1. Curcumin is the active ingredient of the dietary spice turmeric and has been consumed for medicinal purposes for thousands of years. Modern science has shown that curcumin modulates various signaling molecules, including inflammatory molecules, transcription factors, enzymes, protein kinases, protein reductases, carrier proteins, cell survival proteins, drug resistance proteins, adhesion molecules, growth factors, receptors, cell-cycle regulatory proteins, chemokines, DNA, RNA, and metal ions.
2. Because of this polyphenol’s potential to modulate multiple signaling molecules, it has been reported to possess pleiotropic activities. First shown to have anti-bacterial activity in 1949, curcumin has since been shown to have anti-inflammatory, anti-oxidant, pro-apoptotic, chemopreventive, chemotherapeutic, anti-proliferative, wound healing, anti-nociceptive, anti-parasitic, and anti-malarial properties as well. Animal studies have suggested that curcumin may be active against a wide range of human diseases, including diabetes, obesity, neurologic and psychiatric disorders, and cancer, as well as chronic illnesses affecting the eyes, lungs, liver, kidneys, and gastrointestinal and cardiovascular systems.
3. Although many clinical trials evaluating curcumin’s safety and efficacy against human ailments have already been completed, others are still ongoing. Moreover, curcumin is used as a supplement in several countries, including India, Japan, the United States, Thailand, China, Korea, Turkey, South Africa, Nepal, and Pakistan. Although inexpensive, apparently well tolerated, and potentially active, curcumin has yet not been approved for treatment of any human disease.
4. In this article, we discuss the discovery and key biological activities of curcumin, with a particular emphasis on its activities at the molecular, cellular, animal, and human levels.
The interest in curcumin research has increased dramatically over the years (Fig 1D). As of June 2011, more than 4000 articles on curcumin were listed in the National Institutes of Health PubMed database (www.ncbi.nlm.nih.gov/sites/entrez). We now know that curcumin can modulate multiple signaling pathways in either a direct or indirect manner. This polyphenol has been shown to possess activities in animal models of many human diseases. In human clinical trials, curcumin has been found to be safe and efficacious, and the U.S. Food and Drug Administration has approved curcumin as a “generally regarded as safe” compound.