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Antimutagenic and anticarcinogenic activity of natural and synthetic curcuminoids.

Five synthetic curcuminoids and three natural curcuminoids were investigated for their antimutagenic and anti-promotional activity. The natural curcuminoids, curcumin I (diferuloylmethane), curcumin II (feruloyl-p-hydroxycinnamoylmethane) and curcumin III (bis-(p-hydroxycinnamoyl)methane) isolated from Curcuma longa were found to be potent inhibitors of mutagenesis and crotean oil-induced tumour promotion. Curcumin III produced 87.6% inhibition to 2-acetamidofluorene (2-AAF) induced mutagenesis, at a concentration of 100 micrograms/plate, curcumin II and curcumin I produced 70.5% and 68.3% inhibition at the same concentration. All the synthetic curcuminoids were found to inhibit 2-AAF-induced mutagenicity among which salicyl- and anisylcurcuminoids were the most active. Curcumin III was the most effective anti-promotor among natural curcuminoids. While 90% of the control animals were having papillomas on the 10th week of tumour initiation, only 10% of the curcumin III-treated animals, 20% of the curcumin II-treated animals, and 40% of the curcumin I-treated animals were having papillomas. Salicylcurcuminoid, which was causing no papillomas by the 10th week, was the most potent anti-carcinogen among the synthetic curcuminoids. Piperonal curcuminoid also exhibited anti-promotional activity.

Animals↗

Disparate effects of similar phenolic phytochemicals as inhibitors of oxidative damage to cellular DNA.

Phenolic phytochemicals are natural plant substances whose cellular effects have not been completely determined. Nordihydroguaiaretic acid (NDGA) and curcumin are two phenolic phytochemicals with similar molecular structures, suggesting that they possess comparable chemical properties particularly in terms of antioxidant activity. To examine this possibility in a cellular system, this study evaluated the capacities of NDGA and curcumin to function as antioxidants in inhibiting oxidative damage to DNA. Jurkat T-lymphocytes were pre-incubated for 30 min with 0-25 microM of either NDGA or curcumin to allow for uptake. The phenolic phytochemical-treated cells were then oxidatively challenged with 25 microM hydrogen peroxide (H2O2). Afterwards, cells were subjected to alkaline micro-gel electrophoresis (i.e. comet assay) to assess the extent of single-strand breaks in DNA. In a concentration-dependent manner, NDGA inhibited H2O2-induced DNA damage, whereas curcumin did not. In fact, incubating Jurkat T-lymphocytes with curcumin alone actually induced DNA damage. This effect of curcumin on DNA did not appear to reflect the DNA fragmentation associated with apoptosis because there was no proteolytic cleavage of poly-(ADP-ribose)-polymerase, which is considered an early marker of apoptosis. Curcumin-induced damage to DNA was prevented by pre-treatment of the cells with the lipophilic antioxidant, alpha-tocopherol, suggesting that curcumin damaged DNA through oxygen radicals. Therefore, it is concluded that NDGA has antioxidant activity but curcumin has prooxidant activity in cultured cells based on their opposite effects on DNA.

Antioxidants↗

Pharmacodynamic and pharmacokinetic study of oral Curcuma extract in patients with colorectal cancer.

Curcuma spp. extracts, particularly the dietary polyphenol curcumin, prevent colon cancer in rodents. In view of the sparse information on the pharmacodynamics and pharmacokinetics of curcumin in humans, a dose-escalation pilot study of a novel standardized Curcuma extract in proprietary capsule form was performed at doses between 440 and 2200 mg/day, containing 36-180 mg of curcumin. Fifteen patients with advanced colorectal cancer refractory to standard chemotherapies received Curcuma extract daily for up to 4 months. Activity of glutathione S-transferase and levels of a DNA adduct (M(1)G) formed by malondialdehyde, a product of lipid peroxidation and prostaglandin biosynthesis, were measured in patients' blood cells. Oral Curcuma extract was well tolerated, and dose-limiting toxicity was not observed. Neither curcumin nor its metabolites were detected in blood or urine, but curcumin was recovered from feces. Curcumin sulfate was identified in the feces of one patient. Ingestion of 440 mg of Curcuma extract for 29 days was accompanied by a 59% decrease in lymphocytic glutathione S-transferase activity. At higher dose levels, this effect was not observed. Leukocytic M(1)G levels were constant within each patient and unaffected by treatment. Radiologically stable disease was demonstrated in five patients for 2-4 months of treatment. The results suggest that (a) Curcuma extract can be administered safely to patients at doses of up to 2.2 g daily, equivalent to 180 mg of curcumin; (b) curcumin has low oral bioavailability in humans and may undergo intestinal metabolism; and (c) larger clinical trials of Curcuma extract are merited.

Administration, Oral↗

Phenolic anti-inflammatory antioxidant reversal of Abeta-induced cognitive deficits and neuropathology.

Both oxidative damage and inflammation have been implicated in age-related neurodegenerative diseases including Alzheimer's Disease (AD). The yellow curry spice, curcumin, has both antioxidant and anti-inflammatory activities which confer significant protection against neurotoxic and genotoxic agents. We used 22 month Sprague-Dawley (SD) rats to compare the effects of the conventional NSAID, ibuprofen, and curcumin for their ability to protect against amyloid beta-protein (Abeta)-induced damage. Lipoprotein carrier-mediated, intracerebroventricular infusion of Abeta peptides induced oxidative damage, synaptophysin loss, a microglial response and widespread Abeta deposits. Dietary curcumin (2000 ppm), but not ibuprofen, suppressed oxidative damage (isoprostane levels) and synaptophysin loss. Both ibuprofen and curcumin reduced microgliosis in cortical layers, but curcumin increased microglial labeling within and adjacent to Abeta-ir deposits. In a second group of middle-aged female SD rats, 500 ppm dietary curcumin prevented Abeta-infusion induced spatial memory deficits in the Morris Water Maze and post-synaptic density (PSD)-95 loss and reduced Abeta deposits. Because of its low side-effect profile and long history of safe use, curcumin may find clinical application for AD prevention.

Amyloid beta-Peptides↗

Pharmacology of Curcuma longa.

The data reviewed indicate that extracts of Curcuma longa exhibit anti-inflammatory activity after parenteral application in standard animal models used for testing anti-inflammatory activity. It turned out that curcumin and the volatile oil are at least in part responsible for this action. It appears that when given orally, curcumin is far less active than after i.p. administration. This may be due to poor absorption, as discussed. Data on histamine-induced ulcers are controversial, and studies on the secretory activity (HCl, pepsinogen) are still lacking. In vitro, curcumin exhibited antispasmodic activity. Since there was a protective effect of extracts of Curcuma longa on the liver and a stimulation of bile secretion in animals, Curcuma longa has been advocated for use in liver disorders. Evidence for an effect on liver disease in humans is not yet available. From the facts that after oral application only traces of curcumin were found in the blood and that, on the other hand, most of the curcumin is excreted via the faeces it may be concluded that curcumin is absorbed poorly by the gastrointestinal tract and/or underlies presystemic transformation. Systemic effects therefore seem to be questionable after oral application except that they occur at very low concentrations of curcumin. This does not exclude a local action in the gastrointestinal tract.

Animals↗

Dose escalation of a curcuminoid formulation.

BACKGROUND: Curcumin is the major yellow pigment extracted from turmeric, a commonly-used spice in India and Southeast Asia that has broad anticarcinogenic and cancer chemopreventive potential. However, few systematic studies of curcumin's pharmacology and toxicology in humans have been performed. METHODS: A dose escalation study was conducted to determine the maximum tolerated dose and safety of a single dose of standardized powder extract, uniformly milled curcumin (C3 Complextrade mark, Sabinsa Corporation). Healthy volunteers were administered escalating doses from 500 to 12,000 mg. RESULTS: Seven of twenty-four subjects (30%) experienced only minimal toxicity that did not appear to be dose-related. No curcumin was detected in the serum of subjects administered 500, 1,000, 2,000, 4,000, 6,000 or 8,000 mg. Low levels of curcumin were detected in two subjects administered 10,000 or 12,000 mg. CONCLUSION: The tolerance of curcumin in high single oral doses appears to be excellent. Given that achieving systemic bioavailability of curcumin or its metabolites may not be essential for colorectal cancer chemoprevention, these findings warrant further investigation for its utility as a long-term chemopreventive agent.

Administration, Oral↗

Anti-tumour and antioxidant activity of natural curcuminoids.

Matural curcuminoids, curcumin, I, II and III isolated from turmeric (Curcuma longa) were compared for their cytotoxic, tumour reducing and antioxidant activities. Curcumin III was found to be more active than the other two as a cytotoxic agent and in the inhibition of Ehrlich ascites tumour in mice (ILS 74.1%). These compounds were also checked for their antioxidant activity which possibly indicates their potential use as anti-promoters. The amount of curcuminoids (I, II and III) needed for 50% inhibition of lipid peroxidation was 20, 14 and 11 g/m. Concentrations needed for 50% inhibition of superoxides were 6.25, 4.25 and 1.9 micrograms/ml and those for hydroxyl radical were 2.3, 1.8 and 1.8 micrograms/ml, respectively. The ability of these compounds to suppress the superoxide production by macrophages activated with phorbol-12-myristate-13-acetate (PMA) indicated that all the three curcuminoids inhibited superoxide production and curcumin III produced maximum effect. These results indicate that curcumin III is the most active of the curcuminoids present in turmeric. Synthetic curcumin I and III had similar activity to natural curcumins.

Animals↗