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 this 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.
Mild to severe nausea
In patients treated over a long time, blood flow to the heart and lungs may be affected.
Meisoindigo, which is derived from indirubin, has been shown to have similar properties.
This product is currently not sold as a dietary supplement. It is only available for preclinical and clinical studies.
Indirubin is extracted from the indigo plant (Isatis Root,Isatis Leaf). It is a constituent of the 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.
Mechanism of Action
Indirubin inhibits DNA synthesis in rats and cell proliferation in the late-G1 and G2/M phases by selectively inhibiting cyclin-dependent kinases (CDK) (4) by interacting 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, cyclin D1 inhibition, and caspase-3 activation (1). Indirubin may also play a role in inhibiting microtubule assembly, further reducing the rate of cell reproduction (11). Its anti-inflammatory effects may be due to interferon-gamma inhibition (2).
Indirubin is a minor constituent of Indigofera tinctoria; 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 antiproliferative activity against human HT-29 colorectal cancer cells in a solid tumor model (9). IDR-E804, another indirubin derivative, 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-2, AKT, and extracellular signal regulated kinases (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).
Indirubin modulates proliferation and differentiation of keratinocytes derived from patients with psoriasis (10).
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).