Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers

Effects of curcumin on bladder cancer cells and development of urothelial tumors in a rat bladder carcinogenesis model

Curcumin, a well-known dietary pigment derived from Curcuma longa, inhibited growth of several types of malignant cells both in vivo and in vitro. Its effects on cell proliferation and the induction of apoptosis in human bladder cancer cell lines and intravesical activity in a rat bladder tumor model were studied. Exposure of human bladder cancer cells to curcumin resulted in the induction of apoptotic cell death and caused cells to arrest in the G2/M phase. The anti-apoptotic Bcl-2 and Survivin protein was downregulated by the curcumin treatment together with enhancement of the Bax and p53 expression. The inhibitory activities of curcumin were stronger than those of cisplatin and could not be prevented by catalase pretreatment in T24 cells. Clonal assay indicated large-dose and short-term curcumin was lethal to bladder cancer cells. Moreover, the in vivo study revealed curcumin did induce apoptosis in situ, inhibit and slow the development of bladder cancer. These observations suggest that curcumin could prove an effective chemopreventive and chemotherapy agent for bladder cancer.

Curcumin: preventive and therapeutic properties in laboratory studies and clinical trials

Curcumin is a natural polyphenol used in ancient Asian medicine. Since the first article referring to the use of curcumin to treat human disease was published in The Lancet in 1937, >2,600 research studies using curcumin or turmeric have been published in English language journals. The mechanisms implicated in the inhibition of tumorigenesis by curcumin are diverse and appear to involve a combination of antiinflammatory, antioxidant, immunomodulatory, proapoptotic, and antiangiogenic properties via pleiotropic effects on genes and cell-signaling pathways at multiple levels. The potentially adverse sequelae of curcumin's effects on proapoptotic genes, particularly p53, represent a cause for current debate. When curcumin is combined with some cytotoxic drugs or certain other diet-derived polyphenols, synergistic effects have been demonstrated. Although curcumin's low systemic bioavailability after oral dosing may limit access of sufficient concentrations for pharmacologic effects in tissues outside the gastrointestinal tract, chemical analogues and novel delivery methods are in preclinical development to overcome this barrier. This article provides an overview of the extensive published literature on the use of curcumin as a therapy for malignant and inflammatory diseases and its potential use in the treatment of degenerative neurologic diseases, cystic fibrosis, and cardiovascular diseases. Despite the breadth of the coverage, particular emphasis is placed on the prevention and treatment of human cancers.

Black pepper and its pungent principle-piperine: a review of diverse physiological effects

Black pepper (Piper nigrum) is one of the most widely used among spices. It is valued for its distinct biting quality attributed to the alkaloid, piperine. Black pepper is used not only in human dietaries but also for a variety of other purposes such as medicinal, as a preservative, and in perfumery. Many physiological effects of black pepper, its extracts, or its major active principle, piperine, have been reported in recent decades. Dietary piperine, by favorably stimulating the digestive enzymes of pancreas, enhances the digestive capacity and significantly reduces the gastrointestinal food transit time. Piperine has been demonstrated in in vitro studies to protect against oxidative damage by inhibiting or quenching free radicals and reactive oxygen species. Black pepper or piperine treatment has also been evidenced to lower lipid peroxidation in vivo and beneficially influence cellular thiol status, antioxidant molecules and antioxidant enzymes in a number of experimental situations of oxidative stress. The most far-reaching attribute of piperine has been its inhibitory influence on enzymatic drug biotransforming reactions in the liver. It strongly inhibits hepatic and intestinal aryl hydrocarbon hydroxylase and UDP-glucuronyl transferase. Piperine has been documented to enhance the bioavailability of a number of therapeutic drugs as well as phytochemicals by this very property. Piperine's bioavailability enhancing property is also partly attributed to increased absorption as a result of its effect on the ultrastructure of intestinal brush border. Although initially there were a few controversial reports regarding its safety as a food additive, such evidence has been questionable, and later studies have established the safety of black pepper or its active principle, piperine, in several animal studies. Piperine, while it is non-genotoxic, has in fact been found to possess anti-mutagenic and anti-tumor influences.

Bioavailability of curcumin: problems and promises

Curcumin, a polyphenolic compound derived from dietary spice turmeric, possesses diverse pharmacologic effects including anti-inflammatory, antioxidant, antiproliferative and antiangiogenic activities. Phase I clinical trials have shown that curcumin is safe even at high doses (12 g/day) in humans but exhibit poor bioavailability. Major reasons contributing to the low plasma and tissue levels of curcumin appear to be due to poor absorption, rapid metabolism, and rapid systemic elimination. To improve the bioavailability of curcumin, numerous approaches have been undertaken. These approaches involve, first, the use of adjuvant like piperine that interferes with glucuronidation; second, the use of liposomal curcumin; third, curcumin nanoparticles; fourth, the use of curcumin phospholipid complex; and fifth, the use of structural analogues of curcumin (e.g., EF-24). The latter has been reported to have a rapid absorption with a peak plasma half-life. Despite the lower bioavailability, therapeutic efficacy of curcumin against various human diseases, including cancer, cardiovascular diseases, diabetes, arthritis, neurological diseases and Crohn's disease, has been documented. Enhanced bioavailability of curcumin in the near future is likely to bring this promising natural product to the forefront of therapeutic agents for treatment of human disease.

Curcumin enhances the apoptosis-inducing potential of TRAIL in prostate cancer cells: molecular mechanisms of apoptosis, migration and angiogenesis

BACKGROUND

We have recently shown that curcumin (a diferuloylmethane) inhibits growth and induces apoptosis, and also demonstrated that TRAIL induces apoptosis by binding to specific cell surface death receptors in prostate cancer cells. The objectives of this paper were to investigate the molecular mechanisms by which curcumin enhanced the apoptosis-inducing potential of TRAIL in prostate cancer cells.

RESULTS

Curcumin enhanced the apoptosis-inducing potential of TRAIL in androgen-unresponsive PC-3 cells and sensitized androgen-responsive TRAIL-resistant LNCaP cells. Curcumin inhibited the expressions of Bcl-2, Bcl-XL, survivin and XIAP, and induced the expressions Bax, Bak, PUMA, Bim, and Noxa and death receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5) in both cell lines. Overexpression of dominant negative FADD inhibited the interactive effects of curcumin and TRAIL on apoptosis. Treatment of these cells with curcumin resulted in activation of caspase-3, and caspase-9, and drop in mitochondrial membrane potential, and these events were further enhanced when combined with TRAIL. Curcumin inhibited capillary tube formation and migration of HUVEC cells and these effects were further enhanced in the presence of MEK1/2 inhibitor PD98059.

CONCLUSION

The ability of curcumin to inhibit capillary tube formation and cell migration, and enhance the therapeutic potential of TRAIL suggests that curcumin alone or in combination with TRAIL can be used for prostate cancer prevention and/or therapy.

Kinetics of light-induced cis-trans isomerization of four piperines and their levels in ground black peppers as determined by HPLC and LC/MS

The pungent compounds piperine and isomers thereof, secondary metabolites present in black and white pepper fruit, undergo light-induced isomerizations. To facilitate studies in this area, an HPLC method has been developed for analysis and isolation of the following four possible piperine-derived photoinduced isomers: piperine, isopiperine, chavicine, and isochavicine. The limits of detection (LOD) estimated from calibration plots were approximately 15-30 ng for each isomer. Reproducibilities of the analyses were excellent, and recoveries of spiked samples were as follows (average +/- SD; n = 3): chavicine, 98.4 +/- 2.1%; isopiperine, 96.2 +/- 3.2%; piperine, 104 +/- 3.8%; isochavicine, 98.9 +/- 3.0%. To determine the kinetics of these isomerizations, fluorescent light, sunlight, and UV radiation at 254 nm was used to induce cis-trans geometric isomerization as a function of light intensities and time of exposure determined with the aid of high-performance liquid chromatography (HPLC) and liquid chromatography with diode array UV detection-mass spectrometry (LC-DAD/MS). HPLC was also used to determine the distribution of the isomers in four commercial ground black pepper products used as spices in culinary practice. Isomerization increased with light intensities and time of exposure and leveled off at the so-called photostationary phases. The piperine levels of the four products were quite similar, ranging (in wt %) from 10.17 to 11.68. The amounts of the other three isomers ranged from 0.01 to 0.07 of the total for chavicine; from 0.15 to 0.23 for isopiperine; and from 0.37 to 0.42 for isochavicine. The results establish the utility of the HPLC method for simultaneous analysis of the four isomers both in pure form and in black pepper extracts. The dietary significance of the results is discussed.

Design, synthesis, and cytostatic activity of novel cyclic curcumin analogues

A series of novel cyclic analogues of curcumin were synthesized and analyzed for in vitro cytostatic activity. Condensation of 2-acetylcycloalkanones with a variety of aromatic aldehydes resulted in the formation of 2-arylidene-6-(3-arylacryoyl)-cycloalkanone derivatives. A number of these analogues were found to have significant anticancer activity against representative murine and human cancer cell lines during in vitro bioassays. This corroborated with in vitro cytostatic activity against a panel of 60 cell lines studied at the National Cancer Institute (USA).

Curcumin as "Curecumin": from kitchen to clinic

Although turmeric (Curcuma longa; an Indian spice) has been described in Ayurveda, as a treatment for inflammatory diseases and is referred by different names in different cultures, the active principle called curcumin or diferuloylmethane, a yellow pigment present in turmeric (curry powder) has been shown to exhibit numerous activities. Extensive research over the last half century has revealed several important functions of curcumin. It binds to a variety of proteins and inhibits the activity of various kinases. By modulating the activation of various transcription factors, curcumin regulates the expression of inflammatory enzymes, cytokines, adhesion molecules, and cell survival proteins. Curcumin also downregulates cyclin D1, cyclin E and MDM2; and upregulates p21, p27, and p53. Various preclinical cell culture and animal studies suggest that curcumin has potential as an antiproliferative, anti-invasive, and antiangiogenic agent; as a mediator of chemoresistance and radioresistance; as a chemopreventive agent; and as a therapeutic agent in wound healing, diabetes, Alzheimer disease, Parkinson disease, cardiovascular disease, pulmonary disease, and arthritis. Pilot phase I clinical trials have shown curcumin to be safe even when consumed at a daily dose of 12g for 3 months. Other clinical trials suggest a potential therapeutic role for curcumin in diseases such as familial adenomatous polyposis, inflammatory bowel disease, ulcerative colitis, colon cancer, pancreatic cancer, hypercholesteremia, atherosclerosis, pancreatitis, psoriasis, chronic anterior uveitis and arthritis. Thus, curcumin, a spice once relegated to the kitchen shelf, has moved into the clinic and may prove to be "Curecumin".

Curcumin inhibits tumor growth and angiogenesis in ovarian carcinoma by targeting the nuclear factor-kappaB pathway

PURPOSE

Curcumin, a component of turmeric, has been shown to suppress inflammation and angiogenesis largely by inhibiting the transcription factor nuclear factor-kappaB (NF-kappaB). This study evaluates the effects of curcumin on ovarian cancer growth using an orthotopic murine model of ovarian cancer.

EXPERIMENTAL DESIGN

In vitro and in vivo experiments of curcumin with and without docetaxel were done using human ovarian cancer cell lines SKOV3ip1, HeyA8, and HeyA8-MDR in athymic mice. NF-kappaB modulation was ascertained using electrophoretic mobility shift assay. Evaluation of angiogenic cytokines, cellular proliferation (proliferating cell nuclear antigen), angiogenesis (CD31), and apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) was done using immunohistochemical analyses.

RESULTS

Curcumin inhibited inducible NF-kappaB activation and suppressed proliferation in vitro. In vivo dose-finding experiments revealed that 500 mg/kg orally was the optimal dose needed to suppress NF-kappaB and signal transducers and activators of transcription 3 activation and decrease angiogenic cytokine expression. In the SKOV3ip1 and HeyA8 in vivo models, curcumin alone resulted in 49% (P = 0.08) and 55% (P = 0.01) reductions in mean tumor growth compared with controls, whereas when combined with docetaxel elicited 96% (P < 0.001) and 77% reductions in mean tumor growth compared with controls. In mice with multidrug-resistant HeyA8-MDR tumors, treatment with curcumin alone and combined with docetaxel resulted in significant 47% and 58% reductions in tumor growth, respectively (P = 0.05). In SKOV3ip1 and HeyA8 tumors, curcumin alone and with docetaxel decreased both proliferation (P < 0.001) and microvessel density (P < 0.001) and increased tumor cell apoptosis (P < 0.05).

CONCLUSIONS

Based on significant efficacy in preclinical models, curcumin-based therapies may be attractive in patients with ovarian carcinoma.

Cardioprotective effects of curcumin

Curcumin, a major active component of turmeric, is extracted from the powdered dry rhizome of Curcuma longa Linn (Zingiberaceae) and it has been used for centuries in indigenous medicine. We have shown that curcumin has a protective role against myocardial necrosis in rats. The antioxidant activity of curcumin could be attributed to the phenolic and methoxy groups in conjunction with the 1,3-diketone-conjugated diene system, for scavenging of the oxygen radicals. In addition, curcumin is shown to enhance the activities of detoxifying enzymes such as glutathione-S-transferase in vivo. We have also shown that oxygen free radicals exacerbate cardiac damage and curcumin induces cardioprotective effect and it also inhibits free-radical generation in myocardial ischemia in rats. This chapter on the cardioprotective effects of curcumin covers the following aspects: (1) the history of curcumin and its discovery as a potent drug with relevance to cardiovascular diseases; (2) mechanistic role of curcumin in vitro, emphasizing the antiplatelet and anticoagulant effects; (3) cardiovascular properties of curcumin; (4) application of curcumin in different animal models (viz. myocardial ischemia, myocardial infarction, cardiomyopathy, and arrhythmia in vitro and in vivo); (5) curcumin free-radical scavenging activity, particularly against O2 radical and depletion of the oxidative stress.

Pharmacokinetics and pharmacodynamics of curcumin

Curcuma spp. contain turmerin, essential oils, and curcuminoids, including curcumin. Curcumin [1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is regarded as the most biologically active constituent of the spice turmeric and it comprises 2-8% of most turmeric preparations. Preclinical data from animal models and phase I clinical studies performed with human volunteers and patients with cancer have demonstrated low systemic bioavailability following oral dosing. Efficient first-pass metabolism and some degree of intestinal metabolism, particularly glucuronidation and sulfation of curcumin, might explain its poor systemic availability when administered via the oral route. A daily oral dose of 3.6 g of curcumin is compatible with detectable levels of the parent compound in colorectal tissue from patients with cancer. The levels demonstrated might be sufficient to exert pharmacological activity. There appears to be negligible distribution of the parent drug to hepatic tissue or other tissues beyond the gastrointestinal tract. Curcumin possesses wide-ranging anti-inflammatory and anticancer properties. Many of these biological activities can be attributed to its potent antioxidant capacity at neutral and acidic pH, its inhibition of cell signaling pathways at multiple levels, its diverse effects on cellular enzymes, and its effects on cell adhesion and angiogenesis. In particular, curcumin's ability to alter gene transcription and induce apoptosis in preclinical models advocates its potential utility in cancer chemoprevention and chemotherapy. With regard to considerable public and scientific interest in the use of phytochemicals derived from dietary components to combat or prevent human diseases, curcumin is currently a leading agent.

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".

Low Concentrations of Curcumin Induce Growth Arrest and Apoptosis in Skin Keratinocytes Only in Combination with UVA or Visible Light

It is well known that curcumin, a dietary pigment from the plant Curcuma longa, inhibits cell proliferation and induces apoptosis in different cell lines at concentrations ranging from 10 to 150 microM (3.7-55 microg/ml). In this study, we show that curcumin at low concentrations (0.2-1 microg/ml) also has an antiproliferative effect when applied in combination with UVA or visible light. We demonstrate that such a treatment induces apoptosis in human skin keratinocytes represented by the increase of fragmented cell nuclei, release of cytochrome c from mitochondria, activation of caspases-9 and -8, and inhibition of NF-kappaB activity. Furthermore, inhibition of extracellular regulated kinases 1/2 and protein kinase B was found to ensure the proapoptotic effect. Additionally, the EGFR, an upstream regulator of both kinases, was inhibited indicating that apoptosis is induced by blocking survival- and proliferation-associated signal cascades at the receptor level. In summary, these findings suggest a new therapeutic concept for the treatment of hyperproliferative diseases by combining topical curcumin with UVA or visible light. In particular, the latter avoids the use of carcinogenic irradiation that is part of regular phototherapy.

Improving metabolic stability of cancer chemoprotective polyphenols

Dietary flavonoids and other polyphenols have the potential to be developed as effective food supplements as well as drugs for the prevention, as well as treatment of, cancer and other disease conditions. However, their very poor oral bioavailability, mainly due to extensive conjugation by glucuronidation and sulfation, is a severe limiting factor. First, this review shows the use of a simple, commercially available model system, the human hepatic S9 fraction, by which metabolic stability can be assessed effectively and accurately. Second, permethylation of the polyphenols effectively blocks the metabolic conjugation reactions, thereby dramatically increasing both metabolic stability and intestinal absorption, while maintaining or even increasing the biologic activities. Thus, permethylated polyphenols may have a future as chemoprotective agents.

Curcumin for chemoprevention of colon cancer

The most practical approach to reduce the morbidity and mortality of cancer is to delay the process of carcinogenesis through the use of chemopreventive agents. This necessitates that safer compounds, especially those derived from natural sources must be critically examined for chemoprevention. A spice common to India and the surrounding regions, is turmeric, derived from the rhizome of Curcuma longa. Pre-clinical studies in a variety of cancer cell lines including breast, cervical, colon, gastric, hepatic, leukemia, oral epithelial, ovarian, pancreatic, and prostate have consistently shown that curcumin possesses anti-cancer activity in vitro and in pre-clinical animal models. The robust activity of curcumin in colorectal cancer has led to five phase I clinical trials being completed showing the safety and tolerability of curcumin in colorectal cancer patients. To date clinical trials have not identified a maximum tolerated dose of curcumin in humans with clinical trials using doses up to 8000mg per day. The success of these trials has led to the development of phase II trials that are currently enrolling patients. Overwhelming in vitro evidence and completed clinical trials suggests that curcumin may prove to be useful for the chemoprevention of colon cancer in humans. This review will focus on describing the pre-clinical and clinical evidence of curcumin as a chemopreventive compound in colorectal cancer.

Deleterious effect of nitric oxide inhibition in chronic hepatopulmonary syndrome

On the basis of limited experimental and clinical studies, increased activity of the vasodilatory nitric oxide-cyclic guanosine monophosphate pathway is considered to play a key role in the pathogenesis of hepatopulmonary syndrome. We report a 46-year-old woman with Child-Pugh class C cirrhosis and progressive dyspnoea for 12 months. Investigations revealed elevated circulating concentrations of nitric oxide metabolites and exhaled nitric oxide levels, an hyperdynamic circulation with low systemic vascular resistance and mean arterial pressure, a large right to left intrapulmonary shunt fraction on radiolabelled macroaggregated albumin perfusion scanning, positive contrast-enhanced echocardiography, reduced diffusion capacity of carbon monoxide, hypoxaemia and orthodeoxyia, all in keeping with severe hepatopulmonary syndrome. Sequential inhibition of the nitric oxide-cyclic guanosine monophosphate pathway using curcumin (diferuloylmethane), terlipressin and methylene blue was associated with substantial improvements in vascular tone and the hyperdynamic circulation. No improvement, however, in the intrapulmonary shunt was demonstrated. Both hypoxaemia and orthodeoxia were substantially, reproducibly and reversibly worsened with all three treatments. Our findings argue against the contention that intrapulmonary shunting and impairment in arterial oxygenation in hepatopulmonary syndrome are necessarily the consequence of on-going, nitric oxide-cyclic guanosine monophosphate-mediated vasodilatation, at least in the chronic stage, and, given the possibility of substantial worsening of pulmonary oxygen exchange, suggest that inhibition of the nitric oxide-cyclic guanosine monophosphate pathway should be avoided in this setting.

Preclinical assessment of curcumin as a potential therapy for B-CLL

Curcumin, the principle component of the spice turmeric, has been used as an anti-inflammatory medication in India and China for centuries. Recent studies, predominantly using actively dividing cell lines, have suggested that this compound could be used as a chemopreventative or therapeutic agent for epithelial tumors. As curcumin has been reported to inhibit the NIK/IKK complex, an activity that would be expected to induce apoptosis in B cell malignancies, we sought to determine whether curcumin induces apoptosis in vitro in primary chronic lymphocytic leukemia (B-CLL) cells. Primary leukemic cells were incubated with varying dosages of curcumin, followed by assessment for apoptosis. The role of PPARgamma or NF-kappaB signaling in curcumin-induced apoptosis was examined by cotreatment with a PPARgamma antagonist or EMSA of nuclear NFkappaB complexes. We also examined whether a clinically achievable concentration of curcumin (1 microM) would augment the apoptotic effects of fludarabine, dexamethasone, vincristine or the PDE4 inhibitor rolipram. In B-CLL cells from 14 patients, curcumin-induced apoptosis with a mean EC(50) of 5.5 microM. In contrast, the EC(50) for whole mononuclear cells from a healthy donor was 21.8 microM. In a 48 hr wash-out time course, curcumin-induced apoptosis was time-dependent, with a substantial reduction in apoptosis observed when curcumin was removed after 5 hr. Curcumin treatment reduced basal nuclear NF-kappaB levels and 1 microM curcumin augmented both vinca alkaloid and PDE4 inhibitor-induced apoptosis in B-CLL cells. Our studies suggest that curcumin may augment the efficacy of established or experimental therapies for B-CLL.

c-Abl kinase regulates curcumin-induced cell death through activation of c-Jun N-terminal kinase

Curcumin, a natural phenolic compound found in turmeric (Curcuma longa) exhibits anticancer properties, attributed to its antiproliferative and apoptosis-inducing activity. The ubiquitously expressed nonreceptor tyrosine kinase c-Abl regulates stress responses induced by oxidative agents such as ionizing radiation and H2O2. In this study, we show that c-Abl is an important component of the cell death response activated by curcumin and that Abl mediates this response partly through activation of c-Jun N-terminal kinase (JNK). Therefore, inhibition of Abl by STI571 [imatinib (Gleevec)] treatment or down-regulation of Abl expression through Abl-specific short-hairpin RNA (shRNA) diminished cell death induction and JNK activation. Highlighting the interdependent nature of the Abl and JNK signaling in the curcumin-induced cell death response, a JNK inhibitor [anthra(1,9-cd)pyrazol-6(2H)-one-1,9-pyrazoloanthrone (SP600125)] caused very little cell death inhibition in STI571-pretreated cells and in Abl shRNA-expressing cells. Moreover, treatment with Abl and JNK inhibitor alone or together caused similar levels of cell death inhibition. Although p53 induction in response to curcumin treatment is dependent on Abl, we found that Abl-->p53 signaling is not necessary for curcumin-induced cell death. Taken together, the results demonstrate the differential roles played by Abl-->p53 and Abl-->JNK signaling events in modulating the cell death response to curcumin.

Binding of bioactive phytochemical piperine with human serum albumin: A spectrofluorometric study

Piperine, the bioactive alkaloid compound of the spice black pepper (Piper nigrum) exhibits a wide range of beneficial physiological and pharmacological activities. Being essentially water-insoluble, piperine is presumed to be assisted by serum albumin for its transport in blood. In this study, the binding of piperine to serum albumin was examined by employing steady state and time resolved fluorescence techniques. Binding constant for the interaction of piperine with human serum albumin, which was invariant with temperature in the range of 17-47 degrees C, was found to be 0.5 x 10(5)M(-1), having stoichiometry of 1:1. At 27 degrees C, the van't Hoff enthalpy DeltaH degrees was zero; DeltaS degrees and DeltaG degrees were found to be 21.4 cal mol(-1) K(-1) and -6.42 kcal mol(-1). The binding constant increased with the increase of ionic strength from 0.1 to 1.0M of sodium chloride. The decrease of Stern-Volmer constant with increase of temperature suggested that the fluorescence quenching is static. Piperine fluorescence showed a blue shift upon binding to serum albumin, which reverted with the addition of ligands -triiodobenzoic acid and hemin. The distance between piperine and tryptophan after binding was found to be 2.79 nm by Förster type resonance energy transfer calculations. The steady state and time resolved fluorescence measurements suggest the binding of piperine to the subdomain IB of serum albumin. These observations are significant in understanding the transport of piperine in blood under physiological conditions.

High-performance liquid chromatography analysis of curcumin in rat plasma: application to pharmacokinetics of polymeric micellar formulation of curcumin

A simple, rapid and reliable high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of curcumin in rat plasma. Plasma was precipitated with acetonitrile after addition of the internal standard (IS), 4-hydroxybenzophenone. Separation was achieved on a Waters muBondapak C(18) column (3.9 x 300 mm, 5 microm) using acetonitrile (55%) and citric buffer, pH 3.0 (45%) as the mobile phase (flow rate = 1.0 mL/min). The UV detection wavelength was 300 and 428 nm for IS and curcumin, respectively. The extraction efficiencies were 97.08, 95.69 and 94.90% for 50, 200 and 1000 ng/mL of curcumin in rat plasma, respectively. The calibration curve was linear over the range 0.02-1 microg/mL with a correlation coefficient of r(2) > 0.999. The intra- and inter-day coefficients of variation were less than 13%, and mean intra- and inter-day errors were less than +/-6% at 50, 200 and 1000 ng/mL of curcumin. This assay was successfully applied to the pharmacokinetic studies of both solubilized curcumin and its polymeric micellar formulation in rats. It was found that polymeric micelles increased the half-life of curcumin 162-fold that of solubilized curcumin and increased the volume of distribution (Vd(ss)) by 70-fold.

A strategy for controlling potential interactions between natural health products and chemotherapy: a review in pediatric oncology

The high prevalence of complementary and alternative medicine use including natural health products (NHPs) in the pediatric oncology population is well established. The potential for concurrent use of NHPs with conventional chemotherapy necessitates physician awareness regarding the potential risks and benefits that might come from this coadministration. Knowledge of interactions between NHPs and chemotherapy is poorly characterized; however, an understanding of potential mechanisms of interaction by researchers and clinicians is important. Concerns regarding the use of antioxidants during chemotherapy are controversial and evidence exists to support both adherents and detractors in this debate. Our review addresses issues regarding potential interactions between NHPs and chemotherapies used in pediatric oncology from a pharmacokinetic and pharmacodynamic perspective. Examples of combinations of NHP and chemotherapies are briefly presented in addition to a strategy to avoid (or induce) a possible interaction between a NHP and chemotherapy. In conclusion, more clinical research is needed to substantiate or preclude the use of NHPs in the treatment of cancer and especially in combination with chemotherapy.

Piperine, an active principle from Piper nigrum, modulates hormonal and apo lipoprotein profiles in hyperlipidemic rats

PURPOSE

To study the effect of piperine, an alkaloid, on thyroid hormones and apolipoproteins in high-fat-diet (HFD) and antithyroid drug-induced hyperlipidemic rats.

EXPERIMENTAL

Male Wistar rats were first divided into two groups, control diet and high-fat diet (HFD) and then subdivided into four subgroups of ten animals each. The animals were treated with the following regimens for 10 weeks: 1% carboxymethyl cellulose; 10 mg carbimazole (CM)/kg body weight; 10 mg CM + 40 mg piperine/kg body weight, and 10 mg CM + 2 mg atorvastatin /ATV//kg body weight. Lipid profiles, hormone levels, and apolipoprotein levels were studied in all groups.

RESULTS

HFD and/or CM administration significantly elevated the plasma levels of total cholesterol, VLDL, LDL, triglycerides, free fatty acids, and phospholipids, but significantly reduced the HDL levels. Moreover, CM administration significantly reduced apo A-I levels and T3, T4 and testosterone levels while significantly elevating plasma apo B, thyroid stimulating hormone (TSH) and insulin levels. The simultaneous administration of piperine and HFD significantly reduced plasma lipids and lipoproteins levels, except for HDL, which was significantly elevated. Piperine supplementation also improved the plasma levels of apo A-I, T3, T4, testosterone, and I and significantly reduced apo B, TSH, and insulin to near normal levels.

CONCLUSIONS

The data presented here provide evidence that piperine possesses thyrogenic activity, thus modulating apolipoprotein levels and insulin resistance in HFD-fed rats, opening a new view in the management of dyslipidemia by dietary supplementation with nutrients.

Curcumin down regulates smokeless tobacco-induced NF-κB activation and COX-2 expression in human oral premalignant and cancer cells

Smokeless tobacco (ST) consumption is a major cause of oral cancer in South East Asia including India. Recently, we showed that exposure to smokeless tobacco extract (STE) (khaini) results in increased expression and activation of nuclear factor-kappaB (NF-kappaB) and its downstream target cyclooxygenase-2 (COX-2) in human oral cell systems in vitro. The present study was designed to test the hypothesis that curcumin may inhibit the activation of NF-kappaB in ST exposed oral premalignant and cancer cells. Exposure of oral premalignant and cancer cells to curcumin resulted in significant decrease in cell viability and induced apoptosis. STE-induced nuclear translocation and DNA-binding activity of NF-kappaB were inhibited in curcumin pretreated oral premalignant and cancer cells in vitro. Curcumin treatment led to decreased expression of NF-kappaB and COX-2. The tobacco specific nitrosamine, 4-(methylnitrosamino-)-1-(3-pyridyl)-1-butanone (NNK), is one of the carcinogenic components of STE (khaini). We demonstrate that curcumin pretreatment abrogated NNK-induced activation of NF-kappaB and COX-2 expression, suggesting that NNK is one of the factors in STE (khaini) modulated by curcumin. In conclusion, our findings demonstrate for the first time that curcumin downregulates STE (khaini) or NNK-induced NF-kappaB and COX-2 in oral premalignant and cancer cells in vitro.

Curcumin and dehydrozingerone derivatives: synthesis, radiolabeling, and evaluation for beta-amyloid plaque imaging

Alzheimer's disease (AD) is pathologically characterized by the accumulation of amyloid plaques and neurofibrillary tangles in the brain, and thus, the in vivo imaging of plaques and tangles would be beneficial for the early diagnosis of AD. It has been suggested that 5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,4,6-heptatrien-3-one (curcumin) may be responsible for low age-adjusted prevalence of AD in India. In the present study, eight novel derivatives of curcumin and 4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-one (dehydrozingerone) were synthesized and their binding affinities for beta-amyloid (Abeta) aggregates were measured. Of these ligands, fluoropropyl-substituted curcumin (8) showed the highest binding affinity (Ki=0.07 nM), and therefore, 8 was radiolabeled and evaluated as a potential probe for Abeta plaque imaging. Partition coefficient measurement and biodistribution in normal mice demonstrated that [18F]8 has a suitable lipophilicity and reasonable initial brain uptake. Metabolism studies also indicated that [18F]8 is metabolically stable in the brain. These results suggest that [18F]8 is a suitable radioligand for Abeta plaque imaging.

Curcumin Has Potent Liver Preservation Properties in an Isolated Perfusion Model

BACKGROUND

Curcumin has profound antioxidant and anti-inflammatory properties. This research assessed the effect of curcumin on liver preservation.

METHODS

Sprague-Dawley rat livers were flushed with different preservation solutions [Euro-Collins solution (EC), phosphate buffer saline (PBS), University of Wisconsin solution (UW)] with or without curcumin (25-200 microM) and stored at 4 degrees C for 24-48 hours. Livers were then perfused for 120 minutes via the portal vein with oxygenated Krebs-Henseleit bicarbonate buffer solution at a pressure of 18 cm H2O in a perfusion apparatus. The livers in the normal (NL) group were flushed with EC, PBS, or UW, then immediately perfused (zero preservation time).

RESULTS

We found that curcumin at 100 microM concentration had the optimal preservation characteristics. Portal flow rates and bile production were significantly higher and liver enzymes (alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase) were significantly lower in the EC+C livers and PBS+C livers than in the EC or PBS with optimum concentration of 100 microM of curcumin. Comparing UW+C vs. UW livers, at 24 hours there was no difference in these parameters; however, at 36 hours and 48 hours, portal flow rates and bile production were significantly higher in UW+C livers.

CONCLUSIONS

We found that curcumin has inherent organ preservation quality as it enhanced liver preservation in PBS. In addition, curcumin enhanced the preservation quality of EC and UW solutions, thereby extending the preservation time while maintaining the organ quality.

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.

Targeting constitutive and interleukin-6-inducible signal transducers and activators of transcription 3 pathway in head and neck squamous cell carcinoma cells by curcumin (diferuloylmethane)

Numerous reports suggest that interleukin-6 (IL-6) promotes survival and proliferation of tumor cells through the phosphorylation of a cell-signaling protein, signal-transducer-and-activator-of-transcription-3 (STAT3). Constitutive activation of STAT3 in head and neck squamous cell carcinoma (HNSCC) and its role in proliferation of this tumor has been demonstrated. Thus, agents that can suppress STAT3 activation have potential for the treatment of HNSCC. In the present report, we demonstrate that most HNSCC cell lines had constitutively active STAT3 and that curcumin (diferuloylmethane), a pharmacologically safe agent in humans, inhibited STAT3 phosphorylation in a dose- and time-dependent manner. Nuclear translocation of STAT3 was also inhibited by curcumin. The inhibition of STAT3 activation by curcumin was reversible, although even 24 hr after curcumin removal, only partial reversal occurred. Besides inhibiting constitutive expression, curcumin also abrogated the IL-6-induced activation of STAT3 in HNSCC cells. When compared with AG490, a well-characterized JAK2 inhibitor, curcumin was more rapid (30 min vs. 4 hr) and more potent (25 microM vs. 100 microM) inhibitor of STAT3 phosphorylation. Curcumin was also a more potent inhibitor of HNSCC cell proliferation than AG490. Overall, our results demonstrated that curcumin is a potent inhibitor of constitutive and IL-6-induced STAT3 phosphorylation. This mechanism may be at least partially responsible for curcumin's ability to suppress proliferation of HNSCC cells.

Regulation of inflammation and redox signaling by dietary polyphenols

Reactive oxygen species (ROS) play a key role in enhancing the inflammation through the activation of NF-kappaB and AP-1 transcription factors, and nuclear histone acetylation and deacetylation in various inflammatory diseases. Such undesired effects of oxidative stress have been found to be controlled by the antioxidant and/or anti-inflammatory effects of dietary polyphenols such as curcumin (diferuloylmethane, a principal component of turmeric) and resveratrol (a flavonoid found in red wine). The phenolic compounds in fruits, vegetables, tea and wine are mostly derivatives, and/or isomers of flavones, isoflavones, flavonols, catechins, tocopherols, and phenolic acids. Polyphenols modulate important cellular signaling processes such as cellular growth, differentiation and host of other cellular features. In addition, they modulate NF-kappaB activation, chromatin structure, glutathione biosynthesis, nuclear redox factor (Nrf2) activation, scavenge effect of ROS directly or via glutathione peroxidase activity and as a consequence regulate inflammatory genes in macrophages and lung epithelial cells. However, recent data suggest that dietary polyphenols can work as modifiers of signal transduction pathways to elicit their beneficial effects. The effects of polyphenols however, have been reported to be more pronounced in vitro using high concentrations which are not physiological in vivo. This commentary discusses the recent data on dietary polyphenols in the control of signaling and inflammation particularly during oxidative stress, their metabolism and bioavailability.

The anti-inflammatory effect of curcumin in an experimental model of sepsis is mediated by up-regulation of peroxisome proliferator-activated receptor-gamma

OBJECTIVE

Although phytochemical curcumin has been shown to possess anti-inflammatory properties, it remains unknown whether this agent has any beneficial effects in sepsis. The purpose of this study was to demonstrate whether curcumin protects septic animals and, if so, whether activation of peroxisome proliferator-activated receptor (PPAR)-gamma, an anti-inflammatory nuclear receptor, plays any role.

DESIGN

Prospective, controlled, and randomized animal study.

SETTING

A research institute laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

A bolus injection of 0.2 micromol of curcumin was given intravenously to male adult rats, followed by continuous infusion of curcumin (0.24 micromol/day) for 3 days via a primed 2-mL mini-pump. The rats were then subjected to sepsis by cecal ligation and puncture (CLP).

MEASUREMENTS AND MAIN RESULTS

Serum levels of liver enzymes (alanine aminotransferase and aspartate aminotransferase), lactate, albumin, and tumor necrosis factor (TNF)-alpha were measured at 20 hrs after CLP (i.e., late stage of sepsis). In addition, a 10-day survival curve was conducted following CLP and cecal excision with or without curcumin treatment. Furthermore, macrophages cell line RAW 264.7 cells were treated with curcumin followed by stimulation with endotoxin. TNF-alpha and PPAR-gamma expression were then measured. The results indicate that intravenous administration of curcumin before the onset of sepsis attenuated tissue injury, reduced mortality, and decreased the expression of TNF-alpha in septic animals. Similar results were also found when curcumin was administered after the onset of sepsis. Moreover, the down-regulated PPAR-gamma in the liver at 20 hrs after CLP was significantly improved by curcumin treatment. Concurrent administration of curcumin and GW9662, a specific PPAR-gamma antagonist, completely abolished the beneficial effects of curcumin under such conditions. In cultured RAW 264.7 cells, curcumin inhibited endotoxin-induced increases in TNF-alpha expression and markedly up-regulated PPAR-gamma expression without affecting cell viability. Curcumin also prevented morphologic alterations in macrophages induced by endotoxin.

CONCLUSIONS

The protective effect of curcumin makes it or its analogues strong candidates as a novel therapy for sepsis. The beneficial effect of curcumin appears to be mediated by up-regulation of nuclear receptor PPAR-gamma.

Curcumin, an atoxic antioxidant and natural NFkappaB, cyclooxygenase-2, lipooxygenase, and inducible nitric oxide synthase inhibitor: a shield against acute and chronic diseases

BACKGROUND

The world suffers a tsunami of chronic diseases, and a typhoon of acute illnesses, many of which are associated with the inappropriate or exaggerated activation of genes involved in inflammation. Finding therapeutic agents which can modulate the inflammatory reaction is the highest priority in medical research today. Drugs developed by the pharmaceutical industry have thus far been associated with toxicity and side effects, which is why natural substances are of increasing interest.

METHODS

A literature search (PubMed) showed almost 1500 papers dealing with curcumin, most from recent years. All available abstracts were read. Approximately 300 full papers were reviewed.

RESULTS

Curcumin, a component of turmeric, has been shown to be non-toxic, to have antioxidant activity, and to inhibit such mediators of inflammation as NFkappaB, cyclooxygenase-2 (COX-2), lipooxygenase (LOX), and inducible nitric oxide synthase (iNOS). Significant preventive and/or curative effects have been observed in experimental animal models of a number of diseases, including arteriosclerosis, cancer, diabetes, respiratory, hepatic, pancreatic, intestinal and gastric diseases, neurodegenerative and eye diseases.

CONCLUSIONS

Turmeric, an approved food additive, or its component curcumin, has shown surprisingly beneficial effects in experimental studies of acute and chronic diseases characterized by an exaggerated inflammatory reaction. There is ample evidence to support its clinical use, both as a prevention and a treatment. Several natural substances have greater antioxidant effects than conventional vitamins, including various polyphenols, flavonoids and curcumenoids. Natural substances are worth further exploration both experimentally and clinically.

Potential synergism of natural products in the treatment of cancer

Cancer is the second leading cause of death worldwide. There is thus increased interest in alternative treatment modalities that include chemotherapy, hormonal supplements, surgery, radiation therapy, complementary or alterative medicine, used alone or in combination. Therefore patients who are subjected to combination treatments such as hormonal supplements or alternative medicine face considerable risk of drug-drug interactions. The administration of herbal drugs by patients without a physician's prior counseling is increasing globally and there is a possibility of herb-drug interactions too. Herbal drugs or extracts themselves contain a combination of active constituents, which interact within themselves and also between other prescribed pharmaceutical drugs to either enhance (synergize) or decrease (antagonize) the therapeutic effect. This review focuses on a number of reports of herb-drug interactions, their mechanism of action with a special emphasis on dietetic phytochemicals such as quercetin, genistein, curcumin and catechins. All phytochemicals tend to increase the therapeutic effect by blocking one or more targets of the signal transduction pathway, by increasing the bioavailability of the other drug or, by stabilizing the other drug in the system.

Curcumin-artemisinin combination therapy for malaria

Artemisinin and curcumin show an additive interaction in killing Plasmodium falciparum in culture. In vivo, 3 oral doses of curcumin following a single injection of alpha,beta-arteether to Plasmodium berghei-infected mice are able to prevent recrudescence due to alpha,beta-arteether monotherapy and ensure almost 100% survival of the animals.

Cellular foundation of curcumin-induced apoptosis in follicular lymphoma cell lines

OBJECTIVE

Although responsive to first-line treatments, follicular lymphoma (FL) remains a fatal disease of increasing worldwide incidence. In efforts to find novel approaches to inhibit proliferation and induce apoptosis in FL cells, we examined the action of naturally occurring compound curcumin in the three recently established FL cell lines.

MATERIALS AND METHODS

Cytotoxic effects and determination of apoptotic attributes upon curcumin treatment were analyzed using growth inhibition, [(3)H]-thymidine, fluorescence microscopy, and flow cytometry assays, as well as Western blotting. Chemical inhibitor studies for the assessment of caspase and cathepsin contribution were applied. Expression of 10 members of the bcl-2 family proteins was evaluated by immunoblotting.

RESULTS

Curcumin inhibited proliferation and growth, and induced profound apoptosis associated with a shift in the balance of the bcl-2 family proteins, in all cell lines tested. Strikingly, we observed that curcumin-induced caspase-dependent apoptosis is also associated with lysosomal rupture (LMP). An increase in intracellular ROS generation appeared critical for curcumin-evoked LMP, loss of Deltapsi(m,) caspase activation, and cell death, as well as ascorbic acid-mediated enhancement of curcumin's action.

CONCLUSION

We have demonstrated for the first time that curcumin is an efficient inducer of apoptosis in FL cell lines, meriting its further evaluation in vivo.

Mitochondrial and Nuclear DNA Damage Induced by Curcumin in Human Hepatoma G2 Cells

Curcumin is extensively used as a spice and pigment and has anticarcinogenic effects that could be linked to its antioxidant properties. However, some studies suggest that this natural compound possesses both pro- and antioxidative effects. In this study, we found that curcumin induced DNA damage to both the mitochondrial and nuclear genomes in human hepatoma G2 cells. Using quantitative polymerase chain reaction and immunocytochemistry staining of 8-hydroxydeoxyguanosine, we demonstrated that curcumin induced dose-dependent damage in both the mitochondrial and nuclear genomes and that the mitochondrial damage was more extensive. Nuclear DNA fragments were also evident in comet assays. The mechanism underlies the elevated level of reactive oxygen species and lipid peroxidation generated by curcumin. The lack of DNA damage at low doses suggested that low levels of curcumin does not induce DNA damage and may play an antioxidant role in carcinogenesis. But at high doses, we found that curcumin imposed oxidative stress and damaged DNA. These data reinforce the hypothesis that curcumin plays a conflicting dual role in carcinogenesis. Also, the extensive mitochondrial DNA damage might be an initial event triggering curcumin-induced cell death.

Dose escalation of a curcuminoid formulation

BACKGROUND

Curcumin is the major yellow pigment extracted from turmeric, a commonly-used spice in India and Southeast Asia that has broad anticarcinogenic and cancer chemopreventive potential. However, few systematic studies of curcumin's pharmacology and toxicology in humans have been performed.

METHODS

A dose escalation study was conducted to determine the maximum tolerated dose and safety of a single dose of standardized powder extract, uniformly milled curcumin (C3 Complextrade mark, Sabinsa Corporation). Healthy volunteers were administered escalating doses from 500 to 12,000 mg.

RESULTS

Seven of twenty-four subjects (30%) experienced only minimal toxicity that did not appear to be dose-related. No curcumin was detected in the serum of subjects administered 500, 1,000, 2,000, 4,000, 6,000 or 8,000 mg. Low levels of curcumin were detected in two subjects administered 10,000 or 12,000 mg.

CONCLUSION

The tolerance of curcumin in high single oral doses appears to be excellent. Given that achieving systemic bioavailability of curcumin or its metabolites may not be essential for colorectal cancer chemoprevention, these findings warrant further investigation for its utility as a long-term chemopreventive agent.

Apoptosis-inducing effects of curcumin derivatives in human bladder cancer cells

Our aim was to prepare curcumin derivatives and study their apoptosis-inducing effects on bladder cancer cells in order to establish a basis for targeted chemotherapy of cancer. n-Maleoyl-L-valine-curcumin (NVC) and n-maleoyl-glycine-curcumin (NGC) were chemically synthesized. Intracellular esterase activity of the human bladder cancer EJ cell line and renal tubular epithelial (HKC) cells was examined by 6-carboxyfluorescein diacetate fluorometry. After incubation with NVC or NGC for 6-24 h, cell viability was detected by MTT colorimetry. Cell apoptosis and apoptotic rates were measured by acridine orange/ethidium bromide staining, TUNEL labeling and flow cytometry. Intracellular caspase-3 activities were determined by spectrophotometry. The esterase activity within EJ cells was 10.2-fold higher than that of HKC cells, which was abolished by bis-p-nitrophenylphosphate, an esterase inhibitor, resulting in decreases in NVC- and NGC-mediated cell viability arrest. For EJ cells, the IC50 values of NVC (20.1 micromol/l) and NGC (18.7 micromol/l) were close to curcumin (16.5 micromol/l). Meanwhile, their IC50 values on HKC cells were, respectively, 4.06- and 3.23-fold higher than curcumin. Moreover, NVC and NGC induced apoptosis of EJ cells by 10.13-23.36 and 12.42-28.56%, respectively. Administration of these two derivatives resulted in decreased apoptosis of HKC cells compared with curcumin. The caspase-3 activities of EJ cells, but not of HKC cells, were 5.21- and 5.63-fold enhanced by NVC and NGC, respectively. Thus, novel esterase-sensitive curcumin derivatives were synthesized, which induced extensive apoptosis of bladder cancer EJ cells, but not normal cells.

Turmeric extracts containing curcuminoids prevent experimental rheumatoid arthritis

Turmeric has been used for centuries in Ayurvedic medicine as a treatment for inflammatory disorders including arthritis. On the basis of this traditional usage, dietary supplements containing turmeric rhizome and turmeric extracts are also being used in the western world for arthritis treatment and prevention. However, to our knowledge, no data are available regarding antiarthritic efficacy of complex turmeric extracts similar in composition to those available for use as dietary supplements. Therefore, the studies described here were undertaken to determine the in vivo efficacy of well-characterized curcuminoid-containing turmeric extracts in the prevention or treatment of arthritis using streptococcal cell wall (SCW)-induced arthritis, a well-described animal model of rheumatoid arthritis (RA). Arthritic index, a clinical measure of joint swelling, was used as the primary endpoint for assessing the effect of extracts on joint inflammation. An essential oil-depleted turmeric fraction containing 41% of the three major curcuminoids was efficacious in preventing joint inflammation when treatment was started before, but not after, the onset of joint inflammation. A commercial sample containing 94% of the three major curcuminoids was more potent in preventing arthritis than the essential oil-depleted turmeric fraction when compared by total curcuminoid dose per body weight. In conclusion, these data (1) document the in vivo antiarthritic efficacy of an essential oil-depleted turmeric fraction and (2) suggest that the three major curcuminoids are responsible for this antiarthritic effect, while the remaining compounds in the crude turmeric extract may inhibit this protective effect.

From traditional Ayurvedic medicine to modern medicine: identification of therapeutic targets for suppression of inflammation and cancer

Cancer is a hyperproliferative disorder that involves transformation, dysregulation of apoptosis, proliferation, invasion, angiogenesis and metastasis. Extensive research during the last 30 years has revealed much about the biology of cancer. Drugs used to treat most cancers are those that can block cell signalling, including growth factor signalling (e.g., epidermal growth factor); prostaglandin production (e.g., COX-2); inflammation (e.g., inflammatory cytokines: NF-kappaB, TNF, IL-1, IL-6, chemokines); drug resistance gene products (e.g., multi-drug resistance); cell cycle proteins (e.g., cyclin D1 and cyclin E); angiogenesis (e.g., vascular endothelial growth factor); invasion (e.g., matrix metalloproteinases); antiapoptosis (e.g., bcl-2, bcl-X(L), XIAP, survivin, FLIP); and cellular proliferation (e.g., c-myc, AP-1, growth factors). Numerous reports have suggested that Ayurvedic plants and their components mediate their effects by modulating several of these recently identified therapeutic targets. However, Ayurvedic medicine requires rediscovery in light of our current knowledge of allopathic (modern) medicine. The focus of this review is to elucidate the Ayurvedic concept of cancer, including its classification, causes, pathogenesis and prevention; surgical removal of tumours; herbal remedies; dietary modifications; and spiritual treatments.

A potential role of the curry spice curcumin in Alzheimer's disease

There is substantial in-vitro data indicating that curcumin has antioxidant, anti-inflammatory, and anti-amyloid activity. In addition, studies in animal models of Alzheimer's disease (AD) indicate a direct effect of curcumin in decreasing the amyloid pathology of AD. As the widespread use of curcumin as a food additive and relatively small short-term studies in humans suggest safety, curcumin is a promising agent in the treatment and/or prevention of AD. Nonetheless, important information regarding curcumin bioavailability, safety and tolerability, particularly in an elderly population is lacking. We are therefore performing a study of curcumin in patients with AD to gather this information in addition to data on the effect of curcumin on biomarkers of AD pathology.

Protective effect of Piper longum fruit ethanolic extract on radiation induced damages in mice: A preliminary study

The radioprotective property of an ethanolic extract of Piper longum fruits (EEPLF) was investigated in Swiss mice. The white blood cell (WBC) count in irradiated control mice was drastically reduced to 1900 cells/mm3 on third day but in treated animals the count was 2783.3 cells/mm3. The number of bone marrow cells and alpha-esterase positive cells was also enhanced by the EEPLF administration (16.7 x 10(6) cells/femur and 946.5/4000 cells, respectively) when compared to the radiation exposed control animals (12.2 x 10(6) cells/femur and 693.5/4000 cells, respectively). EEPLF reduced the elevated levels of glutathione pyruvate transaminase (GPT), alkaline phosphatase (ALP), and lipid peroxidation (LPO) in liver and serum of radiation treated animals. The extract administration also increased the reduced glutathione (GSH) production to offer the radioprotection.

Chemosensitization and radiosensitization of tumors by plant polyphenols

The treatment of cancer with chemotherapeutic agents and radiation has two major problems: time-dependent development of tumor resistance to therapy (chemoresistance and radioresistance) and nonspecific toxicity toward normal cells. Many plant-derived polyphenols have been studied intently for their potential chemopreventive properties and are pharmacologically safe. These compounds include genistein, curcumin, resveratrol, silymarin, caffeic acid phenethyl ester, flavopiridol, emodin, green tea polyphenols, piperine, oleandrin, ursolic acid, and betulinic acid. Recent research has suggested that these plant polyphenols might be used to sensitize tumor cells to chemotherapeutic agents and radiation therapy by inhibiting pathways that lead to treatment resistance. These agents have also been found to be protective from therapy-associated toxicities. How these polyphenols protect normal cells and sensitize tumor cells to treatment is discussed in this review.

The effects of curcumin on depressive-like behaviors in mice

Curcuma longa is a major constituent of Xiaoyao-san, the traditional Chinese medicinal formula, which has been used effectively to treat depression-related diseases in China. There is no information available about the antidepressant activity of curcumin, the active component of curcuma longa. In the present study, we analyzed the effects of curcumin on depressive-like behaviors in mice, using two animal models of depression. Our results showed that curcumin treatment at 5 and 10 mg/kg (p.o.) significantly reduced the duration of immobility in both the tail suspension and forced swimming tests. These doses that affected the immobile response did not affect locomotor activity. In addition, the neurochemical assays showed that curcumin produced a marked increase of serotonin and noradrenaline levels at 10 mg/kg in both the frontal cortex and hippocampus. Dopamine levels were also increased in the frontal cortex and the striatum. Moreover, curcumin was found to inhibit monoamine oxidase activity in the mouse brain. These findings suggest that the antidepressant-like effects of curcumin may involve the central monoaminergic neurotransmitter systems.

Biological properties of curcumin-cellular and molecular mechanisms of action

Curcuminoids, a group of phenolic compounds isolated from the roots of Curcuma longa (Zingiberaceae), exhibit a variety of beneficial effects on health and on events that help in preventing certain diseases. A vast majority of these studies were carried out with curcumin (diferuloyl methane), which is a major curcuminoid. The most detailed studies using curcumin include anti-inflammatory, antioxidant, anticarcinogenic, antiviral, and antiinfectious activities. In addition, the wound healing and detoxifying properties of curcumin have also received considerable attention. As a result of extensive research on the therapeutic properties of curcumin, some understanding on the cellular, molecular, and biochemical mechanism of action of curcumin is emerging. These findings are summarized in this review.

Curcumin: The story so far

Curcumin is a polyphenol derived from the herbal remedy and dietary spice turmeric. It possesses diverse anti-inflammatory and anti-cancer properties following oral or topical administration. Apart from curcumin's potent antioxidant capacity at neutral and acidic pH, its mechanisms of action include inhibition of several cell signalling pathways at multiple levels, effects on cellular enzymes such as cyclooxygenase and glutathione S-transferases, immuno-modulation and effects on angiogenesis and cell-cell adhesion. Curcumin's ability to affect gene transcription and to induce apoptosis in preclinical models is likely to be of particular relevance to cancer chemoprevention and chemotherapy in patients. Although curcumin's low systemic bioavailability following oral dosing may limit access of sufficient concentrations for pharmacological effect in certain tissues, the attainment of biologically active levels in the gastrointestinal tract has been demonstrated in animals and humans. Sufficient data currently exist to advocate phase II clinical evaluation of oral curcumin in patients with invasive malignancy or pre-invasive lesions of the gastrointestinal tract, particularly the colon and rectum.

Curcumin sensitizes tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis through reactive oxygen species-mediated upregulation of death receptor 5 (DR5)

Curcumin exhibits anti-inflammatory and antitumor activities. Although its functional mechanism has not been elucidated so far, numerous studies have shown that curcumin induces apoptosis in cancer cells. In the present study, we show that subtoxic concentrations of curcumin sensitize human renal cancer cells to the tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-mediated apoptosis. This apoptosis induced by the combination of curcumin and TRAIL is not interrupted by Bcl-2 overexpression. We found that treatment with curcumin significantly induces death receptor 5 (DR5) expression both at its mRNA and protein levels, accompanying the generation of the reactive oxygen species (ROS). Not only the pretreatment with N-acetylcystine but also the ectopic expression of peroxiredoxin II, an antioxidative protein, dramatically inhibited the apoptosis induced by curcumin and TRAIL in combination, blocking the curcumin-mediated DR5 upregulation. Taken together, the present study demonstrates that curcumin enhances TRAIL-induced apoptosis by ROS-mediated DR5 upregulation.

Differential apoptotic and redox regulatory activities of curcumin and its derivatives

We have synthesized different bioconjugates of curcumin, which were tested for their pro- and antioxidant properties. In the present study five representative derivatives of curcumin, i.e., 4,4'-di-(O-acetyl) curcumin, 4,4'-di-(O-glycinoyl) curcumin, 4,4'-di-(O-glycinoyl-di-N-piperoyl) curcumin, 4,4'-di-(O-piperoyl) curcumin, and 4,4'-(O,O-cystinoyl)-3,3'-dimethoxydiphenyl-1,6-heptadiene-3,5-dione, were used for testing their apoptotic potential on tumor cells. Dipiperoyl and diglycinoyl derivatives showed higher apoptotic activity at lower concentrations, whereas diacetyl curcumin had slightly lower apoptotic activity on tumor cells. On the other hand, diglycinoyl-dipiperoyl and cystinoyl heptadiene derivatives had lost their apoptotic potential significantly. The apoptotic activity of these derivatives correlated very well with the generation of ROS by the tumor cells, whereas GSH levels remained unaltered. Our studies also indicate downregulation of Bcl-2 and participation of caspase-3 in the apoptotic death of tumor cells.

Phase I clinical trial of oral curcumin: biomarkers of systemic activity and compliance

Curcumin, a polyphenolic antioxidant derived from a dietary spice, exhibits anticancer activity in rodents and in humans. Its efficacy appears to be related to induction of glutathione S-transferase enzymes, inhibition of prostaglandin E(2) (PGE(2)) production, or suppression of oxidative DNA adduct (M(1)G) formation. We designed a dose-escalation study to explore the pharmacology of curcumin in humans. Fifteen patients with advanced colorectal cancer refractory to standard chemotherapies consumed capsules compatible with curcumin doses between 0.45 and 3.6 g daily for up to 4 months. Levels of curcumin and its metabolites in plasma, urine, and feces were analyzed by high-pressure liquid chromatography and mass spectrometry. Three biomarkers of the potential activity of curcumin were translated from preclinical models and measured in patient blood leukocytes: glutathione S-transferase activity, levels of M(1)G, and PGE(2) production induced ex vivo. Dose-limiting toxicity was not observed. Curcumin and its glucuronide and sulfate metabolites were detected in plasma in the 10 nmol/L range and in urine. A daily dose of 3.6 g curcumin engendered 62% and 57% decreases in inducible PGE(2) production in blood samples taken 1 hour after dose on days 1 and 29, respectively, of treatment compared with levels observed immediately predose (P < 0.05). A daily oral dose of 3.6 g of curcumin is advocated for Phase II evaluation in the prevention or treatment of cancers outside the gastrointestinal tract. PGE(2) production in blood and target tissue may indicate biological activity. Levels of curcumin and its metabolites in the urine can be used to assess general compliance.

Synthesis and biological evaluation of novel curcumin analogs as anti-cancer and anti-angiogenesis agents

A series of novel curcumin analogs were synthesized and screened for anti-cancer and anti-angiogenesis activities at Emory University and at the National Cancer Institute (NCI). These compounds are symmetrical alpha,beta-unsaturated and saturated ketones. The majority of the analogs demonstrated a moderate degree of anti-cancer activity. Compounds 10, 11, and 14 exhibited a high degree of cytotoxicity in the NCI in vitro anti-cancer cell line screen. In addition, this screen revealed that these compounds inhibit tumor cell growth with a higher potency than the commonly used chemotherapeutic drug, cisplatin. In independent in vitro screens conducted at Emory, the same compounds plus 4, 5, 8, 9, and 13 exhibited a high degree of cytotoxicity to tumor cells. Analogs that were effective in the anti-cancer screens were also effective in in vitro anti-angiogenesis assays. Compounds 4, 9, 11, and 14 were most effective in the anti-angiogenesis assays run at Emory. In the assays conducted by the NCI, compound 14 was almost as potent as the anti-angiogenic drug TNP-470, which has undergone clinical trials. Based on the favorable in vitro anti-cancer and anti-angiogenesis results with 14, further in vivo tests were conducted. This compound effectively reduced the size of human breast tumors grown in female athymic nude mice and showed little toxicity. This data, coupled with the remarkable in vitro data, suggests that compound 14 may potentially be an effective chemotherapeutic agent. As a follow-up, a 3D quantitative structure relationship based on 14 has been developed. It shows a cross-validated r2(q2) and a predictive r2(p2) = 0.71. COMPARE analysis suggests the compound to be a possible RNA/DNA antimetabolite, but also implies that the compound's cytotoxicity may arise from a presently unknown mechanism.