CURCUMA LONGA AND ITS ANTI-CANCER ACTIVITY
Curcumin (diferuloylmethane) is the orange and water-insoluble pigment extracted from turmeric, the rhizome of Curcuma longa, a species that belongs to the Zingiberaceae family. The powder obtained from the turmeric root, the main ingredient of curry, contains 2–5% of curcumin. Due to its chemical and biological properties, curcumin is one of the so-called phytochemical compounds, biologically active molecules produced by plants with beneficial effects on health, that also include β-carotene, lycopene, epigallocatechinegallate, and quercetin .The therapeutic use of the plant dates back to Indian Ayurvedic medicine, and curcumin is still nowadays commonly used as a spice and as a colorant in Indian cooking and in the whole South-East Asia. In the last few years, several curcumin analogues have been tested, but in most cases they were found to be less effective than curcumin itself. On the contrary, dimethoxycurcumin showed good results probably because of the absence of free phenolic groups that prevent its conversion to glucuronide and to sulfate, resulting in better bioavailability. In the last years, several studies have confirmed the potential use of curcumin for the prevention and treatment of many different diseases, especially inflammatory ones and cancer. In particular, several studies confirmed a chemopreventive role for curcumin in tumors from different cell types (pancreas, breast, prostate, lung, mantle cell lymphoma, liver, brain, colorectal cancer, and others). Several studies focused the effect of curcumin and its analogs on the nuclear factor κB (NF-κB), and demonstrated that curcumin is able to down regulate the expression of genes involved in apoptosis, proliferation, and transformation, by inhibiting the NF-κB activation.
Turmeric possesses anti -cancer activity because curcuminoids present in turmeric show tremendous free radical scavenging .The of turmeric has been reported in oral, skin, colonic and mammary cancer. The development of oral neoplasma, identified histopathologically as squamous cell carcinomas in animals painted with 4- nitroquinoline-l-oxide (NQO) on their cheek mucosa showed a decrease in lipid peroxidation and tumor burden when administered with turmeric extracts simultaneously. Turmeric 2 or 5% in diet significantly inhibited benzopyrene (BP) induced forestornach pappilomas. Dietary turmeric with catechin was also used as a chemopreventive agent in BP induced forestomach tumors in swiss mice and methyl (acetoxymethyl) nitro amine induced oral mucosal tumors in syrian golden hamsters probably clue to increased forestomach and hepatic glutathione -S-transferase (GST) activity when compared to controls .The rats fed with 0.5% turmeric in diet showed no decrease in xenobiotic metabolizing phase I enzymes, aryl hydrocarbon hydroxylase (AHH) while phase II enzymes, UDP glucuronyl transferase (UDGPT) and GST level vmre significantly elevated in rats fed with 5 and 10% turmeric . The increased activity of phase II enzymes is related to faster metabolism of xenobiotics thus leading to anticancer effects. It is suggested that binding of curcumin to the active site of GST might be involved in the modulation of GST activity in chemoprevention and chemoprotection of cancer.
Chromosomal aberration was examined by micronuclear assay. Turmeric extract did not induce an increased level of chromosomal damage. It was postulated that the clastogenic effect of turmeric might be due to its content of curcumin. Turmeric was found to be non-mutagenic in Ames assay with Salmonella typhimurium strains TA 100, TA98 and TA 97 before or after activation with liver microsomal fraction on cell free extracts of rat cecal microorganisms. The study conducted on human beings fed with turmeric in a dose of 1.5 gm/day for 30 days showed significant reduction in the urinary excretion of mutagens in 16 chronic smokers.
Curcumin and its analogues have been demonstrated to possess various anticancer properties in a series of cancer cell lines, such as pancreatic, lung, ovarian, oral, colorectal, breast carcinoma and even in melanoma cells. In the future, further research will ascertain or not the potential of curcumin analogues as effective chemotherapy agents.