For Patients & Caregivers
Bottom Line: Indirubin has not been shown to prevent or treat cancer in humans.
Indirubin is derived from the Indigo Plant (Isatis Root, Isatis Leaf). It is used as part of a traditional Chinese herbal prescription called Dang Gui Long Hui Wan, to treat chronic myelogenous leukemia (CML). Studies have shown that the substance can help keep cancer cells from reproducing in rats. Indirubin also appears to reduce inflammation by inhibiting part of the immune response. In addition to being extracted from the plant, Indirubin may also be created synthetically in the laboratory.
- To treat chronic myelogenous leukemia
Laboratory and animal studies support this use. Clinical trials have not yet been conducted.
- To reduce inflammation
The results of a small study in patients with head and neck cancer suggest that the anti-inflammatory properties of indirubin (taken as indigowood root powder) reduce mucosal damage from radiation therapy. However further clinical studies are needed to confirm this effect.
- To treat Psoriasis
A few studies show that Indirubin is effective against psoriasis.
Reduce mucosal inflammation from radiation therapy:
A small clinical study enrolled 20 patients with head and neck cancer. Ten of these patients received indirubin (taken as indigowood root powder) for seven weeks during radiation therapy. The results of the study indicated that patients receiving this treatment had significantly less radiation mucositis, anorexia, and difficulty swallowing compared to the untreated patients.
For Healthcare Professionals
Indirubin is extracted from the Indigo plant (Isatis Root, Isatis Leaf). It is a constituent of a traditional Chinese herbal formula, Dang Gui Long Hui Wan used in the treatment of chronic myelogenous leukemia (CML). Indirubin has also been used in Asia as a systemic treatment for psoriasis.
In vitro and animal studies indicate anti-inflammatory (2), antitumor (14)(15), antiangiogenic (19) and neuroprotective (16) effects. Indirubin also inhibits cyclin-dependent kinases in tumor cells (5)(6). A derivate of indirubin was shown to enhance the cytotoxic effects of adriamycin (17).
Clinical studies show efficacy of indirubin in the treatment of psoriasis (18).
A small study of indirubin in patients with head and neck cancer found a reduction in mucosal damage from radiation therapy (3). Meisoindigo, a metabolite of indirubin has also been shown to have similar properties (4). A few cases of positive effects following long term use of indirubin for the treatment of CML (7) have been reported. However further clinical trials are needed to confirm its role.
Indirubin inhibits DNA synthesis in rats and cell proliferation in the late-G1 and G2/M phase by selectively inhibiting cyclin-dependent kinases (CDK) (4) through the interaction with the kinase’s ATP-binding site (6). Indirubin-3-oxime inhibits the growth of human laryngeal cancer cells via induction of CDK inhibitor p21, inhibition of cyclin D1 and activation of caspase-3 (1). Indirubin may also play a role in inhibiting the assembly of microtubules, further reducing the rate of cell reproduction (11). Its anti-inflammatory effects appear to be due to inhibition of interferon-gamma (2). Indirubin is a minor constituent of Indigofera tinctoria, however a synthetic form of the substance was shown to have similar effectiveness against CML (12)(13). One study investigated the inhibitory effect of six indirubin derivatives against HL-60 human promyelocytic leukemia cells (8). One of these derivatives strongly inhibited the growth of HL-60 cancer cells, whereas the others showed only weak cytotoxic activity. An additional study found that four indirubin derivatives exhibited an antiproliferative activity against human HT-29 colorectal cancer cells in a solid tumor model (9). Indirubin modulates the proliferation and differentiation of keratinocytes derived from patients with psoriasis (10).
A derivative of indirubin, IDR-E804 was shown to inhibit angiogenesis by decreasing proliferation, migration and tube formation of vascular endothelial growth factor VEGF-treated human umbilical vein endothelial cells. These effects were accompanied by decreased phosphorylation of VEGF receptor (VEGFR)-2, AKT and extracellular signal regulated kinase (19).
Another study reported that mitochondrial dysfunction may be an important mechanism via which indirubin-3’-oxime induces cell cycle arrest in human neuroblastoma cells (20).
Reported (Oral): Mild to severe nausea, vomiting, abdominal pain, diarrhea, headache and edema. A few patients were found to have pulmonary arterial hypertension and cardiac insufficiency following long-term treatment (4). Long term oral ingestion has also occasionally been associated with hepatitis (10).
You WC, et al. Effect of extracts from indigowood root (Isatis indigotica Fort.) on immune responses in radiation-induced mucositis. J Altern Complement Med. 2009 Jul;15(7):771-8.
This study investigated the effect of indirubin (taken as indigowood root powder) on acute radiation induced mucositis. Twenty patients who were receiving radiation therapy for head and neck cancer were enrolled and randomized into a control or treatment group. The treatment group gargled with a solution made from indigowood root powder dissolved in double-distilled water for three minutes, and then swallowed it, before meals daily for seven weeks. The results of the clinical trial indicated that indigo wood root significantly reduced the severity of radiation mucositis (p=0.01), anorexia (p=0.002), and swallowing difficulty (p=0.002) in treated patients compared to the control group. The authors concluded that indirubin may play a therapeutic role in improving radiation mucositis, anorexia, and difficulty swallowing, but that the exact mechanism and pathways should be further studied.