Curcuma Longa is a perennial herb that belongs to the ginger family. The rhizome is extensively used for imparting color and flavor to food including curries. As a powder, called turmeric, it is also used for medicinal and religious ceremonies.
The benefits of Curcuma longa have been extensively researched, especially by Indian scientists.
Numerous studies have shown that the various constituents of curcuma longa posses potent antioxidant properties. The ability of cucuminoids to reduce hydroxyl and peroxyl free radicals is well documented. Sharma reported curcumin to be an effective agent against lipid peroxidation.
The Central Drug Research Institute in India found curcumin to be the major constituent responsible for the anti-inflammatory activity. The classical model for studying acute effects of anti-inflammatory agents is to test their inhibitory action on the development of rat paw edema - the exudative phase of inflammation - induced, for instance, by the local injection of carrageenins. Thus inflammation is thought to be in part due to the action of prostaglandin derivative from arachidonic acid metabolism. A detailed evaluation of curcumin as a potential non-steroidal anti-inflammatory agent by Srimal and Dhawan found curcumin to be highly effective after oral administration. Curcumin was effective in other models of inflammation including granuloma, pouch, cotton pellet, formalin-induced, and Freund's adjuvant.
The mechanism of anti-inflammatory action of curcumin is not yet known. Some researchers found curcumin to be less effective in adrenalectomized rats, suggesting a participation of corticoidal steroids, while others did not observe any effect of curcumin salts on steroid release from the adrenal cortex. Recently, another, more specific in-vitro method has been developed which allows the study of the inhibitory mechanism of potential drugs. By using rat peritoneal neutrophilis, curcumin was tested for the direct effect on the 5-lipooxygenase activities. Another study found that curcumin was able to inhibit the production of pro-inflammatory mediators in microglial cells that had been stimulated to mount an inflammatory response. Microglial cells are activated after brain injuries and produce proinflammatory mediators and neurotoxic compounds. Curcumin decreased the production of these compounds, apparently by blocking NF-kB, a protein signal in the pathway that leads to their production. The overexpression of pro-inflammatory cytokines contributes to diseases such as Alzheimer's, cerebral ischemia and multiple sclerosis. The ability of curcumin to decrease inflammation presents an approach to slow the progression of these diseases.
Curcumin increases mucin content, thereby protecting the gastric mucosa against irritants. Controversial data exist regarding an anti-ulcerogenic activity of curcumin. Some researchers found a protective effect of curcumin against histamine-induced gastric ulceration, while others reported an ulcerogenic effect of curcumin.
Curcumin also possesses anti-spasmodic properties. Curcumin showed liver protective effects against carbon tetrachloride, D-Galactosamine and peroxide induced cytotoxicity. Curcumin increased bile acid production in dogs and rats.
A sharp and transient hypotensive effect of curcumin was reported in dogs. Curcumin also inhibited collagen and adrenaline-induced aggregation of platelets but did not affect prostacyclin (PGI2) synthesis.
Rao and co-workers reported that rats fed with curcumin and cholesterol in their diet had only half to one-third of the serum and liver cholesterol levels compared to the controlled groups receiving cholesterol alone.
Curcumin inhibited growth of most organisms including: Staph aureus, Streptococci, lactobacilli, corynebacterium, Baccilus aureus, and micrococcus pyogenes. The crude ether and chloroform extracts of curcuma longa showed fungistatic activity against several dermatophytes as well as anti-amoebic activity against Entamoeba histolytica.
A 1993 study showed curcumin as an effective ally in the treatment against HIV. Curcumin was effective in inhibiting the replication of HIV in both acutely infected and chronically infected cells.
The anti-tumor activity of various extracts of curcuma longa has been remarked by several researchers. Topical application of curcumin inhibited the number of TPA-induced tumors by as much as 98%!! Curcumin was found to be a selective and non-competitive inhibitor of phosphorylase kinase.