Indigo naturalis treats chronic psoriasis

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CM NEWS - Topical application of a traditional Chinese medicine is effective in treating plaque-type psoriasis, according to a new study in Taiwan.

The randomized, double-blind study, published in the Archives of Dermatology, was conducted by researchers in Taipei who developed an indigo naturalis ointment.

Plaque psoriasis is a chronic skin disease for which no cure exists, that according to the US-based National Psoriasis Foundation affects 2 to 3% of the world’s population.

Symptoms include raised, inflamed, red lesions covered by a silvery white scale and is commonly found on the elbows, knees, scalp and lower back.

What is indigo naturalis? The Chinese name is qingdai, 青黛. It is a dried pigment of the leaves of the following plants: Baphieacanthuscusia（NEES）BREM (馬藍), Indigofera tinctoria LINN. (木藍), Isatis tinctoria LINN. (菘藍), Isatis indigotica FORT. (草大青) and Polygonum tinctorium LOUR. (蓼藍).

The salty qingdai has been traditionally used in the treatment of high fever in infectious sickness, eczema, chronic myelogenous leukemia, children epilepsy, vomiting blood, nose bleeding, bleeding from cuts, gum inflammation, mouth inflammation, sore throat, boils in the mouth or tongue, tonsillitis, inflammation of the roots of teeth, boils, insect or snake bites, and coughing.

It’s typically taken orally, but long-term use has been linked to stomach and liver problems.

Psoriasis is a chronic skin disease for which no cure is known, though some therapies bring about a remission. It causes red scaly patches, or plaques, which take on a silvery-white appearance and often occur on the arms, elbows, knees and legs.

A study of the findings of a clinical trial involving 42 patients who had had the condition for at least two years was published in the latest issue of Archives of Dermatology.

The researchers found that indigo naturalis in the form of an ointment was safe and effective in treating psoriasis. The team mixed the indigo powder with a base made of petroleum jelly, yellow wax, and olive oil.

“Current steroid-based medication may cause side effects like thinning of the skin, but this (indigo naturalis) has much less side effects,” said lead researcher Yin-Ku Lin of Chang Gung Memorial Hospital and Chang Gung University in Taoyuan, Taiwan, according to Reuters.

None of the patients in the trial had serious adverse effects, though some experienced a mild skin allergy.

They applied indigo naturalis ointment on one side of their bodies and a placebo, or non-medicated, ointment on the other.

Doctors checked on their condition at the start of the treatment and after two, four, six, eight, 10 and 12 weeks.

“The indigo naturalis ointment-treated lesions showed an 81% improvement, the (non-medicated) ointment-treated lesions showed a 26% improvement,” the authors wrote.

For 25 of the patients, plaques that were treated with the indigo were completely or nearly completely cleared.

Indigo naturalis has long been used, externally or ingested, to treat various infections and inflammatory diseases in China and Taiwan, such as mumps, pharyngitis and eczema.

Long-term systemic use has been linked to irritation of the gastrointestinal tract and liver problems, the researchers said. They called for more studies on ways of improving absorption of the ointment.

[Arch Dermatol. 2008;144(11):1457-1464.]

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