Curcumin enhances non-inflammatory phagocytic activity of RAW264.7 cells

Polyphenols: immunonutrients tipping the balance of immunometabolism in chronic diseases

Mounting evidence progressively appreciates the vital interplay between immunity and metabolism in a wide array of immunometabolic chronic disorders, both autoimmune and non-autoimmune mediated. The immune system regulates the functioning of cellular metabolism within organs like the brain, pancreas and/or adipose tissue by sensing and adapting to fluctuations in the microenvironment's nutrients, thereby reshaping metabolic pathways that greatly impact a pro- or anti-inflammatory immunophenotype. While it is agreed that the immune system relies on an adequate nutritional status to function properly, we are only just starting to understand how the supply of single or combined nutrients, all of them termed immunonutrients, can steer immune cells towards a less inflamed, tolerogenic immunophenotype. Polyphenols, a class of secondary metabolites abundant in Mediterranean foods, are pharmacologically active natural products with outstanding immunomodulatory actions. Upon binding to a range of receptors highly expressed in immune cells (e.g. AhR, RAR, RLR), they act in immunometabolic pathways through a mitochondria-centered multi-modal approach. First, polyphenols activate nutrient sensing via stress-response pathways, essential for immune responses. Second, they regulate mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) balance in immune cells and are well-tolerated caloric restriction mimetics. Third, polyphenols interfere with the assembly of NLR family pyrin domain containing 3 (NLRP3) in endoplasmic reticulum-mitochondria contact sites, inhibiting its activation while improving mitochondrial biogenesis and autophagosome-lysosome fusion. Finally, polyphenols impact chromatin remodeling and coordinates both epigenetic and metabolic reprogramming. This work moves beyond the well-documented antioxidant properties of polyphenols, offering new insights into the multifaceted nature of these compounds. It proposes a mechanistical appraisal on the regulatory pathways through which polyphenols modulate the immune response, thereby alleviating chronic low-grade inflammation. Furthermore, it draws parallels between pharmacological interventions and polyphenol-based immunonutrition in their modes of immunomodulation across a wide spectrum of socioeconomically impactful immunometabolic diseases such as Multiple Sclerosis, Diabetes (type 1 and 2) or even Alzheimer's disease. Lastly, it discusses the existing challenges that thwart the translation of polyphenols-based immunonutritional interventions into long-term clinical studies. Overcoming these limitations will undoubtedly pave the way for improving precision nutrition protocols and provide personalized guidance on tailored polyphenol-based immunonutrition plans.

Microcurrent Cloth-Assisted Transdermal Penetration and Follicular Ducts Escape of Curcumin-Loaded Micelles for Enhanced Wound Healing

Purpose

Larger nanoparticles of bioactive compounds deposit high concentrations in follicular ducts after skin penetration. In this study, we investigated the effects of microcurrent cloth on the skin penetration and translocation of large nanoparticle applied for wound repair applications.

Methods

A self-assembly of curcumin-loaded micelles (CMs) was prepared to improve the water solubility and transdermal efficiency of curcumin. Microcurrent cloth (M) was produced by Zn/Ag electrofabric printing to facilitate iontophoretic transdermal delivery. The transdermal performance of CMs combined with M was evaluated by a transdermal system and confocal microscopy. The CMs/iontophoretic combination effects on nitric oxide (NO) production and inflammatory cytokines were evaluated in Raw 264.7 cells. The wound-healing property of the combined treatment was assessed in a surgically created full-thickness circular wound mouse model.

Results

Energy-dispersive X-ray spectroscopy confirmed the presence of Zn/Ag on the microcurrent cloth. The average potential of M was measured to be +214.6 mV in PBS. Large particle CMs (CM-L) prepared using surfactant/cosurfactant present a particle size of 142.9 nm with a polydispersity index of 0.319. The solubility of curcumin in CM-L was 2143.67 μg/mL, indicating 250-fold higher than native curcumin (8.68 μg/mL). The combined treatment (CM-L+M) demonstrated a significant ability to inhibit NO production and increase IL-6 and IL-10 secretion. Surprisingly, microcurrent application significantly improved 20.01-fold transdermal performance of curcumin in CM-L with an obvious escape of CM-L from follicular ducts to surrounding observed by confocal microscopy. The CM-L+M group also exhibited a better wound-closure rate (77.94% on day 4) and the regenerated collagen intensity was approximately 2.66-fold higher than the control group, with a closure rate greater than 90% on day 8 in vivo.

Conclusion

Microcurrent cloth play as a promising iontophoretic transdermal drug delivery accelerator that enhances skin penetration and assists CMs to escape from follicular ducts for wound repair applications.

Curcumin as a Stabilizer of Macrophage Polarization during Plasmodium Infection

Malaria is a parasitic infection responsible for high morbidity and mortality rates worldwide. During the disease, phagocytosis of infected red blood cells by the macrophages induces the production of reactive oxygen (ROS) and nitrogen species (RNS), culminating in parasite death. Curcumin (CUR) is a bioactive compound that has been demonstrated to reduce the production of pro-inflammatory cytokines and chemokines produced by macrophages but to reduce parasitemia in infected mice. Hence, the main purpose of this study is to investigate whether curcumin may interfere with macrophage function and polarization after Plasmodium berghei infection in vitro. In our findings, non-polarized macrophage (M0), classically activated (M1), and alternatively activated (M2) phenotypes showed significantly increased phagocytosis of infected red blood cells (iRBCs) when compared to phagocytosis of uninfected red blood cells (RBCs) 3 h after infection. After 24 h, M1 macrophages exposed to RBCs + CUR showed greater elimination capacity when compared to macrophages exposed to iRBCs + CUR, suggesting the interference of curcumin with the microbicidal activity. Additionally, curcumin increased the phagocytic activity of macrophages when used in non-inflammatory conditions (M0) and reduced the inducible nitric oxide synthase (iNOS) and arginase activities in all macrophage phenotypes infected (M0, M1, and M2), suggesting interference in arginine availability by curcumin and balance promotion in macrophage polarization in neutral phenotype (M0). These results support the view of curcumin treatment in malaria as an adjuvant, promoting a balance between pro- and anti-inflammatory responses for a better clinical outcome.

Biological activities of extracts and compounds from Thai Kae-Lae (Maclura cochinchinensis (Lour.) Corner)

BACKGROUND AND AIMS

The purpose of this study was to investigate the biological properties of Kae-Lae (Maclura cochinchinensis (Lour.) Corner), a traditional medicinal plant used in Ayurvedic recipes in Thailand. To achieve this objective, heartwood samples were collected from 12 sources across Thailand. Fractional extracts (n-hexane, ethyl acetate, and ethanol) and the dominant compounds (morin, resveratrol, and quercetin) were examined for their abilities on cytotoxicity, antioxidant, anti-inflammation, and antileukaemic activity (Wilms' tumour 1 protein was used as a well-known biomarker for leukaemic cell proliferation).

METHODS

The study used MTT to assess cytotoxicity in leukaemic cells (K562, EoL-1, and KG-1a). Antioxidant activities were evaluated using ABTS, DPPH, and FRAP assays. The anti-inflammatory activity was investigated by detecting IL-2, TNF-α, and NO using appropriate detection kits. Wilms' tumour 1 protein expression was measured by Western blotting to determine the anti-leukaemic activity. The inhibition of cell migration was also analyzed to confirm anticancer progression.

RESULTS

Among the tested extract fraction, ethyl acetate No. 001 displayed strong cytotoxicity specifically in EoL-1 cells, while n-hexane No. 008 demonstrated this effect in three cell lines. Resveratrol, on the other hand, displayed cytotoxicity in all the tested cells. Additionally, the three major compounds, morin, resveratrol, and quercetin, exhibited significant antioxidant and anti-inflammatory properties. In particular, resveratrol demonstrated a noteworthy decreased Wilms' tumour 1 protein expression and a reduction in cell proliferation across all cells. Moreover, ethyl acetate No. 001, morin, and resveratrol effectively inhibited MCF-7 cell migration. None of these compounds showed any impact on red blood cell haemolysis.

CONCLUSION

Based on these findings, it can be concluded that Kae-Lae has promising chemotherapeutic potential against leukaemic cells, with fractional extracts (ethyl acetate and n-hexane) and resveratrol exhibiting the most potent cytotoxic, antioxidant, anti-inflammatory, and anti-cell migration activities.

Tumor immunomodulatory effects of polyphenols

Polyphenols, commonly found in various plants, have attracted enormous attention due to their potential pharmacological activity, especially antitumor activity dependent on immune function. In recent years, the development of nanomedicine can counteract the low bioavailability of polyphenols and improve the effect of tumor treatment. Among them, metal-phenolic networks (MPNs), which utilize various metal ions and phenolic ligands for coordination binding, have now become candidates for polyphenol-based nanomedicine treatment of tumors. In this mini-review, we described the classification of polyphenols and their mechanisms in antitumor immune responses, and provided suggestions for the next steps of treating tumors with polyphenols.

Optimisation of enzyme-assisted extraction of Erythronium sibiricum bulb polysaccharide and its effects on immunomodulation

In this study, polysaccharides of Erythronium sibiricum bulb were extracted using enzyme-assisted extraction technology and then optimised by response surface methodology. The characteristics and immunomodulatory activities of the polysaccharide (E1P) were investigated. Setting the yield of polysaccharides as the index, the effects of amylase content, zymolytic time, extraction pH and zymolytic temperature were investigated. The optimal extraction conditions for polysaccharides were as follows: amylase content, 1% weight of pre-treated powder; zymolytic time, 2 h; extraction pH, 7.5; and zymolytic temperature, 55 °C. The yield was predicted to be 61.10%, which agreed with the value obtained in confirmatory experiments (59.71% ± 2.72%). Further research indicated that the primary component of E1P is glucose; however, it also contains a small quantity of galactose and arabinose. In vitro assays showed that E1P and ESBP (another kind of E. sibiricum bulb polysaccharide extracted by water decoction in our previous study) could significantly promote the cellular viability and phagocytosis of RAW264.7 cells without cytotoxicity. Moreover, they could enhance the ability to secrete nitric oxide and cytokines such as TNF-α and IL-1β. However, the immunomodulatory activities of E1P were better than those of ESBP. According to the results of this study, enzyme-assisted extraction represents a new strategy for extracting E. sibiricum bulb polysaccharides with higher yield and better immune activity.

IL-10-Dependent Amelioration of Chronic Inflammatory Disease by Microdose Subcutaneous Delivery of a Prototypic Immunoregulatory Small Molecule

One of the interventional strategies to reestablish the immune effector/regulatory balance, that is typically altered in chronic inflammatory diseases (CID), is the reinforcement of endogenous immunomodulatory pathways as the one triggered by interleukin (IL)-10. In a recent work, we demonstrated that the subcutaneous (sc) administration of an IL-10/Treg-inducing small molecule-based formulation, using a repetitive microdose (REMID) treatment strategy to preferentially direct the effects to the regional immune system, delays the progression of atherosclerosis. Here we investigated whether the same approach using other IL-10-inducing small molecule, such as the safe, inexpensive, and widely available polyphenol curcumin, could induce a similar protective effect in two different CID models. We found that, in apolipoprotein E deficient mice, sc treatment with curcumin following the REMID strategy induced atheroprotection that was not consequence of its direct systemic lipid-modifying or antioxidant activity, but instead paralleled immunomodulatory effects, such as reduced proatherogenic IFNγ/TNFα-producing cells and increased atheroprotective FOXP3⁺ Tregs and IL-10-producing dendritic and B cells. Remarkably, when a similar strategy was used in the neuroinflammatory model of experimental autoimmune encephalomyelitis (EAE), significant clinical and histopathological protective effects were evidenced, and these were related to an improved effector/regulatory cytokine balance in restimulated splenocytes. The essential role of curcumin-induced IL-10 for neuroprotection was confirmed by the complete abrogation of the clinical effects in IL-10-deficient mice. Finally, the translational therapeutic prospection of this strategy was evidenced by the neuroprotection observed in mice starting the treatment one week after disease triggering. Collectively, results demonstrate the power of a simple natural IL-10-inducing small molecule to tackle chronic inflammation, when its classical systemic and direct pharmacological view is shifted towards the targeting of regional immune cells, in order to rationally harness its immunopharmacological potential. This shift implies that many well-known IL-10-inducing small molecules could be easily reformulated and repurposed to develop safe, innovative, and accessible immune-based interventions for CID.

The role of macrophage polarization and function in environmental toxicant-induced cancers

Macrophages are a critical member of the innate immune system and can intensify tumor invasiveness and assist the growth of neoplastic cells. Moreover, they have the capability to reinforce immunosuppression and angiogenesis. Various investigations suggest that health-related issues, including inflammatory disorders and neoplastic diseases may be caused by environmental toxicant exposure. However, it is still unclear what role these environmental toxicants play in causing carcinogenesis by disturbing the mechanisms of migration, polarization, differentiation, and immune-stimulatory functions of macrophages. Accordingly, in this article, we will explore the interaction between environmental chemicals and inflammatory macrophage processes at the molecular level and their association with tumor progression and carcinogenesis.

Targeting non-apoptotic cell death in cancer treatment by nanomaterials: Recent advances and future outlook

Many tumors develop resistance to most of the apoptosis-based cancer therapies. In this sense targeting non-apoptotic forms of cell death including necroptosis, autophagy and ferroptosis may have therapeutic benefits in apoptosis-defective cancer cells. Nanomaterials have shown great advantages in cancer treatment owing to their unique characteristics. Besides, the capability of nanomaterials to induce different forms of cell death has gained widespread attention in cancer treatment. Reports in this field reflect the therapeutic potential of necroptotic cell death induced by nanomaterials in cancer. Also, autophagic cell death induced by nanomaterials alone and as a part of chemo-, radio- and photothermal therapy holds great promise as anticancer therapeutic option. Besides, ferroptosis induction by iron-based nanomaterials in drug delivery, immunotherapy, hyperthermia and imaging systems shows promising results in malignancies. Hence, this review is devoted to the latest efforts and the challenges in this field of research and its clinical merits.

Semisynthetic quercetin-quinone mitigates BV-2 microglia activation through modulation of Nrf2 pathway

During brain ageing, microglia, the resident immune cells of the CNS, are immunologically activated and contribute to neuroinflammation, a vicious cycle that supports development of neurological disorders. Therapeutic approaches focus mainly on downregulation of their pro-inflammatory activated state that is associated with health benefits. Electrophilic compounds, such as natural quinones and their reduced pro-electrophilic precursors, flavonoids, represent a wide group of diverse substances with important biological effects. They can cause considerable cytotoxicity when used at higher dosages, but on the other hand, they have versatile health benefits at lower dosages. In this study, we investigated the cytotoxicity and prooxidant profile of synthetic conjugate of two electrophilic compounds, quercetin and 1,4-naphthoquinone, 4'-O-(2-chloro-1,4-naphthoquinone-3-yloxy) quercetin (CHNQ), and its attenuation of inflammatory responses and modulation of Nrf2 pathway in BV-2 microglial cells. CHNQ showed higher cytotoxicity than its precursors, accompanied by promotion of production of reactive oxygen species along with G2/M cell cycle arrest at higher concentrations tested. Nevertheless, at a lower non-toxic concentration, CHNQ, more significantly than did its precursors, downregulated LPS-stimulated microglia cells as documented by decreased iNOS, COX-2 and TNFα protein levels. Moreover, CHNQ most effectively upregulated expression of phase II antioxidant enzyme HO-1 and β5 subunit of constitutive proteasome. The enhanced anti-inflammatory effect of CHNQ was accompanied by prominent increase in cytosolic expression of Nrf2 and c-Jun, however, induction effect on nuclear Nrf2 translocation was comparable to QUER. Moreover, a conditioned medium from activated BV-2 cells co-treated with quercetin and CHNQ maintained viability of neuron-like PC12 cells. The compounds tested did not show any disturbance of phagocytosis of live or dead PC12 cells. The present experimental data predict a preventive and therapeutic potential of semisynthetic derivative CHNQ in ageing and related pathologies, mediated by activation of proteins of the antioxidant response.

Macrophage plasticity, polarization and function in response to curcumin, a diet-derived polyphenol, as an immunomodulatory agent

Monocytes and macrophages are important cells of the innate immune system that have diverse functions, including defense against invading pathogens, removal of dead cells by phagocytosis, antigen presentation in the context of MHC class I and class II molecules, and production of various pro-inflammatory cytokines and chemokines such as IL-1β, IL-6, TNF-α and MCP-1. In addition, pro-inflammatory (M1) and anti-inflammatory (M2) macrophages clearly play important roles in the progression of several inflammatory diseases. Therefore, therapies that target macrophage polarization and function by either blocking their trafficking to sites of inflammation, or skewing M1 to M2 phenotype polarization may hold clinical promise in several inflammatory diseases. Dietary-derived polyphenols have potent natural anti-oxidative properties. Within this group of polyphenols, curcumin has been shown to suppress macrophage inflammatory responses. Curcumin significantly reduces co-stimulatory molecules and also inhibits MAPK activation and the translocation of NF-κB p65. Curcumin can also polarize/repolarize macrophages toward the M2 phenotype. Curcumin-treated macrophages have been shown to be highly efficient at antigen capture and endocytosis via the mannose receptor. These novel findings provide new perspectives for the understanding of the immunopharmacological role of curcumin, as well as its therapeutic potential for impacting macrophage polarization and function in the context of inflammation-related disease. However, the precise effects of curcumin on the migration, differentiation, polarization and immunostimulatory functions of macrophages remain unknown. Therefore, in this review, we summarized whether curcumin can influence macrophage polarization, surface molecule expression, cytokine and chemokine production and their underlying pathways in the prevention of inflammatory diseases.

Immunosuppressive Effects of Natural α,β-Unsaturated Carbonyl-Based Compounds, and Their Analogs and Derivatives, on Immune Cells: A Review

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or immune deficiency diseases. Compounds containing α,β-unsaturated carbonyl-based moieties are often reactive. The reactivity of these groups is responsible for their diverse pharmacological activities, and the most important and widely studied include the natural compounds curcumin, chalcone, and zerumbone. Numerous studies have revealed the mainly immunosuppressive and anti-inflammatory activities of the aforesaid compounds. This review highlights the specific immunosuppressive effects of these natural α,β-unsaturated carbonyl-based compounds, and their analogs and derivatives on different types of immune cells of the innate (granulocytes, monocytes, macrophages, and dendritic cells) and adaptive (T cells, B cells, and natural killer cells) immune systems. The inhibitory effects of these compounds have been comprehensively studied on neutrophils, monocytes and macrophages but their effects on T cells, B cells, natural killer cells, and dendritic cells have not been well investigated. It is of paramount importance to continue generating experimental data on the mechanisms of action of α,β-unsaturated carbonyl-based compounds on immune cells to provide useful information for ensuing research to discover new immunomodulating agents.

Effects of curcumin on Helicobacter pylori infection

BACKGROUND

Curcumin is a well-established natural molecule with significant biological and pharmaceutical effects. Its effects on Helicobacter pylori (H. pylori) infection have been repeatedly confirmed both in animal and human models. This study directly compared five different samples to evaluate if the effects are general or if they differ among samples.

METHODS

Using a mouse model, we studied the effects of curcumin on lipid peroxide (LPO) level, myeloperoxidase (MPO) and urease activity, number of colonized bacteria, levels of anti-H. pylori antibodies, biofilm formation, IFN-γ, IL-4, gastrin and somatostatin levels in serum, and minimum inhibitory concentration. In addition, we evaluated the effects on biofilm production and antibacterial antibody response.

RESULTS

In all tests, one sample (Sabinsa) was consistently the most active.

CONCLUSIONS

All curcumin samples showed some anti-H. pylori effects, but only some of the tested samples had significant activity.

Transient spectra study on photo-dynamics of curcumin

A novel mechanism of DNA damage induced by photosensitized curcumin (Cur) was explored using laser flash photolysis, pulse radiolysis and gel electrophoresis. Cur neutral radical (Cur) was confirmed as an identical product in photo-sensitization of Cur by laser flash photolysis and pulse radiolysis. A series of reaction rate constants between Cur and nucleic acid bases/nucleotides were determined by pulse radiolysis. Gel electrophoresis was carried out to investigate damage induced by photosensitized Cur to biologically active DNA. The results indicate that the damage to DNA may be caused by Cur produced from the photosensitization of Cur.

Curcumin inhibits development and cell adhesion in Dictyostelium discoideum: Implications for YakA signaling and GST enzyme function

The molecular basis for nutraceutical properties of the polyphenol curcumin (Curcuma longa, Turmeric) is complex, affecting multiple factors that regulate cell signaling and homeostasis. Here, we report the effect of curcumin on cellular and developmental mechanisms in the eukaryotic model, Dictyostelium discoideum. Dictyostelium proliferation was inhibited in the presence of curcumin, which also suppressed the prestarvation marker, discoidin I, members of the yakA-mediated developmental signaling pathway, and expression of the extracellular matrix/cell adhesion proteins (DdCAD and csA). This resulted in delayed chemotaxis, adhesion, and development of the organism. In contrast to the inhibitory effects on developmental genes, curcumin induced gstA gene expression, overall GST activity, and generated production of reactive oxygen species. These studies expand our knowledge of developmental and biochemical signaling influenced by curcumin, and lends greater consideration of GST enzyme function in eukaryotic cell signaling, development, and differentiation.

Modulation of BV-2 microglia functions by novel quercetin pivaloyl ester

Chronic inflammation in brain plays a critical role in major neurodegenerative diseases such as Alzheimer's, Parkinson's disease, stroke or multiple sclerosis. Microglia, resident macrophages and intristinc components of CNS, appear to be main effectors in this pathological process. Quercetin, a naturally occurring flavonoid, was proven to downregulate inflammatory genes in microglia. Synthetically modified quercetin, 3'-O-(3-chloropivaloyl) quercetin (CPQ), is assumed to possess better biological availability and enhanced antioxidant properties. In the present study, antineuroinflammatory capability of the novel compound CPQ was assessed in BV-2 microglial cells. Our data show that treatment with CPQ attenuated the production of the inflammatory mediators, nitric oxide (NO) and tumour necrosis factor-α (TNF-α), in LPS-stimulated microglia somewhat more efficiently than did quercetin (p > 0.05 for CPQ vs. quercetin-treated group). Also, protein level of inducible NO synthase (iNOS) in LPS-activated BV-2 microglia was to some extent more effectively supressed by CPQ than by unmodified flavonoid. In consistence with the extent of their effects on pro-inflammatory markers, CPQ and quercetin showed down-regulation of NFκB activation. This quercetin analogue caused also a decline in BV-2 microglia proliferation with interfering with cell cycle progression (p < 0.001 for CPQ vs. quercetin-treated group). However, CPQ did not remarkably affect cell viability. In addition, CPQ showed a minor better suppression of PMA-induced generation of superoxide than did quercetin. Neither CPQ nor quercetin influenced phagocytosis of BV-2 cells. These results point to the therapeutic potential of 3'-O-(3-chloropivaloyl)quercetin (CPQ) as a novel antiinflammatory drug in neurodegenerative diseases, mediating favourable modulation of pro-inflammatory functions of microglia.

Anti-Inflammatory Effects of Novel Standardized Solid Lipid Curcumin Formulations

Inflammation and the presence of pro-inflammatory cytokines are associated with numerous chronic diseases such as type-2 diabetes mellitus, cardiovascular disease, Alzheimer's disease, and cancer. An overwhelming amount of data indicates that curcumin, a polyphenol obtained from the Indian spice turmeric, Curcuma longa, is a potential chemopreventive agent for treating certain cancers and other chronic inflammatory diseases. However, the low bioavailability of curcumin, partly due to its low solubility and stability in the digestive tract, limits its therapeutic applications. Recent studies have demonstrated increased bioavailability and health-promoting effects of a novel solid lipid particle formulation of curcumin (Curcumin SLCP, Longvida(®)). The goal of this study was to evaluate the aqueous solubility and in vitro anti-inflammatory effects of solid lipid curcumin particle (SLCP) formulations using lipopolysaccharide (LPS)-stimulated RAW 264.7 cultured murine macrophages. SLCPs treatment significantly decreased nitric oxide (NO) and prostaglandin-E2 (PGE2) levels at concentrations ranging from 10 to 50 μg/mL, and reduced interleukin-6 (IL-6) levels in a concentration-dependent manner. Transient transfection experiments using a nuclear factor-kappa B (NF-κB) reporter construct indicate that SLCPs significantly inhibit the transcriptional activity of NF-κB in macrophages. Taken together, these results show that in RAW 264.7 murine macrophages, SLCPs have improved solubility over unformulated curcumin, and significantly decrease the LPS-induced pro-inflammatory mediators NO, PGE2, and IL-6 by inhibiting the activation of NF-κB.

Low-dose curcumin stimulates proliferation, migration and phagocytic activity of olfactory ensheathing cells

One of the promising strategies for neural repair therapies is the transplantation of olfactory ensheathing cells (OECs) which are the glial cells of the olfactory system. We evaluated the effects of curcumin on the behaviour of mouse OECs to determine if it could be of use to further enhance the therapeutic potential of OECs. Curcumin, a natural polyphenol compound found in the spice turmeric, is known for its anti-cancer properties at doses over 10 µM, and often at 50 µM, and it exerts its effects on cancer cells in part by activation of MAP kinases. In contrast, we found that low-dose curcumin (0.5 µM) applied to OECs strikingly modulated the dynamic morphology, increased the rate of migration by up to 4-fold, and promoted significant proliferation of the OECs. Most dramatically, low-dose curcumin stimulated a 10-fold increase in the phagocytic activity of OECs. All of these potently stimulated behavioural characteristics of OECs are favourable for neural repair therapies. Importantly, low-dose curcumin gave a transient activation of p38 kinases, which is in contrast to the high dose curcumin effects on cancer cells in which these MAP kinases tend to undergo prolonged activation. Low-dose curcumin mediated effects on OECs demonstrate cell-type specific stimulation of p38 and ERK kinases. These results constitute the first evidence that low-dose curcumin can modulate the behaviour of olfactory glia into a phenotype potentially more favourable for neural repair and thereby improve the therapeutic use of OECs for neural repair therapies.

Therapeutic potential of turmeric in Alzheimer's disease: curcumin or curcuminoids?

Alzheimer's disease (AD) is the most common form of dementia. There is limited choice in modern therapeutics, and drugs available have limited success with multiple side effects in addition to high cost. Hence, newer and alternate treatment options are being explored for effective and safer therapeutic targets to address AD. Turmeric possesses multiple medicinal uses including treatment for AD. Curcuminoids, a mixture of curcumin, demethoxycurcumin, and bisdemethoxycurcumin, are vital constituents of turmeric. It is generally believed that curcumin is the most important constituent of the curcuminoid mixture that contributes to the pharmacological profile of parent curcuminoid mixture or turmeric. A careful literature study reveals that the other two constituents of the curcuminoid mixture also contribute significantly to the effectiveness of curcuminoids in AD. Therefore, it is emphasized in this review that each component of the curcuminoid mixture plays a distinct role in making curcuminoid mixture useful in AD, and hence, the curcuminoid mixture represents turmeric in its medicinal value better than curcumin alone. The progress in understanding the disease etiology demands a multiple-site-targeted therapy, and the curcuminoid mixture of all components, each with different merits, makes this mixture more promising in combating the challenging disease.

A comparative study of curcuminoids to measure their effect on inflammatory and apoptotic gene expression in an Aβ plus ibotenic acid-infused rat model of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder, which depicts features of chronic inflammatory conditions resulting in cellular death and has limited therapeutic options. We aimed to explore the effect of a curcuminoid mixture and its individual components on inflammatory and apoptotic genes expression in AD using an Aβ+ibotenic acid-infused rat model. After 5 days of treatment with demethoxycurcumin, hippocampal IL-1β levels were decreased to 118.54 ± 47.48 and 136.67 ± 31.96% respectively at 30 and 10mg/kg, compared with the amyloid treated group (373.99 ± 15.28%). After 5 days of treatment, the curcuminoid mixture and demethoxycurcumin effectively decreased GFAP levels in the hippocampus. When studied for their effect on apoptotic genes expression, the curcuminoid mixture and bisdemethoxycurcumin effectively decreased caspase-3 level in the hippocampus after 20 days of treatment, where bisdemethoxycurcumin showed a maximal rescuing effect (92.35 ± 3.07%) at 3mg/kg. The curcuminoid mixture at 30 mg/kg decreased hippocampal FasL level to 70.56 ± 3.36% after 5 days of treatment and 19.01 ± 2.03% after 20 days. In the case of Fas receptor levels, demethoxycurcumin decreased levels after 5 days of treatment with all three doses showing a maximal effect (189.76 ± 15.01%) at 10mg/kg. Each compound was effective after 20 days in reducing Fas receptor levels in the hippocampus. This study revealed the important effect of curcuminoids on genes expression, showing that, each component of the curcuminoid mixture distinctly affects gene expression, thus highlighting the therapeutic potential of curcuminoids in AD.

The plant-based immunomodulator curcumin as a potential candidate for the development of an adjunctive therapy for cerebral malaria

The clinical manifestations of cerebral malaria (CM) are well correlated with underlying major pathophysiological events occurring during an acute malaria infection, the most important of which, is the adherence of parasitized erythrocytes to endothelial cells ultimately leading to sequestration and obstruction of brain capillaries. The consequent reduction in blood flow, leads to cerebral hypoxia, localized inflammation and release of neurotoxic molecules and inflammatory cytokines by the endothelium. The pharmacological regulation of these immunopathological processes by immunomodulatory molecules may potentially benefit the management of this severe complication. Adjunctive therapy of CM patients with an appropriate immunomodulatory compound possessing even moderate anti-malarial activity with the capacity to down regulate excess production of proinflammatory cytokines and expression of adhesion molecules, could potentially reverse cytoadherence, improve survival and prevent neurological sequelae. Current major drug discovery programmes are mainly focused on novel parasite targets and mechanisms of action. However, the discovery of compounds targeting the host remains a largely unexplored but attractive area of drug discovery research for the treatment of CM. This review discusses the properties of the plant immune-modifier curcumin and its potential as an adjunctive therapy for the management of this complication.

Immunomodulatory and therapeutic activity of curcumin

Inflammation is a disease of vigorous uncontrolled activated immune responses. Overwhelming reports have suggested that the modulation of immune responses by curcumin plays a dominant role in the treatment of inflammation and metabolic diseases. Observations from both in-vitro and in-vivo studies have provided strong evidence towards the therapeutic potential of curcumin. These studies have also identified a plethora of biological targets and intricate mechanisms of action that characterize curcumin as a potent 'drug' for numerous ailments. During inflammation the functional influence of lymphocytes and the related cross-talk can be modulated by curcumin to achieve the desired immune status against diseases. This review describes the regulation of immune responses by curcumin and effectiveness of curcumin in treatment of diseases of diverse nature.

Curcuminoids enhance memory in an amyloid-infused rat model of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease. There are a limited number of therapeutic options available for the treatment of AD. Curcuminoids (a mixture of bisdemethoxycurcumin, demethoxycurcumin and curcumin) is the main chemical constituent found in turmeric, a well known curry spice, having potential in the treatment of AD. The objective of this study was to investigate the effects of curcuminoid mixture and individual constituents on spatial learning and memory in an amyloid-beta (Abeta) peptide-infused rat model of AD and on the expression of PSD-95, synaptophysin and camkIV. Curcuminoid mixture showed a memory-enhancing effect in rats displaying AD-like neuronal loss only at 30 mg/kg, whereas individual components were effective at 3-30 mg/kg. A shorter duration treatment with test compounds showed that the curcuminoid mixture and bisdemethoxycurcumin increased PSD-95 expression in the hippocampus at 3-30 mg/kg, with maximum effect at a lower dose (3 mg/kg) with respective values of 470.5 and 587.9%. However, after a longer duration treatment, two other compounds (demethoxycurcumin and curcumin) also increased PSD-95 to 331.7 and 226.2% respectively at 30 mg/kg. When studied for their effect on synaptophysin in the hippocampus after the longer duration treatment, the curcuminoid mixture and all three individual constituents increased synaptophysin expression. Of these, demethoxycurcumin was the most effective showing a 350.1% increase (P<0.01) at 30 mg/kg compared to the neurotoxin group. When studied for their effect on camkIV expression after longer treatment in the hippocampus, only demethoxycurcumin at 30 mg/kg increased levels to 421.2%. These compounds salvaged PSD-95, synaptophysin and camkIV expression levels in the hippocampus in the rat AD model, which suggests multiple target sites with the potential of curcuminoids in spatial memory enhancing and disease modifying in AD.

Curcumin dramatically enhances retinoic acid-induced superoxide generating activity via accumulation of p47-phox and p67-phox proteins in U937 cells

The membrane bound cytochrome b558 composed of large gp91-phox and small p22-phox subunits, and cytosolic proteins p40-, p47- and p67-phox are important components of superoxide (O(2)(-))-generating system in phagocytes and B lymphocytes. A lack of this system in phagocytes is known to cause serious life-threatening infections. Here, we describe that curcumin, a polyphenol responsible for the yellow color of curry spice turmeric, dramatically activates the O(2)(-)-generating system during retinoic acid (RA)-induced differentiation of human monoblastic leukemia U937 cells to macrophage-like cells. When U937 cells were cultured in the presence of RA and curcumin, the O(2)(-)-generating activity increased more than 4-fold compared with that in the absence of the latter. Semiquantitative RT-PCR showed that co-treatment with RA and curcumin slightly enhanced gene expressions of the five components compared with those of the RA-treatment only. On the other hand, immunoblot analysis revealed that co-treatment with RA and curcumin caused remarkable accumulation of protein levels of p47-phox (to 7-fold) and p67-phox (to 4-fold) compared with those of the RA-treatment alone. These results suggested that curcumin dramatically enhances RA-induced O(2)(-)-generating activity via accumulation of cytosolic p47-phox and p67-phox proteins in U937 cells. Therefore, it should have the potential as an effective modifier in therapy of leukemia and/or as an immunopotentiator.