PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Curcumin”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources

Curcumin improves wound healing by modulating collagen and decreasing reactive oxygen species.

Wound healing consists of an orderly progression of events that re-establish the integrity of the damaged tissue. Several natural products have been shown to accelerate the healing process. The present investigation was undertaken to determine the role of curcumin on changes in collagen characteristics and antioxidant property during cutaneous wound healing in rats. Full-thickness excision wounds were made on the back of rat and curcumin was administered topically. The wound tissues removed on 4th, 8th and 12th day (post-wound) were used to analyse biochemical and pathological changes. Curcumin increased cellular proliferation and collagen synthesis at the wound site, as evidenced by increase in DNA, total protein and type III collagen content of wound tissues. Curcumin treated wounds were found to heal much faster as indicated by improved rates of epithelialisation, wound contraction and increased tensile strength which were also confirmed by histopathological examinations. Curcumin treatment was shown to decrease the levels of lipid peroxides (LPs), while the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), activities were significantly increased exhibiting the antioxidant properties of curcumin in accelerating wound healing. Better maturation and cross linking of collagen were observed in the curcumin treated rats, by increased stability of acid-soluble collagen, aldehyde content, shrinkage temperature and tensile strength. The results clearly substantiate the beneficial effects of the topical application of curcumin in the acceleration of wound healing and its antioxidant effect.

Administration, Topical↗

Inhibition of lipoxygenase 1 by phosphatidylcholine micelles-bound curcumin.

Curcumin (diferuloyl methane) from rhizomes of Curcuma longa L. binds to phosphatidylcholine (PC) micelles. The binding of curcumin with PC micelles was followed by fluorescence measurements. Curcumin emits at 490 nm with an excitation wavelength of 451 nm after binding to PC-mixed micelles stabilized with deoxycholate. Curcumin in aqueous solution does not inhibit dioxygenation of fatty acids by Lipoxygenase 1 (LOX1). But, when bound to PC micelles, it inhibits the oxidation of fatty acids. The present study has shown that 8.6 microM of curcumin bound to the PC micelles is required for 50% inhibition of linoleic acid peroxidation. Lineweaver-Burk plot analysis has indicated that curcumin is a competitive inhibitor of LOX1 with Ki of 1.7 microM for linoleic and 4.3 microM for arachidonic acids, respectively. Based on spectroscopic measurements, we conclude that the inhibition of LOX1 activity by curcumin can be due to binding to active center iron and curcumin after binding to the PC micelles acts as an inhibitor of LOX1.

Arachidonic Acids↗

Inhibition of human immunodeficiency virus type-1 integrase by curcumin.

Curcumin (diferuloylmethane) is the yellow pigment in turmeric (Curcuma longa L.) that is widely used as a spice, food coloring (curry) and preservative. Curcumin exhibits a variety of pharmacological effects including antitumor, anti-inflammatory, and anti-infectious activities and is currently in clinical trials for AIDS patients. The effects of curcumin have been determined on purified human immunodeficiency virus type 1 (HIV-1) integrase. Curcumin has an inhibitory concentration50 (IC50) for strand transfer of 40 microM. Inhibition of an integrase deletion mutant containing only amino acids 50-212 suggests that curcumin interacts with the integrase catalytic core. Two structural analogs, methyl cinnamate and chlorogenic acid, were inactive. Energy minimization studies suggest that the anti-integrase activity of curcumin could be due to an intramolecular stacking of two phenyl rings that brings the hydroxyl groups into close proximity. The present data suggest that HIV-1 integrase inhibition may contribute to the antiviral activity of curcumin. These observations suggest new strategies for antiviral drug development that could be based upon curcumin as a lead compound for the development of inhibitors of HIV-1 integrase.

Antiviral Agents↗

In vitro studies on the intestinal absorption of curcumin in rats.

When everted sacs of rat intestines were incubated with 50-750- micrograms of curcumin in 10 ml incubation medium, 30-80% of the added curcumin disappeared from the mucosal side. No curcumin was however detectable in the serosal fluid. Less than 3% of the added curcumin was found in the tissue at the highest concentration. In experiments with [3H[ curcumin, 5-6% of added radioactivity was found in the serosal side. TLC examination of the mucosal extract showed the presence of 2 compounds, 1 corresponding to curcumin and the other to a less polar, colourless compound. The serosal fluid had no curcumin but a compound whose RF was identical with the colourless compound present in the mucosal side. These experiments indicated that curcumin undergoes transformation during absorption from the intestine.

Animals↗

Curcumin protects human chondrocytes from IL-l1beta-induced inhibition of collagen type II and beta1-integrin expression and activation of caspase-3: an immunomorphological study.

Interleukin 1beta (IL-1beta) is a pleiotropic pro-inflammatory cytokine that plays a key role in mediating cartilage degradation in osteoarticular disorders such as osteoarthritis (OA) and rheumatoid arthritis (RA). At the cellular level, IL-1beta activates matrix degrading enzymes, down-regulates expression of matrix components and induces chondrocyte apoptosis. Curcumin (diferuloylmethane) is an anti-inflammatory phytochemical agent that has recently been shown to antagonize the pro-inflammatory effects of cytokines in chondrocytes and other cells. To test the hypothesis that curcumin also protects chondrocytes from morphological alterations induced by IL-1beta, we investigated its in vitro effects on apoptotic signalling proteins and key cartilage-specific matrix components in IL-1beta-stimulated chondrocytes. Human articular chondrocytes were pre-treated with 10 ng/mI IL-1beta alone for 30 min before being co-treated with IL-1beta and 50 microM curcumin for 5, 15 or 30 min, respectively. The ultrastructural morphology of chondrocytes was investigated by transmission electron microscopy. The production of collagen type II, the adhesion and signal transduction receptor beta1-integrin, the apoptosis marker activated caspase-3 was analysed by immunohistochemistry, immunoelectron microscopy and Western blotting. Transmission electron microscopy of chondrocytes stimulated with IL-1beta revealed early degenerative changes which were relieved by curcumin co-treatment. The suppression of collagen type II and beta1-integrin synthesis by IL-1beta was inhibited by curcumin. Additionally, curcumin antagonized IL-1beta-induced caspase-3 activation in a time-dependent manner. This study clearly demonstrates that curcumin exerts anti-apoptotic and anti-catabolic effects on IL-1beta-stimulated articular chondrocytes. Therefore curcumin may have novel therapeutic potential as an adjunct nutraceutical chondroprotective agent for treating OA and related osteoarticular disorders.

Caspase 3↗

Detection and quantitation of curcumin in mouse lung cell cultures by matrix-assisted laser desorption ionization time of flight mass spectrometry.

A method to detect and quantify curcumin and two curcuminoid metabolites in biological matrices, including mouse serum and mouse lung cell cultures, was developed. Standard curves between 0.04 and 10.00 nmol curcumin were prepared in serum, giving correlation coefficients of 0.94-0.99. Alcoholic extraction, concentration, and addition of dilute hydrochloric acid to stabilize the curcumin were essential to the reproducibility of the protocol. Untreated and curcumin-treated mouse lung fibrotic and nonfibrotic cell cultures were analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry utilizing this method. Curcumin uptake was calculated to be 7.0-11.6% for the saline-treated cells and 7.4-11.9% for the bleomycin-treated cultures. Curcumin was not detected in untreated cells. Two additional peaks (m/z=399 and 429) were observed in the curcumin-treated cells. These may be curcumin-derived products resulting from HCl treatment of the tissue samples.

Animals↗

Suppressive effects of dietary curcumin on the increased activity of renal ornithine decarboxylase in mice treated with a renal carcinogen, ferric nitrilotriacetate.

Curcumin, a natural, biologically active compound extracted from rhizomes of Curcuma species, has been shown to act as a biological response modifier in various disorders. We have reported previously that the dietary supplementation of curcumin enhances the activities of antioxidant and phase II metabolizing enzymes in mice (M. Iqbal, S.D. Sharma, Y. Okazaki, M. Fujisawa, S. Okada, Dietary supplementation of curcumin enhances antioxidant and phase II metabolizing enzymes in ddY mice: possible role in protection against chemical carcinogenesis and toxicity, Pharmacol and Toxicol. 92 (2003) 33_38.) and inhibits ferric nitrilotriacetate (Fe-NTA) induced oxidative injury of lipids and DNA in vitro (M. Iqbal, Y. Okazaki, S. Okada, In vitro curcumin modulates Ferric Nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H(2)O(2))-induced peroxidation of microsomal membrane lipids and DNA damage, Teratogenesis Carcinogenesis and Mutagenesis Supplement 23 (2003) 151-160.). In our present study, Fe-NTA, a known complete renal carcinogen, which generate ROS in vivo, was given intraperitoneally to mice and curcumin was tested for its ability to inhibits oxidative stress and the activity of ornithine decarboxylase (ODC) as well as histopathological changes in the kidney. Substantial changes in glutathione, antioxidant enzymes as well as changes in phase II metabolizing enzymes were observed in the kidney at 12 h after treatment with Fe-NTA (9.0 mg Fe/kg body weight). Effect of oxidative stress induced by Fe-NTA were also demonstrated by the increase in lipid peroxidation as monitored by formation of thiobarbituric acid-reactive substances and 4-hydroxy-2-nonenal (HNE)-modified proteins in kidney. Likewise, the level of protein carbonyl contents, an indicator of protein oxidation was also increased after Fe-NTA administration. However, the changes in these parameters were restored to normal in curcumin-pretreated mice. The ODC activity in the kidney was significantly increased by Fe-NTA, while the increased ODC activity induced by Fe-NTA was normalized in curcumin-pretreated mice. In addition, curcumin pretreatment almost completely prevented kidney biomolecules from oxidative damage and protected the tissue against observed histopathological alterations.

Analysis of Variance↗

Anti-oxidant activities of curcumin and related enones.

The natural product curcumin (diferuloylmethane, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), obtained from the spice turmeric, exhibits numerous biological activities including anti-cancer, anti-inflammatory, and anti-angiogenesis activities. Some of these biological activities may derive from its anti-oxidant properties. There are conflicting reports concerning the structural/electronic basis of the anti-oxidant activity of curcumin. Curcumin is a symmetrical diphenolic dienone. A series of enone analogues of curcumin were synthesized that included: (1) curcumin analogues that retained the 7-carbon spacer between the aryl rings; (2) curcumin analogues with a 5-carbon spacer; and (3) curcumin analogues with a 3-carbon spacer (chalcones). These series included members that retained or were devoid of phenolic groups. Anti-oxidant activities were determined by the TRAP assay and the FRAP assay. Most of the analogues with anti-oxidant activity retained the phenolic ring substituents similar to curcumin. However, a number of analogues devoid of phenolic substituents were also active; these non-phenolic analogues are capable of forming stable tertiary carbon-centered radicals.

Antioxidants↗

Induction of apoptosis in human lung cancer cells by curcumin.

Curcumin, a phenolic compound from the rhizome of the plant Curcuma longa has anti-inflammatory, antioxidant and anti-cancer activities. Although the precise mode of action of this compound is not yet elucidated, studies have shown that chemo-preventive action of curcumin might be due to its ability to induce apoptosis and to arrest cell cycle. This study investigated the cellular and molecular changes induced by curcumin leading to the induction of apoptosis in human lung cancer cell lines-A549 and H1299. A549 is p53 proficient and H1299 is p53 null mutant. The lung cancer cells were treated with curcumin (0-160 microM) for 12-72 h. Curcumin inhibited the growth of both the cell lines in a concentration dependent manner. Growth inhibition of H1299 cell lines was both time and concentration dependent. Curcumin induced apoptosis in both the lung cancer cell lines. A decrease in expression of p53, bcl-2, and bcl-X(L) was observed after 12 h exposure of 40 microM curcumin. Bak and Caspase genes remained unchanged up to 60 microM curcumin but showed decrease in expression levels at 80-160 microM. The data also suggest a p53 independent induction of apoptosis in lung cancer cells.

Adenocarcinoma↗

Antitumor effects of curcumin, alone or in combination with cisplatin or doxorubicin, on human hepatic cancer cells. Analysis of their possible relationship to changes in NF-kB activation levels and in IAP gene expression.

The hepatic cancer HA22T/VGH cell line, which constitutively expresses activated nuclear factor-kappaB (NF-kB), was chosen as a model to examine the antitumor activity of curcumin, also in relationship to its possible influences on the activation of the transcription factor and on the expression of the inhibitory of apoptosis proteins (IAPs) and of other NF-kB target genes. Curcumin exerted cell growth inhibitory and apoptotic effects, related, at least part, to free radical generation and mainly dependent on caspase-9 and -3 activation. The combination of curcumin with cisplatin resulted in a synergistic antitumor activity and that with doxorubicin in additivity or sub-additivity. Curcumin exerted biphasic changes in the levels of NF-kB, with an increase at 8 h after its administration and a decrease at 16 h. For the combinations of curcumin with the other drugs, the levels of the transcription factor were lower than those predicted from the effects of the single agents, especially with a blunting of the remarkable increases in NF-kB activation induced by doxorubicin. Except for Bcl-2, the HA22T/VGH cells expressed different other genes, including the IAPs, implicated in cell proliferation and survival. Curcumin determined early changes in COX-2 and c-myc mRNAs, which were down-regulated, and in livin mRNA, which was up-regulated. Later it decreased Bcl-X(L) mRNA and increased Bcl-X(S) and c-IAP-2 mRNAs. Cisplatin and doxorubicin exerted distinct effects on gene expression. The cytotoxic interactions between curcumin and these agents were accompanied by synergistic (in particular with cisplatin) or additive effects of decrease in the expression of different genes, including c-myc, Bcl-X(L), c-IAP-2, NAIP and XIAP. However, the combinations attenuated also certain other influences on mRNA expression of the single agents, like, for example, the increases in Bcl-X(s) given by curcumin and doxorubicin. Overall, the effects of the drugs, alone or in combination, on tumor cell growth, cell death and gene expression did not show a simple relationship to the relative influences on NF-kB activation, inferring that they can be due also to other mechanisms.

Antibiotics, Antineoplastic↗

Curcumin inhibits protease-activated receptor-2 and -4-mediated mast cell activation.

BACKGROUND: Curcumin, a major yellow pigment and active component of turmeric powder extracted from Curcuma longa L. (Gingiberaceae), has been shown to possess anti-inflammatory and anti-cancer activities. Protease-activated receptors (PARs) play a role in inflammation, and human leukemic mast cells (HMC-1) co-express PAR2 and PAR4. In the present study, the effect of curcumin on PAR2- and PAR4-mediated HMC-1 activation was examined. METHODS: HMC-1 cells were stimulated with trypsin (100 nmol/l, PAR2 and PAR4 agonist), SLIGKV-NH(2) (100 microM, PAR2-activating peptide) or GYPGQV-NH(2) (100 micromol/l PAR4-activating peptide) in the presence or absence of curcumin (1, 10, and 100 micromol/l). TNF-alpha secretion was measured by enzyme-linked immunosorbent assay (ELISA). TNF-alpha and tryptase mRNA were measured by reverse-transcription PCR (RT-PCR). Mitogen-activated protein kinase (MAPK) activation was assessed by Western blot analysis. Trypsin activity was measured using the substrate Bz-DL-Arg-p-nitroanilide (BAPNA). RESULTS: Curcumin (10 and 100 micromol/l) inhibited TNF-alpha secretion from trypsin or activating peptide-stimulated HMC-1. Curcumin (10 and 100 micromol/l) also inhibited TNF-alpha and tryptase mRNA expression in trypsin-stimulated HMC-1. Furthermore, curcumin inhibited trypsin-induced extracellular signal-regulated kinase (ERK) phosphorylation. However, curcumin did not affect the trypsin activity even at 100 micromol/l. CONCLUSION: Curcumin inhibits PAR2- and PAR4-mediated human mast cell activation, not by inhibition of trypsin activity but by block of ERK pathway.

Cell Line, Tumor↗

Amelioration of immune cell number depletion and potentiation of depressed detoxification system of tumor-bearing mice by curcumin.

BACKGROUND: The true therapeutic benefit of the use of natural products, especially acceptable dietary components such as curcumin, which can spare the normal cells and boost host immunity, has opened new horizons in cancer prevention and treatment. METHODS: In our model system we used Ehrlich's ascites carcinoma cells grown in peritoneal carity of Swiss albino mice and curcumin was fed every alternative day. RESULTS: Here, we report that curcumin administration to tumor-bearing mice decreased tumor cell number significantly in a dose-dependent manner. Furthermore, tumor-induced depletion of immune cell number of the host, as was evidenced from the decrease in bone marrow progenitor as well as thymic and splenic mononuclear cell numbers, was reintrated by curcumin. In fact, curcumin inhibited tumor-induced apoptosis of both thymocytes and splenocytes thereby restoring immune cell numbers to normal level in treated Ehrlich's ascites carcinoma-bearing mice. Moreover, curcumin was not toxic to the host; rather in tumor-bearing mice it inhibited hematopoietic toxicity, acted as a hepatoprotective agent and activated depressed anti-oxidant and detoxification systems. CONCLUSION: The ability of curcumin to regress tumor as well as to protect the host from tumor-induced immunosuppression and toxicity strongly supports the candidacy of curcumin as a potential agent for the dietary therapy of cancer.

Animals↗

Effect of curcumin on protein glycosylation, lipid peroxidation, and oxygen radical generation in human red blood cells exposed to high glucose levels.

Curcumin (diferuloylmethane) is the most active component of turmeric. It is believed that curcumin is a potent antioxidant and anti-inflammatory agent. Experimental studies with diabetic animals demonstrate that curcumin supplementation can suppress cataract development and collagen cross-linking, promote wound healing, and lower blood lipids and glucose levels. The mechanism by which curcumin may cause diabetes-associated vascular damage to regress is not known. Erythrocytes were treated with high levels of glucose (mimicking diabetes) in the presence or absence of curcumin (0-10 muM) in the medium at 37 degrees C for 24 h. This study demonstrates that curcumin prevents protein glycosylation and lipid peroxidation caused by high glucose levels using an erythrocyte cell model. This study also suggests that curcumin may inhibit oxygen radical production caused by high glucose concentrations in a cell-free system, and increase glucose utilization in erythrocytes. This provides evidence for a novel mechanism by which curcumin supplementation may prevent the cellular dysfunction associated with diabetes.

Blood Glucose↗

Through metal binding, curcumin protects against lead- and cadmium-induced lipid peroxidation in rat brain homogenates and against lead-induced tissue damage in rat brain.

Curcumin, the major constituent of turmeric is a known, naturally occurring antioxidant. The present study examined the ability of this compound to protect against lead-induced damage to hippocampal cells of male Wistar rats, as well as lipid peroxidation induced by lead and cadmium in rat brain homogenate. The thiobarbituric assay (TBA) was used to measure the extent of lipid peroxidation induced by lead and cadmium in rat brain homogenate. The results show that curcumin significantly protects against lipid peroxidation induced by both these toxic metals. Coronal brain sections of rats injected intraperitoneally with lead acetate (20 mg/kg) in the presence and absence of curcumin (30 mg/kg) were compared microscopically to determine the extent of lead-induced damage to the cells in the hippocampal CA1 and CA3 regions, and to establish the capacity of curcumin to prevent such damage. Lead-induced damage to the neurons was significantly curtailed in the rats injected with curcumin. Possible chelation of lead and cadmium by curcumin as its mechanism of neuroprotection against such heavy metal insult to the brain was investigated using electrochemical, ultraviolet spectrophotometric and infrared spectroscopic analyses. The results of the study show that there is an interaction between curcumin and both cadmium and lead, with the possible formation of a complex between the metal and this ligand. These results imply that curcumin could be used therapeutically to chelate these toxic metals, thus potentially reducing their neurotoxicity and tissue damage.

Animals↗

Neuroprotective effect of curcumin in middle cerebral artery occlusion induced focal cerebral ischemia in rats.

Free radical induced neuronal damage is implicated in cerebral ischemia reperfusion (IR) injury and antioxidants are reported to have neuroprotective activity. Several in vitro and in vivo studies have proved the antioxidant potential of curcumin and its metabolites. Hence, in the present study the neuroprotective potential of curcumin was investigated in middle cerebral artery occlusion (MCAO) induced focal cerebral IR injury. 2 h of MCAO and 22 h of reperfusion resulted in the infarct volume of 210.39 +/- 31.25 mm3. Administration of curcumin 100 and 300 mg/kg, i.p. 30 min. after MCAO produced 37.23 +/- 5.10% and 46.39 +/- 10.23% (p < 0.05) reduction in infarct volume, respectively. Ischemia induced cerebral edema was reduced in a dose dependent manner. Curcumin at 300 mg/kg, i.p. produced 50.96 +/- 6.04% reduction in edema (p < 0.05) volume. Increase in lipid peroxidation after MCAO in ipsilateral and contralateral hemisphere of brain was observed, which was reduced by curcumin (300 mg/kg, i.p.)-treatment. Decrease in superoxide dismutase and glutathione peroxidase activity was observed in ipsilateral hemisphere of MCAO animal. Curcumin-treatment (300 mg/kg, i.p.) prevented IR injury mediated fall in glutathione peroxide activity. Peroxynitrite measured using rhodamine123 fluorescence and anti-nitrotyrosine immunofluorescence indicated increased peroxynitrite formation after IR insult. Curcumin-treatment reduced peroxynitrite formation and hence the extent of tyrosine nitration in the cytosolic proteins. These results suggest the neuroprotective potential of curcumin in cerebral ischemia and is mediated through its antioxidant activity.

Animals↗

Curcumin modulates drug metabolizing enzymes in the female Swiss Webster mouse.

Curcumin, the yellow pigment found in turmeric, exhibits potent chemopreventative properties in both in vivo and in vitro cancer models. We hypothesized that this effect may occur via curcumin-mediated changes in enzymes involved in both carcinogen bioactivation and estrogen metabolism. Female Swiss Webster mice were treated with either curcumin (200 mg/kg or 400 mg/kg, p.o.) or vehicle control for 1 or 2 weeks. The results demonstrated that curcumin had no effect on the catalytic activities of ovarian aromatase, hepatic catechol-O-methyltransferase or hepatic UDP-glucuronosyltransferase. However, both doses of curcumin caused a 25% decrease in CYP1A catalytic activity, but not polypeptide levels, following 2 weeks of treatment. Additionally, following 2 weeks of curcumin at 400 mg/kg, there was a 20% decrease in the catalytic activity and a 28% decrease in polypeptide levels of CYP3A. While 2 weeks of curcumin treatment (400 mg/kg) caused a 20% increase in glutathione S-transferase activity, there was no parallel increase in hepatic stores of the co-factor glutathione. In conclusion small changes in CYP1A, CYP3A and GST following long term treatment (2 weeks) suggest that the combination of all three metabolic pathways may play a small role in curcumin's chemopreventative action.

Animals↗

Antidepressant effects of curcumin in the forced swim test and olfactory bulbectomy models of depression in rats.

Curcuma longa is a major constituent of Xiaoyao-san, the traditional Chinese medicinal formula, which has been used to effectively manage stress and depression-related disorders in China. Curcumin is the active component of curcuma longa, and we hypothesized that curcumin would have an influence on depressive-like behaviors. The purpose of the present study was to confirm the putative antidepressant effect of chronic administrations of curcumin (1.25, 2.5, 5 and 10 mg/kg, p.o.) in the forced swimming test and bilateral olfactory bulbectomy (OB) models of depression in rats. In the first study, chronic treatment with curcumin (14 days) reduced the immobility time in the forced swimming test. In the second experiment, curcumin reversed the OB-induced behavioral abnormalities such as hyperactivity in the open field, as well as deficits in step-down passive avoidance. In addition, OB-induced low levels of serotonin (5-HT), noradrenaline (NA), high 5-hydroxyindoleacetic acid (5-HIAA) and 4-dihydroxyphenylacetic acid (DOPAC) in the hippocampus were observed, and were completely reversed by curcumin administration. A slight decrease in 5-HT, NA and dopamine (DA) levels was found in the frontal cortex of OB rats which was also reversed by curcumin treatment. These results confirm the antidepressant effects of curcumin in the forced swim and the OB models of depression in rats, and suggest that these antidepressant effects may be mediated by actions in the central monoaminergic neurotransmitter systems.

Animals↗

Biologic evaluation of curcumin and structural derivatives in cancer chemoprevention model systems.

Curcumin is a natural product widely used as a spice in food. It has been shown to inhibit cyclooxygenase (COX)-1 and -2 and to suppress lipopolysaccharide-induced COX-2 and iNOS gene expression. In the present study, curcumin and 22 of its derivatives were evaluated for their chemopreventive potential. Based on COX-2 inhibition, curcumin (IC50=15.9 microM), 1,7-bis(3-fluoro-4-hydroxyphenyl)-1,6-heptadiene-3,5-dione (19) (IC50=23.7 microM) and 2,6-bis(3-fluoro-4-hydroxybenzylidene)cyclohexanone (23) (IC50=5.5 microM) were found to be most potent. Tricyclic derivatives 2,6-bis(4-hydroxy-3-methoxybenzylidene)cyclohexanone (10), 2,6-bis(4-hydroxy-3,5-dimethoxybenzylidene)cyclohexanone (13) and 2,5-bis(4-hydroxy-3,5-dimethoxybenzylidene)cyclopentanone (21) inhibited LPS-induced COX-2 and iNOS gene expression in murine macrophages with potency equal to curcumin. RT-PCR experiments demonstrated suppression of COX-2 and iNOS gene expression occurred at the transcriptional level. The most active compounds in the macrophage assays, 13 and 23, were also the most cytotoxic, however. Topical application of curcumin, 10, 13, 21, and 6, a methoxy derivative of curcumin, showed strong inhibition of 12-O-tetradecanoyl-13-acetate (TPA)-induced ornithine decarboxylase (ODC) activity in mouse skin. These data suggest that structural elements responsible for COX-1 and COX-2 inhibition do not correlate well with those responsible for inhibiting COX-2 and iNOS gene expression, but elements capable of inhibiting COX-2 and iNOS gene expression also contribute to inhibition of TPA-induced ODC activity. The most potent compounds in these assays, 10, 13 and 21, as well as curcumin, were further evaluated for inhibition of 7,12-dimethylbenz(a)anthracene (DMBA)-induced preneoplastic lesion formation in a mouse mammary organ culture model, and dose-dependent responses were observed. Most potent effects were at concentrations between 1 and 5 microM for 10, 13 and 21, and at 10 microM for curcumin. These data demonstrate the substitution pattern on the aromatic moiety is especially crucial for activity.

Animals↗