Properties: Bitter, salty, cold

Meridans Entered:
Primary: Liver, Heart, Lung and Stomach

1. Clears Heat, resolves Fire toxicity, cools the Blood and reduces maculae
   Maculae due to Blood Heat (Xue Stage Heat)
   Can be used alone for bleeding due to Blood Heat, especially epistaxis where it is placed on cotton wool as a nasal plug.
2. Clears Heat, resolves Fire toxicity, cools the Blood, disperses Stagnation and reduces swelling
   Throat inflammation, dysphagia, sores of the mouth or mumps due to blazing Heat (internal or topical)
3. Drains Liver Fire, dispels Summerheat and extinguishes Wind to stop tremors
   Convulsions, red eyes, sore throat and other manifestations of Heat, especially Summerheat, affecting the Liver
4. Clears Liver Fire, drains Lung Heat and cools the Blood
   Cough due to Lung Heat Cough and chest pain due to Liver Fire attacking the Lungs
5. Expels Gu Parasites
   Chronic inflammatory disease (Fruehauf, 2015)

Suggested Daily Dosage: 1.5-3g as pills or powder internally. Should not be decocted because it is insoluble in water.

• Indigotin
  Hydroxyindole that gives indigo its characteristic colour. The natural leaves contain indican which is a colourless indolyl glucoside that dissolves in water, whereupon it is acted upon by bacteria that cleave the molecule to become the aglycone form indoxyl. This then reacts with oxygen to become indigotin which has a deep blue colour and is insoluable in water, enabling it to be filtered out.
• Indirubin
  Indole alkaloid structural isomer of indigo dye that has been researched for the treatment of proliferative diseases such as cancer and psoriasis (Blažević et al., 2015). It has not yet approved for use but is in clinical trial stage as topical treatment of psoriasis. It has also been studied for use in ulcerative colitis (Sugimoto, Naganuma & Kanai, 2016).
  It is often the byproduct of bacterial metabolism, responsible for "purple urine bag syndrome", when bacteria metabolise indoxyl sulfate found naturally in urine.
• Isoindigotin
  Indole alkaloid structural isomer of indigo.
• Isatin
  Indole derivative obtained by oxidation of Indigo dye with nitric acid and chromic acids. It is an active MAOI with dopaminergic properties (Justo et al., 2016) and is used to synthesise many drugs.
• Tryptanthrine
  Organonitrogen heterocyclic compound, an organic heterotetracyclic compound and an alkaloid antibiotic.
• Taraxasterol
  Pentacyclic triterpenoid phytosterol with anti-inflammatory properties.
• β-Sitosterol
  Phytosterol with a role as a sterol methyltransferase inhibitor, an anticholesteremic drug and an antioxidant.

Quality Tests:
True indigo is insoluble in water, alcohol, or ether, but soluble in DMSO, chloroform, nitrobenzene, and concentrated sulfuric acid. Thus, if it is placed in warm water and stirred the natural herb does not dissolve. When filtered through paper the water should come out clear. If it does dissolve completely, it may have been adulterated with water soluble paint. The true herb should float on the surface also but other acceptable substitutes may not (but need to check this fact - could be other way around), however they will also not dissolve (visiting professor from Taiwan at Westminster Polyclinic, 2017).