the pyrrolizidine alkaloid components.
Alkanna is a biennial or perennial herbaceous plant growing from 0.3 to 0.6 m in height with pubescent lanceolate leaves. It bears blue to purple trumpet-shaped flowers arranged in loose, 1-sided scorpioid racemes. The dried cylindrical, fissured rhizome has exfoliating, brittle, and dark purple bark on the outside and remains of bristly leaf and stem pieces near the crown region. 1 While native to southern Europe, the plant is also grown in and imported from Albania, India, Egypt, and Turkey. 1 , 2 Alkanna root belongs to the plant family Boraginaceae and contains pyrrolizidine alkaloids that aid in plant defense against insect herbivores. Although pyrrolizidine alkaloids are found in all plant organs, they are concentrated in the roots of these plants. 3
Alkanna should not be confused with another plant also known as alkanet, but which is the related Anchusa officinalis L. of the same family (Borage). A decoction (tea) of A. officinalis leaves and roots for coughs and chest disorders was described in older herbals. 4
Alkanna and related plants have long been referred to as henna and used as a dye for cloth. Alkanna has also been used to impart a red color to fats, oils, and waxes. 1 The Greek physician Hippocrates (ca. 460 to 370 BC) recorded the use of alkanna root for the treatment of skin ulcers, and the botanist Theophrastus (ca. 371 to 287 BC) suggested that it could be used as a dye and in medications. Greek physician and pharmacologist Dioscorides (ca. 49 to 90 AD) also described alkanna's properties. 5
Alkanna root contains a mixture of red pigments found in the bark at levels of up to 5% to 6%. These consist mainly of fat-soluble naphthazarin (5,8-dihydroxy-1, 4-naphthaquinone) components, such as alkannin and related esters. 1 , 6 The red pigments are soluble in fatty oils, which makes them useful for the detection of oily materials in microscopic powders during histological examination. Like some other members of the Borage family, pyrrolizidine alkaloids have been found in Alkanna tinctoria , but levels have not been determined. 1 The alkannin esters of beta, beta-dimethylacrylic acid, beta-acetoxy-isovaleric acid, isovaleric acid, and angelic acid have also been isolated from the root. 7
Uses and PharmacologyWound healing/Antimicrobial activity
Today, alkanna root is used almost exclusively as a cosmetic dye. 1 Orally, it has been used for diarrhea and gastric ulcers. Traditionally, topical alkanna root has been used to treat skin wounds and diseases. Crude extracts of A. tinctoria , possessed antimicrobial activity in screening. 8 Several pharmaceutical ointments, such as Helixderm and Histoplastin Red (approved and marketed in Greece) contain alkannin as the active ingredient, and they have been shown to exert activity against gram-positive bacteria, gram-negative bacteria, and fungi. Additionally, alkannin may exert bactericidal action on Pseudomonas aeruginosa , a bacteria that forms biofilms against wound healing. 5 Alkannin may also possess antiviral action against the herpes simplex virus.Animal data
A. tinctoria has been studied in male rabbits with partial thickness, severe, and olive oil burns. A solution of A. tinctoria 16% was applied twice daily to the left side of the animal. The right side served as a control. Partial thickness burn wounds were completely healed in 7 to 10 days, and olive oil burn wounds were healed in 26 days. However, severe burn wounds were unresponsive to A. tinctoria . 9Clinical data
Alkanna root has demonstrated potential antiaging effects. One study found that both monomeric and oligomeric alkannin exhibited high radical scavenging activity. Additionally, an olive oil extract containing A. tinctoria possessed radical scavenging activity at room temperature; however, when it was heated, this activity was decreased. 10 Thus, alkanna root's role in cosmetics may extend beyond serving solely as a dye.
No recent clinical data justify human dosage.
Documented adverse effects. Contains pyrrolizidine alkaloids. Avoid use. 11 Animal studies in rats have shown that pyrrolizidine alkaloid-induced toxicity can affect offspring, with suckling young rats more likely to develop pyrrolizidine alkaloid-induced hepatotoxicity than their mothers. 2 , 12
Pyrrolizidine alkaloids are substrates for the cytochrome P450 3A4 isoenzyme. Inducers of this enzyme, including rifampin, St. John's wort, and phenobarbital, may increase the conversion of pyrrolizidine alkaloids to toxic metabolites. 3
Alkanna root may cause acute liver failure, cirrhosis, pneumonitis, pulmonary hypertension, or heart failure. Toxic byproducts from the hepatic metabolism of pyrrolizidine alkaloids are transported to the lungs where they may cause pulmonary toxicity. Sinusoidal-obstruction syndrome, also known as venoocclusive disease, is a hepatic complication associated with bone marrow transplantation that may occur in patients consuming products containing pyrrolizidine alkaloids. Pyrrolizidine alkaloids have been shown to be carcinogenic in animals, specifically associated with hepatocellular and squamous cell carcinomas and liver angiosarcomas. 3
The pyrrolizidine alkaloid components in alkanna root may cause liver and/or lung toxicity. The most hepatotoxic pyrrolizidine alkaloids include the cyclic diesters, such as retrorsine and senecionine. Fulvine and monocrotaline have been implicated in causing liver and pulmonary toxicities. 3 Specifically, pyrrolizidine alkaloids cause liver cell enlargement, disturbances in liver cell metabolism with functional losses, and fatty degeneration in the liver. 2
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