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

Enhancement in in vitro anti-angiogenesis activity and cytotoxicity in lung cancer cell by pectin-PVP based curcumin particulates

The aim of this work was to prepare pectin-poly (vinyl pyrrolidone) [PVP] based curcumin particulates to enhance the anticancer potential of curcumin, solubility and allow its localized controlled release. Pectin-PVP based curcumin particulates (PECTIN-PVP CUR) were prepared by spray drying technique in different ratios and were evaluated for surface morphology, micromeritics, flowability, particle size, drug content, in vitro dissolution, inhalable fraction, anti-angiogenesis/angiolysis and cytotoxicity. Results of micromeritic properties, Carr's index, Hausner's ratio and angle of repose were satisfactory. The batch CP3 was considered as optimum, due to excellent flowability, acceptable aggregation and enhanced solubility. The particle size and size distribution data of selected batch CP3 showed 90% of curcumin particulates having size less than 2.74μm, which may deposit to lungs. Twin Impinger studies showed that 29% of respirable fraction was generated, which could be directly delivered to lungs. The in vitro dissolution data showed many fold increase in dissolution rate. Angiolytic activity and MTT assay of PECTIN-PVP CUR have demonstrated enhancement in the anti-tumor potential, compared to curcumin alone. Altogether, PECTIN-PVP CUR were found suitable for local delivery and enhance its anticancer potential of curcumin.

A review of curcumin as a biological stain and as a self-visualizing pharmaceutical agent

Curcumin has been widely used to color textiles but, unlike other natural dyes such as hematoxylin or saffron, it rarely has been discussed as a biological stain. Aspects of the physicochemistry of curcumin relevant to biological staining and self-visualization, i.e., its acidic properties, lipophilicity, metal and pseudometal complexes, and optical properties, are summarized briefly here. Reports of staining of non-living biological specimens in sections and smears, both fixed and unfixed, including specimens embedded in resin, are summarized here. Staining of amyloid, boron and chromatin are outlined and possible reaction mechanisms discussed. Use of curcumin as a vital stain also is described, both in cultured monolayers and in whole organisms. Staining mechanisms are considered especially for the selective uptake of curcumin into cancer cells. Staining with curcumin labeled nanoparticles is discussed. Toxicity and safety issues associated with the dye also are presented.

Efficacy of Turmeric Extracts and Curcumin for Alleviating the Symptoms of Joint Arthritis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Although turmeric and its curcumin-enriched extracts have been used for treating arthritis, no systematic review and meta-analysis of randomized clinical trials (RCTs) have been conducted to evaluate the strength of the research. We systemically evaluated all RCTs of turmeric extracts and curcumin for treating arthritis symptoms to elucidate the efficacy of curcuma for alleviating the symptoms of arthritis. Literature searches were conducted using 12 electronic databases, including PubMed, Embase, Cochrane Library, Korean databases, Chinese medical databases, and Indian scientific database. Search terms used were “turmeric,” “curcuma,” “curcumin,” “arthritis,” and “osteoarthritis.” A pain visual analogue score (PVAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used for the major outcomes of arthritis. Initial searches yielded 29 articles, of which 8 met specific selection criteria. Three among the included RCTs reported reduction of PVAS (mean difference: −2.04 [−2.85, −1.24]) with turmeric/curcumin in comparison with placebo (P < .00001), whereas meta-analysis of four studies showed a decrease of WOMAC with turmeric/curcumin treatment (mean difference: −15.36 [−26.9, −3.77]; P = .009). Furthermore, there was no significant mean difference in PVAS between turmeric/curcumin and pain medicine in meta-analysis of five studies. Eight RCTs included in the review exhibited low to moderate risk of bias. There was no publication bias in the meta-analysis. In conclusion, these RCTs provide scientific evidence that supports the efficacy of turmeric extract (about 1000 mg/day of curcumin) in the treatment of arthritis. However, the total number of RCTs included in the analysis, the total sample size, and the methodological quality of the primary studies were not sufficient to draw definitive conclusions. Thus, more rigorous and larger studies are needed to confirm the therapeutic efficacy of turmeric for arthritis.

Curcumin-loaded redox response of self-assembled micelles for enhanced antitumor and anti-inflammation efficacy

At present, it has become evident that inflammation plays a critical role in tumor growth; meanwhile, chemotherapeutic agents using nanocarriers have been suggested as a promising strategy in cancer treatment. In this study, novel redox-responsive micelles were prepared from monomethoxy-poly(ethylene glycol)-chitosan-S-S-hexadecyl (C₁₆-SS-CS-mPEG). These micelles were able to carry and deliver drugs into tumor cells. To serve as a control, monomethoxy-poly(ethylene glycol)-chitosan-C-C-hexadecyl (C₁₆-CC-CS-mPEG) was developed in a similar fashion to that used to yield C₁₆-CC-CS-mPEG without a redox-responsive disulfide bond. The cellular uptake mechanisms of both micelles were determined. The efficient intracellular drug release from micelles in MCF-7 cells was further confirmed. Results indicated that curcumin (Cur) could rapidly form C₁₆-SS-CS-mPEG@ Cur micelles when exposed to reducing agents and efficaciously enhance intracellular accumulation. The cytotoxicity assay demonstrated that C₁₆-SS-CS-mPEG@Cur exhibited satisfactory cytotoxicity against MCF-7 cells. Anti-inflammation assay results indicated that C₁₆-SS-CS-mPEG@Cur treatment significantly downregulated tumor necrosis factor (TNF-α) expression and showed good anti-inflammatory effects in tumor microenvironment. Most importantly, antitumor effects in vivo showed satisfactory therapeutic effects with C₁₆-SS-CS-mPEG@Cur. Hence, C₁₆-SS-CS-mPEG@Cur micelles can be useful in tumor therapy.

Chemical constituents and biological research on plants in the genus Curcuma

Curcuma, a valuable genus in the family Zingiberaceae, includes approximately 110 species. These plants are native to Southeast Asia and are extensively cultivated in India, China, Sri Lanka, Indonesia, Peru, Australia, and the West Indies. The plants have long been used in folk medicine to treat stomach ailments, stimulate digestion, and protect the digestive organs, including the intestines, stomach, and liver. In recent years, substantial progress has been achieved in investigations regarding the chemical and pharmacological properties, as well as in clinical trials of certain Curcuma species. This review comprehensively summarizes the current knowledge on the chemistry and briefly discusses the biological activities of Curcuma species. A total of 720 compounds, including 102 diphenylalkanoids, 19 phenylpropene derivatives, 529 terpenoids, 15 flavonoids, 7 steroids, 3 alkaloids, and 44 compounds of other types isolated or identified from 32 species, have been phytochemically investigated. The biological activities of plant extracts and pure compounds are classified into 15 groups in detail, with emphasis on anti-inflammatory and antitumor activities.

Curcumin Attenuates N-Nitrosodiethylamine-Induced Liver Injury in Mice by Utilizing the Method of Metabonomics

N-Nitrosodiethylamine (DEN) exists as a food additive in cheddar cheese, processed meats, beer, water, and so forth. It is a potent hepatocarcinogen in animals and humans. Curcumin as a natural dietary compound decreased DEN-induced hepatocarcinogenesis in this research. According to the histopathological examination of liver tissues and biomarker detection in serum and livers, it was demonstrated that curcumin attenuated DEN-induced hepatocarcinogenesis through parts of regulating the oxidant stress enzymes (T-SOD and CAT), liver function (ALT and AST) and LDHA, AFP level, and COX-2/PGE2 pathway. Furthermore, curcumin attenuated metabolic disorders via increasing concentration of glucose and fructose, and decreasing levels of glycine and proline, and mRNA expression of GLUT1, PKM and FASN. Docking study indicated that curcumin presented strong affinity with key metabolism enzymes such as GLUT1, PKM, FASN and LDHA. There were a number of amino acid residues involved in curcumin-targeting enzymes of hydrogen bonds and hydrophobic interactions. All in all, curcumin exhibited a potent liver protective agent inhibiting chemically induced liver injury through suppressing liver cellular metabolism in the prospective application.

Physical and Chemical Stability of Curcumin in Aqueous Solutions and Emulsions: Impact of pH, Temperature, and Molecular Environment

The utilization of curcumin as a nutraceutical in food and supplement products is often limited because of its low water solubility, poor chemical stability, and low oral bioavailability. This study examined the impact of pH, storage temperature, and molecular environment on the physical and chemical stability of pure curcumin in aqueous solutions and in oil-in-water emulsions. Unlike naturally occurring curcuminoid mixtures (that contain curcumin, demethoxy-curcumin, and bisdemethoxy-curcumin), pure curcumin was highly unstable to chemical degradation in alkaline aqueous solutions (pH ≥7.0) and tended to crystallize out of aqueous acidic solutions (pH <7). These effects were attributed to changes in the molecular structure of curcumin under different pH conditions. The curcumin crystals formed were relatively large (10-50 μm), which made them prone to rapid sedimentation. The incorporation of curcumin into oil-in-water emulsions (30% MCT, 1 mg curcumin/g MCT, d₃₂ ≈ 298 nm) improved its water dispersibility and chemical stability. After incubation at 37 °C for 1 month, >85% of curcumin was retained by emulsions stored under acidic conditions (pH <7), whereas 62, 60, and 53% was retained by emulsions stored at pH 7.0, 7.4, and 8.0, respectively. There was little change in the color of curcumin-loaded emulsions when stored under acidic conditions, but their yellow color faded when stored under alkaline conditions. There was no evidence of droplet aggregation or creaming in emulsions stored for 31 days at ambient temperature. These results suggest that emulsion-based delivery systems may be suitable for improving the water dispersibility and chemical stability of curcumin, which would facilitate its application in foods and supplements.

ErbB Proteins as Molecular Target of Dietary Phytochemicals in Malignant Diseases

ErbB proteins overexpression, in both normal and mutated forms, is associated with invasive forms of cancer prone to metastasis and with stronger antiapoptotic mechanisms and therefore more challenging to treat. Downstream effectors of ErbB receptors mediating these phenotypic traits include MAPK, STAT, and PI3K/AKT/mTOR pathways. Various phytochemical compounds were studied for their large number of biological effects including anticancer activity. Among these compounds, epigallocatechin-3-gallate (EGCG), the main catechin from green tea leaves, and curcumin, component of the curry powder, constituted the object of numerous studies. Both compounds were shown to act directly either on ErbB expression, or on their downstream signaling molecules. In this paper we aim to review the involvement of ErbB proteins in cancer as well as the biologic activity of EGCG and curcumin in ErbB expressing and overexpressing malignancies. The problems arising in the administration of the two compounds due to their reduced bioavailability when orally administered, as well as the progress made in this field, from using novel formulations to improved dosing regimens or improved synthetic analogs, are also discussed.

Designing biopolymer microgels to encapsulate, protect and deliver bioactive components: Physicochemical aspects

Biopolymer microgels have considerable potential for their ability to encapsulate, protect, and release bioactive components. Biopolymer microgels are small particles (typically 100nm to 1000μm) whose interior consists of a three-dimensional network of cross-linked biopolymer molecules that traps a considerable amount of solvent. This type of particle is also sometimes referred to as a nanogel, hydrogel bead, biopolymer particles, or microsphere. Biopolymer microgels are typically prepared using a two-step process involving particle formation and particle gelation. This article reviews the major constituents and fabrication methods that can be used to prepare microgels, highlighting their advantages and disadvantages. It then provides an overview of the most important characteristics of microgel particles (such as size, shape, structure, composition, and electrical properties), and describes how these parameters can be manipulated to control the physicochemical properties and functional attributes of microgel suspensions (such as appearance, stability, rheology, and release profiles). Finally, recent examples of the utilization of biopolymer microgels to encapsulate, protect, or release bioactive agents, such as pharmaceuticals, nutraceuticals, enzymes, flavors, and probiotics is given.

Silence of long noncoding RNA PANDAR switches low-dose curcumin-induced senescence to apoptosis in colorectal cancer cells

Long noncoding RNAs (lncRNAs) are emerging as having multiple roles in cancer progression. However, roles of lncRNAs in chemotherapy for colorectal cancer (CRC) remain unclear. This study investigated the biological functions of lncRNA PANDAR in CRC cells treated with curcumin chemotherapy. Herein, we identified that PANDAR expression was not notably differential in CRC tissues compared with the corresponding normal tissues. Consistently, in vitro experiments revealed that knockdown of PANDAR could not change the proliferation, apoptosis, or senescence of CRC cells. Further analyses showed that low-dose curcumin could induce senescence in CRC cells without affecting cell apoptosis. Moreover, expression of PANDAR was increased in curcumin-treated CRC cells. Furthermore, silencing PANDAR in curcumin-treated cells increased apoptosis and greatly attenuated senescence possibly by stimulating the expression of PUMA. Together, these findings indicate that knockdown of lncRNA PANDAR switches curcumin-induced senescence to apoptosis, which may be potentially valuable in CRC therapy.

Dual Effect of Curcumin-Zinc Complex in Controlling Diabetes Mellitus in Experimentally Induced Diabetic Rats

Ultrasound-assisted extraction of curcumin from Curcuma longa was performed in an ultrasonic bath at 30°C using ethanol for 40 min. A successful attempt has been made to prepare curcumin-zinc (Zn) complex using a simple chemical procedure. The complex formation and its stoichiometry were characterized using elemental analysis, Fourier transform (FT)-IR and UV spectroscopy which revealed the interaction of Zn(II) ion (M) with curcumin (ligand, L) to proceed via (ML) complex type formation. Oral administration of curcumin-Zn complex at a concentration of 150 mg/kg body weight/rat/d for 45 d in streptozotocin-induced diabetic rats in comparison to curcumin and/or Zn administration exerted a hypoglycemic effect. A significant reduction in blood glucose, glycosylated hemoglobin (Hb)A1c, and lipid profile parameters with an excellent improvement in plasma insulin levels have been attained. Also, the reduced activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine in the diabetic rats treated with the complex exhibited the non-toxic nature of the curcumin-Zn complex. Finally, the larger extent of the complex in hyperglycemic improvement in comparison to curcumin and/or Zn supplementation was interpreted by its dual action on glucose and insulin maintenance.

The Essential Medicinal Chemistry of Curcumin

Curcumin is a constituent (up to ∼5%) of the traditional medicine known as turmeric. Interest in the therapeutic use of turmeric and the relative ease of isolation of curcuminoids has led to their extensive investigation. Curcumin has recently been classified as both a PAINS (pan-assay interference compounds) and an IMPS (invalid metabolic panaceas) candidate. The likely false activity of curcumin in vitro and in vivo has resulted in >120 clinical trials of curcuminoids against several diseases. No double-blinded, placebo controlled clinical trial of curcumin has been successful. This manuscript reviews the essential medicinal chemistry of curcumin and provides evidence that curcumin is an unstable, reactive, nonbioavailable compound and, therefore, a highly improbable lead. On the basis of this in-depth evaluation, potential new directions for research on curcuminoids are discussed.

Improved bioavailability of curcumin in liposomes prepared using a pH-driven, organic solvent-free, easily scalable process

pH-driven method, an organic solvent-free and easily scale-upable method, was firstly utilized to prepared curcumin-loaded liposomes.

Reversible loading of thiol-modified curcumin in an engineered protein capsid

The dodecahedral capsid formed by Aquifex aeolicus lumazine synthase (AaLS) is a promising protein scaffold for bionanotechnological applications.

Curcumin-cyclodextrin complexes enhanced the anti-cancer effects of curcumin

Curcumin (CUR), as a yellow pigment in the spice turmeric (Curcuma longa), possessed a pleiotropic application containing cancer therapy. Due to its poor oral bioavailability, the objective of this study was to investigate the use of curcumin-cyclodextrin complexes (CD15) as an approach to cancer chemoprevention. In this study, CUR encapsulation into the β-cyclodextrin (CD) cavity was achieved by the saturated aqueous solution method. CD15 was characterized by Fourier transform infrared (FTIR) and UV spectra analyses. An optimized CD15 was evaluated by cellular uptake and anti-cancer activity. As a result, CD15 enhanced curcumin delivery and improved its therapeutic efficacy compared with free curcumin in vivo and in vitro. Therefore, through regulation of MAPK/NF-κB pathway, CD15 up-regulated p53/p21 pathway, down-regulated CyclinE-CDK2 combination and increased Bax/caspase 3 expression to induce cellar apoptosis and G1-phase arrest. In conclusion, these results suggested that CD15 formulation should be used as a system for improving curcumin delivery and its therapeutic efficacy in lung cancer.

c-Jun N-terminal kinase-dependent apoptotic photocytotoxicity of solvent exchange-prepared curcumin nanoparticles

Indian spice curcumin is known for its anticancer properties, but the anticancer mechanisms of nanoparticulate curcumin have not been completely elucidated. We here investigated the in vitro anticancer effect of blue light (470 nm, 1 W)-irradiated curcumin nanoparticles prepared by tetrahydrofuran/water solvent exchange, using U251 glioma, B16 melanoma, and H460 lung cancer cells as targets. The size of curcumin nanocrystals was approximately 250 nm, while photoexcitation induced their oxidation and partial agglomeration. Although cell membrane in the absence of light was almost impermeable to curcumin nanoparticles, photoexcitation stimulated their internalization. While irradiation with blue light (1-8 min) or nanocurcumin (1.25-10 μg/ml) alone was only marginally toxic to tumor cells, photoexcited nanocurcumin displayed a significant cytotoxicity depending both on the irradiation time and nanocurcumin concentration. Photoexcited nanocurcumin induced phosphorylation of c-Jun N-terminal kinase (JNK), mitochondrial depolarization, caspase-3 activation, and cleavage of poly (ADP-ribose) polymerase, indicating apoptotic cell death. Accordingly, pharmacologial inhibition of JNK and caspase activity rescued cancer cells from photoexcited nanocurcumin. On the other hand, antioxidant treatment did not reduce photocytotoxicity of nanocurcumin, arguing against the involvement of oxidative stress. By demonstrating the ability of photoexcited nanocurcumin to induce oxidative-stress independent, JNK- and caspase-dependent apoptosis, our results support its further investigation in cancer therapy.

Degranulation Inhibitors from Medicinal Plants in Antigen-Stimulated Rat Basophilic Leukemia (RBL-2H3) Cells

Mast cells and basophils play important roles in both immediate- and late-phase reactions of type 1 allergy. Histamine, which is released from mast cells and basophils stimulated by an antigen or degranulation inducers, is usually determined as a degranulation marker in experiments on immediate allergic reactions in vitro. β-Hexosaminidase is also stored in secretory granules of the cells and is released concomitantly with histamine when the cells are immunologically activated, and recently this enzyme activity in the medium has been used as a marker of the degranulation. In this paper, we review our studies on the search for degranulation inhibitors, such as flavonoids, stilbenes, and curcuminoids, from medicinal plants using rat basophilic leukemia (RBL-2H3) cells.

In vitro study on potential pharmacological activity of curcumin analogues and their copper complexes

Curcumin and its derivatives have attracted great interest in the prevention and treatment of Alzheimer's disease, thanks both to the ability to hinder the formation of amyloid-beta (Aβ) aggregates and the ability to bind Cu (II) ion. In this article, we explore the ability of curcumin derivatives of K2T series to affect amyloid Aβ_1-40 aggregation. These derivatives were obtained by introducing the t-butyl ester group through a methylenic spacer on the central carbon atom of the β-diketo moiety of curcumin frame. The studied curcuminoids were demonstrated to inhibit Aβ_1-40 fibrillization at substoichiometric concentrations with IC₅₀ value near that of curcumin. In addition, the antioxidant properties and DNA interaction of their Cu(II) complexes is evaluated. The structure of Cu(II)-K2T31 complex is also proposed on the basis of DFT calculation.

TPGS-Stabilized Curcumin Nanoparticles Exhibit Superior Effect on Carrageenan-Induced Inflammation in Wistar Rat

Curcumin, a hydrophobic polyphenol compound derived from the rhizome of the Curcuma genus, has a wide spectrum of biological and pharmacological applications. Previously, curcumin nanoparticles with different stabilizers had been produced successfully in order to enhance solubility and per oral absorption. In the present study, we tested the anti-inflammatory effect of d-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS)-stabilized curcumin nanoparticles in vivo. Lambda-carrageenan (λ-carrageenan) was used to induce inflammation in rats; it was given by an intraplantar route and intrapelurally through surgery in the pleurisy test. In the λ-carrageenan-induced edema model, TPGS-stabilized curcumin nanoparticles were given orally one hour before induction and at 0.5, 4.5, and 8.5 h after induction with two different doses (1.8 and 0.9 mg/kg body weight (BW)). Sodium diclofenac with a dose of 4.5 mg/kg BW was used as a standard drug. A physical mixture of curcumin-TPGS was also used as a comparison with a higher dose of 60 mg/kg BW. The anti-inflammatory effect was assessed on the edema in the carrageenan-induced paw edema model and by the volume of exudate as well as the number of leukocytes reduced in the pleurisy test. TPGS-stabilized curcumin nanoparticles with lower doses showed better anti-inflammatory effects, indicating the greater absorption capability through the gastrointestinal tract.

Isothiouronium modification empowers pyrimidine-substituted curcumin analogs potent cytotoxicity and Golgi localization

Most of protein post-translational modifications occur in the Golgi and many human diseases are associated with abnormal Golgi function or improper post translational modifications of proteins in the Golgi. In this study, we designed and synthesized 4 × 6 series of novel isothiouronium-modified (E,E)-4,6-bis(styryl)-pyrimidine analogs and found that they localized at the Golgi as visualized by the intrinsic fluorescence of the analogs. The isothiouronium-modified analogs had potent cytotoxicity in both normal (Chinese Hamster Ovary or CHO) and cancer cells. Furthermore, permethylated isothiouronium-modified analogs showed cancer cell-selective cytotoxicity. The molecular mechanisms underlying Golgi localization of isothiouronium-modified compounds were investigated using 7 CHO and 4 human cancer cell lines and the results indicated that the compounds had binding partners in the Golgi. Thus, isothiouronium-modified analogs might be promising anticancer agents, novel Golgi staining reagents, and useful research tools for studying Golgi functions in normal or cancer cells and in Golgi-related human diseases.

Amyloid binding properties of curcumin analogues in Alzheimer's disease postmortem brain tissue

The presence of β-amyloid (Aβ) containing plaques in the brain is a hallmark of Alzheimer's disease (AD) and serves as a biomarker for confirmation of diagnosis postmortem. Early diagnosis is of great importance for optimal treatment and for monitoring disease progression in the brain. Highly specific and sensitive biomarkers are thus greatly needed to assess therapeutic efficacy, not only clinically, but also in terms of clearance of histopathological lesions and decelerated neurodegeneration. The objective of the present study was to give more insight into the binding of curcumin analogues, curcuminoids, to Aβ containing plaques in postmortem tissue from AD patients. In vitro autoradiography was utilized to explore affinity and displacement of the curcuminoids; curcumin, demethoxycurcumin (DMC), bisdemethoxycurcumin (BDMC) and dimethoxycurcumin (DIMC). We found that BDMC had the highest affinity for Aβ containing plaques in cortical AD brain tissue in comparison to other curcuminoids. Subsequently, [(3)H]BDMC showed significantly higher specific binding in cortical AD brain tissue compared to control subjects. These findings suggest that curcumin analogues, especially BDMC, may serve as a potential radioligands for Aβ plaque neuroimaging.

New Pathogenic Concepts and Therapeutic Approaches to Oxidative Stress in Chronic Kidney Disease

In chronic kidney disease inflammatory processes and stimulation of immune cells result in overproduction of free radicals. In combination with a reduced antioxidant capacity this causes oxidative stress. This review focuses on current pathogenic concepts of oxidative stress for the decline of kidney function and development of cardiovascular complications. We discuss the impact of mitochondrial alterations and dysfunction, a pathogenic role for hyperuricemia, and disturbances of vitamin D metabolism and signal transduction. Recent antioxidant therapy options including the use of vitamin D and pharmacologic therapies for hyperuricemia are discussed. Finally, we review some new therapy options in diabetic nephropathy including antidiabetic agents (noninsulin dependent), plant antioxidants, and food components as alternative antioxidant therapies.

Encapsulation of curcumin in cyclodextrin-metal organic frameworks: Dissociation of loaded CD-MOFs enhances stability of curcumin

Curcumin has been successfully encapsulated in cyclodextrin-metal organic frameworks (CD-MOFs) without altering their crystallinity. The interaction between curcumin and CD-MOFs is strong through hydrogen bond type interaction between the OH group of cyclodextrin of CD-MOFs and the phenolic hydroxyl group of the curcumin. Interestingly, dissolving the curcumin loaded CD-MOFs crystals in water results in formation of a unique complex between curcumin, γCD and potassium cations. In fact, the initial interaction between curcumin and CD-MOF is crucial for the formation of the latter. This new complex formed in alkaline media at pH 11.5 has maximum absorbance at 520nm and emittance at 600nm. Most importantly, the stability of curcumin in this complex was enhanced by at least 3 orders of magnitude compared to free curcumin and curcumin:γ-CD at pH 11.5. These results suggest a promising benign system of CD-MOFs, which can be used to store and stabilize curcumin for food applications.

Safety, Tolerance, and Enhanced Efficacy of a Bioavailable Formulation of Curcumin With Fenugreek Dietary Fiber on Occupational Stress: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

Drug delivery systems capable of delivering free (unconjugated) curcuminoids is of great therapeutic significance, since the absorption of bioactive and permeable form plays a key factor in mediating the efficacy of a substance which undergoes rapid biotransformation. Considering the recent understanding on the relatively high bioactivities and blood-brain-barrier permeability of free curcuminoids over their conjugated metabolites, the present human study investigated the safety, antioxidant efficacy, and bioavailability of CurQfen (curcumagalactomannoside [CGM]), a food-grade formulation of natural curcumin with fenugreek dietary fiber that has shown to possess improved blood-brain-barrier permeability and tissue distribution in rats. In this randomized double-blinded and placebo-controlled trial, 60 subjects experiencing occupational stress-related anxiety and fatigue were randomized to receive CGM, standard curcumin, and placebo for 30 days (500 mg twice daily). The study demonstrated the safety, tolerance, and enhanced efficacy of CGM in comparison with unformulated standard curcumin. A significant improvement in the quality of life (P < 0.05) with considerable reduction in stress (P < 0.001), anxiety (P < 0.001), and fatigue (P < 0.001) was observed among CGM-treated subjects as compared with the standard curcumin group, when monitored by SF-36, Perceived Stress Scale with 14 items, and Beck Anxiety Inventory scores. Improvement in the quality of life was further correlated with the significant enhancement in endogenous antioxidant markers (P < 0.01) and reduction in lipid peroxidation (P < 0.001). Further comparison of the free curcuminoids bioavailability after a single-dose (500 mg once per day) and repeated-dose (500 mg twice daily for 30 days) oral administration revealed enhanced absorption and improved pharmacokinetics of CGM upon both single- (30.7-fold) and repeated-dose (39.1-fold) administrations.

Curcumin and Resveratrol as Promising Natural Remedies with Nanomedicine Approach for the Effective Treatment of Triple Negative Breast Cancer

Researchers have made considerable progress in last few decades in understanding mechanisms underlying pathogenesis of breast cancer, its phenotypes, its molecular and genetic changes, its physiology, and its prognosis. This has allowed us to identify specific targets and design appropriate chemical entities for effective treatment of most breast cancer phenotypes, resulting in increased patient survivability. Unfortunately, these strategies have been largely ineffective in the treatment of triple negative breast cancer (TNBC). Hormonal receptors lacking render the conventional breast cancer drugs redundant, forcing scientists to identify novel targets for treatment of TNBC. Two natural compounds, curcumin and resveratrol, have been widely reported to have anticancer properties. In vitro and in vivo studies show promising results, though their effectiveness in clinical settings has been less than satisfactory, owing to their feeble pharmacokinetics. Here we discuss these naturally occurring compounds, their mechanism as anticancer agents, their shortcomings in translational research, and possible methodology to improve their pharmacokinetics/pharmacodynamics with advanced drug delivery systems.

Sauces, spices, and condiments: definitions, potential benefits, consumption patterns, and global markets

Spices and condiments are an important part of human history and nutrition, and have played an important role in the development of most cultures around the world. According to the Codex Alimentarius, the category of salts, spices, soups, sauces, salads, and protein products includes substances added to foods to enhance aroma and taste. Spices have been reported to have health benefits as antioxidant, antibiotic, antiviral, anticoagulant, anticarcinogenic, and anti-inflammatory agents. Health claims about the benefits of condiments for disease prevention or health improvement need to be science based and extensively supported by evidence; data on their preventive or protective potential in humans are currently limited. The condiments market has been growing continuously over the last few years, with the quantity of products sold under the category of sauces, dressings, and condiments during the period 2008-2013 increasing from 31,749,000 to 35,795,000 metric tons. About 50 of the 86 spices produced in the world are grown in India. From 2008 to 2013, the United States was the largest importer of spices, followed by Australia, the United Kingdom, Canada, and Russia. The main buyers of fish sauce are Vietnam and Thailand, with purchases of 333,000 and 284,000 metric tons in 2013, respectively. The sauces and condiments category is dynamic, with large differences in consumption in habits and practices among countries. This paper aims to establish definitions and discuss potential health benefits, consumption patterns, and global markets for sauces, spices, and condiments.

Overdose Intake of Curcumin Initiates the Unbalanced State of Bodies

Curcumin is the major active component of turmeric and widely used as a spice and coloring agent in food. However, its safety evaluation has been little investigated. To evaluate the 90-day subchronic toxicity of curcumin in rats, its general observation, clinical biochemistry, pathology, and metabolomics were evaluated. The results showed that curcumin induced liver injury through the generation of the overexpression of reactive oxygen species (ROS) and pro-inflammatory cytokines IL-6 and the decreases of the levels of antioxidant enzyme SOD and detoxified enzyme GST. Meanwhile, for the self-protection of rats, curcumin treatment activated the transcription of Nrf-2 and elevated the expression of HO-1 to reduce tissue damage. Furthermore, curcumin significantly increased key mRNA levels of HK2, PKM2, LDHA, CES, Cpt1, Cpt2, FASN, and ATP5b and decreased levels of GLUT2 and ACC1 to enhance glycolysis and inhibit lipid metabolism and TCA cycle. Therefore, overdose or long-term intake of curcumin could initiate the unbalanced state of bodies through oxidative stress, inflammation, and metabolic disorders, which induces liver injury. Intermittent administration of curcumin is necessary in our daily lives.

A Kinetic Degradation Study of Curcumin in Its Free Form and Loaded in Polymeric Micelles

Curcumin, a phenolic compound, possesses many pharmacological activities and is under clinical evaluation to treat different diseases. However, conflicting data about its stability have been reported. In this study, the kinetic degradation of curcumin from a natural curcuminoid mixture under various conditions (pH, temperature, and dielectric constant of the medium) was investigated. Moreover, the degradation of pure curcumin at some selected conditions was also determined. To fully solubilize curcumin and to prevent precipitation of curcumin that occurs when low concentrations of co-solvent are present, a 50:50 (v/v) aqueous buffer/methanol mixture was used as standard medium to study its degradation kinetics. The results showed that degradation of curcumin both as pure compound and present in the curcuminoid mixture followed first order kinetic reaction. It was further shown that an increasing pH, temperature, and dielectric constant of the medium resulted in an increase in the degradation rate. Curcumin showed rapid degradation due to autoxidation in aqueous buffer pH = 8.0 with a rate constant of 280 × 10(-3) h(-1), corresponding with a half-life (t1/2) of 2.5 h. Dioxygenated bicyclopentadione was identified as the final degradation product. Importantly, curcumin loaded as curcuminoid mixture in ω-methoxy poly (ethylene glycol)-b-(N-(2-benzoyloxypropyl) methacrylamide) (mPEG-HPMA-Bz) polymeric micelles and in Triton X-100 micelles was about 300-500 times more stable than in aqueous buffer. Therefore, loading of curcumin into polymeric micelles is a promising approach to stabilize this compound and develop formulations suitable for further pharmaceutical and clinical studies.

Determining whether curcumin degradation/condensation is actually bioactivation (Review)

Curcumin has been shown to exert therapeutic or protective effects against a variety of diseases, such as cancer, pulmonary diseases, neurological, liver, metabolic, autoimmune, cardiovascular diseases and numerous other chronic ailments. Over 116 clinical studies on curcumin in humans were registered with the US National Institutes of Health in 2015. However, it is mystifying how curcumin can be so effective in the treatment of many diseases since it has very low water solubility and bioavailability. Furthermore, curcumin is not stable under various conditions; its degradation or condensation into different bioactive compounds may be responsible for its biological activities rather than curcumin itself. In this review, we provide evidence of curcumin degradation and condensation into different compounds which have or may have health benefits themselves. Literature reviews strongly suggest that these molecules contribute to the observed health benefits, rather than curcumin itself.

ROS generation mediates the anti-cancer effects of WZ35 via activating JNK and ER stress apoptotic pathways in gastric cancer

Gastric cancer is one of the leading causes of cancer mortality in the world, and finding novel agents and strategies for the treatment of advanced gastric cancer is of urgent need. Curcumin is a well-known natural product with anti-cancer ability, but is limited by its poor chemical stability. In this study, an analog of curcumin with high chemical stability, WZ35, was designed and evaluated for its anti-cancer effects and underlying mechanisms against human gastric cancer. WZ35 showed much stronger anti-proliferative effects than curcumin, accompanied by dose-dependent induction of cell cycle arrest and apoptosis in gastric cancer cells. Mechanistically, our data showed that WZ35 induced reactive oxygen species (ROS) production, resulting in the activation of both JNK-mitochondrial and ER stress apoptotic pathways and eventually cell apoptosis in SGC-7901 cells. Blockage of ROS production totally reversed WZ35-induced JNK and ER stress activation as well as cancer cell apoptosis. In vivo, WZ35 showed a significant reduction in SGC-7901 xenograft tumor size in a dose-dependent manner. Taken together, this work provides a novel anticancer candidate for the treatment of gastric cancer, and importantly, reveals that increased ROS generation might be an effective strategy in human gastric cancer treatment.

How does curcumin work with poor bioavailability? Clues from experimental and theoretical studies

Curcumin is a natural product with multiple biological activities and numerous potential therapeutic applications. However, its poor systemic bioavailability fails to explain the potent pharmacological effects and hinders its clinical application. Using experimental and theoretical approaches, we compared curcumin and its degradation products for its biological activities against Alzheimer's disease (AD), including the superoxide anion radical (O2(.-))-scavenging activity, Aβ fibrils (fAβ) formation-inhibiting activity, and enzymatic inhibition activity. We showed that compared to the parent compound curcumin, the degradation products mixture possessed higher O2(.-)-scavenging activity and stronger inhibition against fAβ formation. The docking simulations revealed that the bioactive degradation products should make important contribution to the experimentally observed enzymatic inhibition activities of curcumin. Given that curcumin is readily degraded under physiological condition, our findings strongly suggested that the degradation products should make important contribution to the diverse biological activities of curcumin. Our novel findings not only provide novel insights into the complex pharmacology of curcumin due to its poor bioavailability, but also open new avenues for developing therapeutic applications of this natural product.

Curcumin inhibits metastasis in human papillary thyroid carcinoma BCPAP cells via down-regulation of the TGF-β/Smad2/3 signaling pathway

Thyroid cancers usually possess a good prognosis while the risks of recurrence and metastasis turn out to be a disturbing issue. Curcumin [bis(4-hydroxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione] is a natural polyphenolic compound mainly found in turmeric (Curcuma longa). Our previous studies have demonstrated that curcumin showed proliferation-inhibitory and apoptosis-inducing effects on K1 papillary thyroid cancer cells. However, the mechanism underlying the inhibition effects of curcumin on thyroid cancer cells remains unclear. Herein, we demonstrated that curcumin remarkably increased the expression of the epithelial marker E-cadherin and repressed the expression of the mesenchymal marker vimentin in human papillary thyroid carcinoma BCPAP cells. Curcumin also suppressed multiple metastatic steps of BCPAP cells, including cell attachment, spreading as well as migration. In addition, the transcription, secretion and activation of matrix metalloproteinases (MMPs) induced by transforming growth factor-β1 (TGF-β1) in BCPAP cells were mitigated upon curcumin treatment. Further evidence showed that curcumin decreased TGF-β1-mediated phosphorylation of Smad2 and Smad3. These results revealed that curcumin inhibited the TGF-β1-induced epithelial-mesenchymal transition (EMT) via down-regulation of Smad2/3 signaling pathways. Our findings provide new evidence that the anti-metastatic and anti-EMT activities of curcumin may contribute to the development of chemo-preventive agents for thyroid cancer treatment.

Pharmacological inhibition of lipid droplet formation enhances the effectiveness of curcumin in glioblastoma

Increased lipid droplet number and fatty acid synthesis allow glioblastoma multiforme, the most common and aggressive type of brain cancer, to withstand accelerated metabolic rates and resist therapeutic treatments. Lipid droplets are postulated to sequester hydrophobic therapeutic agents, thereby reducing drug effectiveness. We hypothesized that the inhibition of lipid droplet accumulation in glioblastoma cells using pyrrolidine-2, a cytoplasmic phospholipase A2 alpha inhibitor, can sensitize cancer cells to the killing effect of curcumin, a promising anticancer agent isolated from the turmeric spice. We observed that curcumin localized in the lipid droplets of human U251N glioblastoma cells. Reduction of lipid droplet number using pyrrolidine-2 drastically enhanced the therapeutic effect of curcumin in both 2D and 3D glioblastoma cell models. The mode of cell death involved was found to be mediated by caspase-3. Comparatively, the current clinical chemotherapeutic standard, temozolomide, was significantly less effective in inducing glioblastoma cell death. Together, our results suggest that the inhibition of lipid droplet accumulation is an effective way to enhance the chemotherapeutic effect of curcumin against glioblastoma multiforme.

Food-grade nanoparticles for encapsulation, protection and delivery of curcumin: comparison of lipid, protein, and phospholipid nanoparticles under simulated gastrointestinal conditions

The potential of three nanoparticle-based delivery systems to improve curcumin bioavailability was investigated: lipid nPs (nanoemulsions); protein nPs (zein nanosuspensions); and, phospholipid nPs (nanoliposomes).

A novel aminoclay–curcumin hybrid for enhanced chemotherapy

“One-pot” synthesis is developed to fabricate the AC–Cur hybrid with high bioavailability.