- Dyer’s woad leaf
- Da Qing Ye
For Patients & Caregivers
Isatis leaf has not been tested in clinical trials, so it is not known if it works in humans. It should not be used to treat SARS, HIV, or other serious diseases.
Isatis leaf extract is derived from the same plant from which indigo dye is made. It has been used in combination with other botanicals in traditional Chinese medicine and Ayurveda for thousands of years. Isatis leaf has anti-inflammatory properties. Laboratory studies suggest that indirubin, an active compound in isatis, stops cell duplication and therefore may be useful in cancer treatment. Other lab experiments show that isatis extract can kill certain viruses and counteract some symptoms and tissue damage from bacterial infections. However, this botanical has not yet been evaluated in clinical trials and therefore it remains uncertain whether these effects occur in the human body.
Isatis root has both similar and different properties from isatis leaf.
- To prevent and treat cancer
Lab studies show that an active compound in isatis stops cell duplication, but there is no evidence from clinical trials that it can prevent or treat cancer. In China, isatis is used in combination with other botanicals to treat chronic myelogenous leukemia.
- To treat diarrhea or gastrointestinal disorders
Isatis extracts have anti-inflammatory activity in the laboratory setting. A pulverized version of the extract is used in China to treat ulcerative colitis.
- To treat hepatitis
Isatis extracts have anti-inflammatory effects.
- To treat HIV and AIDS
No scientific evidence supports this use.
- To treat respiratory infections
Although isatis has antiviral activity, there is no evidence from clinical trials that it can effectively treat infections.
For Healthcare Professionals
Isatis leaf is derived from the isatis plant and is a source of indigo dye. In both traditional Chinese medicine (TCM) and Ayurveda, it is used in combination with isatis root and other herbs to treat the common cold, sore throat, mumps, respiratory ailments, other febrile diseases, hepatitis, and malignant tumors (1) (2). The pulverized form, known as Qing Dai, has been used to treat ulcerative colitis (3), and topically to treat oral sores and sore throat. Isatis leaf is one of the ingredients used in PC-SPES, an herbal formula used to treat prostate cancer. It is also used in Danggui Longhui Wan, a formula used to treat chronic myelocytic leukemia (CML) in China (4).
In vitro and in vivo studies indicate that isatis has antimicrobial, antiendotoxic (5), antiviral (6) (7) (8), immunostimulatory (9), anti-inflammatory (10) (11), and chemotherapeutic (12) properties. In several instances, the pharmacologic effects of isatis leaves were found to be greater than that of the roots (5) (8). A small preliminary study in healthy volunteers has also indicated anti-inflammatory (13) properties with topical isatis leaf.
Isatis root has both overlapping and different properties from isatis leaf.
In vitro, isatis leaf inhibits cyclooxygenase-2 (COX-2) with preferential effects on COX-2–catalysed prostaglandin synthesis (10). The alkaloid tryptanthrin has been identified as the inhibitor of COX-2 (10) and 5-lipoxygenase (5-LOX) (13) (18). Indirubin, another active component, inhibits cyclin-dependent kinases (CDKs) and prevents proliferation by arresting cells in the G2/M phase (4). Other alkaloids isolated from isatis can inhibit leukocyte function and attenuate the production of mediators related to inflammatory responses (11). A compound isolated from isatisine A showed moderate anti-HIV-1 activity (7). One laboratory study found better virucidal activity for leaf than root extracts when tested for swine pseudorabies virus (8).
Animal models suggest that isatis leaf can reduce allergic airway inflammation and hyperresponsiveness by inhibiting production of Th2 cytokines IL-4 and IL-5, and RANTES (9). Another model suggests that when used as postexposure prophylaxis, isatis leaf can attenuate lung tissue damage and reduce lung virus titers (6).
In vitro and animal studies demonstrated the induction of hepatocellular cancer cell death by isatis through a distinguished caspase-independent apoptotic pathway (12).