"Clicked" sugar-curcumin conjugate: modulator of amyloid-β and tau peptide aggregation at ultralow concentrations

The synthesis of a water/plasma soluble, noncytotoxic, "clicked" sugar-derivative of curcumin with amplified bioefficacy in modulating amyloid-β and tau peptide aggregation is presented. Curcumin inhibits amyloid-β and tau peptide aggregation at micromolar concentrations; the sugar-curcumin conjugate inhibits Aβ and tau peptide aggregation at concentrations as low as 8 nM and 0.1 nM, respectively. In comparison to curcumin, this conveniently synthesized Alzheimer's drug candidate is a more powerful antioxidant.

Ayurvedic medicine and anaesthesia

The use of herbal medicines has increased dramatically over the past few years. The United States alone noted a 380% increase in the consumption of these products. Although the common practice of taking over-the-counter herbal soups, herbal teas and other such prepacked preparations was not associated with adverse events at large, still, some herbs are known to cause problems, especially when large doses are taken. The American Society of Anaesthesiologist (ASA) has taken a conservative stance and recommended that it is prudent to stop these products at least 2–3 weeks prior to anaesthesia and surgery. This advice may be difficult to implement as most preoperative evaluations occur only a few days prior to surgery. Some of the Ayurvedic preparations have shown to improve the patient outcome when taken during the perioperative period. Hence, the conservative stance by ASA may not always benefit the patient. More scientific studies are needed to have more targeted recommendations. This article puts forward the facts that need to be addressed by researchers in the future.

Interaction of curcumin nanoformulations with human plasma proteins and erythrocytes

Background

Recent studies report curcumin nanoformulation(s) based on polylactic-co-glycolic acid (PLGA), β-cyclodextrin, cellulose, nanogel, and dendrimers to have anticancer potential. However, no comparative data are currently available for the interaction of curcumin nanoformulations with blood proteins and erythrocytes. The objective of this study was to examine the interaction of curcumin nanoformulations with cancer cells, serum proteins, and human red blood cells, and to assess their potential application for in vivo preclinical and clinical studies.

Methods

The cellular uptake of curcumin nanoformulations was assessed by measuring curcumin levels in cancer cells using ultraviolet-visible spectrophotometry. Protein interaction studies were conducted using particle size analysis, zeta potential, and Western blot techniques. Curcumin nanoformulations were incubated with human red blood cells to evaluate their acute toxicity and hemocompatibility.

Results

Cellular uptake of curcumin nanoformulations by cancer cells demonstrated preferential uptake versus free curcumin. Particle sizes and zeta potentials of curucumin nanoformulations were varied after human serum albumin adsorption. A remarkable capacity of the dendrimer curcumin nanoformulation to bind to plasma protein was observed, while the other formulations showed minimal binding capacity. Dendrimer curcumin nanoformulations also showed higher toxicity to red blood cells compared with the other curcumin nanoformulations.

Conclusion

PLGA and nanogel curcumin nanoformulations appear to be very compatible with erythrocytes and have low serum protein binding characteristics, which suggests that they may be suitable for application in the treatment of malignancy. These findings advance our understanding of the characteristics of curcumin nanoformulations, a necessary component in harnessing and implementing improved in vivo effects of curcumin.

Modulation of Nrf2/ARE pathway by food polyphenols: a nutritional neuroprotective strategy for cognitive and neurodegenerative disorders

In recent years, there has been a growing interest, supported by a large number of experimental and epidemiological studies, for the beneficial effects of some phenolic substances, contained in commonly used spices and herbs, in preventing various age-related pathologic conditions, ranging from cancer to neurodegenerative diseases. Although the exact mechanisms by which polyphenols promote these effects remain to be elucidated, several reports have shown their ability to stimulate a general xenobiotic response in the target cells, activating multiple defense genes. Data from our and other laboratories have previously demonstrated that curcumin, the yellow pigment of curry, strongly induces heme-oxygenase-1 (HO-1) expression and activity in different brain cells via the activation of heterodimers of NF-E2-related factors 2 (Nrf2)/antioxidant responsive element (ARE) pathway. Many studies clearly demonstrate that activation ofNrf2 target genes, and particularly HO-1, in astrocytes and neurons is strongly protective against inflammation, oxidative damage, and cell death. In the central nervous system, the HO system has been reported to be very active, and its modulation seems to play a crucial role in the pathogenesis of neurodegenerative disorders. Recent and unpublished data from our group revealed that low concentrations of epigallocatechin-3-gallate, the major green tea catechin, induces HO-1 by ARE/Nrf2 pathway in hippocampal neurons, and by this induction, it is able to protect neurons against different models of oxidative damages. Furthermore, we have demonstrated that other phenolics, such as caffeic acid phenethyl ester and ethyl ferulate, are also able to protect neurons via HO-1 induction. These studies identify a novel class of compounds that could be used for therapeutic purposes as preventive agents against cognitive decline.

Encapsulation of curcumin in self-assembling peptide hydrogels as injectable drug delivery vehicles

Curcumin, a hydrophobic polyphenol, is an extract of turmeric root with antioxidant, anti-inflammatory and anti-tumorigenic properties. Its lack of water solubility and relatively low bioavailability set major limitations for its therapeutic use. In this study, a self-assembling peptide hydrogel is demonstrated to be an effective vehicle for the localized delivery of curcumin over sustained periods of time. The curcumin-hydrogel is prepared in-situ where curcumin encapsulation within the hydrogel network is accomplished concurrently with peptide self-assembly. Physical and in vitro biological studies were used to demonstrate the effectiveness of curcumin-loaded β-hairpin hydrogels as injectable agents for localized curcumin delivery. Notably, rheological characterization of the curcumin-loaded hydrogel before and after shear flow have indicated solid-like properties even at high curcumin payloads. In vitro experiments with a medulloblastoma cell line confirm that the encapsulation of the curcumin within the hydrogel does not have an adverse effect on its bioactivity. Most importantly, the rate of curcumin release and its consequent therapeutic efficacy can be conveniently modulated as a function of the concentration of the MAX8 peptide.

A polymeric nanoparticle formulation of curcumin (NanoCurc™) ameliorates CCl4-induced hepatic injury and fibrosis through reduction of pro-inflammatory cytokines and stellate cell activation

Plant-derived polyphenols such as curcumin hold promise as a therapeutic agent in the treatment of chronic liver diseases. However, its development is plagued by poor aqueous solubility resulting in poor bioavailability. To circumvent the suboptimal bioavailability of free curcumin, we have developed a polymeric nanoparticle formulation of curcumin (NanoCurc™) that overcomes this major pitfall of the free compound. In this study, we show that NanoCurc™ results in sustained intrahepatic curcumin levels that can be found in both hepatocytes and non-parenchymal cells. NanoCurc™ markedly inhibits carbon tetrachloride-induced liver injury, production of pro-inflammatory cytokines and fibrosis. It also enhances antioxidant levels in the liver and inhibits pro-fibrogenic transcripts associated with activated myofibroblasts. Finally, we show that NanoCurc™ directly induces stellate cell apoptosis in vitro. Our results suggest that NanoCurc™ might be an effective therapy for patients with chronic liver disease.

Selection of herbal therapeutics against deltatoxin mediated Clostridial infections

Clostridium perfringens (a versatile pathogenic bacterium) secretes enterotoxins (the deltatoxin, virulent factor) and causes food borne gastroenteritis and gasgangrene. The organism was isolated and characterized from improperly cooked meat and poultry samples. The isolated organism showed multiple drug resistance indicating that the treatment is challenging. Hence, there is need for improved therapeutic agents. The rational design of improved therapeutics requires the crystal structure for the toxin. However, the structure for the toxin is not yet available in its native form. Thus, we modeled the toxin structure using α- hemolysin of Staphylococcus aureus (PDB: 3M4D chain A) as template. The docking of the toxin with the herbal extract curcumin (1,7-bis(4-hydroxy-3- methoxyphenyl)hepta-1,6-diene-3,5-dione) showed a binding energy of -8.6 Kcal/mol, in comparison to the known antibiotic Linezolid with binding energy of -6.1 Kcal/mol. This data finds application in the design and development of novel compounds against the deltatoxin from Clostridium perfringens.

Chemoprevention in familial adenomatous polyposis

Familial adenomatous polyposis (FAP) predictably leads to adenomas and eventual adenocarcinomas in the lower gastrointestinal tract and less frequently, the upper gastrointestinal tract. Chemopreventive strategies have been studied in FAP patients to delay the development of adenomas in the upper and lower gastrointestinal tract, as well as to prevent recurrence of adenomas in the retained rectum of patients after prophylactic surgery with colectomy and ileorectal anastamosis (IRA). The nonsteroidal anti-inflammatory drug (NSAID) sulindac and selective cyclooxygenase-2 (COX-2) inhibitor celecoxib reduce polyposis of the retained rectum after colectomy with IRA. Reports of cardiovascular risks of some NSAIDs and selective COX-2 inhibitors have led to promising studies of lower doses in combination with ursodeoxycholic acid, statin, and difluoromethylornithine. Curcumin and eicosapentaenoic acid show efficacy in small clinical trials of FAP chemoprevention. This article will review the concept of chemoprevention and the current clinical literature in FAP chemoprevention.

The effect of curcumin (turmeric) on Alzheimer's disease: An overview

This paper discusses the effects of curcumin on patients with Alzheimer's disease (AD). Curcumin (Turmeric), an ancient Indian herb used in curry powder, has been extensively studied in modern medicine and Indian systems of medicine for the treatment of various medical conditions, including cystic fibrosis, haemorrhoids, gastric ulcer, colon cancer, breast cancer, atherosclerosis, liver diseases and arthritis. It has been used in various types of treatments for dementia and traumatic brain injury. Curcumin also has a potential role in the prevention and treatment of AD. Curcumin as an antioxidant, anti-inflammatory and lipophilic action improves the cognitive functions in patients with AD. A growing body of evidence indicates that oxidative stress, free radicals, beta amyloid, cerebral deregulation caused by bio-metal toxicity and abnormal inflammatory reactions contribute to the key event in Alzheimer's disease pathology. Due to various effects of curcumin, such as decreased Beta-amyloid plaques, delayed degradation of neurons, metal-chelation, anti-inflammatory, antioxidant and decreased microglia formation, the overall memory in patients with AD has improved. This paper reviews the various mechanisms of actions of curcumin in AD and pathology.

Physico-chemical studies on the evaluation of the antioxidant activity of herbal extracts and active principles of some Indian medicinal plants

Understanding of the efficacy and mechanism for the reaction of the biologically important radicals with natural and/or synthetic antioxidants is the first step towards the development of future therapeutic agents. The kinetic parameters e.g., formation and decay rate constants predict the efficacy of an antioxidant and its fate after reaction. These parameters also dictate the ease with which competing reactions would occur in a bio-environment. The spectroscopic parameters provide the clue to the site of free radical attack to these antioxidants. Here, in this article an attempt has been made to show the use of physico-chemical methods in the evaluation of antioxidant activity of some important medicinal plants commonly used in India and the subcontinent. The systems chosen here for discussions are herbal extracts as such, curcumin from turmeric, methoxy phenols from Indian spices, dehydrogingerdione from ginger and bakuchiol from Psoralea corylifolia. All the examples shown in this article illustrate the potential of the pulse radiolysis coupled with kinetic spectroscopy and other physicochemical techniques for the study of antioxidants either in the form of mixture as in herbal extract or as an isolated compound.

Inhibitory effect of rutin and curcumin on experimentally-induced calcium oxalate urolithiasis in rats

BACKGROUND

Renal epithelial cell injury by reactive oxygen species is pre-requisite step in the pathogenesis of urolithiasis. Rutin and curcumin are polyphenolic compounds known to have antioxidant and anti-inflammatory activities, but their effect on urolithiasis is yet to be elucidated. In the present study, we have investigated the inhibitory effect of rutin and curcumin on calcium oxalate urolithiasis in Wistar albino rats.

METHODS

Calcium oxalate urolithiasis was induced experimentally by administration of 0.75% v/v ethylene glycol with 1% w/v ammonium chloride in drinking water for three days followed by only 0.75% v/v ethylene glycol for 25 days. Rutin (20 mg/kg body weight) and curcumin (60 mg/kg body weight) were given once daily for 28 days by oral route. After treatment period, calcium and oxalate levels in urine and kidney tissue homogenate were measured. Kidney was also used for histopathological examination.

RESULTS

Stone-induction with ethylene glycol and ammonium chloride resulted in elevated levels of calcium and oxalate in the urine and kidney sample, whereas supplementation of rutin and curcumin restored it near to normal. Histopathological study revealed minimum tissue damage and less number of calcium oxalate deposits in kidney of animal treated with rutin and curcumin as compared to calculi-induced animal.

CONCLUSION

The data suggest that the rutin and curcumin inhibits calcium oxalate urolithiasis. This effect is mediated possibly through a lowering of urinary concentration of stone forming constituents, anti-inflammatory and antioxidant effects.

The potential role of curcumin (diferuloylmethane) in plasma cell dyscrasias/paraproteinemia

Plasma cell dyscrasias, most commonly associated with paraproteinemia, are a diverse group of diseases. Monoclonal gammopathy of undefined significance (MGUS) can precede multiple myeloma, a progressive neoplastic disease. MGUS occurs in association with a variety of other diseases and currently no treatment is recommended but rather “watchful waiting”. Given that the size of the M-protein is a risk factor for disease progression, early intervention with the aim of reducing the paraprotein load would provide an innovative therapeutic tool. Preliminary results from our pilot study show a drop of between 5% and 30% serum paraprotein in patients taking curcumin compared with patients on placebo. Curcumin is a diferuloylmethane present in extracts of the rhizome of the Curcuma longa plant. As a natural product, this has exciting potential in the treatment of plasma cell dyscrasias.

Role of insulin as a growth promoter in regulating the response of curcumin in human primary gingival fibroblasts: An in vitro study

BACKGROUND

The aim of this investigation was to evaluate the biochemical and morphologic changes in human primary gingival fibroblasts (hPGF) treated with curcumin (CUR) and insulin (I) plus curcumin (CUR) in a dose-dependent fashion.

MATERIALS AND METHODS

Human gingival fibroblasts were obtained from gingival biopsies. Curcumin was dissolved in ethanol, diluted with Dulbecco's modified Eagle's medium (DMEM) to obtain dilutions and bovine insulin was dissolved in 0.01 N HCl and diluted with DMEM. Cells were exposed to different concentrations of CUR and insulin (1 mug/ml) plus CUR for next 48 hours at 37 degrees C and cellular growth profile was assessed using sulforhodamine-B (SRB), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and fluorescence-activated cell sorter (FACS).

RESULTS

The cell viability in both the treatments at lower concentrations of SRB (1 and 10 muM) and MTT (1 muM) were found to be significantly higher than that observed at higher concentrations, while apoptosis in both the treatments at lower concentrations was observed to be significantly lower than at higher concentrations. Also, the cell viability of I + CUR at lower concentrations of SRB (1, 10 and 25 muM) and MTT (1 muM) were found to be significantly higher than the respective CUR, while apoptosis at higher concentrations (50, 75 and 100 muM), especially at 75 muM was significantly low. The IC(50) of I + CUR of SRB, MTT and FACS were 1.1, 1.0 and 1.4 times higher than respective concentrations of CUR.

CONCLUSIONS

Insulin (1 mug/ml) exerted cytoproliferative and curcumin exerted cytocidal effects (in a dose-dependent manner) on hPGF. Insulin (1 mug/ml) and curcumin at different concentrations when added together decreased the cytocidal effect of curcumin.

A Mechanistic Approach for Modulation of Arsenic Toxicity in Human Lymphocytes by Curcumin, an Active Constituent of Medicinal Herb Curcuma longa Linn

Chronic exposure of humans to high concentrations of arsenic in drinking water is associated with skin lesions, peripheral vascular disease, hypertension, blackfoot disease and a high risk of cancer. Arsenic induces single strand breaks, DNA-protein crosslinks and apurinic sites in DNA, which are prerequisites for induction of cancer. Amelioration of such damages with natural compounds could be an effective strategy to combat arsenic toxicity. Curcumin is the active ingredient of turmeric, a common household spice, which is a rich source of polyphenols and this compound has been extensively studied as a chemopreventive agent against many types of cancer. The present study investigates whether curcumin could counteract the DNA damage caused by arsenic as assessed by single cell gel electrophoresis (SCGE) using peripheral blood lymphocytes, from healthy donors. It was observed that DNA damage induced by arsenic could be efficiently reduced by curcumin and the effect was more pronounced when lymphocytes were pre-incubated with curcumin prior to arsenic insult. Arsenic caused DNA damage by generation of reactive oxygen species (ROS) and enhancement of lipid peroxidation levels. Curcumin counteracted the damage by quenching ROS, decreasing the level of lipid peroxidation and increasing the level of phase II detoxification enzymes like catalase, superoxide dismutase and glutathione peroxidase. Curcumin also enhanced the DNA repair activity against arsenic induced damage. The expression of polymerase, a repair enzyme, was found to be highly elevated when arsenite induced damaged cells were allowed to repair in presence of curcumin. Results indicate that curcumin has significant role in confronting the deleterious effect caused by arsenic, which could be an economic mode of arsenic mitigation among rural population in West Bengal, India.

The impact of ionization States of matrix metalloproteinase inhibitors on docking-based inhibitor design

The influence of ionization states of hydroxamates and retrohydroxamates and the presence of zinc ions in the active site were investigated using the wild-type and E402Q mutant of MMP-9. The deprotonated hydroxamates showed a significantly enhanced enrichment factor in the presence of zinc ions. A pharmacophore model was developed based on the deprotonated compounds and was used to identify four structurally diverse compounds with antiproliferative activities.

Curcumin: an anti-inflammatory molecule from a curry spice on the path to cancer treatment

Oxidative damage and inflammation have been pointed out in preclinical studies as the root cause of cancer and other chronic diseases such as diabetes, hypertension, Alzheimer's disease, etc. Epidemiological and clinical studies have suggested that cancer could be prevented or significantly reduced by treatment with anti-oxidant and anti-inflammatory drugs, therefore, curcumin, a principal component of turmeric (a curry spice) showing strong anti-oxidant and anti-inflammatory activities, might be a potential candidate for the prevention and/or treatment of cancer and other chronic diseases. However, curcumin, a highly pleiotropic molecule with an excellent safety profile targeting multiple diseases with strong evidence on the molecular level, could not achieve its optimum therapeutic outcome in past clinical trials, largely due to its low solubility and poor bioavailability. Curcumin can be developed as a therapeutic drug through improvement in formulation properties or delivery systems, enabling its enhanced absorption and cellular uptake. This review mainly focuses on the anti-inflammatory potential of curcumin and recent developments in dosage form and nanoparticulate delivery systems with the possibilities of therapeutic application of curcumin for the prevention and/or treatment of cancer.

Curcumin suppresses intestinal polyps in APC Min mice fed a high fat diet

Colorectal cancer (CRC) is a leading cause of cancer deaths in the United States. Various risk factors have been associated with CRC including increasing age and diet. Epidemiological and experimental studies have implicated a diet high in fat as an important risk factor for colon cancer. High fat diets can promote obesity resulting in insulin resistance and inflammation and the development of oxidative stress, increased cell proliferation, and suppression of apoptosis. Because of the high consumption of dietary fats, especially saturated fats, by Western countries, it is of interest to see if non-nutrient food factors might be effective in preventing or delaying CRC in the presence of high saturated fat intake. Curcumin (Curcuma longa), the main yellow pigment in turmeric, was selected to test because of its reported anti-tumor activity. APC Min mice, which develop intestinal polyps and have many molecular features of CRC, were fed a diet containing 35% pork fat, 33% sucrose, and a protein and vitamin mineral mixture (HFD) with or without 0.5% curcumin. These cohorts were compared to APC Min mice receiving standard rodent chow (RC) with 8% fat. APC Min mice fed the HFD for 3 months had a 23% increase in total number of polyps compared to APC Min mice on RC. Curcumin was able to significantly reverse the accelerated polyp development associated with the HFD suggesting it may be effective clinically in helping prevent colon cancer even when ingesting high amounts of fatty foods. The anti-tumor effect of curcumin was shown to be associated with enhanced apoptosis and increased efficiency of DNA repair. Since curcumin prevented the gain in body weight seen in APC Min mice ingesting the HFD, modulation of energy metabolism may also be a factor.

Cyclodextrin-mediated entrapment of curcuminoid 4-[3,5-bis(2-chlorobenzylidene-4-oxo-piperidine-1-yl)-4-oxo-2-butenoic acid] or CLEFMA in liposomes for treatment of xenograft lung tumor in rats

We recently reported a novel curcuminoid 4-[3,5-bis(2-chlorobenzylidene-4-oxo-piperidine-1-yl)-4-oxo-2-butenoic acid] or CLEFMA as a potent anti-proliferative agent, and showed that it induces autophagic cell death in lung cancer cells. We are now reporting a drug-in-CD-in-liposome approach to formulate CLEFMA liposomes that could be labeled with Tc-99m radionuclide for non-invasive imaging of their biodistribution. CLEFMA encapsulation was enabled by hydroxypropyl-β-cyclodextrin. In vitro studies showed that CLEFMA possessed more potent anti-proliferative activity in lung adenocarcinoma H441 cells than naturally occurring curcumin. At the same time, it had no effect on the proliferative capacity of normal lung fibroblasts. CLEFMA liposomes retained the antiproliferative potency of free CLEFMA, while maintaining its non-toxic nature in normal lung fibroblasts. In nude rats bearing xenograft H441 tumors, the tumor volume significantly reduced after i.v. treatment with CLEFMA liposomes (p<0.05); the tumor inhibition was determined to be 94%. The anti-tumor activity of CLEFMA liposomes was confirmed by the observation that F-18-fluorodeoxyglucose uptake in tumors of treated rats was reduced as compared to those of control rats. Tc-99m-labeled CLEFMA liposomes accumulated in liver (33.7%); spleen showed the largest accumulation on per gram tissue basis (6.2%/g). Upon histopathological examination of liver, lung and kidney, we found no apparent toxicity from multiple CLEFMA liposome administrations. The results demonstrate the utility of liposomes to serve as a carrier for CLEFMA. This study is the first to demonstrate the efficacy of novel curcuminoid CLEFMA in a preclinical model.

Liposome-encapsulated EF24-HPβCD inclusion complex: a preformulation study and biodistribution in a rat model

3,5-Bis(2-fluorobenzylidene)-4-piperidone (EF24) is an anti-proliferative diphenyldifluoroketone analog of curcumin with more potent activity. The authors describe a liposome preparation of EF24 using a "drug-in-CD-in liposome" approach. An aqueous solution of EF24 and hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complex (IC) was used to prepare EF24 liposomes. The liposome size was reduced by a combination of multiple freeze-thaw cycles. Co-encapsulation of glutathione inside the liposomes conferred them with the capability of labeling with imageable radionuclide Tc-99m. Phase solubility analysis of EF24-HPβCD mixture provided k(1:1) value of 9.9 M(-1). The enhanced aqueous solubility of EF24 (from 1.64 to 13.8 mg/mL) due to the presence of HPβCD helped in the liposome preparation. About 19% of the EF24 IC was encapsulated inside the liposomes (320.5 ± 2.6 nm) by dehydration-rehydration technique. With extrusion technique, the size of 177 ± 6.5 nm was obtained without any effect on encapsulation efficiency. The EF24-liposomes were evaluated for anti-proliferative activity in lung adenocarcinoma H441 and prostate cancer PC-3 cells. The EF24-liposomes demonstrated anti-proliferative activity superior to that of plain EF24 at 10 μM dose. When injected in rats, the Tc-99m-labeled EF24-liposomes cleared from blood with an α-t(1/2) of 21.4 min and β-t(1/2) of 397 min. Tissue radioactivity counting upon necropsy showed that the majority of clearance was due to the uptake in liver and spleen. The results suggest that using "drug-in-CD-in liposome" approach is a feasible strategy to formulate an effective parenteral preparation of EF24. In vitro studies show that the liposomal EF24 remains anti-proliferative, while presenting an opportunity to image its biodistribution.

Photophysical properties of bisdemethoxycurcumin

The steady-state absorption and fluorescence, as well as the time-resolved fluorescence properties of bisdemethoxycurcumin dissolved in several solvents differing in polarity and H-bonding capability were measured. The photodegradation quantum yield of the compound in acetonitrile and methanol was determined. The bisdemethoxycurcumin decay mechanisms from the S(1) state were discussed and compared with those of curcumin. The differences in S(1) dynamics observed between bisdemethoxy-curcumin and curcumin could be ascribed to a difference in H-bond acceptor/donor properties of the phenolic OH and a difference in strength of the intramolecular H-bond in the keto-enol moiety within the two molecules.

Pharmacological regulation of neutrophil activity and apoptosis: Contribution to new strategy for modulation of inflammatory processes

Novel strategies of antiinflammatory therapy are based upon pharmacological agents capable to enhance the resolution - i.e. the termination of the beneficial inflammation before it may turn into an adverse chronic stage. In contrast to the current therapy, which antagonises the formation of proinflammatory mediators, the "proresolving" therapy promotes natural antiinflammatory processes. It is likely that several drugs and phytochemicals would act in this way, but this point has not been investigated and thus might be totally overlooked. In this paper, effects of curcumin (diferuloylmethane) were analysed, considering the ability of this natural compound to affect resolution of inflammation through modulation of its important inputs - activity and apoptosis of neutrophils. The presented data indicate that, besides its well-known ability to suppress mechanisms engaged at the onset and progression of inflammation, curcumin could support resolution of inflammation through decreased activity and enhanced apoptosis of neutrophils. This substance decreased the formation of oxidants in neutrophils, both under in vitro conditions and after oral administration to arthritic rats. Moreover, curcumin accelerated spontaneous apoptosis of neutrophils, as indicated by increased externalisation of phosphatidylserine, by intercalation of propidium iodide and by enhanced activity of the executioner caspase-3.

Regulation of the expression of cyclooxygenases and production of prostaglandin I₂ and E₂ in human coronary artery endothelial cells by curcumin

Curcumin regulates prostaglandin (PG) synthesis in a variety of cells. PGE₂ and PGI₂ are generated from arachidonic acid (AA) by cyclooxygenases 1 and 2 (COX-1 and COX-2) and the synthase (PGES and PGI₂S) pathways. This study evaluates the in vitro effect of curcumin on the expression of COX-1, COX-2, PGI₂S and microsomal PGES-1 (mPGES-1), and the production of PGE₂ and PGI₂ in human coronary artery endothelial cells (HCAEC). HCAEC monolayers were incubated with curcumin and the expression of mRNA, protein and the production of PGI₂ and PGE₂ were quantified. Incubation of HCAEC with curcumin led to a time and concentration-dependent increases in COX-2 mRNA with a small but significant decrease in COX-1 mRNA expression. Curcumin also stimulated the expression of PGI₂S and mPGES-1 mRNA. Although curcumin stimulated COX-2, PGI₂S and mPGES-1 gene expression, it failed to increase PGI₂ or PGE₂ production. Interestingly, supplementation of the culture medium with AA increased prostanoid production by both quiescent and curcumin-treated cells. However, in comparison to the quiescent cells, the prostanoid production by curcumin-treated cells was markedly enhanced as AA concentrations in the medium were increased, and the enhanced prostanoid production was blocked by the presence of COX-2 specific inhibitor. Taken together, these results suggest that curcumin regulates prostanoid homeostasis in HCAEC by modulating multiple steps including the expression of COX-1, COX-2, PGI₂S and mPGES-1.

In silico theoretical molecular modeling for Alzheimer's disease: the nicotine-curcumin paradigm in neuroprotection and neurotherapy

The aggregation of the amyloid-β-peptide (AβP) into well-ordered fibrils has been considered as the key pathological marker of Alzheimer‘s disease. Molecular attributes related to the specific binding interactions, covalently and non-covalently, of a library of compounds targeting of conformational scaffolds were computed employing static lattice atomistic simulations and array constructions. A combinatorial approach using isobolographic analysis was stochastically modeled employing Artificial Neural Networks and a Design of Experiments approach, namely an orthogonal Face-Centered Central Composite Design for small molecules, such as curcumin and glycosylated nornicotine exhibiting concentration-dependent behavior on modulating AβP aggregation and oligomerization. This work provides a mathematical and in silico approach that constitutes a new frontier in providing neuroscientists with a template for in vitro and in vivo experimentation. In future this could potentially allow neuroscientists to adopt this in silico approach for the development of novel therapeutic interventions in the neuroprotection and neurotherapy of Alzheimer‘s disease. In addition, the neuroprotective entities identified in this study may also be valuable in this regard.

Urine and serum analysis of consumed curcuminoids using an IkappaB-luciferase surrogate marker assay

BACKGROUND

curcumin metabolites are detectable in body fluids such as serum and urine. We have developed a novel assay that can detect metabolites in such body fluids by measuring their effect on the nuclear factor kappa B/inhibitor of kappa B (NF-κB/IκB) pathway.

PATIENTS AND METHODS

fifteen healthy individuals were enrolled in the study and randomly assigned to two groups: control group (five) and curcumin group (ten). The test group ingested 8 g of the curcuminoids (C(3)-Complex) with 16 oz of bottled water. Blood and urine were collected at 0, 4, 8, and 24 h after ingestion. Degradation of the NF-κB/IκB complex was detected by the Genetic Expression and Measurement (GEM) assay using HCT116 cells stably transfected with PGL3-IκB firefly luciferase.

RESULTS

using our novel GEM assay, the five controls who had not taken curcumin were identified.

CONCLUSION

the GEM assay is a very sensitive and accurate non-invasive assay that could be utilized to detect metabolites in body fluids. It could also serve as a tool to determine participants' compliance during clinical research studies.

Long-term follow-up

Curcumin has been successfully applied to treat inflammatory conditions in experimental research and in clinical trials. The purpose of our study is to evaluate the efficacy of an adjunctive-to-traditional treatment with Norflo tablets (curcumin-phosphatidylcholine complex; Meriva) administered twice a day in recurrent anterior uveitis of different etiologies. The study group consisted of 106 patients who completed a 12-month follow-up therapeutic period. We divided the patients into three main groups of different uveitis origin: group 1 (autoimmune uveitis), group 2 (herpetic uveitis), and group 3 (different etiologies of uveitis). The primary end point of our work was the evaluation of relapse frequency in all treated patients, before and after Norflo treatment, followed by the number of relapses in the three etiological groups. Wilcoxon signed-rank test showed a P < 0.001 in all groups. The secondary end points were the evaluation of relapse severity and of the overall quality of life. The results showed that Norflo was well tolerated and could reduce eye discomfort symptoms and signs after a few weeks of treatment in more than 80% of patients. In conclusion, our study is the first to report the potential therapeutic role of curcumin and its efficacy in eye relapsing diseases, such as anterior uveitis, and points out other promising curcumin-related benefits in eye inflammatory and degenerative conditions, such as dry eye, maculopathy, glaucoma, and diabetic retinopathy.

Specific Inhibition of NEIL-initiated repair of oxidized base damage in human genome by copper and iron: potential etiological linkage to neurodegenerative diseases

Dyshomeostasis of transition metals iron and copper as well as accumulation of oxidative DNA damage have been implicated in multitude of human neurodegenerative diseases, including Alzheimer disease and Parkinson disease. These metals oxidize DNA bases by generating reactive oxygen species. Most oxidized bases in mammalian genomes are repaired via the base excision repair pathway, initiated with one of four major DNA glycosylases: NTH1 or OGG1 (of the Nth family) or NEIL1 or NEIL2 (of the Nei family). Here we show that Fe(II/III) and Cu(II) at physiological levels bind to NEIL1 and NEIL2 to alter their secondary structure and strongly inhibit repair of mutagenic 5-hydroxyuracil, a common cytosine oxidation product, both in vitro and in neuroblastoma (SH-SY5Y) cell extract by affecting the base excision and AP lyase activities of NEILs. The specificity of iron/copper inhibition of NEILs is indicated by a lack of similar inhibition of OGG1, which also indicated that the inhibition is due to metal binding to the enzymes and not DNA. Fluorescence and surface plasmon resonance studies show submicromolar binding of copper/iron to NEILs but not OGG1. Furthermore, Fe(II) inhibits the interaction of NEIL1 with downstream base excision repair proteins DNA polymerase beta and flap endonuclease-1 by 4-6-fold. These results indicate that iron/copper overload in the neurodegenerative diseases could act as a double-edged sword by both increasing oxidative genome damage and preventing their repair. Interestingly, specific chelators, including the natural chemopreventive compound curcumin, reverse the inhibition of NEILs both in vitro and in cells, suggesting their therapeutic potential.

The effect of curcumin on human islet amyloid polypeptide misfolding and toxicity

Type 2 diabetes involves aberrant misfolding of human islet amyloid polypeptide (h-IAPP) and resultant pancreatic amyloid deposits. Curcumin, a biphenolic small molecule, has offered potential benefits in other protein misfolding diseases, such as Alzheimer's disease. Our aim was to investigate whether curcumin alters h-IAPP misfolding and protects from cellular toxicity at physiologically relevant concentrations. The effect of curcumin on h-IAPP misfolding in vitro was investigated by electron paramagnetic resonance spectroscopy, ThT fluorescence and electron microscopy. Our in vitro studies revealed that curcumin significantly reduces h-IAPP fibril formation and aggregates formed in the presence of curcumin display alternative morphology and structure. We then tested a potential protective effect of curcumin against h-IAPP toxicity on β-cells. Micromolar concentrations of curcumin partially protect INS cells from exogenous IAPP toxicity. This protective effect, however, is limited to a narrow concentration range, as curcumin becomes cytotoxic at micromolar concentrations. In different models of endogenous over-expression of h-IAPP (INS cells and h-IAPP transgenic rat islets), curcumin failed to protect β-cells from h-IAPP-induced apoptosis. While curcumin has the ability to inhibit amyloid formation, the present data suggest that, without further modification, it is unlikely to be therapeutically useful in protection of β-cells in type 2 diabetes.

Hazardous effects of curcumin on mouse embryonic development through a mitochondria-dependent apoptotic signaling pathway

In this study, we examined the cytotoxic effects of curcumin, the yellow pigment of Curcuma longa, on the blastocyst stage of mouse embryos, subsequent embryonic attachment, and outgrowth in vitro and in vivo implantation by embryo transfer. Mouse blastocysts were incubated in medium with or without curcumin (6, 12 or 24 μM) for 24 h. Cell proliferation and growth were investigated using dual differential staining, apoptosis was analyzed with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), and implantation and post-implantation development of embryos were measured by in vitro development analysis and in vivo embryo transfer, respectively. Blastocysts treated with 24 μM curcumin displayed significantly increased apoptosis and decreased total cell number. Interestingly, we observed no marked differences in the implantation success rates between curcumin-pretreated and control blastocysts during in vitro embryonic development through implantation with a fibronectin-coated culture dish. However, in vitro treatment with 24 μM curcumin was associated with decreased implantation rate and increased resorption of postimplantation embryos in mouse uterus, as well as decreased fetal weight in the embryo transfer assay. Our results collectively indicate that in vitro exposure to curcumin triggers apoptosis and retards early postimplantation development after transfer to host mice. In addition, curcumin induces apoptotic injury effects on mouse blastocysts through ROS generation, and further promotes mitochondria-dependent apoptotic signaling processes to impair sequent embryonic development.

Targeting miRNAs involved in cancer stem cell and EMT regulation: An emerging concept in overcoming drug resistance

Although chemotherapy is an important therapeutic strategy for cancer treatment, it fails to eliminate all tumor cells due to intrinsic or acquired drug resistance, which is the most common cause of tumor recurrence. Emerging evidence suggests an intricate role of cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT)-type cells in anticancer drug resistance. Recent studies also demonstrated that microRNAs (miRNAs) play critical roles in the regulation of drug resistance. Here we will discuss current knowledge regarding CSCs, EMT and the role of regulation by miRNAs in the context of drug resistance, tumor recurrence and metastasis. A better understanding of the molecular intricacies of drug-resistant cells will help to design novel therapeutic strategies by selective targeting of CSCs and EMT-phenotypic cells through alterations in the expression of specific miRNAs towards eradicating tumor recurrence and metastasis. A particular promising lead is the potential synergistic combination of natural compounds that affect critical miRNAs, such as curcumin or epigallocatechin-3-gallate (EGCG) with chemotherapeutic agents.

Dietary polyphenols and obesity

The prevalence of overweight and obesity and their associated metabolic disorders are considered a major threat to the public’s health. While several diet and exercise programs are available for weight loss and prevention of weight regain, progress is often slow and disappointing. Recently, natural bioactive phytochemicals present in foods have been discovered for their potential health benefit effects on the prevention of chronic disorders such as cancer, cardiovascular disease, inflammatory and metabolic diseases including obesity. Polyphenols are a class of naturally-occurring phytochemicals, of which some such as catechins, anthocynines, resveratrol and curcumin have been shown to modulate physiological and molecular pathways that are involved in energy metabolism, adiposity, and obesity. The potential in vivo, beneficial effects of these polyphenols on adiposity and obesity as complementary agents in the up-regulation of energy expenditure have emerged by investigating these compounds in cell cultures, animal models of obesity and in some human clinical and epidemiological studies. In this brief review, the efficacy of the above-named polyphenols and their potential efficacy to modulate obesity and some associated disorders are discussed.

Identification of amyloid plaques in retinas from Alzheimer's patients and noninvasive in vivo optical imaging of retinal plaques in a mouse model

Noninvasive monitoring of β-amyloid (Aβ) plaques, the neuropathological hallmarks of Alzheimer's disease (AD), is critical for AD diagnosis and prognosis. Current visualization of Aβ plaques in brains of live patients and animal models is limited in specificity and resolution. The retina as an extension of the brain presents an appealing target for a live, noninvasive optical imaging of AD if disease pathology is manifested there. We identified retinal Aβ plaques in postmortem eyes from AD patients (n=8) and in suspected early stage cases (n=5), consistent with brain pathology and clinical reports; plaques were undetectable in age-matched non-AD individuals (n=5). In APP(SWE)/PS1(∆E9) transgenic mice (AD-Tg; n=18) but not in non-Tg wt mice (n=10), retinal Aβ plaques were detected following systemic administration of curcumin, a safe plaque-labeling fluorochrome. Moreover, retinal plaques were detectable earlier than in the brain and accumulated with disease progression. An immune-based therapy effective in reducing brain plaques, significantly reduced retinal Aβ plaque burden in immunized versus non-immunized AD mice (n=4 mice per group). In live AD-Tg mice (n=24), systemic administration of curcumin allowed noninvasive optical imaging of retinal Aβ plaques in vivo with high resolution and specificity; plaques were undetectable in non-Tg wt mice (n=11). Our discovery of Aβ specific plaques in retinas from AD patients, and the ability to noninvasively detect individual retinal plaques in live AD mice establish the basis for developing high-resolution optical imaging for early AD diagnosis, prognosis assessment and response to therapies.

Why pleiotropic interventions are needed for Alzheimer's disease

Alzheimer's disease (AD) involves a complex pathological cascade thought to be initially triggered by the accumulation of beta-amyloid (Abeta) peptide aggregates or aberrant amyloid precursor protein (APP) processing. Much is known of the factors initiating the disease process decades prior to the onset of cognitive deficits, but an unclear understanding of events immediately preceding and precipitating cognitive decline is a major factor limiting the rapid development of adequate prevention and treatment strategies. Multiple pathways are known to contribute to cognitive deficits by disruption of neuronal signal transduction pathways involved in memory. These pathways are altered by aberrant signaling, inflammation, oxidative damage, tau pathology, neuron loss, and synapse loss. We need to develop stage-specific interventions that not only block causal events in pathogenesis (aberrant tau phosphorylation, Abeta production and accumulation, and oxidative damage), but also address damage from these pathways that will not be reversed by targeting prodromal pathways. This approach would not only focus on blocking early events in pathogenesis, but also adequately correct for loss of synapses, substrates for neuroprotective pathways (e.g., docosahexaenoic acid), defects in energy metabolism, and adverse consequences of inappropriate compensatory responses (aberrant sprouting). Monotherapy targeting early single steps in this complicated cascade may explain disappointments in trials with agents inhibiting production, clearance, or aggregation of the initiating Abeta peptide or its aggregates. Both plaque and tangle pathogenesis have already reached AD levels in the more vulnerable brain regions during the "prodromal" period prior to conversion to "mild cognitive impairment (MCI)." Furthermore, many of the pathological events are no longer proceeding in series, but are going on in parallel. By the MCI stage, we stand a greater chance of success by considering pleiotropic drugs or cocktails that can independently limit the parallel steps of the AD cascade at all stages, but that do not completely inhibit the constitutive normal functions of these pathways. Based on this hypothesis, efforts in our laboratories have focused on the pleiotropic activities of omega-3 fatty acids and the anti-inflammatory, antioxidant, and anti-amyloid activity of curcumin in multiple models that cover many steps of the AD pathogenic cascade (Cole and Frautschy, Alzheimers Dement 2:284-286, 2006).

Safe and targeted anticancer efficacy of a novel class of antioxidant-conjugated difluorodiarylidenyl piperidones: differential cytotoxicity in healthy and cancer cells

The development of smart anticancer drugs that can selectively kill cancer cells while sparing the surrounding healthy tissues/cells is of paramount importance for safe and effective cancer therapy. We report a novel class of bifunctional compounds based on diarylidenyl piperidone (DAP) conjugated to an N-hydroxypyrroline (NOH; a nitroxide precursor) group. We hypothesized that the DAP would have cytotoxic (anticancer) activity, whereas the NOH moiety would function as a tissue-specific modulator (antioxidant) of cytotoxicity. The study used four DAPs, namely H-4073 and H-4318 without NOH and HO-3867 and HO-4200 with NOH substitution. The goal of the study was to evaluate the proof-of-concept anticancer-versus-antioxidant efficacy of the DAPs using a number of cancerous (breast, colon, head and neck, liver, lung, ovarian, and prostate cancer) and noncancerous (smooth muscle, aortic endothelial, and ovarian surface epithelial) human cell lines. Cytotoxicity was determined using an MTT-based cell viability assay. All four compounds induced significant loss of cell viability in cancer cells, whereas HO-3867 and HO-4200 showed significantly less cytotoxicity in noncancerous cells. EPR measurements showed a metabolic conversion of the N-hydroxylamine function to nitroxide with significantly higher levels of the metabolite and superoxide radical-scavenging (antioxidant) activity in noncancerous cells compared to cancer cells. Western blot analysis showed that the DAP-induced growth arrest and apoptosis in cancer cells were mediated by inhibition of STAT3 phosphorylation at the Tyr705 and Ser727 residues and induction of apoptotic markers of cleaved caspase-3 and PARP. The results suggest that the antioxidant-conjugated DAPs will be useful as safe and effective anticancer agents for cancer therapy.

Curcumin improves sclerosing cholangitis in Mdr2-/- mice by inhibition of cholangiocyte inflammatory response and portal myofibroblast proliferation

BACKGROUND AND AIM

Chronic cholangiopathies have limited therapeutic options and represent an important indication for liver transplantation. Curcumin, the yellow pigment of the spice turmeric, has pleiotropic actions and attenuates hepatic damage in animal models of chemically-induced liver injury. Whether curcumin has beneficial effects in cholangiopathies is unknown.

METHODS

Potential anticholestatic, anti-inflammatory and antifibrotic mechanisms of curcumin were explored in vivo in Mdr2(-/-) mice as a murine model of chronic cholangiopathy; as well as in vitro in a cholangiocyte cell line (HuCCT1) and portal myofibroblasts (MFBs) isolated from Mdr2(-/-) mice.

RESULTS

Liver damage, cholestasis and fibrosis were reduced in Mdr2(-/-) mice after curcumin feeding. Moreover, curcumin inhibited cholangiocyte proliferation and expression of activation marker vascular cell adhesion molecule-1 in Mdr2(-/-) mice. Curcumin-similar to PPARgamma synthetic agonist troglitazone-directly inhibited TNF-alpha-induced inflammatory activation of cholangiocytes in vitro, whereas these beneficial effects of curcumin were largely blocked by a PPARgamma synthetic antagonist. In addition, curcumin blocked proliferation and activation of portal MFBs by inhibiting ERK1/2 phosphorylation, thus contributing to reduced fibrogenesis.

CONCLUSIONS

These results show that curcumin may have multiple targets in liver including activation of PPARgamma in cholangiocytes and inhibition of ERK1/2 signalling in MFBs, thereby modulating several central cellular events in a mouse model of cholangiopathy. Targeting these pathways may be a promising therapeutic approach to cholangiopathies.

Phytochemicals in cancer prevention and therapy: truth or dare? Toxins (Basel). 2010;2:517-551. [PMID: 22069598 PMCID: PMC3153217 DOI: 10.3390/toxins2040517]

A voluminous literature suggests that an increase in consumption of fruit and vegetables is a relatively easy and practical strategy to reduce significantly the incidence of cancer. The beneficial effect is mostly associated with the presence of phytochemicals in the diet. This review focuses on a group of them, namely isothiocyanate, curcumin, genistein, epigallocatechin gallate, lycopene and resveratrol, largely studied as chemopreventive agents and with potential clinical applications. Cellular and animal studies suggest that these molecules induce apoptosis and arrest cell growth by pleiotropic mechanisms. The anticancer efficacy of these compounds may result from their use in monotherapy or in association with chemotherapeutic drugs. This latter approach may represent a new pharmacological strategy against several types of cancers. However, despite the promising results from experimental studies, only a limited number of clinical trials are ongoing to assess the therapeutic efficacy of these molecules. Nevertheless, the preliminary results are promising and raise solid foundations for future investigations.

The mismatch repair system modulates curcumin sensitivity through induction of DNA strand breaks and activation of G2-M checkpoint

The highly conserved mismatch (MMR) repair system corrects postreplicative errors and modulates cellular responses to genotoxic agents. Here, we show that the MMR system strongly influences cellular sensitivity to curcumin. Compared with MMR-proficient cells, isogenically matched MMR-deficient cells displayed enhanced sensitivity to curcumin. Similarly, cells suppressed for MLH1 or MSH2 expression by RNA interference displayed increased curcumin sensitivity. Curcumin treatment generated comparable levels of reactive oxygen species and the mutagenic adduct 8-oxo-guanine in MMR-proficient and MMR-deficient cells; however, accumulation of gammaH2AX foci, a marker for DNA double-strand breaks (DSB), occurred only in MMR-positive cells in response to curcumin treatment. Additionally, MMR-positive cells showed activation of Chk1 and induction of G(2)-M cell cycle checkpoint following curcumin treatment and inhibition of Chk1 by UCN-01 abrogated Chk1 activation and heightened apoptosis in MMR-proficient cells. These results indicate that curcumin triggers the accumulation of DNA DSB and induction of a checkpoint response through a MMR-dependent mechanism. Conversely, in MMR-compromised cells, curcumin-induced DSB is significantly blunted, and as a result, cells fail to undergo cell cycle arrest, enter mitosis, and die through mitotic catastrophe. The results have potential therapeutic value, especially in the treatment of tumors with compromised MMR function.

Targeting DNA damage and repair by curcumin

Curcumin is a compound with anti-tumor effects in a tolerable dose. A recent paper by Rowe et al described that curcumin induced DNA damage in triple negative breast cancer cells and regulated BRCA1 protein expression and modification.1 Related research and potential use of curcumin will be discussed in this article.

Curcumin targets FOLFOX-surviving colon cancer cells via inhibition of EGFRs and IGF-1R

Curcumin (diferuloylmethane), which has no discernible toxicity, inhibits initiation, promotion and progression of carcinogenesis. 5-Fluorouracil (5-FU) or 5-FU plus oxaliplatin (FOLFOX) remains the backbone of colorectal cancer chemotherapeutics, but produces an incomplete response resulting in survival of cells (chemo-surviving cells) that may lead to cancer recurrence. The present investigation was, therefore, undertaken to examine whether addition of curcumin to FOLFOX is a superior therapeutic strategy for chemo-surviving cells. Forty-eight-hour treatment of colon cancer HCT-116 and HT-29 cells with FOLFOX resulted in 60-70% survival, accompanied by a marked activation of insulin like growth factor-1 receptor (IGF-1R) and minor to moderate increase in epidermal growth factor receptor (EGFR), v-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (HER-2) as well as v-akt murine thymoma viral oncogene homolog 1 (AKT), cyclooxygenase-2 (COX-2) and cyclin-D1. However, inclusion of curcumin to continued FOLFOX treatment for another 48 h greatly reduced the survival of these cells, accompanied by a concomitant reduction in activation of EGFR, HER-2, IGF-1R and AKT, as well as expression of COX-2 and cyclin-D1. More importantly, EGFR tyrosine kinase inhibitor gefitinib or attenuation of IGF-1R expression by the corresponding si-RNA caused a 30-60% growth inhibition of chemo-surviving HCT-116 cells. However, curcumin alone was found to be more effective than both gefitinib and IGF-1R si-RNA mediated growth inhibition of chemo-surviving HCT-116 cells and addition of FOLFOX to curcumin did not increase the growth inhibitory effect of curcumin. Our data suggest that inclusion of curcumin in conventional chemotherapeutic regimens could be an effective strategy to prevent the emergence of chemoresistant colon cancer cells.

Curcumin-the paradigm of a multi-target natural compound with applications in cancer prevention and treatment

As cancer is a multifactor disease, it may require treatment with compounds able to target multiple intracellular components. We summarize here how curcumin is able to modulate many components of intracellular signaling pathways implicated in inflammation, cell proliferation and invasion and to induce genetic modulations eventually leading to tumor cell death. Clinical applications of this natural compound were initially limited by its low solubility and bioavailability in both plasma and tissues but combination with adjuvant and delivery vehicles was reported to largely improve bio-availability of curcumin. Moreover, curcumin was reported to act in synergism with several natural compounds or synthetic agents commonly used in chemotherapy. Based on this, curcumin could thus be considered as a good candidate for cancer prevention and treatment when used alone or in combination with other conventional treatments.

Curcumin potentiates the antitumor effects of gemcitabine in an orthotopic model of human bladder cancer through suppression of proliferative and angiogenic biomarkers

Little progress has been made in the last three decades in the treatment of bladder cancer. Novel agents that are nontoxic and can improve the current standard of care of this disease are urgently needed. Curcumin, a component of Curcuma longa (also called turmeric), is one such agent that has been shown to suppress pathways linked to oncogenesis, including cell survival, proliferation, invasion and angiogenesis. We investigated whether curcumin has potential to improve the current therapy for bladder cancer, using an orthotopic mouse model. Curcumin potentiated the apoptotic effects of gemcitabine against human bladder cancer 253JBV cells in culture. Electrophoretic mobility shift assay revealed that curcumin also suppressed the gemcitabine-induced activation of the cell survival transcription factor NF-kappaB. In an orthotopic mouse model, bioluminescence imaging revealed that while curcumin alone significantly reduced the bladder tumor volume, maximum reduction was observed when curcumin was used in combination with gemcitabine (P<0.01 versus vehicle; P<0.01 versus gemcitabine alone). Curcumin also significantly decreased the proliferation marker Ki-67 and microvessel density (CD31) (P<0.01 versus vehicle; P<0.01 versus gemcitabine alone), but maximum reduction occurred when it was combined with gemcitabine (P<0.01 versus vehicle; P<0.01 versus gemcitabine alone). Curcumin abolished the constitutive activation of NF-kappaB in the tumor tissue; induced apoptosis, and decreased cyclin D1, VEGF, COX-2, c-myc and Bcl-2 expression in the bladder cancer tissue. Overall our results suggest that curcumin alone exhibits significant antitumor effects against human bladder cancer and it further potentiates the effects of gemictabine, possibly through the modulation of NF-kappaB signaling pathway.

Modulation of the BRCA1 Protein and Induction of Apoptosis in Triple Negative Breast Cancer Cell Lines by the Polyphenolic Compound Curcumin

In the current study, we sought to examine the effects of curcumin in a specific type of breast cancer called triple negative breast cancer. These cancers lack expression of the estrogen and progesterone receptors and do not over-express HER2. Current treatment for triple negative breast cancers is limited to cytotoxic chemotherapy, and upon relapse, there are not any therapies currently available. We demonstrate here that the bioactive food compound curcumin induces DNA damage in triple negative breast cancer cells in association with phosphorylation, increased expression, and cytoplasmic retention of the BRCA1 protein. In addition, curcumin promotes apoptosis and prevents anchorage-independent growth and migration of triple negative breast cancer cells. Apoptosis and BRCA1 modulation were not observed in non-transformed mammary epithelial cells, suggesting curcumin may have limited non-specific toxicity. This study suggests that curcumin and potentially curcumin analogues should be tested further in the context of triple negative breast cancer. These results are novel, having never been previously reported, and suggest that curcumin could provide a novel, non-toxic therapy, which could lead to improved survival for patients with triple negative breast cancer. Curcumin should be studied further in this subset of breast cancer patients, for whom treatment options are severely limited.

Curcumin inhibits proliferation of colorectal carcinoma by modulating Akt/mTOR signaling

BACKGROUND

Curcumin, a natural polyphenol product of the plant Curcuma longa, has been shown to inhibit the growth and progression of colorectal cancer; however, the anticancer mechanism of curcumin remains to be elucidated.

MATERIALS AND METHODS

Colorectal cancer cells were treated with curcumin and changes in proliferation, protein and mRNA levels were analyzed.

RESULTS

Curcumin inhibited proliferation of colorectal cancer cells. This effect was mediated by inhibition of mammalian target of rapamycin (mTOR) signaling as evidenced by decreased phosphorylation of downstream effectors of mTOR complex 1 (mTORC1), p70S6K and 4E-BP1. Curcumin decreased total expression of mTOR, Raptor and Rictor protein and mRNA levels. Surprisingly, curcumin induced phosphorylation of Akt(Ser 473); this effect may be attributed to a decrease in levels of the PHLPP1 phosphatase, an inhibitor of Akt.

CONCLUSION

Our data suggest that curcumin, a natural compound, may exert its antiproliferative effects by inhibition of mTOR signaling and thus may represent a novel class of mTOR inhibitor.

Curcumin and cancer cells: how many ways can curry kill tumor cells selectively?

Cancer is a hyperproliferative disorder that is usually treated by chemotherapeutic agents that are toxic not only to tumor cells but also to normal cells, so these agents produce major side effects. In addition, these agents are highly expensive and thus not affordable for most. Moreover, such agents cannot be used for cancer prevention. Traditional medicines are generally free of the deleterious side effects and usually inexpensive. Curcumin, a component of turmeric (Curcuma longa), is one such agent that is safe, affordable, and efficacious. How curcumin kills tumor cells is the focus of this review. We show that curcumin modulates growth of tumor cells through regulation of multiple cell signaling pathways including cell proliferation pathway (cyclin D1, c-myc), cell survival pathway (Bcl-2, Bcl-xL, cFLIP, XIAP, c-IAP1), caspase activation pathway (caspase-8, 3, 9), tumor suppressor pathway (p53, p21) death receptor pathway (DR4, DR5), mitochondrial pathways, and protein kinase pathway (JNK, Akt, and AMPK). How curcumin selectively kills tumor cells, and not normal cells, is also described in detail.

Down-regulation of Notch1 signaling inhibits tumor growth in human hepatocellular carcinoma

In some human cancers, the Notch1 receptor and signaling pathway is upregulated, which increases the oncogenic potential of the cell through prevention of differentiation and inhibition of apoptosis. We sought to evaluate the role of Notch1 in hepatocellular cancer (HCC), and evaluate the therapeutic efficacy of curcumin, a known Notch1 inhibitor. Human liver tumors were compared to normal liver to evaluate for Notch1 and Notch1 Intracellular Domain (NICD). Three human HCC cell lines were exposed to curcumin and evaluated for downstream effectors by Western blot. In addition, standard MTT assays were performed to assess the effect of curcumin in vitro. Finally, a nude mouse xenograft model was utilized to assess the response to curcumin in vivo. High levels of NICD were present in the majority of human HCC samples and all three HCC cell lines. Treatment with curcumin led to a dose-dependent decrease in the expression of NICD associated with the induction of cleaved poly ADP-ribose polymerase (PARP), the degradation of cyclin D1 and increase in cyclin-dependent kinase p21. Curcumin inhibited HCC cell proliferation in vitro. Importantly, transfection of Notch1 small-interfering RNA (siRNA) into HCC cells resulted in cell growth inhibition and apoptosis, recapitulating the effects of curcumin. Finally, treatment with curcumin resulted in a 40% decrease in tumor growth in vivo. These results suggest for the first time that down-regulation of Notch1 signaling with curcumin is an attractive new therapeutic strategy for the treatment of patients with HCC.

Curcumin circumvents chemoresistance in vitro and potentiates the effect of thalidomide and bortezomib against human multiple myeloma in nude mice model

Curcumin (diferuloylmethane), a yellow pigment in turmeric, has been shown to inhibit the activation of nuclear factor-kappaB (NF-kappaB), a transcription factor closely linked to chemoresistance in multiple myeloma cells. Whether curcumin can overcome chemoresistance and enhance the activity of thalidomide and bortezomib, used to treat patients with multiple myeloma, was investigated in vitro and in xenograft model in nude mice. Our results show that curcumin inhibited the proliferation of human multiple myeloma cells regardless of their sensitivity to dexamethasone, doxorubicin, or melphalan. Curcumin also potentiated the apoptotic effects of thalidomide and bortezomib by down-regulating the constitutive activation of NF-kappaB and Akt, and this correlated with the suppression of NF-kappaB-regulated gene products, including cyclin D1, Bcl-xL, Bcl-2, TRAF1, cIAP-1, XIAP, survivin, and vascular endothelial growth factor. Furthermore, in a nude mice model, we found that curcumin potentiated the antitumor effects of bortezomib (P<0.001, vehicle versus bortezomib+curcumin; P<0.001, bortezomib versus bortezomib+curcumin), and this correlated with suppression of Ki-67 (P<0.001 versus control), CD31 (P<0.001 versus vehicle), and vascular endothelial growth factor (P<0.001 versus vehicle) expression. Collectively, our results suggest that curcumin overcomes chemoresistance and sensitizes multiple myeloma cells to thalidomide and bortezomib by down-regulating NF-kappaB and NF-kappaB-regulated gene products.

Curcumin is not a ligand for peroxisome proliferator-activated receptor-γ

Curcumin, a compound found in the spice turmeric, has been shown to possess a number of beneficial biological activities exerted through a variety of different mechanisms. Some curcumin effects have been reported to involve activation of the nuclear transcription factor peroxisome proliferator-activated receptor-γ (PPAR-γ), but the concept that curcumin might be a PPAR-γ ligand remains controversial. Results reported here demonstrate that, in contrast to the PPAR-γ ligands ciglitazone and rosiglitazone, curcumin is inactive in five different reporter or DNA-binding assays, does not displace [(3)H]rosiglitazone from the PPAR-γ ligand-binding site, and does not induce PPAR-γ-dependent differentiation of preadipocytes, while its ability to inhibit fibroblast-to-myofibroblast differentiation is not affected by any of four PPAR-γ antagonists. These multiple lines of evidence conclusively demonstrate that curcumin is not a PPAR-γ ligand and indicate the need for further investigation of the mechanisms through which the compound acts.

Inhibition of human dendritic cell activation by hydroethanolic but not lipophilic extracts of turmeric (Curcuma longa)

Turmeric has been extensively utilized in Indian and Chinese medicine for its immune-modulatory properties. Dendritic cells (DCs) are antigen-presenting cells specialized to initiate and regulate immunity. The ability of DCs to initiate immunity is linked to their activation status. The effects of turmeric on human DCs have not been studied. Here we show that hydroethanolic (HEE) but not lipophilic "supercritical" extraction (SCE) of turmeric inhibits the activation of human DCs in response to inflammatory cytokines. Treatment of DCs with HEE also inhibits the ability of DCs to stimulate the mixed lymphocyte reaction (MLR). Importantly, the lipophilic fraction does not synergize with the hydroethanolic fraction for the ability of inhibiting DC maturation. Rather, culturing of DCs with the combination of HEE and SCE leads to partial abrogation of the effects of HEE on the MLR initiated by DCs. These data provide a mechanism for the anti-inflammatory properties of turmeric. However, they suggest that these extracts are not synergistic and may contain components with mutually antagonistic effects on human DCs. Harnessing the immune effects of turmeric may benefit from specifically targeting the active fractions.

Curcumin protects retinal cells from light-and oxidant stress-induced cell death

Age-related macular degeneration (AMD) is a complex disease that has potential involvement of inflammatory and oxidative stress-related pathways in its pathogenesis. In search of effective therapeutic agents, we tested curcumin, a naturally occurring compound with known anti-inflammatory and antioxidative properties, in a rat model of light-induced retinal degeneration (LIRD) and in retina-derived cell lines. We hypothesized that any compound effective against LIRD, which involves significant oxidative stress and inflammation, would be a candidate for further characterization for its potential application in AMD. We observed significant retinal neuroprotection in rats fed diets supplemented with curcumin (0.2% in diet) for 2 weeks. The mechanism of retinal protection from LIRD by curcumin involves inhibition of NF-kappaB activation and down-regulation of cellular inflammatory genes. When tested on retina-derived cell lines (661W and ARPE-19), pretreatment of curcumin protected these cells from H(2)O(2)-induced cell death by up-regulating cellular protective enzymes, such as HO-1, thioredoxin. Since, curcumin with its pleiotropic activities can modulate the expression and activation of many cellular regulatory proteins such as NF-kappaB, AKT, NRF2, and growth factors, which in turn inhibit cellular inflammatory responses and protect cells; we speculate that curcumin would be an effective nutraceutical compound for preventive and augmentative therapy of AMD.

Synthesis and evaluation of electron-rich curcumin analogues

The natural product curcumin has long been recognized for its medicinal properties and is utilized for the treatment of many diseases. However, it remains unknown whether this activity is based on its presumably promiscuous scaffold, or if it results from the Michael acceptor properties of the alpha,beta-unsaturated 1,3-diketone moiety central to its structure. To probe this issue, electron-rich pyrazole and isoxazole analogues were prepared and evaluated against two breast cancer cell lines, which resulted in the identification of several compounds that exhibit low micromolar to mid nanomolar anti-proliferative activity. A conjugate addition study was also performed to compare the relative electrophilicity of the diketone, pyrazole and isoxazole analogues.