Oral administration of curcumin suppresses production of matrix metalloproteinase (MMP)-1 and MMP-3 to ameliorate collagen-induced arthritis: inhibition of the PKCdelta/JNK/c-Jun pathway

Rheumatoid arthritis-recent advances in pathogenesis and the anti-inflammatory effect of plant-derived COX inhibitors

The majority of people with autoimmune disorders, including those with rheumatoid arthritis, osteoarthritis, and tendonitis report pain, stiffness, and inflammation as major contributors to their worse quality of life in terms of overall health. Of all the available treatment options, COX inhibitors are the ones that are utilized most frequently to ease the symptoms. Various signaling cascades have been reported to be involved in the pathogenesis of rheumatoid arthritis which includes JAK/STAT, MAPK, and NF-kB signaling pathways, and several allopathic inhibitors (tofacitinib and baricitinib) have been reported to target the components of these cascades and have received approval for RA treatment. However, the prolonged use of these COX inhibitors and other allopathic drugs can pose serious health challenges due to their significant side effects. Therefore, searching for a more effective and side effect-free treatment for rheumatoid arthritis has unveiled phytochemicals as both productive and promising. Their therapeutic ability helps develop potent and safe drugs targeting immune-inflammatory diseases including RA. Various scientific databases were used for searching articles such as NCBI, SpringerLink, BioMed Central, ResearchGate, Google Scholar, Scopus, Nature, Wiley Online Library, and ScienceDirect. This review lists various phytochemicals and discusses their potential molecular targets in RA treatment, as demonstrated by various in vitro, in vivo (pre-clinical), and clinical studies. Several pre-clinical and clinical studies suggest that various phytochemicals can be an alternative promising intervention for attenuating and managing inflammation-associated pathogenesis of rheumatoid arthritis.

Curcumin-loaded alginate hydrogels for cancer therapy and wound healing applications: A review

Hydrogels have emerged as a versatile platform for a numerous biomedical application due to their ability to absorb a huge quantity of biofluids. In order to design hydrogels, natural polymers are an attractive option owing to their biocompatibility and biodegradability. Due to abundance in occurrence, cost effectiveness, and facile crosslinking approaches, alginate has been extensively investigated to fabricate hydrogel matrix. Management of cancer and chronic wounds have always been a challenge for pharmaceutical and healthcare sector. In both cases, curcumin have been shown significant improvement and effectiveness. However, the innate restraints like poor bioavailability, hydrophobicity, and rapid systemic clearance associated with curcumin have restricted its clinical translations. The current review explores the cascade of research around curcumin encapsulated alginate hydrogel matrix for wound healing and cancer therapy. The focus of the review is to emphasize the mechanistic effects of curcumin with its fate inside the cells. Further, the review discusses different approaches to designed curcumin loaded alginate hydrogels along with the parameters that regulates their release behavior. Finally, the review is concluded with emphasize on some key aspect on increasing the efficacy of these hydrogels along with novel strategies to further develop curcumin loaded alginate hydrogel matrix with multifacet applications.

Diketo-Ketoenol Tautomers in Curcuminoids: Synthesis, Separation of Tautomers, and Kinetic and Structural Studies

Curcumin and its congeners exist in an equilibrium between diketo and ketoenol tautomers, which have different potencies to bind biomolecules. This work describes procedures for the preparation of 4-alkylated curcumin derivatives and the separation of their two tautomeric forms. Comprehensive NMR studies of the tautomer equilibria in various solvents have been accomplished. Additionally, a pure ketoenol tautomeric form of the active pharmaceutical ingredient (API) ASC-JM17 has been unequivocally determined by X-ray crystallography. Two different polymorphs of this API have been microscopically identified in the X-ray sample and manually separated, and a solid-state NMR study of the two polymorphs has also been performed. This work reports on the slow kinetics of diketo-ketoenol tautomerization in particular solvents that allow the separation and full characterization of both curcuminoids' tautomers.

Curcumin: Useful add-on for Rheumatic Diseases?

Plant-derived nutraceuticals are proposed as new key instruments to represent a profound “back to basics” shift in medical treatment. Data accumulated over the past ten years suggest that curcumin, the major active compound of the turmeric plant, has anti-inflammatory properties. It has yet to be determined whether the anti-inflammatory profile of curcumin is potent enough to justify the application of this substance as a nutritional supplement for patients with rheumatic diseases. To address this question, the most relevant in vitro studies that investigate the mechanism of action of curcumin were reviewed in this article. In addition, a total of 18 animal and human trials were evaluated. The pleiotropic, anti-inflammatory and immunomodulatory effects of curcumin were observed in animal studies. In addition, human trials demonstrated promising findings. In these studies, curcumin was able to reduce the expression of proinflammatory cytokines, lower the level of the C-reactive protein and improve clinical parameters. A limiting factor of the application of curcumin is the inconsistent bioavailability of the substance. Therefore, new formulations have been developed to improve the pharmacodynamic profile of curcumin. The future acceptance of the substance is dependent on new controlled clinical trials with a standardised formulation of curcumin administered as well as standard of care.

A Meta-Analysis of the Impact of Nutritional Supplementation on Osteoarthritis Symptoms

Conflicting evidence exists concerning the effects of nutrient intake in osteoarthritis (OA). A systematic literature review and meta-analysis were performed using PubMed, EMBASE, and Cochrane Library up to November 2021 to assess the effects of nutrients on pain, stiffness, function, quality of life, and inflammation markers. We obtained 52 references including 50 on knee OA. Twelve studies compared 724 curcumin patients and 714 controls. Using the standardized mean difference, improvement was significant with regard to pain and function in the curcumin group compared to placebo, but not with active treatment (i.e., nonsteroidal anti-inflammatory drugs, chondroitin, or paracetamol). Three studies assessed the effects of ginger on OA symptoms in 166 patients compared to 164 placebo controls. Pain was the only clinical parameter that significantly decreased. Vitamin D supplementation caused a significant decrease in pain and function. Omega-3 and vitamin E caused no changes in OA parameters. Herbal formulations effects were significant only for stiffness compared to placebo, but not with active treatment. A significant decrease in inflammatory markers was found, especially with ginger. Thus, curcumin and ginger supplementation can have a favorable impact on knee OA symptoms. Other studies are needed to better assess the effects of omega-3 and vitamin D.

Curcumin and rheumatoid arthritis: A systematic review of literature

BACKGROUND

Curcumin is a natural polyphenol and the main compound from the rhizome of Turmeric (Curcuma longa) and other Curcuma species. It has been widely used for different medical purposes, such as improvement of pain and inflammatory conditions in various diseases.

PURPOSE

This systematic review was aimed to assess all studies regarding the efficacy of the pure form of curcumin (unformulated curcumin) on rheumatoid arthritis (RA).

METHODS

The comprehensive search of the literature was done until September 2020 on the MEDLINE, Embase, Scopus and Web of Knowledge databases. Out of 2079 initial records, 51 articles (13 in vitro and 37 animal and one human) were met our inclusion criteria.

RESULTS

Most studies have shown the curative effects of curcumin on clinical and inflammatory parameters of RA and reported different mechanisms; inhibition of mitogen-activated protein kinase family, extracellular signal-regulated protein kinase, activator protein-1 and nuclear factor kappa B are the main mechanisms associated with the anti-inflammatory function of curcumin in RA. The results of the only human study showed that curcumin significantly improved morning stiffness, walking time and joint swelling.

CONCLUSION

In conclusion, curcumin seems to be useful, and it is recommended that more human studies be performed to approve the cellular and animal results and determine the effective and optimal doses of curcumin on RA patients.

The efficacy and safety of Curcuma longa extract and curcumin supplements on osteoarthritis: a systematic review and meta-analysis

Objective: To assess the efficacy and safety of Curcuma longa extract and curcumin supplements on osteoarthritis (OA).

Methods: The databases such as Pubmed and Cochrane Library were searched to collect the article about Curcuma longa extract and curcumin in the treatment of OA. Then, randomized controlled trials (RCTs) were selected and their data were extracted. Finally, the RevMan5.3 was utilized for risk of bias assessment and meta-analysis, the STATA15.0 were utilized for publication bias assessment, and GRADE tool were used for the evidence quality assessment of primary outcomes.

Results: A total of 15 RCTs involving 1621 participants were included. (1) Compared with placebo, Curcuma longa extract and curcumin (C.) can decrease the visual analog scale (VAS) and The Western Ontario and McMaster Universities (WOMAC) score-pain, the WOMAC score-function and the WOMAC score-stiffness. In terms of adverse events, Curcuma longa extract and curcumin are comparable with those of placebo. (2) Compared with non-steroidal anti-inflammatory drugs (NSAIDs), Curcuma longa extract and curcumin have similar effects on joint pain, function and stiffness. The incidence of adverse events in Curcuma longa extract and curcumin was lower. (3) Compared with the NSAIDs group, C.+NSAIDs can also decrease the VAS and WOMAC score-pain, the WOMAC score-function and the WOMAC score-stiffness. In terms of adverse events, the addition of Curcuma longa extract and curcumin to NSAIDs did not increase adverse events.

Conclusion:Curcuma longa extract and curcumin may be a safer and effective supplement for OA patients. It is recommended to use Curcuma longa extract and curcumin supplement for OA patients for more than 12 weeks.

Molecular insights into phytochemicals exhibiting anti-arthritic activity: systematic review : John Di Battista

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease with an unclear etiology causing severe inflammation, joint pain, and destruction that increases the chance of disability over time. Dysregulation of various immune signaling cascades regulates the formation of synovial hyperplasia and pannus formation. Imbalance in cytokine levels, predominantly proinflammatory cytokines like TNF-α, IL-1, IL-6, IL-17, and IL-12p70 profoundly influences the disease's pathogenesis. Even though various strategies are adopted to treat arthritis, their side effects and cost limit their usage. This review discusses the multiple pathways involved in the pathogenesis of rheumatoid arthritis, provides a systematic analysis of various phytochemicals, and discusses their potential molecular targets in RA treatment.

METHODS

The literature mining was done from scientific databases such as PubMed, Europe PMC, Web of Science, Scopus, etc. The terminologies used for literature mining were Rheumatoid arthritis, phytochemicals, cell signaling pathways, molecular mechanism, etc. RESULTS: NF-κB, MAPKs, and JAK-STAT are the key pathways potentially targeted for RA treatment. However, specific susceptible pathways and potential targets remain unexplored. Besides, the phytochemicals remain an immense source to be exploited for the effective treatment of RA, overcoming the demerits of the conventional strategies. Various in vitro and in vivo findings suggest that polyphenols and flavonoids effectively treat RA conditions overcoming the demerits, such as limitations in usage and toxicity. The phytochemicals should be explored in par with the pathological mechanisms with all the available targets to determine their therapeutic efficacy. Through the established therapeutic efficacy, phytochemicals can help developing therapeutics that are safe and efficacious for RA treatment.

A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial Assessing Efficacy and Safety of a Novel Low-Dose Turmeric Extract Formulation in Healthy Adults with Chronic Knee Pain

BACKGROUND

Knee pain causes functional limitations, eventually compromising the quality of life. We evaluated the efficacy of our water-dispersible turmeric formulation (60% natural curcuminoids, TurmXTRA 60N®-WDTE60N), which exhibited better PK profile at low dose (250 mg) than standard turmeric extract, in alleviating symptoms of chronic knee pain.

METHODS

In this randomized, double-blind, placebo-controlled trial, subjects received either 250 mg WDTE60N capsule (150 mg curcuminoids; n = 53) or appearance-matched placebo capsule (n = 53) once daily for 90 days. Primary endpoint was change in pain score on the visual analogue scale (VAS) after 80-m fast-paced walk test.

RESULTS

A total of 96 subjects completed the study. WDTE60N reduced VAS score from baseline (5.4 ± 0.9) to day 90 (3.8 ± 0.8) with greater mean reduction than placebo (-1.5 ± 0.7 vs -0.6 ± 0.8, p < 0.0001; 2.5 times). It also significantly improved the time taken for 80-m fast-paced walk test and 9-step stair-climb test; and improved all biomarkers compared to placebo (p > 0.05). Three adverse events occurred but were unrelated to study products.

CONCLUSION

WDTE60N 250 mg administered once daily for 3 months, alleviated knee pain, improved joint function in healthy subjects with chronic knee pain, was well tolerated and safe.

Curcumin and its Multi-target Function Against Pain and Inflammation: An Update of Pre-clinical Data

Pain is an unpleasant sensation that has complex and varying causative etiology. Modern drug discovery focuses on identifying potential molecules that target multiple pathways with a safer profile compared to those with a single target. The current treatment of pain and inflammation with the available therapeutics has a number of major side effects. Pain is one of the major clinical problems that need functional therapeutics which act on multiple targets and with low toxicity. Curcumin, a naturally occurring polyphenolic compound from Curcuma longa, has been used for years in Ayurvedic, Chinese, and in many other systems of traditional medicine. Pre-clinical data published thus far demonstrated that curcumin possesses multi-target biological functions, suggesting its potential use to cure different diseases. However, there is no or very brief systematic review of its potential use in pain and inflammation with underlying mechanisms for such activities. Accordingly, the aim of the current review was to update the pre-clinical data of curcumin and its multiple targeting pathways for analgesic and anti-inflammatory effects, and to further propose a molecular mechanism(s). A literature study was conducted using different known databases, including Pubmed, SciFinder, Google Scholar, and Science Direct. Available pre-clinical data suggest the ameliorating effect of curcumin in pain and inflammation is rendered through the modulation of pain pathways, including inhibition of a number of pro-inflammatory mediators, inhibition of oxidative stress and cyclooxygenase-2 (COX-2), down-regulation of Ca2+/calmodulin-depend protein kinase II (CaMKIIα) and calcium channels like transient receptor potential (TRP), modulation of metabotropic glutamate receptor-2 (mGlu2), modulation of monoamine system, inhibition of JAK2/STAT3 signaling pathway, remodeling of extracellular matrix proteins, inhibition of apoptosis, inhibition of JNK/MAPK and ERK/CREB signaling pathway, and activation of the opioid system. Taken all together, it is evident that curcumin is one of the promising, safe, and natural polyphenolic molecules that target multiple molecular pathways in pain and can be beneficial in the treatment and management of pain and inflammation.

Role of natural products in alleviation of rheumatoid arthritis-A review

Rheumatoid arthritis (RHA) is one of the most prevalent complex, chronic, inflammatory diseases, manifested by elevated oxidative stress and inflammatory biomarkers. Prolonged administration of NSAIDs, steroids, and DMARDs, used in the treatment of RHA, is associated with deleterious side effects. This necessitates the urge of new and safe approaches for RHA management, based on the complementary and alternative system of medicine. Documented evidences have suggested that supplementation with nutritional, dietary, and herbal components; can play a crucial role as an adjuvant, in the alleviation of the RHA symptoms, through their influence on the pathological inflammatory processes. Dietary phenolic compounds, flavonoids, carotenoids, and alkaloids with their ability to modulate prooxidant and pro-inflammatory pathways, have been effective in delaying the arthritic disease progression. Moreover, in scientific explorations, herbs containing phenolic compounds, alkaloids, carotenoids flavonoids, spices such as ginger, turmeric, Ayurvedic formulations, different diets such as Mediterranean diet, vegan diet, beverages, and oils such as sesame oil, rice bran oil, vitamins, and probiotics are proven to modulate the action of inflammatory molecules, involved in RHA pathology. Subsequently, the purpose of this review article is to summarize various in vitro, in vivo, and clinical studies in RHA, which have documented remarkable insights into the anti-inflammatory, antioxidant, analgesic, and immunomodulatory, bone erosion preventing properties of dietary, nutritional, and herbal components with the focus on their molecular level mechanisms involved in RHA. Even though major findings were derived from in vitro studies, several in vivo and clinical studies have established the use of diet, herbal, and nutritional management in RHA treatment. PRACTICAL APPLICATIONS: Thickening of the synovial membrane, bone erosion, and cartilage destruction is known to trigger rheumatoid arthritis causing inflammation and pain in bone joints. Continuous intake of NSAIDs, steroids, and DMARD therapy are associated with detrimental side effects. These side effects can be overcome by the use of dietary, nutritional, and herbal interventions based on the complementary and alternative therapy. This concept portrays the food components and other natural components having the potential to promote health, improve general well-being, and reduce the risk of RHA.

Complex effect of continuous curcumin exposure on human bone marrow-derived mesenchymal stem cell regenerative properties through matrix metalloproteinase regulation

Curcumin has been reported to be beneficial for cancers, cardiovascular and neurodegenerative diseases, based on its anti-oxidative, anti-inflammation, anti-tumorigenic and neuroprotective properties. With its high-dose application, curcumin toxicity to systemic tissues is a reasonable concern. Here, we report the responses of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) to continuous curcumin exposure. hBM-MSCs were treated with 0.01-100 μmol/L curcumin continuously in vitro for 7 days. 25 μmol/L curcumin or above significantly attenuated hBM-MSC maintenance, whereas 10 μmol/L curcumin reduced hBM-MSC proliferation and hindered their migration with increasing cell apoptosis. Besides, 5 μmol/L curcumin treatment inhibited hBM-MSC adipogenic differentiation, but enhanced osteogenic differentiation, which depended on matrix metalloproteinase (MMP)-13 expression and activity. Furthermore, curcumin treatment reduced MMP1 expression but up-regulated the immunomodulatory gene IDO1 expression. In summary, this study revealed the complex effects of continuous curcumin exposure on hBM-MSC maintenance and regenerative properties through MMP regulation. Given the complex effects of curcumin, its use for biomedical purposes should be carefully considered in treatment length and dosage.

Cosmeceutical potentials of Curcuma mangga Val. extract in human BJ fibroblasts against MMP1, MMP3, and MMP13

Oxidative stress, the disrupted oxidation-reduction mechanism in our body, is caused by the excessive exposure of free radicals and the impaired antioxidant defenses that can accelerate skin aging. Antioxidants can be obtained from nature, which are available widely in therapeutic-rich plants, such as white saffron (Curcuma mangga Val., denoted as C. mangga). Although many pieces of evidence reveal that C. mangga contains an abundance of phenolic compounds and has antioxidative effects, its cosmeceutical potentials remain unclear. The present study aimed to disclose the unexplored antiaging potentials of C. mangga extract (CME) in oxidative stress-induced human BJ fibroblasts with a focus on collagen protection against pro-inflammatory mediators MMP1, MMP3, and MMP13. The oxidative stress-induced cells were treated with CME and curcumin at different doses. The results showed that treatment using CME (25 μg/mL) could maintain the collagen contents up to 18.45 ± 0.68 μg/mL in H2O2-treated fibroblasts (only ~26.63% reduction in collagen contents), while the figure for the negative control was the lowest (12.79 μg/mL), showing a significant reduction in collagen contents by 49.13%. In addition, the gene expression of pro-inflammatory MMPs arose significantly in BJ fibroblasts after oxidative stress induction using 200 μM H2O2, in which the expression for MMP1, MMP3, and MMP13 increased by 7.10, 38.96, and 2.69 times, respectively. Interestingly, CME treatment (100 μg/mL) could effectively inhibit MMP1, MMP3, and MMP13 gene expression by 3.65, 34.62, and 2.02 times, respectively. In conclusion, CME showed favorable antiaging activities in H2O2-treated human BJ fibroblasts as confirmed by the low levels of gene expression of MPP1, MMP3, and MMP13 after treatment with CME.

Natural products action on pathogenic cues in autoimmunity: Efficacy in systemic lupus erythematosus and rheumatoid arthritis as compared to classical treatments

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), which are characterized by self-perpetuating inflammation and tissue/organ damage, resulting from the failure of lymphocyte auto-tolerance, cause morbidity and mortality worldwide. The current drugs or therapies including conventional non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs), as well as several biologic therapies such as B cell-targeted, T cell-targeted, cytokines-targeted and cytokines receptors-targeted therapy, cannot completely cure SLE and RA, and are always accompanied by unexpected side effects. Therefore, more studies have explored new methods for therapy and found that the herbal medicine as well as its natural products (NPs) exhibited promising therapeutic value through exerting effects of immunomodulation, anti-inflammation, anti-oxidation, and anti-apoptosis, etc. via regulating abnormal responses in kidney, innate and adaptive immune systems, intestine, synoviocytes, as well as bone system including chondrocytes, osteoclasts, joints and paw tissues. In the present review, we will elucidate the current mainstream drugs and therapies for SLE and RA, and summarize the efficacy and mechanisms of NPs in the treatment of SLE and RA based on available findings including in vitro and in vivo animal models, as well as clinical studies, and further analyze the existing challenges, in order to provide comprehensive evidence for improvement of SLE and RA therapy by NPs and to promote management of these two autoimmune diseases.

Flavonoids compounds from Tridax procumbens inhibit osteoclast differentiation by down-regulating c-Fos activation

The total flavonoids from Tridax procumbens (TPFs) have been reported significantly to suppress on RANKL‐induced osteoclast differentiation and bone resorption in mouse primary cultured osteoclasts. However, the effects of ethyl ether fraction of Tridax procumbens flavonoids (TPF) on osteoclastogenesis remain unknown. In this study, we investigated the effects of TPF on lipopolysaccharides (LPS)‐induced osteoclast differentiation, actin ring formation, and explored its molecular mechanism in vitro. Matured osteoclast was counted as the number of tartrate‐resistant acid phosphatase (TRAP)‐positive multinucleated cells, and activity of osteoclast was assessed by performing the pit formation assays. Real‐time polymerase chain reaction (RT‐PCR) was performed for evaluation of the expression of osteoclast differentiation‐related genes. TPF reduced the TRAP‐positive multinucleated osteoclasts, inhibited TRAP and acid phosphatase (ACP) activities and decreased the expression of osteoclast differentiating genes, including cathepsin K, metalloproteinase‐2 (MMP‐2), MMP‐9, MMP‐13 and osteoclast‐associated receptor (OSCAR). Furthermore, osteoclast‐dependent actin rings formation and resorption pits were dramatically inhibited by the treatment with TPF. TPF markedly decreased the expression levels of transcription factors such as c‐Fos, nuclear factor of activated T cells cytoplasmic 1 (NFATc1) and activator protein‐1 (AP‐1). Taken together, our findings indicated that TPF suppressed both osteoclast differentiation and activities. Therefore, TPF might be a promising and emerging drug candidate for the treatment of bone diseases such as osteoporosis.

Glucocorticoids Increase Renal Excretion of Urate in Mice by Downregulating Urate Transporter 1

Both nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids have been widely used for the treatment of gout, a disease promoted by an excess body burden of uric acid (UA); however, their effects on the homeostasis of UA remain poorly understood. The present study showed that 1-week treatments with three NSAIDs (ibuprofen, diclofenac, and indomethacin) had little effect on UA homeostasis in mice, whereas 1-week low doses (1 and 5 mg/kg) of dexamethasone (DEX) significantly decreased serum UA by about 15%. Additionally, low doses of DEX also resulted in increases in hepatic UA concentration and urinary UA excretion, which were associated with an induction of xanthine oxidoreductase (XOR) in the liver and a downregulation of urate transporter 1 (URAT1) in the kidney, respectively. Neither 75 mg/kg DEX nor 100 mg/kg pregnenolone-16α-carbonitrile altered UA concentrations in serum and livers of mice, suggesting that the effect of DEX on UA homeostasis was not due to the pregnane X receptor pathway. Further in vitro studies demonstrated that glucocorticoid receptor (GR) was involved in DEX-mediated downregulation of URAT1. Knockdown of both p65 and c-Jun completely blocked the effect of DEX on URAT1, suggesting that GR regulates URAT1 via its interaction with both nuclear factor κB and activator protein 1 signaling pathways. To conclude, the present study identifies, for the first time, a critical role of glucocorticoids in regulating UA homeostasis and elucidates the mechanism for GR-mediated regulation of URAT1 in mice. SIGNIFICANCE STATEMENT: This study demonstrates, for the first time, a critical role of glucocorticoid receptor in regulating urate transporter 1 in mouse kidney.

Curcumin Inhibits the PERK-eIF2α-CHOP Pathway through Promoting SIRT1 Expression in Oxidative Stress-induced Rat Chondrocytes and Ameliorates Osteoarthritis Progression in a Rat Model

Oxidative stress plays a crucial role in the occurrence and development of osteoarthritis (OA) through the activation of endoplasmic reticulum (ER) stress. Curcumin is a polyphenolic compound with significant antioxidant and anti-inflammatory activity among various diseases. To elucidate the role of curcumin in oxidative stress-induced chondrocyte apoptosis, this study investigated the effect of curcumin on ER stress-related apoptosis and its potential mechanism in oxidative stress-induced rat chondrocytes. The results of flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining showed that curcumin can significantly attenuate ER stress-associated apoptosis. Curcumin inhibited the expression of cleaved caspase3, cleaved poly (ADP-ribose) polymerase (PARP), C/EBP homologous protein (CHOP), and glucose-regulated protein78 (GRP78) and upregulated the chondroprotective protein Bcl2 in TBHP-treated chondrocytes. In addition, curcumin promoted the expression of silent information regulator factor 2-related enzyme 1 (SIRT1) and suppressed the expression of activating transcription factor 4 (ATF4), the ratio of p-PERK/PERK, p-eIF2α/eIF2α. Our anterior cruciate ligament transection (ACLT) rat OA model research demonstrated that curcumin (50 mg/kg and 150 mg/kg) ameliorated the degeneration of articular cartilage and inhibited chondrocyte apoptosis in ACLT rats in a dose-dependent manner. By applying immunohistochemical analysis, we found that curcumin enhanced the expression of SIRT1 and inhibited the expression of CHOP and cleaved caspase3 in ACLT rats. Taken together, our present findings firstly indicate that curcumin could inhibit the PERK-eIF2α-CHOP axis of the ER stress response through the activation of SIRT1 in tert-Butyl hydroperoxide- (TBHP-) treated rat chondrocytes and ameliorated osteoarthritis development in vivo.

Anti-Arthritis Effect through the Anti-Inflammatory Effect of Sargassum muticum Extract in Collagen-Induced Arthritic (CIA) Mice

(1) Background: Rheumatoid arthritis is a chronic autoimmune disease that causes progressive articular damage and functional loss. It is characterized by synovial inflammation that leads to progressive cartilage destruction. For this reason, research on functional foods that reduce the inflammatory response are under progress. (2) Methods: We focused on the anti-inflammatory effects of Sargassum muticum, and confirmed the effect of the extract on the collagen-induced arthritis (CIA) DBA/1J mice model. (3) Results: The extract was given at concentrations of 50, 100, and 200 mg/kg, and the arthritis score and edema volume of the experimental group were significantly different from the CIA group. The level of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ were determined in serum and lymphocytes. The expression of these cytokines in the serum remarkably decreased from S. muticum extract (SME)100 mg/kg, and decreased from SME 200 mg/kg in lymphocytes. Also, immunohistochemical analysis of IL-6 and TNF-α in the joints revealed that the inflammatory response was noticeably lower when treated with S. muticum extract. (4) Conclusions: This study provides results of the experiment of S. muticum extract treatment in a mouse model. The treatment was found to contribute to the alleviation of edema and symptoms by reducing the expression of inflammatory cytokines. It was concluded that it may be a useful substance to help in the mitigation of arthritis symptoms.

Curcumin for the Management of Periodontitis and Early ACPA-Positive Rheumatoid Arthritis: Killing Two Birds with One Stone

We propose curcumin as a preventive measure to avoid/manage periodontitis (PD), and as a natural immunosuppressant for rheumatoid arthritis (RA). PD, mainly caused by Porphyromonas gingivalis forming biofilm and leading to tooth decay, is a major public health issue and a risk factor for the development of RA in humans. P. gingivalis is able to trigger experimental autoimmune arthritis in animal models and in humans can induce citrullinated peptides, which not only are a source of anti-citrullinated antibodies (ACPAs), but also participate in autoreactive responses and disease development. Curcumin appears to have efficient anti-bacterial activity against P. gingivalis infection and biofilm formation. In addition to antibacterial, anti-oxidant, and anti-inflammatory action, curcumin exerts unique immunosuppressant properties via the inhibition of Th17 pro-inflammatory responses and promotion of regulatory T cells, thus suppressing autoimmunity. We introduce curcumin as a natural product for the management of both PD and RA-related autoreactivity, possibly also as a preventive measure in early RA or individuals at high risk to develop RA.

Inhibition of EV71 by curcumin in intestinal epithelial cells

EV71 is a positive-sense single-stranded RNA virus that belongs to the Picornaviridae family. EV71 infection may cause various symptoms ranging from hand-foot-and-mouth disease to neurological pathological conditions such as aseptic meningitis, ataxia, and acute transverse myelitis. There is currently no effective treatment or vaccine available. Various compounds have been examined for their ability to restrict EV71 replication. However, most experiments have been performed in rhabdomyosarcoma or Vero cells. Since the gastrointestinal tract is the entry site for this pathogen, we anticipated that orally ingested agents may exert beneficial effects by decreasing virus replication in intestinal epithelial cells. In this study, curcumin (diferuloylmethane, C₂₁H₂₀O₆), an active ingredient of turmeric (Curcuma longa Linn) with anti-cancer properties, was investigated for its anti-enterovirus activity. We demonstrate that curcumin treatment inhibits viral translation and increases host cell viability. Curcumin does not exert its anti-EV71 effects by modulating virus attachment or virus internal ribosome entry site (IRES) activity. Furthermore, curcumin-mediated regulation of mitogen-activated protein kinase (MAPK) signaling pathways is not involved. We found that protein kinase C delta (PKCδ) plays a role in virus translation in EV71-infected intestinal epithelial cells and that curcumin treatment decreases the phosphorylation of this enzyme. In addition, we show evidence that curcumin also limits viral translation in differentiated human intestinal epithelial cells. In summary, our data demonstrate the anti-EV71 properties of curcumin, suggesting that ingestion of this phytochemical may protect against enteroviral infections.

Curcumin attenuates collagen-induced inflammatory response through the "gut-brain axis"

BACKGROUND

Previous studies have demonstrated that oral administration of curcumin exhibited an anti-arthritic effect despite its poor bioavailability. The present study aimed to explore whether the gut-brain axis is involved in the therapeutic effect of curcumin.

METHODS

The collagen-induced arthritis (CIA) rat model was induced by immunization with an emulsion of collagen II and complete Freund's adjuvant. Sympathetic and parasympathetic tones were measured by electrocardiographic recordings. Unilateral cervical vagotomy (VGX) was performed before the induction of CIA. The ChAT, AChE activities, and serum cytokine levels were determined by ELISA. The expression of the high-affinity choline transporter 1 (CHT1), ChAT, and vesicular acetylcholine transporter (VAChT) were determined by real-time PCR and immunohistochemical staining. The neuronal excitability of the vagus nerve was determined by whole-cell patch clamp recording.

RESULTS

Oral administration of curcumin restored the imbalance between the sympathetic and parasympathetic tones in CIA rats and increased ChAT activity and expression of ChAT and VAChT in the gut, brain, and synovium. Additionally, VGX eliminated the effects of curcumin on arthritis and ACh biosynthesis and transport. Electrophysiological data showed that curcumin markedly increased neuronal excitability of the vagus nerve. Furthermore, selective α7 nAChR antagonists abolished the effects of curcumin on CIA.

CONCLUSIONS

Our results demonstrate that curcumin attenuates CIA through the "gut-brain axis" by modulating the function of the cholinergic system. These findings provide a novel approach for mechanistic studies of anti-arthritic compounds with low oral absorption and bioavailability.

Identification of novel inhibitors of DDR1 against idiopathic pulmonary fibrosis by integrative transcriptome meta-analysis, computational and experimental screening

Idiopathic pulmonary fibrosis (IPF) is a kind of a chronic and fatal lung disease leading to progressive lung function decline. Although several RNA microarray studies on IPF patients have been reported, their results were merely specific to each study with distinct platforms or sample types. In the current study, an integrative transcriptome meta-analysis of IPF was performed to explore regulated pathways, based on four independent expression profiling microarrays of IPF datasets, including 73 samples from IPF tissues or lung fibroblast cells. The results suggested the discoidin domain receptor 1 (DDR1) and downstream c-Jun N-terminal kinases (JNK) pathway may play important roles in the progression of IPF. To our knowledge, discoidin domain receptor 1 (DDR1) is a kind of receptor tyrosine kinase (RTK) with a unique ability to bind both fibrillar and non-fibrillar collagens. Based on the crystallographic structures of DDR1, the combination of molecular dynamics simulation and a hybrid protocol of a virtual screening method, comprised of PBVS (multicomplex-pharmacophore based virtual screening) and DBVS (docking based virtual screening) methods were used for retrieving novel DDR1 inhibitors from the SPECS database. Twelve hit compounds were selected from the hit compounds and shifted to experimental validations, and the most potent compound was evaluated for its anti-IPF capacity on murine IPF models. Thus, these results may provide valuable information for further discovery of potential lead compounds for IPF therapy.

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.

Neutrophils and arthritis: Role in disease and pharmacological perspectives

The inflammatory response in the joint can induce an intense accumulation of leukocytes in the tissue that frequently results in severe local damage and loss of function. Neutrophils are essential cells to combat many pathogens, but their arsenal can contribute or aggravate articular inflammation. Here we summarized some aspects of neutrophil biology, their role in inflammation and indicated how the modulation of neutrophil functions could be useful for the treatment of different forms of arthritis.

Metabolomic Elucidation of the Effects of Curcumin on Fibroblast-Like Synoviocytes in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease characterized by synovial inflammation and joint disability. Curcumin is known to be effective in ameliorating joint inflammation in RA. To obtain new insights into the effect of curcumin on primary fibroblast-like synoviocytes (FLS, N = 3), which are key effector cells in RA, we employed gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS)-based metabolomics. Metabolomic profiling of tumor necrosis factor (TNF)-α-stimulated and curcumin-treated FLS was performed using GC/TOF-MS in conjunction with univariate and multivariate statistical analyses. A total of 119 metabolites were identified. Metabolomic analysis revealed that metabolite profiles were clearly distinct between TNF-α-stimulated vs. the control group (not stimulated by TNF-α or curcumin). Treatment of FLS with curcumin showed that the metabolic perturbation by TNF-α could be reversed to that of the control group to a considerable extent. Curcumin-treated FLS had higher restoration of amino acid and fatty acid metabolism, as indicated by the prominent metabolic restoration of intermediates of amino acid and fatty acid metabolism, compared with that observed in TNF-α-stimulated FLS. In particular, the abundance of glycine, citrulline, arachidonic acid, and saturated fatty acids in TNF-α-stimulated FLS was restored to the control level after treatment with curcumin, suggesting that the effect of curcumin on preventing joint inflammation may be elucidated with the levels of these metabolites. Our results suggest that GC/TOF-MS-based metabolomic investigation using FLS has the potential for discovering the mechanism of action of curcumin and new targets for therapeutic drugs in RA.

Comparative evaluation of the efficacy of curcumin gel with and without photo activation as an adjunct to scaling and root planing in the treatment of chronic periodontitis: A split mouth clinical and microbiological study

Aims and Objectives:

Harnessing Mother Nature's bountiful remedies for rejuvenation has been in vogue since time immemorial. Turmeric contains the polyphenol Curcumin in its rhizome. It produces reactive oxygen species (ROS) with visible light irradiation as photodynamic therapy (PDT) - which validates its use in the treatment of periodontitis. This study compares Curcumin and Curcumin PDT as an adjunct to conventional Scaling and Root Planing (SRP) with SRP alone in the treatment of patients with chronic periodontitis.

Materials and Methods:

Sixty sites in fifteen untreated chronic periodontitis patients were randomly assigned in a split mouth design for one of the treatment modalities; 1) Scaling and root planing (SRP) alone, (2) SRP + Curcumin application for 5 min, (3) SRP + Curcumin application for 5 min + irradiation with blue light emitting diode of wavelength 470 nm for 5 min. (Curcumin PDT) on 0 day.(4) SRP + Curcumin PDT on “0”, 7^th and 21^st day. The clinical parameters included plaque index (PI), bleeding on probing (BOP) measured by sulcus bleeding index (SBI), probing pocket depth (PPD), clinical attachment level (CAL) recorded at the baseline & 3^rd month. The site with greatest probing pocket depth (PPD) was selected from each quadrant for bacterial sampling and culturing for Aggregatibacter actinomycetemcomitans (Aa) and other black pigment producing microorganisms (BPB) like Porphyromonas gingivalis & Prevotella intermedia.

Conclusion:

The present study showed that Curcumin photodynamic therapy is a valuable treatment modality adjunctive to conventional scaling and root planing over Curcumin application. Moreover, multiple adjunctive applications of photodynamic therapy are more beneficial than single application in reducing clinical & microbiological parameters.

Oral administration of curcumin (Curcuma longa) can attenuate the neutrophil inflammatory response in zymosan-induced arthritis in rats

PURPOSE

To evaluate the effect of curcumin in the acute phase of zymosan-induced arthritis.

METHODS

Twenty-eight male rats were subjected to intra-articular infiltration of zymosan of both knees and, in four the infiltration was made with saline. The animals were divided into five groups second received every six hours by gavage: corn oil by (positive and negative control); curcumin (100 mg/kg); prednisone 1 mg/kg/day; prednisone 8 mg/kg. All animals were sacrificed after six, 12, 24 and 48 hours of the infiltration. The knees were removed for evaluation of neutrophil infiltration. The number of neutrophils was counted by computer-assisted analysis of the images. The neutrophil infiltrate was stratified into four grades: 0 = normal; + = mild; ++/+++ = moderate; > ++++ = severe. The results were compared using the Mann-Whitney test and the variance by Kruskal-Wallis test adopting a significance level of 5% (p<0.05).

RESULTS

Curcumin reduces inflammatory activity in the first six hours after zymosan-induced arthritis when compared to saline (p<0.01). This was also observed in animals subjected to administration of prednisone (1 mg/kg) and those treated with prednisone (8 mg/kg). Curcumin was more effective than lower doses of prednisone in the first six hours after induction of the arthritis. After 12, 24 and 48 hours, curcumin does not have the same anti-inflammatory effects when compared to prednisone. After 48 hours, prednisone is more effective than curcumin in reducing the inflammatory infiltrate regardless of the dose of prednisone used.

CONCLUSION

Oral administration of curcumin reduces inflammation in the first six hours after experimentally zymosan-induced arthritis.

Intrathecal curcumin attenuates pain hypersensitivity and decreases spinal neuroinflammation in rat model of monoarthritis

Curcumin is a major component of turmeric and reportedly has anti-inflammatory and anti-oxidant effects. Neuroinflammation has been recognized to play an important role in the pathogenesis of various diseases in the central nervous system. Here we investigated the anti-nociceptive and anti-neuroinflammatory effect of curcumin on arthritic pain in rats. We found that repeated oral treatment with curcumin, either before or after complete Freund’s adjuvant (CFA) injection, dose-dependently attenuated CFA-induced mechanical allodynia and thermal hyperalgesia, but had no effect on joint edema. Repeated intrathecal injection of curcumin reversed CFA-induced pain hypersensitivity. Furthermore, such a curcumin treatment reduced CFA-induced activation of glial cells and production of inflammatory mediators [interleukin-1β (IL-1β), monocyte chemoattractant protein-1 (MCP-1), and monocyte inflammatory protein-1 (MIP-1α)] in the spinal cord. Curcumin also decreased lipopolysaccharide-induced production of IL-1β, tumor necrosis factor-α, MCP-1, and MIP-1α in cultured astrocytes and microglia. Our results suggest that intrathecal curcumin attenuates arthritic pain by inhibiting glial activation and the production of inflammatory mediators in the spinal cord, suggesting a new application of curcumin for the treatment of arthritic pain.

Evaluation of the efficacy of 2% curcumin gel in the treatment of experimental periodontitis

CONTEXT

Local drug delivery (LDD) systems have been proposed for the treatment of periodontitis. Curcumin could be a suitable agent as LDD for the treatment of periodontitis.

AIM

To formulate, evaluate the anti-inflammatory activity and to assess the duration of the action and the efficacy of 2% curcumin gel in the treatment of experimental periodontitis in Wistar albino rat model.

SETTINGS AND DESIGN

Twenty-one Wistar albino rats were randomly assigned to three groups. Periodontitis was induced using ligature model. Group 1: Control; group 2: Plain gel, and group 3: 2% curcumin gel.

MATERIALS AND METHODS

About 2% curcumin gel was prepared. The anti-inflammatory activity and duration of action was assessed. Silk ligature 5-0 was used to induce periodontitis. Gingival index (GI) and probing pocket depth (PPD) were measured. Treatment was done. The rats were sacrificed. Morphometric analysis was performed using stereomicroscope and ImageJ software.

STATISTICAL ANALYSIS USED

Analysis of variance followed by Bonferroni's test, Wilcoxon's test for inter-group comparison, Mann-Whitney test for P value computation was used. The observations are mean ± standard deviation and standard error of the mean. P < 0.01 when compared to control was considered as statistically significant.

RESULTS

About 2% curcumin gel showed 42.98% inhibition of edema and peak activity was noted at 24 h. There was statistically significant change in the GI and PPD. Morphometric analysis did not show any significant difference between groups. No toxic effects were seen on oral administration of 2000 mg/kg of curcumin.

CONCLUSIONS

About 2% curcumin gel was effective in the treatment of experimental periodontitis.

The potential for dietary factors to prevent or treat osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease for which there are no disease-modifying drugs. It is a leading cause of disability in the UK. Increasing age and obesity are both major risk factors for OA and the health and economic burden of this disease will increase in the future. Focusing on compounds from the habitual diet that may prevent the onset or slow the progression of OA is a strategy that has been under-investigated to date. An approach that relies on dietary modification is clearly attractive in terms of risk/benefit and more likely to be implementable at the population level. However, before undertaking a full clinical trial to examine potential efficacy, detailed molecular studies are required in order to optimise the design. This review focuses on potential dietary factors that may reduce the risk or progression of OA, including micronutrients, fatty acids, flavonoids and other phytochemicals. It therefore ignores data coming from classical inflammatory arthritides and nutraceuticals such as glucosamine and chondroitin. In conclusion, diet offers a route by which the health of the joint can be protected and OA incidence or progression decreased. In a chronic disease, with risk factors increasing in the population and with no pharmaceutical cure, an understanding of this will be crucial.

The Effects of Platycodin D, a Saponin Purified from Platycodi Radix, on Collagen-Induced DBA/1J Mouse Rheumatoid Arthritis

The object of this study is to observe the effects of platycodin D, a saponin purified from Platycodi Radix, on mice collagen-induced arthritis (CIA). A daily dose of 200, 100, and 50 mg/kg platycodin D was administered orally to male DBA/1J mice for 40 days after initial collagen immunization. To ascertain the effects administering the collagen booster, CIA-related features (including body weight, poly-arthritis, knee and paw thickness, and paw weight increase) was measured from histopathological changes in the spleen, left popliteal lymph node, third digit, and the knee joint regions. CIA-related bone and cartilage damage improved significantly in the platycodin D-administered CIA mice. Additionally, myeloperoxidase (MPO) levels in the paw were reduced in platycodin D-treated CIA mice compared to CIA control groups. The level of malondialdehyde (MDA), an indicator of oxidative stress, decreased in a dose-dependent manner in the platycodin D group. Finally, the production of IL-6 and TNF-α, involved in rheumatoid arthritis pathogenesis, was suppressed by treatment with platycodin D. Taken together, these results suggest that platycodin D is a promising new effective antirheumatoid arthritis agent, exerting anti-inflammatory, antioxidative and immunomodulatory effects in CIA mice.

Inhibition of the PI3K/AKT-NF-κB pathway with curcumin enhanced radiation-induced apoptosis in human Burkitt's lymphoma

The phosphatidylinositol-3-kinase (PI3K) / protein kinase B (AKT) signal transduction pathway is commonly misregulated in lymphoma and associated with tumorigenesis and enhanced resistance to radiotherapy. Curcumin has been shown to inhibit the PI3K/AKT signal transduction pathway in several tumor models. In this study, we found that curcumin inhibits constitutive and radiation-induced expression of the PI3K/AKT pathway and its downstream regulator nuclear factor kappaB (NF-κB) in human Burkitt's lymphoma, a high-grade non-Hodgkin's lymphoma (NHL). We further demonstrated that the blockage of radiation-induced activation of the PI3K/AKT pathway and its downstream regulator NF-κB by either curcumin or specific PI3/AKT inhibitors (LY294002 for PI3K or SH-5 for AKT) enhance apoptosis in three human Burkitt's lymphoma cell lines (Namalwa, Ramos, and Raji) that were treated with ionizing radiation. However, no synergic effect on radiation-induced apoptosis was found in the cells co-pretreated with curcumin combined with LY294002 or curcumin combined with SH-5. The results from this study suggest that curcumin might play an important role in radiotherapy of high-grade NHL through inhibition of the PI3K/AKT-dependent NF-κB pathway.

The plant-derived glucocorticoid receptor agonist Endiandrin A acts as co-stimulator of colonic epithelial sodium channels (ENaC) via SGK-1 and MAPKs

In a search for secondary plant compounds that bind to the glucocorticoid receptor (GR), the cyclobutane lignan endiandrin A was discovered from the rainforest tree Endiandra anthropophagorum Domin. Our present study aims to characterize the effect of endiandrin A on GR-dependent induction of colonic sodium transport. The effect of endiandrin A was analyzed in GR-expressing colonic HT-29/B6 cells (HT-29/B6-GR). GR transactivation and subcellular localization were investigated by reporter gene assay and immunofluorescence. Epithelial sodium channel (ENaC) was analyzed by qRT-PCR and by measuring amiloride-sensitive short-circuit current (I_sc) in Ussing chambers. Endiandrin A (End A) has been identified as GR receptor binder. However, it did not cause significant GR transactivation as pGRE-luciferase activity was only 7% of that of the maximum effect of dexamethasone. Interestingly, endiandrin A had a significant impact on dexamethasone-dependent sodium absorption in cells co-exposed to tumor necrosis factor (TNF)-α. This was in part due to up-regulation of β- and γ-ENaC subunit expression. Endiandrin A potentiated GR-mediated transcription by increasing GR protein expression and phosphorylation. It inhibited c-Jun N-terminal kinase (JNK) activation induced by dexamethasone and/or TNF-α and increased levels of GR localized to the nucleus. Additionally, endiandrin A increased the serum- and glucocorticoid-induced kinase (sgk)-1 via activation of p38. Finally, the regulation of ENaC function by endiandrin A was confirmed in rat native colon. In conclusion, endiandrin A potentiates glucocorticoid-driven activation of colonic epithelial sodium channels via JNK inhibition and p38 activation due to transcriptional up-regulation of β- and γ-ENaC-subunits along with induction of sgk-1.

Targeting polymer therapeutics to bone

An aging population in the developing world has led to an increase in musculoskeletal diseases such as osteoporosis and bone metastases. Left untreated many bone diseases cause debilitating pain and in the case of cancer, death. Many potential drugs are effective in treating diseases but result in side effects preventing their efficacy in the clinic. Bone, however, provides a unique environment of inorganic solids, which can be exploited in order to effectively target drugs to diseased tissue. By integration of bone targeting moieties to drug-carrying water-soluble polymers, the payload to diseased area can be increased while side effects decreased. The realization of clinically relevant bone targeted polymer therapeutics depends on (1) understanding bone targeting moiety interactions, (2) development of controlled drug delivery systems, as well as (3) understanding drug interactions. The latter makes it possible to develop bone targeted synergistic drug delivery systems.

Curcumin: a potential candidate for matrix metalloproteinase inhibitors

INTRODUCTION

Curcumin, a natural yellow pigment of turmeric, has become focus of interest with regard to its role in regulation of matrix metalloproteinases (MMPs). MMPs are metal-dependent endopeptidases capable of degrading components of the extracellular matrix. MMPs are involved in chronic diseases such as arthritis, Alzheimer's disease, psoriasis, chronic obstructive pulmonary disease, asthma, cancer, neuropathic pain, and atherosclerosis.

AREAS COVERED

Curcumin regulates the expression and secretion of various MMPs. This review documents the matrix metalloproteinase inhibitory activity of curcumin on various diseases viz., cancer, arthritis, and ulcer. Finally, the steps to be taken for getting potent curcuminoids have also been discussed in the structure-activity relationship (SAR) section. From this review, readers can get answer to the question: Is curcumin a potential MMPI candidate?

EXPERT OPINION

Numerous approaches have been taken to beget a molecule with specificity restricted to a particular MMP as well as good oral bioavailability; however, nearly all the molecules lack these criteria. Using quantitative structure-activity relationship (QSAR) modeling and virtual screening, new analogs of curcumin can be designed which will be selectively inhibiting different MMPs.

Curcuma DMSO extracts and curcumin exhibit an anti-inflammatory and anti-catabolic effect on human intervertebral disc cells, possibly by influencing TLR2 expression and JNK activity

Background

As proinflammatory cytokines seem to play a role in discogenic back pain, substances exhibiting anti-inflammatory effects on intervertebral disc cells may be used as minimal-invasive therapeutics for intradiscal/epidural injection. The purpose of this study was to investigate the anti-inflammatory and anti-catabolic potential of curcuma, which has been used in the Indian Ayurvedic medicine to treat multiple ailments for a long time.

Methods

Human disc cells were treated with IL-1β to induce an inflammatory/catabolic cascade. Different extracts of curcuma as well as curcumin (= a component selected based on results with curcuma extracts and HPLC/MS analysis) were tested for their ability to reduce mRNA expression of proinflammatory cytokines and matrix degrading enzymes after 6 hours (real-time RT-PCR), followed by analysis of typical inflammatory signaling mechanisms such as NF-κB (Western Blot, Transcription Factor Assay), MAP kinases (Western Blot) and Toll-like receptors (real-time RT-PCR). Quantitative data was statistically analyzed using a Mann Whitney U test with a significance level of p < 0.05 (two-tailed).

Results

Results indicate that the curcuma DMSO extract significantly reduced levels of IL-6, MMP1, MMP3 and MMP13. The DMSO-soluble component curcumin, whose occurrence within the DMSO extract was verified by HPLC/MS, reduced levels of IL-1β, IL-6, IL-8, MMP1, MMP3 and MMP13 and both caused an up-regulation of TNF-α. Pathway analysis indicated that curcumin did not show involvement of NF-κB, but down-regulated TLR2 expression and inhibited the MAP kinase JNK while activating p38 and ERK.

Conclusions

Based on its anti-inflammatory and anti-catabolic effects, intradiscal injection of curcumin may be an attractive treatment alternative. However, whether the anti-inflammatory properties in vitro lead to analgesia in vivo will need to be confirmed in an appropriate animal model.

Tea polyphenols inhibit rat osteoclast formation and differentiation

Matrix metalloproteinases (MMPs) play an important role in degeneration of the matrix associated with bone and cartilage. Regulation of osteoclast activity is essential in the treatment of bone disease, including osteoporosis and rheumatoid arthritis. Polyphenols in green tea, particularly epigallocatechin-3-gallate (EGCG), inhibit MMPs expression and activity. However, the effects of the black tea polyphenol, theaflavin-3,3'-digallate (TFDG), on osteoclast and MMP activity are unknown. Therefore, we examined whether TFDG and EGCG affect MMP activity and osteoclast formation and differentiation in vitro. TFDG or EGCG (10 and 100 µM) was added to cultures of rat osteoclast precursors cells and mature osteoclasts. Numbers of multinucleated osteoclasts and actin rings decreased in polyphenol-treated cultures relative to control cultures. MMP-2 and MMP-9 activities were lower in TFDG- and EGCG-treated rat osteoclast precursor cells than in control cultures. MMP-9 mRNA levels declined significantly in TFDG-treated osteoclasts in comparison to control osteoclasts. TFDG and EGCG inhibited the formation and differentiation of osteoclasts via inhibition of MMPs. TFDG may suppress actin ring formation more effectively than EGCG. Thus, TFDG and EGCG may be suitable agents or lead compounds for the treatment of bone resorption diseases.

The targets of curcumin

Curcumin (diferuloylmethane), an orange-yellow component of turmeric or curry powder, is a polyphenol natural product isolated from the rhizome of the plant Curcuma longa. For centuries, curcumin has been used in some medicinal preparation or used as a food-coloring agent. In recent years, extensive in vitro and in vivo studies suggested curcumin has anticancer, antiviral, antiarthritic, anti-amyloid, antioxidant, and anti-inflammatory properties. The underlying mechanisms of these effects are diverse and appear to involve the regulation of various molecular targets, including transcription factors (such as nuclear factor-kB), growth factors (such as vascular endothelial cell growth factor), inflammatory cytokines (such as tumor necrosis factor, interleukin 1 and interleukin 6), protein kinases (such as mammalian target of rapamycin, mitogen-activated protein kinases, and Akt) and other enzymes (such as cyclooxygenase 2 and 5 lipoxygenase). Thus, due to its efficacy and regulation of multiple targets, as well as its safety for human use, curcumin has received considerable interest as a potential therapeutic agent for the prevention and/or treatment of various malignant diseases, arthritis, allergies, Alzheimer's disease, and other inflammatory illnesses. This review summarizes various in vitro and in vivo pharmacological aspects of curcumin as well as the underlying action mechanisms. The recently identified molecular targets and signaling pathways modulated by curcumin are also discussed here.

Potent anti-inflammatory effects of systemically administered curcumin modulate periodontal disease in vivo

BACKGROUND AND OBJECTIVE

Curcumin is a plant-derived dietary spice with various biological activities, including anticarcinogenic and anti-inflammatory effects. Its therapeutic applications have been studied in a variety of conditions, including rheumatoid arthritis, colon cancer and depression, but no studies have evaluated the effects of curcumin on periodontal disease in vivo.

MATERIAL AND METHODS

Experimental periodontal disease was induced in rats by placing cotton ligatures around both lower first molars. Curcumin was given to the rats by the intragastric route daily at two dosages (30 and 100 mg/kg) for 15 d. Control animals received ligatures but only the corn oil vehicle by gavage, and no treatment-negative control animals were included. Bone resorption was assessed by micro-computed tomography, and the inflammatory status was evaluated by stereometric analysis. Both RT-qPCR and ELISA were used to determine the expression of interleukin-6, tumor necrosis factor-α and prostaglandin E(2) synthase in the gingival tissues. Modulation of p38 MAPK and nuclear factor-κB activation were assessed by western blotting.

RESULTS

Bone resorption was effectively induced in the experimental period, but it was not affected by either dose of curcumin. Curcumin effectively inhibited cytokine gene expression at both the mRNA and the protein level and produced a dose-dependent inhibition of the activation of nuclear factor-κB in the gingival tissues. Activation of p38 MAPK was not inhibited by curcumin. Curcumin-treated animals also presented a marked reduction of the inflammatory cell infiltrate and increased collagen content and fibroblastic cell numbers.

CONCLUSION

Curcumin did not prevent alveolar bone resorption, but its potent anti-inflammatory effect suggests that it may have a therapeutic potential in periodontal diseases.

Curcumin: A review of anti-cancer properties and therapeutic activity in head and neck squamous cell carcinoma

Curcumin (diferuloylmethane) is a polyphenol derived from the Curcuma longa plant, commonly known as turmeric. Curcumin has been used extensively in Ayurvedic medicine for centuries, as it is nontoxic and has a variety of therapeutic properties including anti-oxidant, analgesic, anti-inflammatory and antiseptic activity. More recently curcumin has been found to possess anti-cancer activities via its effect on a variety of biological pathways involved in mutagenesis, oncogene expression, cell cycle regulation, apoptosis, tumorigenesis and metastasis. Curcumin has shown anti-proliferative effect in multiple cancers, and is an inhibitor of the transcription factor NF-κB and downstream gene products (including c-myc, Bcl-2, COX-2, NOS, Cyclin D1, TNF-α, interleukins and MMP-9). In addition, curcumin affects a variety of growth factor receptors and cell adhesion molecules involved in tumor growth, angiogenesis and metastasis. Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and treatment protocols include disfiguring surgery, platinum-based chemotherapy and radiation, all of which may result in tremendous patient morbidity. As a result, there is significant interest in developing adjuvant chemotherapies to augment currently available treatment protocols, which may allow decreased side effects and toxicity without compromising therapeutic efficacy. Curcumin is one such potential candidate, and this review presents an overview of the current in vitro and in vivo data supporting its therapeutic activity in head and neck cancer as well as some of the challenges concerning its development as an adjuvant chemotherapeutic agent.

Honokiol inhibits the progression of collagen-induced arthritis by reducing levels of pro-inflammatory cytokines and matrix metalloproteinases and blocking oxidative tissue damage

Plant-derived compounds with potent anti-inflammatory activity have attracted a great deal of attention as a source for novel anti-arthritic agents with minimal side effects. We attempted to determine the anti-arthritic effects of orally administered honokiol isolated from Magnolia species. The oral administration of honokiol inhibited the progression and severity of type II collagen (CII)-induced arthritis (CIA) by reducing clinical arthritis scores and paw swelling. The histological analysis demonstrated preserved joint space; and the immunohistochemical data showed that the levels of interleukin (IL)-17, matrix metalloproteinase (MMP)-3, MMP-9, MMP-13, and receptor activator for nuclear factor-κB ligand, as well as nitrotyrosine formation, were substantially suppressed in the honokiol-treated CIA mice. The elevated serum levels of tumor necrosis factor-α and IL-1β in the CIA mice were also restored to control levels via honokiol treatment. In the CIA mice, honokiol inhibited CII- or lipopolysaccharide-stimulated cytokine secretion in spleen cells, as well as CII-stimulated spleen cell proliferation. Furthermore, honokiol treatment reduced CIA-induced oxidative damage in the liver and kidney tissues of CIA mice. Collectively, the oral administration of honokiol inhibited CIA development by reducing the production of pro-inflammatory cytokines, MMP expressions, and oxidative stress. Thus, honokiol is an attractive candidate for an anti-arthritic agent.

Curcumin synergizes with resveratrol to stimulate the MAPK signaling pathway in human articular chondrocytes in vitro

The mitogen-activated protein kinase (MAPK) pathway is stimulated in differentiated chondrocytes and is an important signaling cascade for chondrocyte differentiation and survival. Pro-inflammatory cytokines such as interleukin 1β (IL-1β) play important roles in the pathogenesis of osteoarthritis (OA) and rheumatoid arthritis (RA). In this study, we investigated whether curcumin and resveratrol can synergistically inhibit the catabolic effects of IL-1β, specifically the inhibition of the MAPK and subsequent apoptosis in human articular chondrocytes. Chondrocytes were either left untreated or treated with 10 ng/ml IL-1β or 1 μM U0126, a specific inhibitor of MAPK pathway alone for the indicated time periods or pre-treated with 10 μM curcumin, 10 μM resveratrol or 10 μM resveratrol and 10 μM curcumin for 4 h followed by co-treatment with 10 ng/ml IL-1β or 1 μM U0126 and 10 μM resveratrol, 10 μM curcumin or 10 μM resveratrol and 10 μM curcumin for the indicated time periods. Cultures were evaluated by immunoblotting and transmission electron microscopy. Incubation of chondrocytes with IL-1β resulted in induction of apoptosis, downregulation of β1-integrins and the extracellular signal-regulated kinase 1/2 (Erk1/2). Interestingly, U0126 induced apoptosis and blocked the above-mentioned proteins in a similar way to IL-1β. Furthermore, curcumin and resveratrol inhibited IL-1β- or U0126-induced apoptosis and downregulation of β1-integrins and Erk1/2 in human articular chondrocytes. These results suggest that combining these two natural compounds activates MEK/Erk signaling, a pathway that is involved in the maintenance of chondrocyte differentiation and survival.