Indigo

Scientific Name(s): Baphicacanthus cusia Brem. (Thai indigo), Indigofera anil L., Indigofera suffruticosa Mill. (Guatemalan indigo)., Indigofera tinctoria (French indigo)., Isatis indigotica Fortune ex Lindl., Isatis tinctoria L. subspecies villarsii, Polygonum tinctorium, Strobilanthes cusia (Neess) Kuntze
Common Name(s): Common or Indian Indigo, Indigo naturalis, Qing dai (Traditional Chinese Medicine)

Medically reviewed by Drugs.com. Last updated on Oct 12, 2021.

Clinical Overview

Use

Chiefly a source of dye, indigo also has been used as a nematicide and treatment for a range of ills including scorpion bites and ovarian and stomach cancer.

Dosing

There is no clinical evidence for indigo upon which dosing recommendations can be based.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

None well documented.

Adverse Reactions

Small studies have reported phlebitis-induced colitis and pulmonary arterial hypertension in addition to other mild effects. Indigo may irritate the eyes and may cause dermatitis.

Toxicology

Some species are toxic and cause birth defects.

Scientific Family

• Acanthaceae
• Brassicaceae
• Fabaceae (bean)

Botany

Indigofera plants are perennial shrubs that reach a height of 1 m to 2 m. The French and Guatemalan varieties differ in the shape and size of the leaflets and pods. Isatis indigotica is a biennial or perennial herb native to the Ukraine that is widely distributed in Europe and is an invasive in the United States.Kell 2013

History

Indigo is one of the oldest known natural dyes and is formed through fermentation of a variety of different plants. It has been used in Traditional Chinese Medicine for centuries where it is also known as indigo naturalis, or qing dai. (Gamret 2018, Chanayatht 2002) Indigo can refer to several species of Indigofera that are known for the natural blue colors obtained from the leaflets and branches of this herb.Simon 1984 It has also been obtained from Baphicacanthus cusia, Polygonum tinctorium, and Isatis indigotica.Chanayatht 2002 Before the development of synthetic aniline and indigo dyes, indigo plants were grown commercially in the East Indies and South and Central America. Indigo was a popular dye during the middle ages.Simon 1984 It has been used medicinally as an emetic; the Chinese used the plant to purify the liver, reduce inflammation and fever and to alleviate pain.Simon 1984 Extracts of I. tinctoria have been reported to have nematicide activity and the leaf and plant juice have been used to treat cancers, particularly of the ovaries and stomach.Duke 1985 In addition, the plant has been used for the treatment of numerous ailments ranging from hemorrhoids to scorpion bites.

Chemistry

The blue dye is produced during the fermentation of the leaves, which is commonly accomplished with caustic soda or sodium hydrosulfite.Simon 1984 A paste exudes from the fermenting plant material and this is processed into cakes that are finely ground. The blue color develops as the powder is exposed to air. Indirubin is the red isomer of the blue indigo pigment and has been isolated from B. cusia.Chanayatht 2002

Indigo dye is a derivative of indican, a glucosideDuke1985, Chanayatht 2002 compo...