Effect of curcumin on the production of nitric oxide by cultured rat mammary gland

Is Curcumin Intake Really Effective for Chronic Inflammatory Metabolic Disease? A Review of Meta-Analyses of Randomized Controlled Trials

This review aimed to examine the effects of curcumin on chronic inflammatory metabolic disease by extensively evaluating meta-analyses of randomized controlled trials (RCTs). We performed a literature search of meta-analyses of RCTs published in English in PubMed®/MEDLINE up to 31 July 2023. We identified 54 meta-analyses of curcumin RCTs for inflammation, antioxidant, glucose control, lipids, anthropometric parameters, blood pressure, endothelial function, depression, and cognitive function. A reduction in C-reactive protein (CRP) levels was observed in seven of ten meta-analyses of RCTs. In five of eight meta-analyses, curcumin intake significantly lowered interleukin 6 (IL-6) levels. In six of nine meta-analyses, curcumin intake significantly lowered tumor necrosis factor α (TNF-α) levels. In five of six meta-analyses, curcumin intake significantly lowered malondialdehyde (MDA) levels. In 14 of 15 meta-analyses, curcumin intake significantly reduced fasting blood glucose (FBG) levels. In 12 of 12 meta-analyses, curcumin intake significantly reduced homeostasis model assessment of insulin resistance (HOMA-IR). In seven of eight meta-analyses, curcumin intake significantly reduced glycated hemoglobin (HbA1c) levels. In eight of ten meta-analyses, curcumin intake significantly reduced insulin levels. In 14 of 19 meta-analyses, curcumin intake significantly reduced total cholesterol (TC) levels. Curcumin intake plays a protective effect on chronic inflammatory metabolic disease, possibly via improved levels of glucose homeostasis, MDA, TC, and inflammation (CRP, IL-6, TNF-α, and adiponectin). The safety and efficacy of curcumin as a natural product support the potential for the prevention and treatment of chronic inflammatory metabolic diseases.

Attenuation of Inflammatory Responses in Breast and Ovarian Cancer Cells by a Novel Chalcone Derivative and Its Increased Potency by Curcumin

Background

Breast and ovarian cancers are two common malignancies in women and a leading cause of death globally. The aim of the present study was to explore the effects of a novel chalcone derivative 1-(4-(methylsulfonyl)phenyl)-3-(phenylthio)-3-(p-tolyl)propane-1-one (MPP) individually or combined with curcumin, a well-known herbal medicine with anticancer properties, as a new combination therapy on inflammatory pathways in breast and ovarian cancer cell lines.

Methods

LPS-induced NF-κB DNA-binding activity and the levels of proinflammatory cytokines were measured in the MPP- and MPP-curcumin combination-treated MDA-MB-231 and SKOV3 cells by ELISA-based methods. The expression of COX2, INOS, and MMP9 genes and nitrite levels was also evaluated by real-time qRT-PCR and Griess method, respectively. IκB levels were evaluated by Western blotting.

Results

MPP significantly inhibited the DNA-binding activity of NF-κB in each cell line and subsequently suppressed the expression of downstream genes including COX2, MMP9, and INOS. The levels of proinflammatory cytokines, as well as NO, were also decreased in response to MPP. All the effects of MPP were enhanced by the addition of curcumin. MPP, especially when combined with curcumin, caused a remarkable increase in the concentration of IκB.

Conclusion

MPP and its coadministration with curcumin effectively reduced the activity of the NF-κB signaling pathway, leading to a reduced inflammatory response in the environment of cancer cells. Thus, MPP, either alone or combined with curcumin, might be considered an effective remedy for the suppression of inflammatory processes in breast and ovarian cancer cells.

Protective effect of curcumin on zebrafish liver under ethanol-induced oxidative stress

Oxidative stress has an important role in determining severe damage to the liver, including steatosis. Curcumin (CUR) is a natural polyphenol compound with antioxidant potential but its mechanism is still unclear. In this study, 2% ethanol (ETH) was used to establish a liver injury model in Tg (fabp10: Ps Red) transgenic zebrafish with the fluorescent liver. Ethanol-treated zebrafish had an increased vacuole rate at 144 h post-fertilization (hpf), thus confirming the effectiveness of the proposed model in inducing liver damage. However, when ethanol was submitted to co-exposure with curcumin, fluorescence area and signal intensity, as well as vacuole rate, were similar to the levels found in the control group. RNA-seq results showed that ethanol and CUR affected the regulation of catalytic activity and phenylalanine metabolism, biosynthesis of amino acids, and arginine and proline metabolism signaling pathways. QRT-PCR analysis also showed that treatment with CUR led to the downregulation of genes involved in the Nrf2-Keap1 signaling pathway and altered the expression pattern of genes related to glutathione metabolism (gsr, gpx1a, gstp1, gsto1, and idh1a). CUR also induced an increase in GSH content and recovered decreased GSH caused by ethanol exposure. The findings discussed herein indicate that CUR can promote glutathione synthesis, which aided in the recovery from ethanol-induced liver damage in zebrafish larvae.

Harnessing polyphenol power by targeting eNOS for vascular diseases

Vascular diseases arise due to vascular endothelium dysfunction in response to several pro-inflammatory stimuli and invading pathogens. Thickening of the vessel wall, formation of atherosclerotic plaques consisting of proliferating smooth muscle cells, macrophages and lymphocytes are the major consequences of impaired endothelium resulting in atherosclerosis, hypercholesterolemia, hypertension, type 2 diabetes mellitus, chronic renal failure and many others. Decreased nitric oxide (NO) bioavailability was found to be associated with anomalous endothelial function because of either its reduced production level by endothelial NO synthase (eNOS) which synthesize this potent endogenous vasodilator from L-arginine or its enhanced breakdown due to severe oxidative stress and eNOS uncoupling. Polyphenols are a group of bioactive compounds having more than 7000 chemical entities present in different cereals, fruits and vegetables. These natural compounds possess many OH groups which are largely responsible for their strong antioxidative, anti-inflammatory antithrombotic and anti-hypersensitive properties. Several flavonoid-derived polyphenols like flavones, isoflavones, flavanones, flavonols and anthocyanidins and non-flavonoid polyphenols like tannins, curcumins and resveratrol have attracted scientific interest for their beneficial effects in preventing endothelial dysfunction. This article will focus on in vitro as well as in vivo and clinical studies evidences of the polyphenols with eNOS modulating activity against vascular disease condition while their molecular mechanism will also be discussed.

Mechanism underlying nephroprotective property of curcumin against sodium nitrite-induced nephrotoxicity in male Wistar rat

The current work examined the outcome of curcumin (20 mg/kg body weight/day) administration on arginase and adenosine deaminase (ADA) activities and other kidney markers, as well as markers of oxidative stress, in Wistar rats exposed to sodium nitrite (NaNO₂ ) (60 mg/kg of body weight, single dose) for 28 days. The results revealed that the NaNO₂ exposed rats had significantly altered the ADA activities, arginase activities alongside other biomarkers of kidney function, and oxidative stress. However, pretreatment with curcumin significantly mitigated the altered activities ADA and arginase as well as other parameters. This was supported by the histopathological examination of the kidney tissues. Our findings suggest that the alteration in the activities of ADA and arginase could be involved in the mechanism of action employed by NaNO₂ and curcumin in the respective induction and prevention of nephrotoxicity. PRACTICAL APPLICATIONS: These results suggest that moderate exposure to the acceptable daily dose of curcumin can improve food-related kidney damage through regulations of ADA and arginase activities, enhancement in the antioxidant system, and suppression of lipid peroxidation.

Curcumin and Intestinal Inflammatory Diseases: Molecular Mechanisms of Protection

Intestinal inflammatory diseases, such as Crohn’s disease, ulcerative colitis, and necrotizing enterocolitis, are becoming increasingly prevalent. While knowledge of the pathogenesis of these related diseases is currently incomplete, each of these conditions is thought to involve a dysfunctional, or overstated, host immunological response to both bacteria and dietary antigens, resulting in unchecked intestinal inflammation and, often, alterations in the intestinal microbiome. This inflammation can result in an impaired intestinal barrier allowing for bacterial translocation, potentially resulting in systemic inflammation and, in severe cases, sepsis. Chronic inflammation of this nature, in the case of inflammatory bowel disease, can even spur cancer growth in the longer-term. Recent research has indicated certain natural products with anti-inflammatory properties, such as curcumin, can help tame the inflammation involved in intestinal inflammatory diseases, thus improving intestinal barrier function, and potentially, clinical outcomes. In this review, we explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its antimicrobial and immunomodulatory properties, as well as its potential to alter the intestinal microbiome. Curcumin may play a significant role in intestinal inflammatory disease treatment in the future, particularly as an adjuvant therapy.

Curcumin as an anti-inflammatory agent: Implications to radiotherapy and chemotherapy

Cancer is the second cause of death worldwide. Chemotherapy and radiotherapy are the most common modalities for the treatment of cancer. Experimental studies have shown that inflammation plays a central role in tumor resistance and the incidence of several side effects following both chemotherapy and radiotherapy. Inflammation resulting from radiotherapy and chemotherapy is responsible for adverse events such as dermatitis, mucositis, pneumonitis, fibrosis, and bone marrow toxicity. Chronic inflammation may also lead to the development of second cancer during years after treatment. A number of anti-inflammatory drugs such as nonsteroidal anti-inflammatory agents have been proposed to alleviate chronic inflammatory reactions after radiotherapy or chemotherapy. Curcumin is a well-documented herbal anti-inflammatory agents. Studies have proposed that curcumin can help management of inflammation during and after radiotherapy and chemotherapy. Curcumin targets various inflammatory mediators such as cyclooxygenase-2, inducible nitric oxide synthase, and nuclear factor κB (NF-κB), thereby attenuating the release of proinflammatory and profibrotic cytokines, and suppressing chronic production of free radicals, which culminates in the amelioration of tissue toxicity. Through modulation of NF-κB and its downstream signaling cascade, curcumin can also reduce angiogenesis, tumor growth, and metastasis. Low toxicity of curcumin is linked to its cytoprotective effects in normal tissues. This protective action along with the capacity of this phytochemical to sensitize tumor cells to radiotherapy and chemotherapy makes it a potential candidate for use as an adjuvant in cancer therapy. There is also evidence from clinical trials suggesting the potential utility of curcumin for acute inflammatory reactions during radiotherapy such as dermatitis and mucositis.

Prevention from radiation damage by natural products

BACKGROUND

Radiotherapy is a mainstay of cancer treatment since decades. Ionizing radiation (IR) is used for destruction of cancer cells and shrinkage of tumors. However, the increase of radioresistance in cancer cells and radiation toxicity to normal tissues are severe concerns. The exposure to radiation generates intracellular reactive oxygen species (ROS), which leads to DNA damage by lipid peroxidation, removal of thiol groups from cellular and membrane proteins, strand breaks and base alterations.

HYPOTHESIS

Plants have to deal with radiation-induced damage (UV-light of sun, other natural radiation sources). Therefore, it is worth speculating that radioprotective mechanisms have evolved during evolution of life. We hypothesize that natural products from plants may also protect from radiation damage caused as adverse side effects of cancer radiotherapy.

METHODS

The basis of this systematic review, we searched the relevant literature in the PubMed database.

RESULTS

Flavonoids, such as genistein, epigallocatechin-3-gallate, epicatechin, apigenin and silibinin mainly act as antioxidant, free radical scavenging and anti-inflammatory compounds, thus, providing cytoprotection in addition to downregulation of several pro-inflammatory cytokines. Comparable effects have been found in phenylpropanoids, especially caffeic acid phenylethylester, curcumin, thymol and zingerone. Besides, resveratrol and quercetin are the most important cytoprotective polyphenols. Their radioprotective effects are mediated by a wide range of mechanisms mainly leading to direct or indirect reduction of cellular stress. Ascorbic acid is broadly used as antioxidant, but it has also shown activity in reducing cellular damage after irradiation mainly due to its antioxidant capabilities. The metal ion chelator, gallic acid, represents another natural product attenuating cellular damage caused by radiation.

CONCLUSIONS

Some secondary metabolites from plants reveal radioprotective features against cellular damage caused by irradiation. These results warrant further analysis to develop phytochemicals as radioprotectors for clinical use.

Cucurmin, anticancer, & antitumor perspectives: A comprehensive review

Cucurmin, a naturally yellow component isolated from turmeric, ability to prevent various life-style related disorders. The current review article mainly emphasizes on different anticancer perspectives of cucurmin, i.e., colon, cervical, uterine, ovarian, prostate head and neck, breast, pulmonary, stomach and gastric, pancreatic, bladder oral, oesophageal, and bone cancer. It holds a mixture of strong bioactive molecule known as cucurminoids that has ability to reduce cancer/tumor at initial, promotion and progression stages of tumor development. In particular, these compounds block several enzymes required for the growth of tumors and may therefore involve in tumor treatments. Moreover, it modulates an array of cellular progressions, i.e., nitric oxide synthetase activity, protein kinase C activity, epidermal growth factor (EGF) receptor intrinsic kinase activity, nuclear factor kappa (NF-kB) activity, inhibiting lipid peroxidation and production of reactive oxygen species. However, current manuscript summarizes most of the recent investigations of cucurmin but still further research should be conducted to explore the role of curcumin to mitigate various cancers.

Structure, chaperone-like activity and allergenicity profile of bovine caseins upon peroxynitrite modification: New evidences underlying mastitis pathomechanisms

Mastitis, an inflammatory reaction frequently develops in response to intra-mammary bacterial infection‌‌, may induce the generation of peroxynitrite (PON)‌ which is a highly potent reactive oxygen and nitrogen species. Caseins as the intrinsically unfolded proteins seem feasible substrates to react with PON. Therefore, in the current study, structural and functional aspects of both β-casein (β-CN) and whole casein fraction (WCF) were evaluated after PON modification, using a variety of techniques. Modification of the bovine caseins with PON results in an important enhancement in the carbonyl, nitrotryptophan, nitrotyrosine and dityrosine content of these proteins‌. The results of fluorescence and far UV-CD assessments suggested significant structural alteration of caseins upon PON-modification. The chaperone-like activity of β-casein was significantly altered after PON modification. The results of scanning electron microscopy suggest that bovine caseins display unique morphological features after treatment with PON. Also, the PON-modified caseins preserved their allergenicity profile and displayed partial resistance against digestion by the pancreatic proteases. Ascorbic acid, an important antioxidant component of milk, was also capable to significantly prevent the PON-induced structural damages in bovine milk caseins. In conclusion, our results suggest that PON may have significant role in the structural and functional alteration of milk caseins. Also, the PON-induced structural damaging effects of caseins might be effectively prevented by a sufficient level of milk antioxidant components particularly by ascorbic acid.

Curcumin: the spicy modulator of breast carcinogenesis

Worldwide breast cancer is the most common cancer in women. For many years clinicians and the researchers are examining and exploring various therapeutic modalities for breast cancer. Yet the disease has remained unconquered and the quest for cure is still going on. Present-day strategy of breast cancer therapy and prevention is either combination of a number of drugs or a drug that modulates multiple targets. In this regard natural products are now becoming significant options. Curcumin exemplifies a promising natural anticancer agent for this purpose. This review primarily underscores the modulatory effect of curcumin on the cancer hallmarks. The focus is its anticancer effect in the complex pathways of breast carcinogenesis. Curcumin modulates breast carcinogenesis through its effect on cell cycle and proliferation, apoptosis, senescence, cancer spread and angiogenesis. Largely the NFkB, PI3K/Akt/mTOR, MAPK and JAK/STAT are the key signaling pathways involved. The review also highlights the curcumin mediated modulation of tumor microenvironment, cancer immunity, breast cancer stem cells and cancer related miRNAs. Using curcumin as a therapeutic and preventive agent in breast cancer is perplexed by its diverse biological activity, much of which remains inexplicable. The information reviewed here should point toward potential scope of future curcumin research in breast cancer.

Curcumin represses the activity of inhibitor-κB kinase in dextran sulfate sodium-induced colitis by S-nitrosylation

In this study, we investigated the preventive effects of curcumin using dextran sulfate sodium (DSS)-induced colitis and the potential role of curcumin in regulation of anti-inflammation through S-nitrosylation. After curcumin treatment for 6days, the body weight and disease activity index of DSS-induced mice was alleviated and the colonic length was also rescued. Western blot presented that the protein expression of iNOS can be reduced by curcumin. Consistently, mRNA level of iNOS and pro-inflammatory cytokines, such as TNFα, IL-1β, and IL-6, was also repressed. Moreover, Curcumin reduced the amount of nitrite in DSS-induced colitis but not affected total S-nitrosylation level on proteins on day 6, indicating that curcumin inhibited NO oxidation. Furthermore, the protection of S-nitrosylation on IKKβ in DSS-induced colitis for 6days by curcumin caused the repression of IκB phosphorylation and NF-κB activation. In conclusion, this study verified that curcumin-mediated S-nitrosylation may be as an important regulator for anti-inflammation in DSS-induced colitis of mice.

Anticataractogenic effect of hesperidin in galactose-induced cataractogenesis in Wistar rats

AIM: To explore the anticataractogenic potential of hesperidin, a flavanone, in galactose-induced cataractogenesis.

METHODS: In this study, cataract was induced by administering galactose enriched food in a set of rats. Effect of different dosages of hesperidin (25, 50 and 75 mg/kg body weight) were administered simultaneously with galactose in prevention of cataract was determined in another set. In both sets of animals, the levels of peroxidation, oxidants (NO and OH), antioxidants (enzymatic: Superoxide dismutase, catalase, glutathione S-transferase, GPx and non-enzymatic: Reduced glutathione, vitamin E), aldose reductase and sorbitol were determined in the eye lens. In addition, glucose and lipid peroxidation levels were also tested in serum. The quantitative changes in lens inducible nitric oxide synthase (iNOS) and its expression were also determined using Western blot and real-time polymerase chain reaction analyses.

RESULTS: Galactose enriched food produced cataract in both the eye lens as a sequel to elevated serum glucose. Simultaneous administration of hesperidin not only reduced serum glucose but also prevented cataract development, through reduced levels of reactive oxygen species (NO and OH) and iNOS expression as well as elevated enzymic and non-enzymic antioxidants were observed in the eye lens.

CONCLUSION: These results indicate the preventive effect of hesperidin against cataract in hyperglycemic rats.

Fluorination Effects on NOS Inhibitory Activity of Pyrazoles Related to Curcumin

A series of new (E)-3(5)-[β-(aryl)-ethenyl]-5(3)-phenyl-1H-pyrazoles bearing fluorine atoms at different positions of the aryl group have been synthesized starting from the corresponding β-diketones. All compounds have been characterized by elemental analysis, DSC as well as NMR (¹H, ¹³C, ¹⁹F and ¹⁵N) spectroscopy in solution and in solid state. Three structures have been solved by X-ray diffraction analysis, confirming the tautomeric forms detected by solid state NMR. The in vitro study of their inhibitory potency and selectivity on the activity of nNOS and eNOS (calcium-calmodulin dependent) as well as iNOS (calcium-calmodulin independent) isoenzymes is presented. A qualitative structure–activity analysis allowed the establishment of a correlation between the presence/absence of different substituents with the inhibition data proving that fluorine groups enhance the biological activity. (E)-3(5)-[β-(3-Fluoro-4-hydroxyphenyl)-ethenyl]-5(3)-phenyl-1H-pyrazole (13), is the best inhibitor of iNOS, being also more selective towards the other two isoforms.

Evolution of availability of curcumin inside poly-lactic-co-glycolic acid nanoparticles: impact on antioxidant and antinitrosant properties

Purpose

Curcumin exhibits antioxidant properties potentially beneficial for human health; however, its use in clinical applications is limited by its poor solubility and relative instability. Nanoparticles exhibit interesting features for the efficient distribution and delivery of curcumin into cells, and could also increase curcumin stability in biological systems. There is a paucity of information regarding the evolution of the antioxidant properties of nanoparticle-encapsulated curcumin.

Method

We described a simple method of curcumin encapsulation in poly-lactic-co-glycolic acid (PLGA) nanoparticles without the use of detergent. We assessed, in epithelial cells and in an acellular model, the evolution of direct antioxidant and antinitrosant properties of free versus PLGA-encapsulated curcumin after storage under different conditions (light vs darkness, 4°C vs 25°C vs 37°C).

Results

In epithelial cells, endocytosis and efflux pump inhibitors showed that the increased antioxidant activity of PLGA-encapsulated curcumin relied on bypassing the efflux pump system. Acellular assays showed that the antioxidant effect of curcumin was greater when loaded in PLGA nanoparticles. Furthermore, we observed that light decreased, though heat restored, antioxidant activity of PLGA-encapsulated curcumin, probably by modulating the accessibility of curcumin to reactive oxygen species, an observation supported by results from quenching experiments. Moreover, we demonstrated a direct antinitrosant activity of curcumin, enhanced by PLGA encapsulation, which was increased by light exposure.

Conclusion

These results suggest that the antioxidant and antinitrosant activities of encapsulated curcumin are light sensitive and that nanoparticle modifications over time and with temperature may facilitate curcumin contact with reactive oxygen species. These results highlight the importance of understanding effects of nanoparticle maturation on an encapsulated drug’s activity.

The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

Curcumin, an active component of turmeric in the prevention and treatment of ulcerative colitis: preclinical and clinical observations

Inflammatory bowel disease (IBD) comprising of ulcerative colitis (UC) and Crohn's disease (CD) is a major ailment affecting the small and large bowel. In clinics, IBD is treated using 5-amninosalicylates, antibiotics, the steroids and immunomodulators. Unfortunately, the long term usages of these agents are associated with undue side effects and compromise the therapeutic advantage. Accordingly, there is a need for novel agents that are effective, acceptable and non toxic to humans. Preclinical studies in experimental animals have shown that curcumin, an active principle of the Indian spice turmeric (Curcuma longa Linn) is effective in preventing or ameliorating UC and inflammation. Over the last few decades there has been increasing interest in the possible role of curcumin in IBD and several studies with various experimental models of IBD have shown it to be effective in mediating the inhibitory effects by scavenging free radicals, increasing antioxidants, influencing multiple signaling pathways, especially the kinases (MAPK, ERK), inhibiting myeloperoxidase, COX-1, COX-2, LOX, TNF-α, IFN-γ, iNOS; inhibiting the transcription factor NF-κB. Clinical studies have also shown that co-administration of curcumin with conventional drugs was effective, to be well-tolerated and treated as a safe medication for maintaining remission, to prevent relapse and improve clinical activity index. Large randomized controlled clinical investigations are required to fully understand the potential of oral curcumin for treating IBD.

Curcuminoid analogs inhibit nitric oxide production from LPS-activated microglial cells

The chemically modified analogs, the demethylated analogs 4-6, the tetrahydro analogs 7-9 and the hexahydro analogs 10-12, of curcumin (1), demethoxycurcumin (2) and bisdemethoxycurcumin (3) were evaluated for their inhibitory activity on lipopolysaccharide activated nitric oxide (NO) production in HAPI microglial cells. Di-O-demethylcurcumin (5) and O-demethyldemethoxycurcumin (6) are the two most potent compounds that inhibited NO production. The analogs 5 and 6 were twofold and almost twofold more active than the parent curcuminoids 1 and 2, respectively. Moreover, the mRNA expression level of inducible NO synthase was inhibited by these two compounds. The strong neuroprotective activity of analogs 5 and 6 provide potential alternative compounds to be developed as therapeutics for neurological disorders associated with activated microglia.

Antioxidant Pathways and Chemical Mechanism of Curcumin

Curcumin, a hydrophobic polyphenol derived from rhizome (turmeric) of the herbCurcuma longa, have been shown to exhibit antioxidant, anticarcinogenic anti-inflammatory, antimicrobial and nephroprotective activities,et al. Among these, its potent antioxidant activity is worthwhile of special attention, because oxidative stress is involved in the pathogenesis of cancer, neurodegenerative diseases,et al. This review focuses on the ways that curcumin exerts its antioxidant activity, including direct chemical reaction with free radicals, chelation with metals ions which results in oxidative stress, regulation of antioxidant-related enzyme activity and gene expression. Meanwhile the disputed chemical antioxidant mechanism is also discussed.

NO to breast: when, why and why not?

Nitric oxide is a pleiotropic ancestral molecule, which elicits beneficial effect in many physiological settings but is also tenaciously expressed in numerous pathological conditions, particularly breast tumors. Nitric oxide is particularly harmful in adipogenic milieu of the breast, where it initiates and promotes tumorigenesis. Epidemiological studies have associated populations at a greater risk for developing breast cancer, predominantly estrogen receptor positive tumors, to express specific polymorphic forms of endothelial nitric oxide synthase, that produce sustained low levels of nitric oxide. Low sustained nitric oxide generates oxidative stress and inflammatory conditions at susceptible sites in the heterogeneous microenvironment of the breast, where it promotes cancer related events in specific cell types. Inflammatory conditions also stimulate inducible nitric oxide synthase expression, which dependent on the microenvironment, could promote or inhibit mammary tumors. In this review we re-examine the mechanisms by which nitric oxide promotes initiation and progression of breast cancer and address some of the controversies in the field.

Curcumin supplementation protects from genotoxic effects of arsenic and fluoride

The present study was aimed to evaluate curcumin as a potential natural antioxidant to mitigate the genotoxic effects of arsenic (As) and fluoride (F) in human peripheral blood lymphocytes. The study was divided into nine groups consisting of negative control, positive control treated with ethyl methane sulphonate (EMS; 1.93 mM) and curcumin control with only curcumin (1.7 microM) in blood culture. As (1.4 microM) and F (34 microM) were added alone as well as in combination, to the cultures, with and without curcumin. Cultures were analysed for chromosomal aberrations (both structural and numerical) and primary DNA damage via comet assay as the genotoxic parameters after an exposure duration of 24h. Results revealed that curcumin efficiently ameliorates the toxic effect of As and F by reducing the frequency of structural aberrations (>60%), hypoploidy (>50%) and primary DNA damage. In conclusion, curcumin mitigates the genotoxic effects of the two well known water contaminants (As and F) effectively and efficiently at the given concentration in vitro.

Targeting specific cell signaling transduction pathways by dietary and medicinal phytochemicals in cancer chemoprevention

Natural phytochemicals derived from dietary sources or medicinal plants have gained significant recognition in the potential management of several human clinical conditions. Much research has also been geared towards the evaluation of plant extracts as effective prophylactic agents since they can act on specific and/or multiple molecular and cellular targets. Plants have been an abundant source of highly effective phytochemicals which offer great potential in the fight against cancer by inhibiting the process of carcinogenesis through the upregulation of cytoprotective genes that encode for carcinogen detoxifying enzymes and antioxidant enzymes. The mechanistic insight into chemoprevention further includes induction of cell cycle arrest and apoptosis or inhibition of signal transduction pathways mainly the mitogen-activated protein kinases (MAPK), protein kinases C (PKC), phosphoinositide 3-kinase (PI3K), glycogen synthase kinase (GSK) which lead to abnormal cyclooxygenase-2 (COX-2), activator protein-1 (AP-1), nuclear factor-kappaB (NF-κB) and c-myc expression. Effectiveness of chemopreventive agents reflects their ability to counteract certain upstream signals that leads to genotoxic damage, redox imbalances and other forms of cellular stress. Targeting malfunctioning molecules along the disrupted signal transduction pathway in cancer represent a rational strategy in chemoprevention. NF-κB and AP-1 provide mechanistic links between inflammation and cancer, and moreover regulate tumor angiogenesis and invasiveness, indicating that signaling pathways that mediate their activation provide attractive targets for new chemotherapeutic approaches. Thus cell signaling cascades and their interacting factors have become important targets of chemoprevention and phenolic phytochemicals and plant extracts seem to be promising in this endeavor.

Anti-cataractogenic effect of curcumin and aminoguanidine against selenium-induced oxidative stress in the eye lens of Wistar rat pups: An in vitro study using isolated lens

The aim of this study was to investigate whether curcumin and aminoguanidine (AG) prevent selenium-induced cataractogenesis in vitro. On postpartum day 8, transparent isolated lens were incubated in 24 well plates containing Dulbecco's Modified Eagle Medium (DMEM). Isolated lens of group I were incubated with DMEM medium alone. Group II: lenses incubated in DMEM containing 100microM sodium selenite; group III: lenses incubated in DMEM containing 100microM sodium selenite and 100microM curcumin; group IV: lenses incubated in DMEM containing 100microM sodium selenite and 200microM curcumin; group V: lenses incubated in DMEM containing 100microM sodium selenite and 100microM AG; group V: lenses incubated in DMEM containing 100microM sodium selenite and 200microM AG. On day 12, cataract development was graded using an inverted microscope and the lenses were analyzed for enzymic as well as non-enzymic antioxidants, lipid peroxidation (LPO), nitric oxide (NO), superoxide anion (O(2)(-)) and hydroxyl radical generation (OH) and inducible nitric oxide synthase (iNOS) activity by Western blotting and RT-PCR. All control lenses in group I were clear (0). In groups II and III, all isolated lenses developed cataract with variation in levels (+++ or ++), whereas isolated lenses from groups IV, V and VI were clear (0). In agreement to this, a decrease in antioxidants and increased free radical generation and also iNOS expression were observed in selenium exposed lenses when compared to other groups. AG (100microM) was found to be more effective in anti-cataractogenic effect than curcumin (200microM). Curcumin and AG suppressed selenium-induced oxidative stress and cataract formation in isolated lens from Wistar rat pups, possibly by inhibiting depletion of enzymic as well as non-enzymic antioxidants, and preventing uncontrolled generation of free radicals and also by inhibiting iNOS expression. Our results implicate a major role for curcumin and AG in preventing cataractogenesis in selenite-exposed lenses, wherein AG was found to be more potent.

Role of curcumin in health and disease

Curcumin (diferuloylmethane) is an orange-yellow component of turmeric (Curcuma longa), a spice often found in curry powder. In recent years, considerable interest has been focused on curcumin due to its use to treat a wide variety of disorders without any side effects. It is one of the major curcuminoids of turmeric, which impart its characteristic yellow colour. It was used in ancient times on the Indian subcontinent to treat various illnesses such as rheumatism, body ache, skin diseases, intestinal worms, diarrhoea, intermittent fevers, hepatic disorders, biliousness, urinary discharges, dyspepsia, inflammations, constipation, leukoderma, amenorrhea, and colic. Curcumin has the potential to treat a wide variety of inflammatory diseases including cancer, diabetes, cardiovascular diseases, arthritis, Alzheimer's disease, psoriasis, etc, through modulation of numerous molecular targets. This article reviews the use of curcumin for the chemoprevention and treatment of various diseases.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Effect of insulin and its combination with resveratrol or curcumin in attenuation of diabetic neuropathic pain: participation of nitric oxide and TNF-alpha

Diabetic neuropathic pain, an important microvascular complication in diabetes mellitus, is recognized as one of the most difficult types of pain to treat. The underlying mechanisms of painful symptoms may be closely associated with hyperglycaemia but a lack of the understanding of its proper aetiology, inadequate relief, development of tolerance and potential toxicity of classical antinociceptives warrant the investigation of newer agents to relieve this pain. The aim of the present study was to explore the antinociceptive effect of insulin and its combinations with resveratrol and curcumin in attenuating diabetic neuropathic pain. The study also aimed to examine the effect of these combinations on tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) levels in streptozotocin (STZ) induced diabetic mice. Four weeks after a single intraperitoneal injection of streptozotocin (200 mg/kg), mice were tested in the tail immersion and hot-plate assays. Diabetic mice exhibited significant hyperalgesia along with increased plasma glucose and decreased body weights compared with control mice. Chronic treatment with insulin (10 IU/kg/day, s.c.) and its combinations with antioxidants (resveratrol 20 mg/kg or curcumin 60 mg/kg, p.o.) for 4 weeks starting from the 4th week of STZ injection significantly attenuated thermal hyperalgesia and the hot-plate latencies. There was a significant inhibition of TNF-alpha and NO levels when these drugs were given in combination compared with their effects per se. These results indicate an antinociceptive activity of resveratrol and curcumin and point towards the beneficial effect of these combinations with insulin in attenuating diabetic neuropathic pain, possibly through the participation of NO and TNF-alpha.

Curcumin reverses breast tumor exosomes mediated immune suppression of NK cell tumor cytotoxicity

An important characteristic of tumors is that they at some point in their development overcome the surveillance of the immune system. Tumors secrete exosomes, multivesicular bodies containing a distinct set of proteins that can fuse with cells of the circulating immune system. Purified exosomes from TS/A breast cancer cells, but not non-exosomal fractions, inhibit (at concentrations of nanograms per ml protein) IL-2-induced natural killer (NK) cell cytotoxicity. The dietary polyphenol, curcumin (diferuloylmethane), partially reverses tumor exosome-mediated inhibition of natural killer cell activation, which is mediated through the impairment of the ubiquitin-proteasome system. Exposure of mouse breast tumor cells to curcumin causes a dose-dependent increase in ubiquitinated exosomal proteins compared to those in untreated TS/A breast tumor cells. Furthermore, exosomes isolated from tumor cells pretreated with curcumin have a much attenuated inhibition of IL-2 stimulated NK cell activation. Jak3-mediated activation of Stat5 is required for tumor cytotoxicity of IL-2 stimulated NK cells. TS/A tumor exosomes strongly inhibit activation of Stat5, whereas the tumor exosomes isolated from curcumin-pretreated tumor cells have a lowered potency for inhibition of IL-2 stimulated NK cell cytotoxicity. These data suggest that partial reversal of tumor exosome-mediated inhibition of NK cell tumor cytotoxicity may account for the anti-cancer properties of curcumin.

Polyphenols and cancer cell growth

Polyphenols constitute an important group of phytochemicals that gained increased research attention since it was found that they could affect cancer cell growth. Initial evidence came from epidemiologic studies suggesting that a diet that includes regular consumption of fruits and vegetables (rich in polyphenols) significantly reduces the risk of many cancers. In the present work we briefly review the effects of polyphenols on cancer cell fate, leading towards growth, differentiation and apoptosis. Their action can be attributed not only to their ability to act as antioxidants but also to their ability to interact with basic cellular mechanisms. Such interactions include interference with membrane and intracellular receptors, modulation of signaling cascades, interaction with the basic enzymes involved in tumor promotion and metastasis, interaction with oncogenes and oncoproteins, and, finally, direct or indirect interactions with nucleic acids and nucleoproteins. These actions involve almost the whole spectrum of basic cellular machinery--from the cell membrane to signaling cytoplasmic molecules and to the major nuclear components--and provide insights into their beneficial health effects. In addition, the actions justify the scientific interest in this class of compounds, and provide clues about their possible pharmaceutical exploitation in the field of oncology.

Inhibitory effect of curcumin on nitric oxide production from lipopolysaccharide-activated primary microglia

Curcumin has been shown to exhibit anti-inflammatory, antimutagenic, and anticarcinogenic activities. However, the modulatory effect of curcumin on the functional activation of primary microglial cells, brain mononuclear phagocytes causing the neuronal damage, largely remains unknown. The current study examined whether curcumin influenced NO production in rat primary microglia and investigated its underlying signaling pathways. Curcumin decreased NO production in LPS-stimulated microglial cells in a dose-dependent manner, with an IC(50) value of 3.7 microM. It also suppressed both mRNA and protein levels of inducible nitric oxide synthase (iNOS), indicating that this drug may affect iNOS gene expression process. Indeed, curcumin altered biochemical patterns induced by LPS such as phosphorylation of all mitogen-activated protein kinases (MAPKs), and DNA binding activities of nuclear factor-kappaB (NF-kappaB) and activator protein (AP)-1, assessed by reporter gene assay. By analysis of inhibitory features of specific MAPK inhibitors, a series of signaling cascades including c-Jun N-terminal kinase (JNK), p38 and NF-kappaB was found to play a critical role in curcumin-mediated NO inhibition in microglial cells. The current results suggest that curcumin is a promising agent for the prevention and treatment of both NO and microglial cell-mediated neurodegenerative disorders.

Comparison of Anti-inflammatory Activities of Six Curcuma Rhizomes: A Possible Curcuminoid-independent Pathway Mediated by Curcuma phaeocaulis Extract

We aimed to compare the anti-inflammatory activities of six species of Curcuma drugs using adjuvant arthritis model mice. When orally administered 1 day before the injection of adjuvant, the methanol extract of Curcuma phaeocaulis significantly inhibited paw swelling and the serum haptoglobin concentration in adjuvant arthritis mice. Also when orally administered 1 day after the injection of adjuvant, the methanol extract of Curcuma phaeocaulis significantly inhibited paw swelling. Other Curcuma species (Curcuma longa, Curcuma wenyujin, Curcuma kwangsiensis, Curcuma zedoaria and Curcuma aromatica) had no significant inhibitory effects on adjuvant-induced paw swelling. Cyclooxygenase (COX)-2 activity was significantly inhibited by the methanol extract of C. phaeocaulis. Curcuminoids' (curcumin, bis-demethoxycurcumin and demethoxycurcumin) were rich in C. longa, but less in C. phaeocaulis and C. aromatica, not in C. wenyujin, C. kwangsiensis and C. zedoaria, suggesting that curcuminoids' contents do not relate to inhibition of arthritis swelling. Therefore, C. phaeocaulis may be a useful drug among Curcuma species for acute inflammation, and the active constituents of C. phaeocaulis are not curcuminoids.

Curcumin attenuates thermal hyperalgesia in a diabetic mouse model of neuropathic pain

Diabetic neuropathic pain, an important microvascular complication in diabetes mellitus is recognised as one of the most difficult types of pain to treat. A lack of the understanding of its aetiology, inadequate relief, development of tolerance and potential toxicity of classical antinociceptives warrant the investigation of the newer agents to relieve this pain. The aim of the present study was to explore the antinociceptive effect of curcumin and its effect on tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) release in streptozotocin induced diabetic mice. Four weeks after a single intraperitoneal injection of streptozotocin (200 mg/kg), mice were tested in the tail immersion and hot-plate assays. Diabetic mice exhibited significant hyperalgesia along with increased plasma glucose and decreased body weights as compared with control mice. Chronic treatment with curcumin (15, 30 and 60 mg/kg body weight; p.o.) for 4 weeks starting from the 4th week of streptozotocin injection significantly attenuated thermal hyperalgesia and the hot-plate latencies. Curcumin also inhibited the TNF-alpha and NO release in a dose dependent manner. These results indicate an antinociceptive activity of curcumin possibly through its inhibitory action on NO and TNF-alpha release and point towards its potential to attenuate diabetic neuropathic pain.

Molecular targets of dietary agents for prevention and therapy of cancer

While fruits and vegetables are recommended for prevention of cancer and other diseases, their active ingredients (at the molecular level) and their mechanisms of action less well understood. Extensive research during the last half century has identified various molecular targets that can potentially be used not only for the prevention of cancer but also for treatment. However, lack of success with targeted monotherapy resulting from bypass mechanisms has forced researchers to employ either combination therapy or agents that interfere with multiple cell-signaling pathways. In this review, we present evidence that numerous agents identified from fruits and vegetables can interfere with several cell-signaling pathways. The agents include curcumin (turmeric), resveratrol (red grapes, peanuts and berries), genistein (soybean), diallyl sulfide (allium), S-allyl cysteine (allium), allicin (garlic), lycopene (tomato), capsaicin (red chilli), diosgenin (fenugreek), 6-gingerol (ginger), ellagic acid (pomegranate), ursolic acid (apple, pears, prunes), silymarin (milk thistle), anethol (anise, camphor, and fennel), catechins (green tea), eugenol (cloves), indole-3-carbinol (cruciferous vegetables), limonene (citrus fruits), beta carotene (carrots), and dietary fiber. For instance, the cell-signaling pathways inhibited by curcumin alone include NF-kappaB, AP-1, STAT3, Akt, Bcl-2, Bcl-X(L), caspases, PARP, IKK, EGFR, HER2, JNK, MAPK, COX2, and 5-LOX. The active principle identified in fruit and vegetables and the molecular targets modulated may be the basis for how these dietary agents not only prevent but also treat cancer and other diseases. This work reaffirms what Hippocrates said 25 centuries ago, let food be thy medicine and medicine be thy food.

Curcumin inhibits cell motility and alters microfilament organization and function in prostate cancer cells

Curcumin is a dietary phytochemical associated with anti-tumorigenic effects, but the mechanisms by which it inhibits cancer cell growth and metastasis are not completely understood. For example, little information is available regarding the effects of curcumin on cytoskeletal organization and function. In this study, time-lapse video and immunofluorescence labeling methods were used to demonstrate that curcumin significantly alters microfilament organization and cell motility in PC-3 and LNCaP human prostate cancer cells in vitro. Curcumin rapidly arrests cell movements and subsequently alters cell shape in the highly motile PC-3 cell line, but has a less noticeable effect on the relatively immobile LNCaP cell line. Stress fibers are augmented, and the overall quantity of f-actin appears to increase in both types of cells following curcumin treatment. Cytochalasin B (CB) disrupts microfilament organization in both cell lines, and causes vigorous membrane blebbing in PC-3 cells, but not LNCaP cells. Pre-treatment of cells with curcumin suppresses changes in microfilament organization caused by CB, and blocks PC-3 membrane blebbing. At least some of the effects of curcumin appear to be mediated by protein kinase C (PKC), as treatment with the PKC inhibitor bisindolylmaleimide inhibits the ability of curcumin to block CB-induced membrane blebbing. These findings demonstrate that curcumin exerts significant effects on the actin cytoskeleton in prostate cancer cells, including altering microfilament organization and function. This is a novel observation that may represent an important mechanism by which curcumin functions as a chemopreventative agent, and as an inhibitor of angiogenesis and metastasis.

Nitric oxide produced by inducible nitric oxide synthase is associated with mammary tumorigenesis in irradiated rats

This study evaluated whether nitric oxide (NO) derived from nitric oxide synthase (NOS) induced by radiation is associated with tumorigenesis in the mammary glands. When rats were exposed to whole-body irradiation with gamma-rays (1.5 Gy) immediately after weaning and then treated with diethylstilbestrol, as an irradiated control, the tumor incidence (85%) was increased 7.6-fold in comparison with that (11.1%) of the non-irradiated control. The tumor incidence declined to 28.6% in the rats injected intraperitoneally with phenyl-N-tert-butylnitrone (PBN, 160 mg/kg), an inhibitor of inducible NOS (iNOS) expression and also a spin trapping agent, 30 min before irradiation. Also, the tumor incidence (25%) in rats orally administered with N-(3-(aminomethyl)-benzyl)-acetamide (1400W, 2.3+/-0.1 mg/day), a highly selective inhibitor of iNOS, dissolved in drinking water for 3 days after the irradiation was less than one-third of that in the irradiated control. On treatment with PBN or 1400W, no adenocarcinoma developed. Many of the mammary tumors that developed in the irradiated rats were positive for the estrogen receptor (ER). In contrast, ER was not detected in the tumors yielded from irradiated rats administered with PBN or 1400W. These results indicate that iNOS-derived NO may participate in the formation of estrogen-dependent mammary adenocarcinomas following radiation.

Reactions of superoxide radicals with curcumin: probable mechanisms by optical spectroscopy and EPR

Reactions of superoxide-crown ether complex with curcumin have been studied in acetonitrile. Optical absorption spectra showed that curcumin on reaction with superoxide forms a blue color intermediate absorbing at 560 nm, which subsequently decayed in a few hours with the development of the absorption band corresponding to the parent curcumin. The regeneration was 100% at low superoxide concentrations (1:1, or 1:2 or 1:3 of curcumin:superoxide) but reduced to 60% at high superoxide concentration (>1:5). The regeneration of curcumin is confirmed by HPLC analysis. Stopped-flow studies in acetonitrile following either the decay of parent curcumin at 420 nm or formation of 560 nm absorption have been used to determine the rate constant for the reaction of superoxide with curcumin. EPR studies confirmed the disappearance of characteristic superoxide signal in presence of curcumin with the formation of new featureless signal with g = 2.0067. Based on these studies it is concluded that at low superoxide concentrations curcumin effectively causes superoxide dismutation without itself undergoing any chemical change. At higher concentrations of superoxide, curcumin inhibits superoxide activity by reacting with it.

Role of phenolic O-H and methylene hydrogen on the free radical reactions and antioxidant activity of curcumin

To understand the relative importance of phenolic O-H and the CH-H hydrogen on the antioxidant activity and the free radical reactions of Curcumin, (1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione), biochemical, physicochemical, and density functional theory (DFT) studies were carried out with curcumin and dimethoxy curcumin (1,7-bis[3, 4-dimethoxy phenyl]-1,6-heptadiene-3,5-dione). The antioxidant activity of these compounds was tested by following radiation-induced lipid peroxidation in rat liver microsomes, and the results suggested that at equal concentration, the efficiency to inhibit lipid peroxidation is changed from 82% with curcumin to 24% with dimethoxy curcumin. Kinetics of reaction of (2,2'-diphenyl-1-picrylhydrazyl) DPPH, a stable hydrogen abstracting free radical was tested with these two compounds using stopped-flow spectrometer and steady state spectrophotometer. The bimolecular rate constant for curcumin was found to be approximately 1800 times greater than that for the dimethoxy derivative. Cyclic voltammetry studies of these two systems indicated two closely lying oxidation peaks at 0.84 and 1.0 V vs. SCE for curcumin, while only one peak at 1.0 V vs. SCE was observed for dimethoxy curcumin. Pulse radiolysis induced one-electron oxidation of curcumin and dimethoxy curcumin was studied at neutral pH using (*)N(3) radicals. This reaction with curcumin produced phenoxyl radicals absorbing at 500 nm, while in the case of dimethoxy curcumin a very weak signal in the UV region was observed. These results suggest that, although the energetics to remove hydrogen from both phenolic OH and the CH(2) group of the beta-diketo structure are very close, the phenolic OH is essential for both antioxidant activity and free radical kinetics. This is further confirmed by DFT calculations where it is shown that the -OH hydrogen is more labile for abstraction compared to the -CH(2) hydrogen in curcumin. Based on various experimental and theoretical results it is definitely concluded that the phenolic OH plays a major role in the activity of curcumin.

Curcumin attenuates allergen-induced airway hyperresponsiveness in sensitized guinea pigs

Anti-asthmatic property of curcumin (diferuloylmethane), a natural product from the rhizomes of Curcuma longa, has been tested in a guinea pig model of airway hyperresponsiveness. We sensitized guinea pigs with ovalbumin (OVA) to develop certain characteristic features of asthma: allergen induced airway constriction and airway hyperreactivity to histamine. Guinea pigs were treated with curcumin during sensitization (to examine its preventive effect) or after developing impaired airways features (to examine its therapeutic effect). Status of airway constriction and airway hyperreactivity were determined by measuring specific airway conductance (SGaw) using a non-invasive technique, constant-volume body plethysmography. Curcumin (20 mg/kg body weight) treatment significantly inhibits OVA-induced airway constriction (p<0.0399) and airway hyperreactivity (p<0.0043). The results demonstrate that curcumin is effective in improving the impaired airways features in the OVA-sensitized guinea pigs.

Suppression of nitric oxide oxidation to nitrite by curcumin is due to the sequestration of the reaction intermediate nitrogen dioxide, not nitric oxide

Curcumin, a phytochemical with antioxidant and other cytoprotective properties, has been reported to reduce nitrite formation during nitric oxide (NO) oxidation in solution. This decrease in nitrite production was attributed to the direct sequestration of NO by curcumin. In this report, we confirm that curcumin inhibits nitrite formation from DEA/NO-derived NO in a concentration-dependent manner. However, curcumin over a concentration range of 3-50 microM had no effect on the concentration of free NO (0.5 microM) in solution at 37 degrees C as assessed using an NO electrode. We conclude that the inhibitory effect of curcumin on the oxidation of NO to nitrite is due to its known sequestration of the reaction intermediate nitrogen dioxide (NO(2)). The ability of curcumin to sequester NO(2), but not NO, suggests that curcumin may be useful for separating the actions of NO(2) from those of NO in various biological systems.

Role of nitric oxide in radiation-induced initiation of mammary tumorigenesis in rats

Nitric oxide (NO) and its reaction products have been shown to cause DNA damage and to be mutagenic. To elucidate whether NO produced by irradiation participates in the initiation of mammary tumorigenesis, we performed experiments using the nitric oxide-specific scavenger Fe(2+)-diethyldithiocarbamate complex (Fe(DETC)(2)) or a selective inhibitor for inducible nitric oxide synthase (iNOS), S,S(')-(4-phenylene-bis(1,2-ethanedinyl))bis-isothiourea (1,4-PB-ITU). Mother rats at day 21 of lactation were injected simultaneously with diethyldithiocarbamate intraperitoneally and Fe(2+)-citrate subcutaneously to form Fe(DETC)(2), in vivo, and then irradiated with 1.5Gy gamma-rays immediately after the injection. An additional injection of chemicals followed twice at 8 and 24h after the irradiation in the same manner. Both control and treated rats were then implanted with diethylstilbestrol pellets as a tumor promoter. The mammary tumor incidence in the experimental group was significantly reduced to one-fourth of that in the irradiated-alone group as the control. On the other hand, when mother rats took drinking water containing 0.005% 1,4-PB-ITU for 6 days from 3 days prior to irradiation at day 21 of lactation, a low tumor incidence in the iNOS inhibitor-treated groups was observed in the 1-year period. This report is the first to show that the NO derived from iNOS is an important radical for radiation-induced initiation of tumorigenesis of mammary glands in rats.

Chemopreventive potential of cyclic diarylheptanoids

Eleven cyclic diarylheptanoids and seven related compounds were screened as potential antitumor promoters by using the in vitro short-term 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus early antigen (EBV-EA) activation assay. In addition, the cyclic diarylheptanoid myricanone (2) was examined for antitumor initiating activity in a two-stage carcinogenesis assay of mouse skin tumors induced by peroxynitrite as an initiator and TPA as a promoter. Myricanone (2) exhibited significant antitumor-initiating effect on mouse skin. These data suggest that cyclic, as well as linear, diarylheptanoids might be valuable chemopreventors.

Radioprotective action of curcumin extracted from Curcuma longa LINN: inhibitory effect on formation of urinary 8-hydroxy-2'-deoxyguanosine, tumorigenesis, but not mortality, induced by gamma-ray irradiation

PURPOSE

We evaluated the radioprotective action of curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] extracted from Curcuma longa LINN against the acute and chronic effects and the mortality induced by exposure to radiation using female rats.

METHODS AND MATERIALS

For the assay of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine, a marker for acute effects, Wistar-MS virgin rats were fed the basal diet with exposure at 0 or 3 Gy to gamma-rays from a 60Co source as the control. Rats in the experimental groups received whole-body irradiation with 3 Gy and were fed a diet containing 1% (wt/wt) curcumin for 3 days before and/or 2 days after irradiation. The urine was collected for a 24-h period between 1 and 2 days after irradiation. Urine samples were used to determine the 8-OHdG level using an enzyme-linked immunosorbent assay and the creatinine level by a modified Jaffé reaction. For long-term effects, rats at Day 17 of pregnancy were fed a diet containing curcumin for 3 days before and/or 3 days after irradiation with 1.5 Gy, and received a pellet of diethylstilbestrol as the promoter. The rats were examined for mammary and pituitary tumors for 1 year. To determine survival, virgin rats received whole-body irradiation with 9.6 Gy and were fed a diet containing curcumin for 3 days before and/or 3 days after irradiation. After irradiation, all rats were assessed daily for survival for 30 days.

RESULTS

Acutely in virgin rats irradiated with 3 Gy, the creatinine-corrected concentration and total amount of 8-OHdG in the 24-h urine samples were higher (approximately 1.3-fold) than the corresponding values in the nonirradiated controls. Adding curcumin to the diet for 3 days before and/or 2 days after irradiation reduced the elevated 8-OHdG levels by 50-70%. The evaluation of the protective action of curcumin against the long-term effects revealed that curcumin significantly decreased the incidence of mammary and pituitary tumors. However, the experiments on survival revealed that curcumin was not effective when administered for 3 days before and/or 3 days after irradiation (9.6 Gy).

CONCLUSION

These findings demonstrate that curcumin can be used as an effective radioprotective agent to inhibit acute and chronic effects, but not mortality, after irradiation.