Chinese Name : 大青葉
Latin Name : Folium Isatidis
This herb is the dried leaf and stems of Isatis indigotica Fort. of the family Cruciferae. It is mainly grown in the Anhui, Fujian, Guangxi, Hebei, and Jiangsu provinces of China. Collected in the summer, it is cleaned and used unprocessed either fresh or dried.
Isatis leaf, similar to isatis root, is used for epidemic febrile disease. It clears away pathogenic Heat and toxins from the blood, high fever, restlessness, unconsciousness, delirium, maculas, and skin eruptions. Today, it is taken for common colds, influenza, upper-respiratory-system infections, pneumonia,acute contagious hepatitis, and bacterial dysentery. Isatis leaf is good for treating a number of viral infections and its effect is stronger than isatis root.
Use of Isatis Leaf in TCM
Bitter in taste and very cold, it acts on the heart, lung, and stomach meridians.
Effects, Medicinal Uses and Combinations
- Removes noxious Heat and detoxifies: for febrile ailments and to remove pathogenic Heat from the blood, isatis leaf is mixed with rhinoceros horn, dried rehmannia, scrophularia root, and gardenia, as in Xi Jiao Da Qing Tang. For the early stages of Wind-Heat-type colds, it is blended with lonicera, arctium, and other herbs.
- Relieves throat infections:the juice of the fresh herb can be used as a tea or as a mouthwash to treat canker sores, sore throat, and erysipelas. It is often combined with honeysuckle flower and scrophularia root.
In a decoction of 10 to 15 g or prepared as a tea.
People with Cold, stomach and spleen deficiency, or diarrhea should use this herb with caution.
Side Effects and Toxicity
No undesirable side effects or toxicity were reported at the therapeutic dose in classical Chinese materia medica.
Isatis leaf contains two main ingredients: indirubin and indigo. Pigments, qingdainone, tryptanthrin, isatin, and n-nunacosan have also been isolated.
Isatis leaf is antimicrobial, antiviral, anti-inflammatory, and antipyretic, and increases the activity of phogocytosis of white blood cells. A decoction of the leaves inhibited the growth of S.aureus, alpha-streptococcus, N.meningitidis, N.catarrhalis,S.pneumoniae,S.typi, E.coli, H. influenza, C.diphtheria, and S.dysenteriae. The herb was also inhibitory against encephalitis B virus, mumps virus, and influenza virus. It is lethal to leptospirae.