The regulatory role of curcumin on platelet functions

Natural supplements in antiphospholipid syndrome: A case for further study

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombotic events and/or pregnancy complications in the presence of persistently positive antiphospholipid antibodies (aPL). Although long-term anticoagulation with vitamin K antagonists is considered standard of care, there is an unmet need for safe therapeutics as primary thromboprophylaxis or adjuncts to standard of care in APS. APS is driven by oxidative stress, procoagulant, proinflammatory and angiogenic pathways. For these reasons there has been an increased interest into the investigation of antithrombotic, anti-inflammatory and anti-oxidant properties of natural supplements in APS. The objective of this review is to summarize the mechanistic, epidemiologic and clinical evidence behind the use of natural supplements in APS, with a specific focus on vitamin D, omega-3 fatty acids, coenzyme Q10, gingerol, and isoquercetin. This review should serve as a compelling argument for the future study of natural supplements in APS.

Surface Engineering of Bioactive Coatings for Improved Stent Hemocompatibility: A Comprehensive Review

Cardiovascular diseases continue to be a major contributor to illness and death on a global scale, and the implementation of stents has given rise to a revolutionary transformation in the field of interventional cardiology. The thrombotic and restenosis complications associated with stent implantation pose ongoing challenges. In recent years, bioactive coatings have emerged as a promising strategy to enhance stent hemocompatibility and reduce thrombogenicity. This review article provides an overview of the surface engineering techniques employed to improve the hemocompatibility of stents and reduce thrombus formation. It explores the mechanisms underlying thrombosis and discusses the factors influencing platelet activation and fibrin formation on stent surfaces. Various bioactive coatings, including anticoagulant agents, antiplatelet agents, and surface modifications, are discussed in detail, highlighting their potential in reducing thrombogenicity. This article also highlights a multitude of surface modification techniques which can be harnessed to enhance stent hemocompatibility including plasma treatment, physical vapor deposition (PVD), chemical vapor deposition (CVD), and electrodeposition. These techniques offer precise control over surface properties such as roughness, charge, and composition. The ultimate goal is to reduce platelet adhesion, tailor wettability, or facilitate the controlled release of bioactive agents. Evaluation methods for assessing hemocompatibility and thrombogenicity are also reviewed, ranging from in vitro assays to animal models. Recent advances in the field, such as nanotechnology-based coatings and bioactive coatings with controlled drug release systems, are highlighted. Surface engineering of bioactive coatings holds great promise for enhancing the long-term outcomes of stent implantation by enhancing hemocompatibility and reducing thrombogenicity. Future research directions and potential clinical applications are discussed, underscoring the need for continued advancements in this field.

The Effect of Curcumin-Loaded Glucan Nanoparticles on Immune Cells: Size as a Critical Quality Attribute

Curcumin is known for its multiple health benefits, largely due to its antioxidant and anti-inflammatory properties. It has been extensively studied as a therapeutic agent, however, it does not have good clinical efficacy due to its poor water solubility and bioavailability. Despite accepting the encapsulation of this compound in polymeric particles as one of the most promising strategies to increase its therapeutic value, these nanoparticles have fallen short of expectations due to a lack of assessment of their possible adverse effects on the immune system. Therefore, in this work, we report on a new method to encapsulate curcumin into glucan nanoparticles and their effects on cells of the immune system were evaluated. Two different-sized curcumin-loaded glucan NPs (GluCur 100 and GluCur 380) were produced, each with an encapsulation efficiency close to 100%, and were characterized regarding their size distribution, surface properties, and morphology. The results revealed the greatest hemolytic effect and cytotoxicity for the smallest particles (100 nm) tested in human PBMCs and RAW 264.7 cells. Although GluCur 380 NPs showed a weaker ROS production, they were able to inhibit the production of NO by macrophages. Furthermore, we found that the coagulation time was not affected by both sized-particles as well as platelet function. Additionally, both nanoparticles induced lymphocyte proliferation and TNF-α secretion by Mo-DCs. In conclusion, this report emphasizes the importance of the immunotoxicity assessment and how this is dependent on the intrinsic properties of nanomaterials, hopefully contributing to increasing the safety of nanomedicines.

Cardioprotective Effects of Vitex negundo: A Review of Bioactive Extracts and Compounds

There has been accumulating interest in the application of medicinal plants as alternative medicine to treat various diseases and/or to develop modern medicines. Vitex negundo is one of such medicinal plants that has been of interest to many researchers and has been of use in traditional medicine. V. negundo is found in Sri Lanka, Madagascar, Malaysia, India, China, The Philippines and East Africa. Therapeutic properties of V. negundo have previously been reviewed. Different parts, preparations and bioactive components of V. negundo possess potential protective and therapeutic effects against cardiovascular disease and related conditions as demonstrated in previous studies. We review the present state of scientific knowledge on the potential use of V. negundo and some of its bioactive components in protecting against cardiovascular diseases and related pathologies. Previous studies in animal and non-animal experimental models, although limited in number and vary in design, seem to support the cardioprotective effect of V. negundo and some of its active components. However, there is need for further preclinical and clinical studies to validate the use of V. negundo and its active constituents in protection and treatment of cardiovascular diseases. Additionally, since only a few V. negundo compounds have been evaluated, specific cardioprotective effects or mechanisms and possible side effects of other V. negundo compounds need to be extensively evaluated.

Regulatory Effects of Curcumin on Platelets: An Update and Future Directions

The rhizomatous plant turmeric, which is frequently used as a spice and coloring ingredient, yields curcumin, a bioactive compound. Curcumin inhibits platelet activation and aggregation and improves platelet count. Platelets dysfunction results in several disorders, including inflammation, atherothrombosis, and thromboembolism. Several studies have proved the beneficial role of curcumin on platelets and hence proved it is an important candidate for the treatment of the aforementioned diseases. Moreover, curcumin is also frequently employed as an anti-inflammatory agent in conventional medicine. In arthritic patients, it has been shown to reduce the generation of pro-inflammatory eicosanoids and to reduce edema, morning stiffness, and other symptoms. Curcumin taken orally also reduced rats' acute inflammation brought on by carrageenan. Curcumin has also been proven to prevent atherosclerosis and platelet aggregation, as well as to reduce angiogenesis in adipose tissue. In the cerebral microcirculation, curcumin significantly lowered platelet and leukocyte adhesion. It largely modulated the endothelium to reduce platelet adhesion. Additionally, P-selectin expression and mice survival after cecal ligation and puncture were improved by curcumin, which also altered platelet and leukocyte adhesion and blood-brain barrier dysfunction. Through regulating many processes involved in platelet aggregation, curcuminoids collectively demonstrated detectable antiplatelet activity. Curcuminoids may therefore be able to prevent disorders linked to platelet activation as possible therapeutic agents. This review article proposes to highlight and discuss the regulatory effects of curcumin on platelets.

Safety Considerations for Natural Products Commonly Used By Patients with Allergic Disease

Natural products are a category of Complementary and Alternative Medicine that includes medicinal plants, vitamins, and dietary supplements. These products are often utilized by patients with allergies in conjunction with, or as an alternative to, their conventional medical therapies. Despite the wide use of these modalities, many clinicians often have limited knowledge and training in their use. It is important for health care providers to know the safety and risks of these products that their patients may use. This Clinical Commentary reviews the side effects and adverse reactions of several natural products commonly used by patients with allergies and gives an overview of the U.S. Food and Drug Administration requirements for manufacturing, advertising and distribution.

The Antioxidant, Anti-Platelet and Anti-Coagulant Properties of Phenolic Compounds, Associated with Modulation of Hemostasis and Cardiovascular Disease, and Their Possible Effect on COVID-19

Patients affected by coronavirus disease 2019 (COVID-19) demonstrate a range of hemostasis dysfunctions, such as coagulation dysfunction and changes in blood platelet function, this being a major cause of death. These complications may also be associated with oxidative stress. Recently, various papers, including some reviews, have suggested that the use of dietary bioactive compounds, including phenolic compounds, may play a significant role in the treatment of COVID-19. However, while some phenolic compounds, such as curcumin, resveratrol, myricetin and scutellarian, have been found to have antiviral effects against COVID-19, recommendations regarding the use of such compounds to prevent or reduce the risk of CVDs during COVID-19 infection remain tentative. The present mini-review examines the antioxidant, anti-platelet and anticoagulant and antiviral activities of selected phenolic compounds and the possible implications for their use in treating CVDs associated with COVID-19. This review also examines whether these phenolic compounds can be promising agents in the modulation of hemostasis and CVDs during COVID-19. While their properties have been well documented in various in vitro and in vivo studies, particularly their positive role in the prophylaxis and treatment of CVDs, less is known regarding their prophylactic potential against CVDs during COVID-19, and no credible evidence exists for their efficiency in humans or animals. In such cases, no in vitro or in vivo studies are available. Therefore, it cannot be unequivocally stated whether treatment with these phenolic compounds offers benefits against CVDs in patients with COVID-19.

Curcumin-Rich Curry Consumption and Neurocognitive Function from 4.5-Year Follow-Up of Community-Dwelling Older Adults (Singapore Longitudinal Ageing Study)

The potential neurocognition protective effects of dietary curcumin in curry consumed with food was investigated in this study of 2734 community-dwelling adults (aged ≥ 55, mean ± SD: 65.9 ± 7.4). We analyzed longitudinal data of baseline curry consumption (“never or rarely”, “occasionally”: <once a month, “often”: >once a month and <once a week, “very often”: >once a week or daily) and baseline and 4.5-year follow-up cognitive function in mixed model analyses controlling for confounding risk factors. Significant between-exposure differences were found for Digit Span-Backward (DS-B), Verbal Fluency-Animals (VF-A) and Block Design (BD). Compared to “never or rarely” consumption, “very often” and “often” consumptions were associated with higher DS-B performance; “very often”—with higher VF-A, and “occasional”, “often” and “very often” consumptions—with higher BD: Cohen’s d: from 0.130 to 0.186. Among participants with cardiometabolic and cardiac diseases (CMVD), curry consumption was associated with significantly higher DS-B and VF-A. Among CMVD-free participants, curry consumption was associated with significantly higher DS-B, VF-A and BD: Cohen’s d: from 0.098 to 0.305. The consumption of dietary curcumin was associated with the maintenance over time of higher functioning on attention, short-term working memory, visual spatial constructional ability, language and executive function among community-dwelling older Asian adults.

Curcumin by activation of adenosine A2A receptor stimulates protein kinase a and potentiates inhibitory effect of cangrelor on platelets

Curcumin is a natural polyphenol derived from the turmeric plant (Curcuma longa) which exhibits numerous beneficial effects on different cell types. Inhibition of platelet activation by curcumin is well known, however molecular mechanisms of its action on platelets are not fully defined. In this study, we used laser diffraction method for analysis of platelet aggregation and Western blot for analysis of intracellular signaling mechanisms of curcumin effects on platelets. We identified two new molecular mechanisms involved in the inhibitory effects of curcumin on platelet activation. Firstly, curcumin by activation of adenosine A_2A receptor stimulated protein kinase A activation and phosphorylation of Vasodilator-stimulated phosphoprotein. Secondly, we demonstrated that curcumin even at low doses, which did not inhibit platelet aggregation, potentiated inhibitory effect of ADP receptor P2Y₁₂ antagonist cangrelor which partly could be explained by activation of adenosine A_2A receptor.

Bioactive nano yarns as surgical sutures for wound healing

Surgical sutures are the most widely used medical device in any surgical procedure worldwide. In this study, modified electrospinning technique has been used as manufacturing technique to produce nanofiber bundles twisted simultaneously to obtain nanofiber yarns. Taking the advantage of nanofiber yarns in terms of biomimetic structure, mechanical strength and handling properties, the material is chosen. Curcumin, a natural compound is incorporated to the nanofiber yarns by blend electrospinning technique for its anti-inflammatory, antibiotic and wound healing properties. The synthesized nanofiber yarns were characterized by various characterization techniques such as XRD, FTIR, SEM, Tensile testing, stem cell interaction, hemocompatibility, bacterial response, drug release profiling and in vivo studies. Curcumin loaded nanofiber yarns demonstrated sustained release with improved antibacterial, antiplatelet, cell migration and stem cell interaction in vitro. The results from skin inflammation animal model revealed that curcumin laden nanofiber yarn suture manifested reduced inflammation and cellularity. The three dimensional structure, adequate mechanical strength and biological properties of the nanofiber yarn provide naive environment for wound healing with the balanced degradation of suture material in rat model.

Curcumin Nanoparticles as Promising Therapeutic Agents for Drug Targets

Curcuma longa is very well-known medicinal plant not only in the Asian hemisphere but also known across the globe for its therapeutic and medicinal benefits. The active moiety of Curcuma longa is curcumin and has gained importance in various treatments of various disorders such as antibacterial, antiprotozoal, cancer, obesity, diabetics and wound healing applications. Several techniques had been exploited as reported by researchers for increasing the therapeutic potential and its pharmacological activity. Here, the dictum is the new room for the development of physicochemical, as well as biological, studies for the efficacy in target specificity. Here, we discussed nanoformulation techniques, which lend support to upgrade the characters to the curcumin such as enhancing bioavailability, increasing solubility, modifying metabolisms, and target specificity, prolonged circulation, enhanced permeation. Our manuscript tried to seek the attention of the researcher by framing some solutions of some existing troubleshoots of this bioactive component for enhanced applications and making the formulations feasible at an industrial production scale. This manuscript focuses on recent inventions as well, which can further be implemented at the community level.

When metal-organic framework mediated smart drug delivery meets gastrointestinal cancers

Cancers of the gastrointestinal tract constitute one of the most common cancer types worldwide and a ∼58% increase in the global number of cases has been estimated by IARC for the next twenty years. Recent advances in drug delivery technologies have attracted scientific interest for developing and utilizing efficient therapeutic systems. The present review focuses on the use of nanoscale MOFs (Nano-MOFs) as carriers for drug delivery and imaging purposes. In pursuit of significant improvements to current gastrointestinal cancer chemotherapy regimens, systems that allow multiple concomitant therapeutic options (polytherapy) and controlled release are highly desirable. In this sense, MOF-based nanotherapeutics represent a significant step towards achieving this goal. Here, the current state-of-the-art of interdisciplinary research and novel developments into MOF-based gastrointestinal cancer therapy are highlighted and reviewed.

An overview on plants cannabinoids endorsed with cardiovascular effects

Nowadays cardiovascular diseases (CVDs) are the major causes for the reduction of the quality of life. The endocannabinoid system is an attractive therapeutic target for the treatment of cardiovascular disorders due to its involvement in vasomotor control, cardiac contractility, blood pressure and vascular inflammation. Alteration in cannabinoid signalling can be often related to cardiotoxicity, circulatory shock, hypertension, and atherosclerosis. Plants have been the major sources of medicines until modern eras in which researchers are experiencing a rediscovery of natural compounds as novel therapeutics. One of the most versatile plant is Cannabis sativa L., containing phytocannabinoids that may play a role in the treatment of CVDs. The aim of this review is to collect and investigate several less studied plants rich in cannabinoid-like active compounds able to interact with cannabinoid system; these plants may play a pivotal role in the treatment of disorders related to the cardiovascular system.

Pharmacological properties and underlying mechanisms of curcumin and prospects in medicinal potential

Curcumin, isolated from Curcuma longa L., is a fat-soluble natural compound that can be obtained from ginger plant tuber roots, which accumulative evidences have demonstrated that it can resist viral and microbial infection and has anti-tumor, reduction of blood lipid and blood glucose, antioxidant and removal of free radicals, and is active against numerous disorders various chronic diseases including cardiovascular, pulmonary, neurological and autoimmune diseases. In this article is highlighted the recent evidence of curcuminoids applied in sevral aspects of medical problem particular in COVID-19 pandemics. We have searched several literature databases including MEDLINE (PubMed), EMBASE, the Web of Science, Cochrane Library, Google Scholar, and the ClinicalTrials.gov website via using curcumin and medicinal properties as a keyword. All studies published from the time when the database was established to May 2021 was retrieved. This review article summarizes the growing confirmation for the mechanisms related to curcumin's physiological and pharmacological effects with related target proteins interaction via molecular docking. The purpose is to provide deeper insight and understandings of curcumin's medicinal value in the discovery and development of new drugs. Curcumin could be used in the prevention or therapy of cardiovascular disease, respiratory diseases, cancer, neurodegeneration, infection, and inflammation based on cellular biochemical, physiological regulation, infection suppression and immunomodulation.

Curcumin at Low Doses Potentiates and at High Doses Inhibits ABT-737-Induced Platelet Apoptosis

Curcumin is a natural bioactive component derived from the turmeric plant Curcuma longa, which exhibits a range of beneficial activities on human cells. Previously, an inhibitory effect of curcumin on platelets was demonstrated. However, it is unknown whether this inhibitory effect is due to platelet apoptosis or procoagulant platelet formation. In this study, curcumin did not activate caspase 3-dependent apoptosis of human platelets, but rather induced the formation of procoagulant platelets. Interestingly, curcumin at low concentration (5 µM) potentiated, and at high concentration (50 µM) inhibited ABT-737-induced platelet apoptosis, which was accompanied by inhibition of ABT-737-mediated thrombin generation. Platelet viability was not affected by curcumin at low concentration and was reduced by 17% at high concentration. Furthermore, curcumin-induced autophagy in human platelets via increased translocation of LC3I to LC3II, which was associated with activation of adenosine monophosphate (AMP) kinase and inhibition of protein kinase B activity. Because curcumin inhibits P-glycoprotein (P-gp) in cancer cells and contributes to overcoming multidrug resistance, we showed that curcumin similarly inhibited platelet P-gp activity. Our results revealed that the platelet inhibitory effect of curcumin is mediated by complex processes, including procoagulant platelet formation. Thus, curcumin may protect against or enhance caspase-dependent apoptosis in platelets under certain conditions.

A reduced graphene oxide-β-cyclodextrin nanocomposite-based electrode for electrochemical detection of curcumin

In this study, a sensitive electrochemical sensor was fabricated based on a beta-cyclodextrin–reduced graphene oxide (β-CD–rGO) nanocomposite for measuring curcumin concentration.

Possible Mechanisms and Special Clinical Considerations of Curcumin Supplementation in Patients with COVID-19

The novel coronavirus outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was recognized in late 2019 in Wuhan, China. Subsequently, the World Health Organization declared coronavirus disease 2019 (COVID-19) as a pandemic on 11 March 2020. The proportion of potentially fatal coronavirus infections may vary by location, age, and underlying risk factors. However, acute respiratory distress syndrome (ARDS) is the most frequent complication and leading cause of death in critically ill patients. Immunomodulatory and anti-inflammatory agents have received great attention as therapeutic strategies against COVID-19. Here, we review potential mechanisms and special clinical considerations of supplementation with curcumin as an anti-inflammatory and antioxidant compound in the setting of COVID-19 clinical research.

Resveratrol, curcumin and gallic acid attenuate glyoxal-induced damage to rat renal cells

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RES, CUR and GA protected renal cells from GO–induced cells death.

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RES, CUR and GA reduced formation of ROS.

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RES, CUR and GA diminished lipid peroxidation products.

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RES, CUR and GA repressed GO-induced mitochondrial membrane potential collapse.

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RES, CUR and GA decreased lysosomal membrane leakage in GO-treated cells.

Glyoxal (GO), a by-product of glucose auto-oxidation, is involved in the glycation of proteins/ lipids and formation of advanced glycation (AGE) and lipoxidation (ALE) end products. AGE/ALE were shown to contribute to diabetic complications development/progression such as nephropathy. Diabetic nephropathy progression has an oxidative nature. Given the antioxidant effects of polyphenols, potential protective effects of resveratrol, curcumin and gallic acid, in rat renal cells treated with GO, were evaluated in the present work. According to our results, incubation of GO with the cells reduced their viability and led to membrane lysis, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial membrane potential collapse, and lysosomal membrane leakage. These findings were prevented by pre-treatment with resveratrol, curcumin and gallic acid. Mitochondrial and lysosomal toxic interactions appear to worsen oxidative stress/cytotoxicity produced by GO. Resveratrol, curcumin and gallic acid inhibited ROS formation and attenuated GO-induced renal cell death.

Curcumin, a traditional spice component, can hold the promise against COVID-19?

The severity of the recent pandemic and the absence of any specific medication impelled the identification of existing drugs with potential in the treatment of Coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Curcumin, known for its pharmacological abilities especially as an anti-inflammatory agent, can be hypothesized as a potential candidate in the therapeutic regimen. COVID-19 has an assorted range of pathophysiological consequences, including pulmonary damage, elevated inflammatory response, coagulopathy, and multi-organ damage. This review summarizes the several evidences for the pharmacological benefits of curcumin in COVID-19-associated clinical manifestations. Curcumin can be appraised to hinder cellular entry, replication of SARS-CoV-2, and to prevent and repair COVID-19-associated damage of pneumocytes, renal cells, cardiomyocytes, hematopoietic stem cells, etc. The modulation and protective effect of curcumin on cytokine storm-related disorders are also discussed. Collectively, this review provides grounds for its clinical evaluation in the therapeutic management of SARS-CoV-2 infection.

Anti-hypertensive effect of crocin and hesperidin combination in high-fat diet treated rats

Cardiovascular diseases are the leading cause of death worldwide. Hypertension is the most important cause of such conditions. The use of medicinal herbs is of particular importance due to their lower cost and side effects. The aim of the present study was to compare the effect of hesperidin (HES) and crocin (CRO) alone and in combination, on blood pressure in a rat model of high-fat diet (HFD)-induced hypertension, using invasive carotid artery measurements. Animals were randomly assigned to the following groups: control group (received standard chow diet), HFD control group (received HFD containing 32% kcal of fat and 0.1% cholesterol), and three groups of HFD-treated animals that were treated with a single dose of CRO (20 mg/kg), HES (20 mg/kg), or CRO + HES (20 + 20 mg/kg). Except for the control group, rats received HFD for 7 weeks. On day 50, CRO, HES and normal saline were administered intraperitoneally and carotid arteries of the rats were cannulated. Three hours after the carotid artery cannulation, mean arterial blood pressure (MAP), systolic and diastolic blood pressure (SBP and DBP), and heart rate (HR) were measured using an intra-arterial catheter with the use of a Power Lab system. Data was analyzed using SPSS software. Rats that received HFD for 49 days presented a significant increase in SBP, HR and MAP compared to the control group (P<0.001). Whereas, HFD-treated rats of the CRO + HES group showed lower levels of SBP, HR and MAP; however, DBP remained unaffected. HES administration in HFD treated rats resulted in a significant decrease in SBP compared to the HFD control group with no significant differences in MAP. The hypotensive effects of the simultaneous administration of CRO and HES in HFD-hypertensive rats suggest the need for further study of these two natural products as a potential preventive measure against hypertension development, especially in patients with high normal blood pressure.

Nanoparticles Targeting STATs in Cancer Therapy

Over the past decades, an increase in the incidence rate of cancer has been witnessed. Although many efforts have been made to manage and treat this life threatening condition, it is still one of the leading causes of death worldwide. Therefore, scientists have attempted to target molecular signaling pathways involved in cancer initiation and metastasis. It has been shown that signal transducers and activator of transcription (STAT) contributes to the progression of cancer cells. This important signaling pathway is associated with a number of biological processes including cell cycle, differentiation, proliferation and apoptosis. It appears that dysregulation of the STAT signaling pathway promotes the migration, viability and malignancy of various tumor cells. Hence, there have been many attempts to target the STAT signaling pathway. However, it seems that currently applied therapeutics may not be able to effectively modulate the STAT signaling pathway and suffer from a variety of drawbacks such as low bioavailability and lack of specific tumor targeting. In the present review, we demonstrate how nanocarriers can be successfully applied for encapsulation of STAT modulators in cancer therapy.

Biological properties of metal complexes of curcumin

Curcumin, a naturally occurring phenolic compound isolated from Curcuma longa, has different pharmacological effects, including antiinflammatory, antimicrobial, antioxidant, and anticancer properties. However, curcumin has been found to have a limited bioavailability because of its hydrophobic nature, low-intestinal absorption, and rapid metabolism. Therefore, there is a need for enhancing the bioavailability and its solubility in water in order to increase the pharmacological effects of this bioactive compound. One strategy is curcumin complexation with transition metals to circumvent the abovementioned problems. Curcumin can undergo chelation with various metal ions to form metallo-complexes of curcumin, which may show greater effects as compared with curcumin alone. Promising results with metal curcumin complexes have been observed with regard to antioxidant, anticancer, and antimicrobial activity, as well as in treatment of Alzheimer's disease. The present review provides a concise summary of the characterization and biological properties of curcumin-metal complexes. © 2019 BioFactors, 45(3):304-317, 2019.

Curcumin: a potent agent to reverse epithelial-to-mesenchymal transition

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is involved in tumor progression, invasion, migration and metastasis. EMT is a process by which polarized epithelial cells acquire motile mesothelial phenotypic features. This process is initiated by disassembly of cell-cell contacts through the loss of epithelial markers and replacement of these markers by mesenchymal markers. Reconstruction of the cytoskeleton and degradation of the tumor basement membrane ensures the spread of invasive malignant tumor cells to distant locations. Accumulating evidence indicates that curcumin, as a well-known phytochemical, can inhibit EMT/metastasis through various mechanisms and pathways in human tumors.

CONCLUSIONS

In this review, we summarize the mechanisms by which curcumin may affect EMT in cells under pathological conditions to understand its potential as a novel anti-tumor agent. Curcumin can exert chemo-preventive effects by inhibition and reversal of the EMT process through both TGF-β-dependent (e.g. in hepatoma and retinal pigment epithelial cancer) and -independent (e.g. in oral cancer, colorectal cancer, pancreatic cancer, hepatocellular carcinoma, breast cancer, melanoma, prostate cancer, bladder cancer, thyroid cancer and lung cancer) pathways. Curcumin can also mitigate chemoresistance through EMT suppression and promotion of the antiproliferative effects of conventional chemotherapeutics. Therefore, curcumin has the potential to be used as a novel adjunctive agent to prevent tumor metastasis, which may at least partly be attributed to its hampering of the EMT process.

Hormetic effects of curcumin: What is the evidence?

Curcumin (diferuloylmethane), a component of the yellow powder prepared from the roots of Curcuma longa or Zingiberaceae (known as turmeric) is not only widely used to color and flavor food but also used as a pharmaceutical agent. Curcumin demonstrates anti-inflammatory, anticarcinogenic, antiaging, and antioxidant activity, as well as efficacy in wound healing. Notably, curcumin is a hormetic agent (hormetin), as it is stimulatory at low doses and inhibitory at high doses. Hormesis by curcumin could be also a particular function at low doses (i.e., antioxidant behavior) and another function at high dose (i.e., induction of autophagy and cell death). Recent findings suggest that curcumin exhibits biphasic dose-responses on cells, with low doses having stronger effects than high doses; examples being activation of the mitogen-activated protein kinase signaling pathway or antioxidant activity. This indicates that many effects induced by curcumin are dependent on dose and some effects might be greater at lower doses, indicative of a hormetic response. Despite the consistent occurrence of hormetic responses of curcumin in a wide range of biomedical models, epidemiological and clinical trials are needed to assess the nature of curcumin's dose-response in humans. Fortunately, more than one hundred clinical trials with curcumin and curcumin derivatives are ongoing. In this review, we provide the first comprehensive analysis supportive of the hormetic behavior of curcumin and curcumin derivatives.