Dimethoxycurcumin, a structural analogue of curcumin, induces apoptosis in human renal carcinoma caki cells through the production of reactive oxygen species, the release of cytochrome C, and the activation of caspase-3

A curcumin-nicotinoyl derivative and its transition metal complexes: synthesis, characterization, and in silico and in vitro biological behaviors

Curcumin-nicotinoyl (Cur-Nic) was synthesized by the chemical modification of the curcumin structure, characterized, and used as a ligand for the synthesis of copper(II) and zinc(II) complexes. The biological activities of Cur-Nic and its metal complexes were predicted using the PASS and Swiss Target Prediction online software, respectively, and docking studies with tyrosine-protein kinase SRC were performed using the PyRx software to predict their anticancer activities. The toxicity effects of the complexes on a human breast cancer cell line (MCF-7) compared to a healthy breast cell line (MCF-10A) were investigated by the MTS assay. Although the metal complexes maintained the least toxicity against normal cells, the results indicated that compared to curcumin and Cur-Nic, the cytotoxicity toward cancer cells increased due to the complexation process. Moreover, the antibacterial evaluation of the compounds against a Gram-positive bacterium (MRSA) and a Gram-negative bacterium (E. coli) indicated that the Cu(II) complex and Cur-Nic were the best, respectively. Also, the Zn(II) complex was the most stable compound, and the Cu(II) complex was the best ROS scavenger based on the in vitro evaluation.

The Effect of Natural Substances Contained in Bee Products on Prostate Cancer in In Vitro Studies

Prostate cancer is a common cancer in men in older age groups. The WHO forecasts an increase in the incidence of prostate cancer in the coming years. Patients may not respond to treatment, and may not tolerate the side effects of chemotherapy. Compounds of natural origin have long been used in the prevention and treatment of cancer. Flavonoids obtained from natural products, e.g., propolis, are compounds with proven antibacterial and antiviral efficacy which modulate the immune response and may be useful as adjuvants in chemotherapy. The main aim of the present study was to evaluate the cytotoxic and pro-apoptotic properties of selected flavonoids on prostate cancer cells of the LNCaP line. The compounds used in this study were CAPE, curcumin (CUR), and quercetin (QUE). Mitochondrial and lysosome metabolism was assessed by the XTT-NR-SRB triple assay as well as by the fluorescent staining techniques. Staining for reactive oxygen species was performed as well. The experiment showed that each of the tested compounds has a cytotoxic effect on the LNCaP cell line. Different types of cell death were induced by the tested compounds. Apoptosis was induced by quercetin, while autophagy-specific changes were observed after using CAPE. Compounds obtained from other bee products have antiproliferative and cytotoxic activity against LNCaP prostate cancer cells.

Characterization of Electrospun BDMC-Loaded PLA Nanofibers with Drug Delivery Function and Anti-Inflammatory Activity

Controlled drug release systems are the subject of many investigations to achieve the therapeutic effect of drugs. They have numerous advantages, such as localized effects, lower side effects, and less onset of action. Among drug-delivery systems, electrospinning is a versatile and cost-effective method for biomedical applications. Furthermore, electrospun nanofibers are promising as drug carrier candidates due to their properties that mimic the extracellular matrix. In this work, electrospun fibers were made of Poly-L-lactic acid (PLA), one of the most widely tested materials, which has excellent biocompatible and biodegradable properties. A curcuminoid, bisdemethoxycurcumin (BDMC) was added in order to complete the drug delivery system. The PLA/BDMC membranes were characterized, and biological characteristics were examined in vitro. The results show that the average fiber diameter was reduced with the drug, which was mainly released during the first 24 h by a diffusion mechanism. It was seen that the use of our membranes loaded with BDMC enhanced the rate of proliferation in Schwann cells, the main peripheral neuroglial cells, and modulated inflammation by reducing NLRP3 inflammasome activation. Considering the results, the prepared PLA/BDMC membranes hold great potential for being used in tissue engineering applications.

Curcumin in the treatment of urological cancers: Therapeutic targets, challenges and prospects

Urological cancers include bladder, prostate and renal cancers that can cause death in males and females. Patients with urological cancers are mainly diagnosed at an advanced disease stage when they also develop resistance to therapy or poor response. The use of natural products in the treatment of urological cancers has shown a significant increase. Curcumin has been widely used in cancer treatment due to its ability to trigger cell death and suppress metastasis. The beneficial effects of curcumin in the treatment of urological cancers is the focus of current review. Curcumin can induce apoptosis in the three types of urological cancers limiting their proliferative potential. Furthermore, curcumin can suppress invasion of urological cancers through EMT inhibition. Notably, curcumin decreases the expression of MMPs, therefore interfering with urological cancer metastasis. When used in combination with chemotherapy agents, curcumin displays synergistic effects in suppressing cancer progression. It can also be used as a chemosensitizer. Based on pre-clinical studies, curcumin administration is beneficial in the treatment of urological cancers and future clinical applications might be considered upon solving problems related to the poor bioavailability of the compound. To improve the bioavailability of curcumin and increase its therapeutic index in urological cancer suppression, nanostructures have been developed to favor targeted delivery.

A Promising Anticancer Agent Dimethoxycurcumin: Aspects of Pharmacokinetics, Efficacy, Mechanism, and Nanoformulation for Drug Delivery

Curcumin is a well-known anticancer natural product with various significant bioactivities that has been well documented, but its widespread use is mainly hindered by insufficient ADME properties such as poor solubility and low metabolic stability. Dimethoxycurcumin (DiMC) is a kind of lipophilic compound derived from curcumin that maintains its anticancer potency and has greatly improved systematic bioavailability. Therefore, DiMC is regarded as a promising plant-derived anticancer agent that deserves to be well developed. Herein, we concentrate on the published work by those from original research groups concerned with the pharmacokinetics, efficacy, and mechanism of DiMC involved in the treatment of various tumors, as well as the nanoformulations for effective drug delivery.

Therapeutic effect of curcumin in gastrointestinal cancers: A comprehensive review

Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.

Perspectives for synthetic curcumins in chemoprevention and treatment of cancer: An update with promising analogues

Curcumin, a pure compound extracted from the flowering plant, turmeric (Curcuma longa. Zingiberaceae), is a common dietary ingredient found in curry powder. It has been studied extensively for its anti-inflammatory, antioxidant, antimicrobial and anti-tumour activities. Evidence is accumulating demonstrating its potential in chemoprevention and as an anti-tumour agent for the treatment of cancer. Despite demonstrated safety and tolerability, the clinical application of curcumin is frustrated by its poor solubility, metabolic instability and low oral bioavailability. Consequently researchers have tried novel techniques of formulation and delivery as well as synthesis of analogues with enhanced properties to overcome these barriers. This review presents the synthetic analogues of curcumin that have proven their anticancer potential from different studies. It also highlights studies that combined these analogues with approved chemotherapies and delivered them via novel techniques. Currently, there are no reports of clinical studies on any of the synthetic congeners of curcumin and this presents an opportunity for future research. This review presents the synthetic analogues of curcumin and makes a compelling argument for their potential application in the management of cancerous disease.

The electrical pulse application enhances intra-cellular localization and potentiates cytotoxicity of curcumin in breast cancer cells

Breast cancer is the most common cancer of women, and fifth leading cause of mortality worldwide. Existing breast cancer regimens are costly and produce severe side effects. This highlights a need for the development of efficient novel therapies, which are cost effective and limit side effects. An electrical pulse (EP)-based chemo therapy, known as electrochemotherapy (ECT) using the natural compound curcumin could be an effective alternative. ECT is a non-surgical modality, which produces excellent anti-tumor efficacy at small drug concentrations due to increased uptake of drugs. In clinics, ECT is shown to be effective in treating advanced, recurrent, and metastatic breast cancers, which are refractory to multiple modalities. ECT with curcumin triggers apoptotic cell death in breast cancer cells and could be an effective alternative, due to curcumin's low cost and reduced side-effects. However, there is a lack of studies quantifying the uptake of curcumin in response to EP application. Towards this, we determined the uptake of different curcuminoids (curcumin, desmethoxycurcumin, and bisdemethoxycurcumin) upon EP application and their impact on cell cytotoxicity. Additionally, we studied the combined effect of calcium chloride (CaCl₂) and a curcuminoids (Cur) mixture, based on initial studies suggesting calcium electroporation as a potential inexpensive anti-cancer treatment. Our results indicate EP with Cur increases cellular uptake, cell shrinkage, and cytotoxicity. The EP + Cur resulted in the highest uptake of the bisdemethoxycurcumin. Further, EP also potentiated the cytotoxicity of CaCl₂ and of the Cur and CaCl₂ combination against breast cancer cells and caused apoptosis. Our preliminary data pave the way to further studies on Cur and CaCl₂ combination treating breast cancer.

Dimethoxycurcumin reduces proliferation and induces apoptosis in renal tumor cells more efficiently than demethoxycurcumin and curcumin

Curcumin (Cur), is a pigment with antiproliferative activity but has some pharmacokinetic limitations, which led researchers to look for more effective structure analogs. This work investigated the effects of Cur and compared them with the two analogs, demethoxycurcumin (DeMC) and dimethoxycurcumin (DiMC), to elucidate their mechanisms of action. The cytotoxic, antiproliferative, and genotoxic effects these compounds were correlated based on gene expression analysis in the human renal adenocarcinoma cells (786-O). Cur decreased CYP2D6 expression and exhibited cytotoxic effects, such as inducing monopolar spindle formation and mitotic arrest mediated by the increase in CDKN1A (p21) mRNA. This dysregulation induced cell death through a caspase-independent pathway but was mediated by decrease in MTOR and BCL2 mRNA expression, suggesting that apoptosis occurred by autophagy. DeMC and DiMC had similar effects in that they induced monopolar spindle and mitotic arrest, were genotoxic, and activated GADD45A, an important molecule in repair mechanisms, and CDKN1A. However, the induction of apoptosis by DeMC was delayed and regulated by the decrease of antiapoptotic mRNA BCL.XL and subsequent activation of caspase 9 and caspase 3/7. DiMC treatment increased the expression of CYP1A2, CYP2C19, and CYP3A4 and exhibited higher cytotoxicity compared with other compounds. It induced apoptosis by increasing mRNA expression of BBC3, MYC, and CASP7 and activation of caspase 9 and caspase 3/7. These data revealed that different gene regulation processes are involved in cell death induced by Cur, DeMC, and DiMC. All three can be considered as promising chemotherapy candidates, with DiMC showing the greatest potency.

Demethoxycurcumin increases the sensitivity of cisplatin-resistant non-small lung cancer cells to cisplatin and induces apoptosis by activating the caspase signaling pathway

Patients with non-small cell lung cancer (NSCLC) can develop strong drug resistance following long-term treatment with platinum-based drugs. Increasing doses of chemotherapeutic drugs fail to obtain better results, and serious complications occur. It has been demonstrated that upregulation of excision repair cross-complementary 1 (ERCC1) in lung cancer cells is closely associated with cell resistance to platinum-based chemotherapy. In addition, curcumin (CMN) enhances antitumor effects in NSCLC by downregulating ERCC1. The aim of the present study was to investigate the effects of demethoxycurcumin (DMC), a curcuminoid, on the reversal of resistance of NSCLC cells in vitro and in vivo. The present study demonstrated that DMC significantly increased the sensitivity of DDP in DDP-resistant A549 (A549/DDP) cells. The results from an MTT assay demonstrated that DMC combined with DDP significantly attenuated the proliferation of A549/DDP cells. Furthermore, DMC exhibited decreased toxicity in normal lung fibroblast MRC-5 cells. In addition, following treatment of A549/DDP cells with a combination of DMC and DDP, the expression of ERCC1 was reduced, the protein levels of Bcl-2 and Bax were decreased and increased, respectively, whereas caspase-3 was activated, according to results from western blotting. Finally, DDP combined with DMC significantly attenuated A549/DDP cell-derived tumor growth in vivo. Taken together, the findings from the present study suggested that DMC in combination with DDP may be considered as a novel combination regimen for restoring DDP sensitivity in DDP-resistant NSCLC cells.

Berberine associated photodynamic therapy promotes autophagy and apoptosis via ROS generation in renal carcinoma cells

Renal cell carcinoma (RCC) consists of the most lethal common urological cancer and the clinical practice has shown that resistant RCC to commons therapies is extremely high. Berberine is an isoquinoline alkaloid, presents in different kinds of plants and it has long been used in Chinese medicine. It has several properties, such as antioxidant, anti-inflammatory, anti-diabetic, anti-microbial and anti-cancer. Moreover, berberine has photosensitive characteristics and its association with photodynamic therapy (PDT) is effective against tumor cells. This study aimed to evaluate the effects of berberine associated with PDT in renal carcinoma cell lines. The cellular viability assay showed increased cytotoxicity in concentration and time-dependent manner. Berberine presented efficient internalization in all cell lines analyzed. In addition, after treatment with berberine associated with PDT, it was observed a high phototoxicity effect with less than 20 % of viable cells. In this study we observed that the increase of reactive oxygen species (ROS) levels was accompanied by an increase of autophagy levels and apoptosis by caspase 3 activity, suggesting cell death by both mechanisms. Additionally, three target genes of anti-cancer drugs were differentially expressed in 786-O cells, being that Vascular Endothelial Growth Factor-D (FIGF) and Human Telomerase Reverse Transcriptase (TERT) gene presented low expression and Polo Like Kinase 3 (PLK3) presented overexpression after treatment with berberine associated with PDT. In this study, the proposed treatment triggered metabolites changes related to cell proliferation, tumorigenesis and angiogenesis. Thus, it was possible to suggest that berberine has promising potential as a photosensitizing agent in a photodynamic therapy, because it induced significant anticancer effects on renal carcinoma cells.

Small-molecule compounds target paraptosis to improve cancer therapy

According to its different occurrence mechanism, programmed cell death (PCD) is divided into apoptosis, autophagy, necrosis, paraptosis and so on. Paraptosis is morphologically different from apoptosis and autophagy, which exhibit cytoplasmic vacuolation derived from the ER, independent of caspase, absence of apoptotic morphology. Recent researches have implied that a variety of small molecule compounds, such as celastrol, curcumin, can induce paraptosis-associated cell death as the reagent to enhance anti-cancer activity. A better understanding of paraptosis will lay the foundation to develop new therapeutic strategies to treat human cancers that make full use of small-molecule compounds.

Role of curcumin in the management of pathological pain

BACKGROUND

Pathological pain conditions can be triggered after peripheral nerve injury and/or inflammation. It is a major clinical problem that is poorly treated with available therapeutics. Curcumin is a phenolic compound derived from Curcuma longa, being widely used for its antioxidant, anti-inflammatory and immunomodulatory effects.

PURPOSE

This review systematically summarized updated information on the traditional uses of curcumin in order to explore antinociceptive effects in pathological pain and evaluate future therapeutic opportunities clinically. Moreover, some structure-activity relationships would greatly enrich the opportunity of finding new and promising lead compounds and promote the reasonable development of curcumin.

METHODS

PubMed were searched and the literature from the year 1976 to January 2018 was retrieved using keywords pain and curcumin.

RESULTS

This review systematically summarized updated information on the traditional uses, chemical constituents and bioactivities of curcumin, and highlights the recent development of the mechanisms of curcumin in the pathological pain by sciatic nerve injury, spinal cord injury, diabetic neuropathy, alcoholic neuropathy, chemotherapy induced peripheral neuroinflammtion, complete Freund's adjuvant (CFA) injection or carrageenan injection. Importantly, the clinical studies provide a compelling justification for its use as a dietary adjunct for pain relief. And we also present multiple approaches to improve bioavailability of curcumin for the treatment of pathological pain.

CONCLUSION

This review focuses on pre-clinical and clinical studies in the treatment of pathological pain. Although the mechanisms of pain mitigating effects are not very clear, there is compelling evidence proved that curcumin plays an essential role. However, further high-quality clinical studies should be undertaken to establish the clinical effectiveness of curcumin in patients suffering from pathological pain. Potential methods of increase the water solubility and bioavailability of curcumin still need to be studied. These approaches will help in establishing it as remedy for pathological pain.

Demethoxycurcumin: A naturally occurring curcumin analogue with antitumor properties

The eradication of cancer in a patient remains an elusive challenge despite advances in early detection and diagnosis, chemo- and immunotherapy, pinpoint radiation treatments, and expert surgical intervention. Although significant gains have been made in our understanding of cancer cell biology, a definite cure for most cancers does not exist at present. Thus, it is not surprising that the research and medical communities continue to explore the importance and therapeutic potential of natural products in their multimodality cancer treatment approach. Curcuminoids found in turmeric are one such class of natural products that have been extensively investigated for their potential to halt the progression of cancer cell proliferation and, more important, to stop metastasis from occurring. In this review, we examine one curcuminoid (demethoxycurcumin [DMC]) largely because of its increased stability and better aqueous solubility at physiological pH, unlike the more well-known curcuminoid (curcumin), which is largely unabsorbed after oral ingestion. The present review will focus on the signaling pathways that DMC utilizes to modulate the growth, invasion, and metastasis of cancer cells in an effort to provide enhanced mechanistic insight into DMC's action as it pertains to brain, ovarian, breast, lung, skin, and prostate cancer. Additionally, this review will attempt to provide an overview of DMC's mechanism of action by modulating apoptosis, cell cycle, angiogenesis, metastasis, and chemosensitivity. Lastly, it is hoped that increased understanding will be gained concerning DMC's interactive role with microRNA-551a, 5' adenosine monophosphate-activated protein kinase, nuclear factor-κB, Wnt inhibitory factor-1, and heat shock protein 70 to affect the progression of cancer.

Curcuminoids Induce Reactive Oxygen Species and Autophagy to Enhance Apoptosis in Human Oral Cancer Cells

Numerous studies support the use of herbal medicine or natural products for chemotherapy in human cancers. Reports have associated curcumin (CUR), dimethoxy curcumin (DMC) and bisdemethoxycurcumin (BDMC) with numerous biological activities including anticancer activities, but no available information have shown that these induced apoptotic cell death and autophagy in human oral cancer cells. In the present study, we investigated the effect of CUR, DMC and BDMC on the cell viability, apoptotic cell death, reactive oxygen species (ROS), Ca[Formula: see text], mitochondria membrane potential (MMP) and caspase activities using flow cytometry assay and autophagy by monodansylcadaverine (MDC) and acridine orange (AO) staining in human oral cancer SAS cells. Results indicated that CUR, DMC and BDMC decreased total viable cell number through the induction of cell autophagy and apoptosis in SAS cells. Cells were pretreated with N-acetyl-cysteine (NAC), 3-methyladenine (3MA), rapamycin and carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoro-methylketone (Z-VAD-fmk) and then were treated with CUR, DMC and BDMC that led to increased total viable cell number when compared to CUR, DMC and BDMC treatments only. Results indicated induced apoptotic cell death through ROS, mitochondria-dependent pathway and induction of cell autophagy. Based on those observations, we suggest that CUR, DMC and BDMC could be used as a potential anticancer agent in human oral cancer.

Curcumin and its synthetic analogue dimethoxycurcumin differentially modulates antioxidant status of normal human peripheral blood mononuclear cells

Curcumin is a polyphenol derived from the herb Curcuma longa, which has been extensively studied in terms of its antitumour, antioxidant, and chemopreventive activity as well as various other effects. In the present work we compared curcumin with its synthetic analogue dimethoxycurcumin (dimc) in terms of its antioxidant enzyme-modulating effects in human peripheral blood mononuclear cells (PBMC). We found that these compounds modulate antioxidant enzymes differentially. Both curcumin and dimethoxycurcumin effected a decrease in lipid peroxidation status in PBMC, however, curcumin had better activity in this regard. An increase in the activity of catalase was seen in the case of curcumin-treated PBMC, whereas dimc increased catalase activity significantly to almost twofold level. Real time-polymerase chain reaction (RT-PCR) analysis revealed significant up-regulation of catalase at mRNA level post treatment with curcumin as well as dimc, however, dimc had better activity in this regard. Glutathione reductase (GR) activity and reduced glutathione levels increased in the case of peripheral blood mononuclear cells (PBMC) treated with curcumin, however, the trend was reversed with dimethoxycurcumin where, both glutathione reductase activity and reduced glutathione levels were significantly reduced. RT-PCR analysis of glutathione reductase mRNA levels showed decrease in mRNA levels post treatment with dimethoxycurcumin (dimc) further corroborating GR enzyme assay results, however, we could not obtain significant result post curcumin treatment. NFkB reporter assay and western blot analysis of nuclear as well as cytosolic fractions of NFkB revealed that curcumin inhibits NFkB activation whereas inhibition was much less with dimc. It has been reported that curcumin and dimc exerts differential cytotoxicity in normal and tumour cells and the reason for this had been attributed to the differential uptake of these compounds by normal cells and tumour cells. Based on our results we propose that differential modulation of antioxidant enzymes via NFkB pathway could be the reason behind differential cytotoxicity of dimc as well as curcumin in normal cells and tumour cells in addition to differential uptake of these compounds as reported previously.

Demethoxycurcumin, a Natural Derivative of Curcumin Abrogates Rotenone-induced Dopamine Depletion and Motor Deficits by Its Antioxidative and Anti-inflammatory Properties in Parkinsonian Rats

Background:

Parkinson's disease (PD) is a progressive neurodegenerative disorder (NDD) associated with the loss of dopaminergic neurons in the substantia nigra and subsequently has an effect on motor function and coordination. The pathology of PD is multifactorial, in which neuroinflammation and oxidative damage are the two of the main protagonists.

Objectives:

The present study aims to assess the potential antioxidant and anti-inflammatory effects of demethoxycurcumin (DMC), a natural derivative of curcumin, against rotenone-induced PD in rats.

Materials and Methods:

Rats were randomized and divided into six groups: control, rotenone (0.5 mg/kg/day, intraperitoneal in sunflower oil) treated for 7 days, rotenone and DMC (5, 10, and 20 mg/kg b.w) cotreated, and DMC (20 mg/kg b.w) alone treated groups.

Results:

Based on the dopamine concentration and biochemical estimations, the effective dose of DMC was selected and the chronic study was performed. At the end of the experimental period, behavioral studies and protein expression patterns of inflammatory markers were analyzed. Rotenone treatment led to motor dysfunctions, neurochemical deficits, and oxidative stress and enhanced expressions of inflammatory markers, whereas oral administration of DMC attenuated all the above.

Conclusion:

Even though further research is needed to prove its efficacy in clinical trial, the results of our study showed that DMC may offer a promising and new therapeutic lead for the treatment of NDDs including PD.

SUMMARY

Curcumin and their derivatives have been shown to be potent neuroprotective effect

Demethoxycurcumin (DMC) amolerated the rotenone induced behavioural alterations

DMC abrogated the rotenone induced dopamine deficits

DMC attenuated the rotenone induced oxidative stress

DMC diminished the rotenone mediated inflammation.

Abbreviations used: COX-2: Cyclooxygenase-2; DA: Dopamine; DMC: Demethoxycurcumin; DMRT: Duncan's multiple range test; GSH: Reduced glutathione; GPx: Glutathione peroxidase; IL-1 β: Interleukin-1 β; IL-6: Interleukin-6; iNOS: Inducible nitric oxide synthase; PD: Parkinson's disease; SN: Substantia nigra; SOD: Superoxide dismutase; TBARS: Thiobarbituric acid reactive substances; TNF-α: Tumor necrosis factor-α.

Curcumin Analog DK1 Induces Apoptosis in Human Osteosarcoma Cells In Vitro through Mitochondria-Dependent Signaling Pathway

Osteosarcoma is one of the primary malignant bone tumors that confer low survival rates for patients even with intensive regime treatments. Therefore, discovery of novel anti-osteosarcoma drugs derived from natural products that are not harmful to the normal cells remains crucial. Curcumin is one of the natural substances that have been extensively studied due to its anti-cancer properties and is pharmacologically safe considering its ubiquitous consumption for centuries. However, curcumin suffers from a poor circulating bioavailability, which has led to the development of a chemically synthesized curcuminoid analog, namely (Z)-3-hydroxy-1-(2-hydroxyphenyl)-3-phenylprop-2-en-1-one (DK1). In this study, the cytotoxic effects of the curcumin analog DK1 was investigated in both U-2OS and MG-63 osteosarcoma cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell death was microscopically examined via acridine orange/propidium iodide (AO/PI) double staining. Flow cytometer analysis including Annexin V/Fluorescein isothiocyanate (FITC), cell cycle analysis and JC-1 were adapted to determine the mode of cell death. Subsequently in order to determine the mechanism of cell death, quantitative polymerase chain reaction (qPCR) and proteome profiling was carried out to measure the expression of several apoptotic-related genes and proteins. Results indicated that DK1 induced U-2 OS and MG-63 morphological changes and substantially reduced cell numbers through induction of apoptosis. Several apoptotic genes and proteins were steadily expressed after treatment with DK1; including caspase 3, caspase 9, and BAX, which indicated that apoptosis occurred through a mitochondria-dependent signaling pathway. In conclusion, DK1 could be considered as a potential candidate for an anti-osteosarcoma drug in the near future, contingent upon its ability to induce apoptosis in osteosarcoma cell lines.

The Role of Compounds Derived from Natural Supplement as Anticancer Agents in Renal Cell Carcinoma: A Review

Renal Cell Carcinoma (RCC) is the most prominent kidney cancer derived from renal tubules and accounts for roughly 85% of all malignant kidney cancer. Every year, over 60,000 new cases are registered, and about 14,000 people die from RCC. The incidence of this has been increasing significantly in the U.S. and other countries. An increased understanding of molecular biology and the genomics of RCC has uncovered several signaling pathways involved in the progression of this cancer. Significant advances in the treatment of RCC have been reported from agents approved by the Food and Drug Administration (FDA) that target these pathways. These agents have become drugs of choice because they demonstrate clinical benefit and increased survival in patients with metastatic disease. However, the patients eventually relapse and develop resistance to these drugs. To improve outcomes and seek approaches for producing long-term durable remission, the search for more effective therapies and preventative strategies are warranted. Treatment of RCC using natural products is one of these strategies to reduce the incidence. However, recent studies have focused on these chemoprevention agents as anti-cancer therapies given they can inhibit tumor cell grow and lack the severe side effects common to synthetic compounds. This review elaborates on the current understanding of natural products and their mechanisms of action as anti-cancer agents. The present review will provide information for possible use of these products alone or in combination with chemotherapy for the prevention and treatment of RCC.

Interferon-α adjuvant therapy decreases the recurrence of early clear cell renal cell carcinoma and improves the prognosis of Chinese patients

The survival time of patients with early clear cell renal cell carcinoma (ccRCC) is fairly long, but 20% to 30% of patients with localized tumors experience relapse, and the effect of IFN-α on survival has not been well studied in patients with early ccRCC. In this study, 208 patients with early ccRCC were treated with surgery, and 54 of the patients received IFN-α as adjuvant therapy. The remaining 115 patients were treated with surgery but not with IFN-α therapy. The primary endpoint was the recurrence rate, 20.37% (11/54) and 33.04% (38/115) in the IFN-α and surgery-only group, respectively. The secondary endpoint was progression-free survival (PFS), which was 123.70 (95% CI: 107.18-140.22) months for the IFN-α group, and 95.80 (95% CI: 82.18-109.42) months for the non-IFN-α group; this difference was significant (P < 0.05). The main side effects were pyrexia (61.11%), muscle pain (24.07%), malaise (9.26%), anorexia (5.56%), hepatic dysfunction (3.70%) and renal dysfunction (1.85%). Moreover, a multivariate regression identified older age, higher BMI index and smoking as significant and independent predictors of decreased PFS (P < 0.05). Overall, IFN-α therapy significantly improved PFS in Chinese patients with early ccRCC and was an independent prognostic factor (P < 0.05). In conclusion, our study showed that adjuvant IFN-α therapy decreased the recurrence rate and prolonged PFS in patients with ccRCC. Thus, this treatment may help clinicians to select a better treatment modality and better predict survival in these patients.

In vitro additive antitumor effects of dimethoxycurcumin and 5-fluorouracil in colon cancer cells

Dimethoxycurcumin (DMC) is a lipophilic analog of curcumin, an effective treatment for colon cancer, which has greater chemical and metabolic stability. Chemotherapy treatments, such as 5‐fluorouracil (5‐Fu), play a key role in the current management of colon cancer. In this study, we investigated the antitumor efficacy of DMC in combination with 5‐Fu in SW480 and SW620 colon cancer cells. CCK‐8 assay was used to evaluate the inhibitory effect of DMC and 5‐Fu on cancer cells proliferation, and the combination index was calculated. The influence of DMC and 5‐Fu on cell cycle, apoptosis, reactive oxygen species (ROS) production, and mitochondrial membrane potential in SW480 and SW620 cells was determined using flow cytometry, and the related signaling pathways were detected by western blot. Transmission electron microscopy was used to observe endoplasmic reticulum expansion. DMC‐ and/or 5‐Fu‐induced apoptosis, stimulated G0/G1 phase arrest, increased ROS levels, decreased mitochondrial membrane potential, and enhanced endoplasmic reticulum expansion. The induction of apoptosis is involved in the increasing of Bax and cytochrome c and decreasing of Bcl2 expressions. Increased production of ROS was accompanied by upregulation of CHOP and Noxa. Combination therapy of DMC and 5‐Fu had increased efficacy on the above pathways compared with either drug alone. Based on the calculated IC₅₀, combination treatment with DMC and 5‐Fu had an additive antitumor effect in both cell lines. Combined treatment with DMC and 5‐Fu led to an additive antitumor effect in colon cancer cells that was related to apoptosis induction, G0/G1 phase arrest, increased ROS production, decreased mitochondrial membrane potential, and enhanced endoplasmic reticulum expansion.

Neuroprotective effect of Demethoxycurcumin, a natural derivative of Curcumin on rotenone induced neurotoxicity in SH-SY 5Y Neuroblastoma cells

Background

Mitochondrial dysfunction and oxidative stress are the main toxic events leading to dopaminergic neuronal death in Parkinson’s disease (PD) and identified as vital objective for therapeutic intercession. This study investigated the neuro-protective effects of the demethoxycurcumin (DMC), a derivative of curcumin against rotenone induced neurotoxicity.

Methods

SH-SY5Y neuroblastoma cells are divided into four experimental groups: untreated cells, cells incubated with rotenone (100 nM), cells treated with DMC (50 nM) + rotenone (100 nM) and DMC alone treated. 24 h after treatment with rotenone and 28 h after treatment with DMC, cell viability was assessed using the MTT assay, and levels of ROS and MMP, plus expression of apoptotic protein were analysed.

Results

Rotenone induced cell death in SH-SY5Y cells was significantly reduced by DMC pretreatment in a dose-dependent manner, indicating the potent neuroprotective effects of DMC. Rotenone treatment significantly increases the levels of ROS, loss of MMP, release of Cyt-c and expression of pro-apoptotic markers and decreases the expression of anti-apoptotic markers.

Conclusions

Even though the results of the present study indicated that the DMC may serve as a potent therapeutic agent particularly for the treatment of neurodegenerative diseases like PD, further pre-clinical and clinical studies are required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1720-5) contains supplementary material, which is available to authorized users.

Biological and pharmacological evaluation of dimethoxycurcumin: A metabolically stable curcumin analogue with a promising therapeutic potential

Dimethoxycurcumin (DiMC) is a synthetic analog of curcumin with superior inter-related pro-oxidant and anti-cancer activity, and metabolic stability. Numerous studies have shown that DiMC reserves the biologically beneficial features, including anti-inflammatory, anti-carcinogenic, and cytoprotective properties, almost to the same extent as curcumin exhibits. DiMC lacks the phenolic-OH groups as opposed to curcumin, dimethoxycurcumin, and bis-demethoxycurcumin that all vary in the number of methoxy groups per molecule, and has drawn the attentions of researchers who attempted to discover the structure-activity relationship (SAR) of curcumin. In this regard, tetrahydrocurcumin (THC), the reduced and biologically inert metabolite of curcumin, denotes the significance of the conjugated α,β diketone moiety for the curcumin activity. DiMC exerts unique molecular activities compared to curcumin, including induction of androgen receptor (AR) degradation and suppression of the transcription factor activator protein-1 (AP-1). The enhanced AR degradation on DiMC treatment suggests it as a novel anticancer agent against resistant tumors with androgenic etiology. Further, DiMC might be a potential treatment for acne vulgaris. DiMC induces epigenetic alteration more effectively than curcumin, although both showed no direct DNA hypomethylating activity. Given the metabolic stability, nanoparticulation of DiMC is more promising for in vivo effectiveness. However, studies in this regard are still in its infancy. In the current review, we portray the various molecular and biological functions of DiMC reported so far. Whenever possible, the efficiency is compared with curcumin and the reasons for DiMC being more metabolically stable are elaborated. We also provide future perspective investigations with respect to varying DiMC-nanoparticles.

Demethoxycurcumin inhibited human epithelia ovarian cancer cells’ growth via up-regulating miR-551a

Curcumin is a natural agent that has ability to dampen tumor cells’ growth. However, the natural form of curcumin is prone to degrade and unstable in vitro. Here, we demonstrated that demethoxycurcumin (a curcumin-related demethoxy compound) could inhibit cell proliferation and induce apoptosis of ovarian cancer cells. Moreover, IRS2/PI3K/Akt axis was inactivated in cells treated with demethoxycurcumin. Quantitative real-time reverse transcription polymerase chain reaction demonstrated that miR-551a was down-regulated in ovarian cancer tissues and ovarian cancer cell lines. Over-expression of miR-551a inhibited cell proliferation and induced apoptosis of ovarian cancer cells, whereas down-regulation of miR-551a exerted the opposite function. Luciferase assays confirmed that there was a binding site of miR-551a in IRS2, and we found that miR-551a exerted tumor-suppressive function by targeting IRS2 in ovarian cancer cells. Remarkably, miR-551a was up-regulated in the cells treated with demethoxycurcumin, and demethoxycurcumin suppressed IRS2 by restoration of miR-551a. In conclusion, demethoxycurcumin hindered ovarian cancer cells’ malignant progress via up-regulating miR-551a.

Dimethoxy Curcumin Induces Apoptosis by Suppressing Survivin and Inhibits Invasion by Enhancing E-Cadherin in Colon Cancer Cells

Background

Dimethoxy curcumin (DMC) is a kind of lipophilic analog of curcumin with great improvement in chemical and metabolic stability. DMC has been studied in breast and renal cancer, but no research in colon cancer has been found yet.

Material/Methods

Two colon cancer cells (HT-29 and SW480) and one normal human colon mucosal epithelial cell (NCM460) were used in this study. We studied the effect of DMC on the proliferation in vitro and in vivo. Transwell migration assay was used to estimate the inhibition of DMC on invasion. Moreover, the expressions of PARP, caspase-3, survivin and E-cadherin were detected to uncover the related signaling pathways by western blotting assay both in vitro and in vivo.

Results

DMC significantly inhibited the growth of colon cancer cells in dose-dependent manner; IC50 for DMC was calculated to be 43.4, 28.2 and 454.8μM on HT-29, SW480 and NCM460. DMC significantly increased the apoptosis in both HT-29 (p=0.0051) and SW480 (p=0.0013) cells in vitro, and significantly suppressed the growth of both cell lines in vivo. Moreover, DMC reduced the number of migrated cells in both HT-29 (p=0.007) and SW480 (p=0.004) cells. By western blotting analysis, the cleavage of pro-caspases-3 and PARP were clearly induced by DMC to their active form, while the expression of survivin was reduced and E-cadherin was enhanced in both cells in vitro and in vivo.

Conclusions

DMC may exert an effective anti-tumor effect in colon cancer cells by down-regulating survivin and upregulating E-cadherin.

Demethoxycurcumin was prior to temozolomide on inhibiting proliferation and induced apoptosis of glioblastoma stem cells

Temozolomide (TMZ) is widely used for treating glioblastoma (GBM), which can effectively inhibit the GBM growth for some months; however, it still could not prevent the invariable recurrence of GBM. The existence of glioma stem cells (GSCs) was considered to be a key factor. But TMZ has poor effects on GSCs. Recently, demethoxycurcumin (DMC) has been shown to display anti-tumor activities in malignant gliomas. However, its effects and the potential mechanisms on GSCs were still unclear. Our study showed that DMC was prior to TMZ on resulting in a significant increase in GSC apoptosis and a marked inhibition of cell growth in vitro. And combined treatment of DMC and TMZ showed more significant anti-GSC effects. Further research into the underlying mechanism demonstrated that this novel combinatorial regimen leads to changes of multiple cell signaling pathways including reactive oxygen species (ROS) production and caspase-3 signaling mitochondria-related apoptosis activation as well as inactivation of JAK/STAT3 signaling pathway. Taken together, our data demonstrate that the anti-GSC effects of DMC are better than TMZ, and combined treatment of DMC and TMZ has much stronger effects on GSCs.

A monocarbonyl analogue of curcumin, 1,5-bis(3-hydroxyphenyl)-1,4-pentadiene-3-one (Ca 37), exhibits potent growth suppressive activity and enhances the inhibitory effect of curcumin on human prostate cancer cells

Prostate carcinoma is one of the leading causes of cancer-related morbidity and mortality in males in western countries. Curcumin exhibits growth-suppressive activity against several cancers, including prostate cancer, but it has poor bioavailability. The purpose of this study was to evaluate the anticancer potency and mechanism of a curcumin analogue, 1,5-bis(3-hydroxyphenyl)-1,4-pentadiene-3-one (Ca 37), in human prostate cancer. Studies were performed in established human prostate cancer cell lines (PC-3 and DU145) as well as in a murine xenograft tumor (PC-3) model. Ca 37 presented a preferential suppression capacity against growth and migration toward prostate cancer cells compared with curcumin. Ca 37 impaired the bioenergetics system, promoted cell cycle arrest and apoptosis activation in PC-3 cells. In addition, 0.5 μmol (6.65 mg/kg body weight) of Ca 37 significantly inhibited the growth of the prostate xenografted tumors, whereas 6 μmol (110 mg/kg body weight) of curcumin had little effect. Furthermore, a combination of Ca 37 and curcumin resulted in enhanced antitumor activity in prostate cancer cells. N-Acetylcysteine abrogated both reactive oxygen species (ROS) production and viability loss induced by Ca 37 but partially prevented growth inhibition in PC-3 cells treated with curcumin alone, or a combination with Ca 37. The data indicate that induction of ROS plays a vital role in the growth inhibitory effect of Ca 37 in PC-3 cells. This study suggests that Ca 37, alone or in combination with curcumin, may be a promising anticancer agent for prostate cancer therapy.

Bioavailability of a Sustained Release Formulation of Curcumin

CONTEXT

Curcumin has a number of beneficial effects, such as functioning as a potent antioxidant,1 anti-inflammatory, 2 and anticancer agent. Because of its poor oral bioavailability, very high oral doses and repeated dosing have been used to obtain effective plasma levels, with mixed results. High doses of curcumin may cause gastric disturbance, often resulting in poor patient compliance.

OBJECTIVE

The objective of this study was to compare the relative bioavailability of MicroActive Curcumin-an advanced, micronized formulation of curcumin that is 25% curcuminoids in a sustained release matrix-with that of an unformulated, 95% pure curcumin powder.

DESIGN

A dissolution study compared the solubility of the formulated and the unformulated curcumin. The research team also performed a single-dose, 12-h, crossover uptake study with 10 participants and a high-dose tolerability and accumulation study with 3 participants, comparing the 2 forms of curcumin.

SETTING

The study was done in MAZE Laboratories (Purchase, NY, USA).

PARTICIPANTS

Ten healthy male and female volunteers, aged 21-66 y, took part in the single-dose study. Three participants, 2 female and 1 male aged 40-55 y, took part in the tolerability and accumulation study. The participants were people from the community.

INTERVENTION

For the dissolution study, the research team filled hard gelatin capsules with unformulated 95% curcumin powder and the MicroActive Curcumin powder to the equivalent of 25 mg curcuminoids. For the single-dose study, participants received 500 mg of curcumin in 2 forms. MicroActive Curcumin capsules were administered after breakfast, and blood samples were drawn at 1, 2, 4, 8, and 12 h postdose. After a 7-d washout period, the protocol was repeated for unformulated, 95% curcumin powder capsules. For the tolerability study, the unformulated, 95% curcumin powder was given at a dose that provided 2 g of curcumin for 7 d followed by 5 g of curcumin for an additional 7 d. After a washout period of 14 d, the protocol was repeated with MicroActive Curcumin. Participants then continued to take the MicroActive Curcumin for >3 mo.

OUTCOME MEASURES

For the dissolution study, the curcumin was quantified at room temperature using reverse-phase, high-performance liquid chromatography (HPLC) with a Phenomenex Luna column (150 × 4.6 mm, 5 μm) (Phenomenex Inc, Torrance, CA, USA). For the single-dose and the tolerability studies, hydrolysis of conjugates and extraction of curcuminoids from the plasma were performed. The curcuminoids were quantified using reverse-phase HPLC with an ultraviolet-visible detector as described above.

RESULTS

The dissolution study indicated that the sustained-release curcumin had greater dissolution for 12 h at all points tested, compared with the unformulated curcumin. Very little of the unformulated curcumin powder had been released at the end of the 12 h. The results of the single-dose uptake study indicated that the sustained-release formula was 9.7 × more bioavailable than the unformulated powder (P < .001, paired t test). Additionally, all participants showed uptake from the sustained-release formulation. That formulation also resulted in significant increases in the plasma demethoxylated curcuminoids, but the research team did not observe the same increases for the unformulated curcumin powder. The sustained-release formulation was well tolerated, without adverse effects in the high-dose tolerability study.

CONCLUSIONS

Formulation of micronized curcumin in a combination of surfactants, oils, and polymers improves the absorption of curcumin. In addition, the unique plasma demethylated curcuminoid profile may enhance the therapeutic effects of MicroActive Curcumin not observed with unformulated curcumin at moderate and well-tolerated doses. MicroActive Curcumin was well tolerated, without any adverse effects in a high-dose tolerability study. These properties have the potential to make high-dose curcumin supplementation more accessible through simplified incorporation into food and beverage preparations.

Stronger proteasomal inhibition and higher CHOP induction are responsible for more effective induction of paraptosis by dimethoxycurcumin than curcumin

Although curcumin suppresses the growth of a variety of cancer cells, its poor absorption and low systemic bioavailability have limited its translation into clinics as an anticancer agent. In this study, we show that dimethoxycurcumin (DMC), a methylated, more stable analog of curcumin, is significantly more potent than curcumin in inducing cell death and reducing the clonogenicity of malignant breast cancer cells. Furthermore, DMC reduces the tumor growth of xenografted MDA-MB 435S cells more strongly than curcumin. We found that DMC induces paraptosis accompanied by excessive dilation of mitochondria and the endoplasmic reticulum (ER); this is similar to curcumin, but a much lower concentration of DMC is required to induce this process. DMC inhibits the proteasomal activity more strongly than curcumin, possibly causing severe ER stress and contributing to the observed dilation. DMC treatment upregulates the protein levels of CCAAT-enhancer-binding protein homologous protein (CHOP) and Noxa, and the small interfering RNA-mediated suppression of CHOP, but not Noxa, markedly attenuates DMC-induced ER dilation and cell death. Interestingly, DMC does not affect the viability, proteasomal activity or CHOP protein levels of human mammary epithelial cells, suggesting that DMC effectively induces paraptosis selectively in breast cancer cells, while sparing normal cells. Taken together, these results suggest that DMC triggers a stronger proteasome inhibition and higher induction of CHOP compared with curcumin, giving it more potent anticancer effects on malignant breast cancer cells.

Liposome encapsulation of curcumin: physico-chemical characterizations and effects on MCF7 cancer cell proliferation

The role of curcumin (diferuloylmethane), for cancer treatment has been an area of growing interest. However, due to its low absorption, the poor bioavailability of curcumin limits its clinical use. In this study, we reported an approach of encapsulation a curcumin by nanoliposome to achieve an improved bioavailability of a poorly absorbed hydrophobic compound. We demonstrated that liposomal preparations to deliver curcumin increase its bioavailability. Liposomes composed of salmon's lecithin also improved curcumin bioavailability compared to those constituted of rapeseed and soya lecithins. A real-time label-free cell analysis system based on real-time cell impedance monitoring was used to investigate the in vitro cytotoxicity of liposomal preparations.

Inhibitory effect of resveratrol against duck enteritis virus in vitro

Duck viral enteritis (DVE) is an acute, contagious herpesvirus infection of ducks, geese, and swans of all ages and species. This disease has been responsible for significant economic losses in domestic and wild waterfowl as a result of mortality, and decreased egg production. Resveratrol is a naturally occurring phytoalexin in specific plants and exhibits inhibitory activity against many kinds of virus. In this paper, resveratrol was found to inhibit duck enteritis virus (DEV) replication in a dose-dependent manner, with a 50% inhibition concentration of 3.85 μg/mL. The inhibition in virus multiplication in the presence of resveratrol was not attributed to direct inactivation or inhibition of virus attachment to the host cells, but to the inhibition of viral multiplication in host cells. The assay of the time of addition limited the drug effect during the first 8 h of infection. This conclusion was supported by the ultrastructure images of the early stage of DEV infection, which showed that the replication of virus nucleic acid and the formation of the capsid in the cell nucleus were suppressed. In the indirect immunofluorescence assay, proteins expression in DEV infected duck embryo fibroblasts (DEFs) within 24 h post-infection (p.i.) was also effectively suppressed by resveratrol. In summary, the resveratrol has a good activity against DEV infection in vitro, which could be attributed to that fact that several essential immediate early viral proteins for virus replication were impacted by resveratrol.

Anti-Acanthamoebic properties of resveratrol and demethoxycurcumin

Acanthamoeba is an opportunist protist pathogen that is known to infect the cornea to produce eye keratitis and the central nervous system to produce fatal granulomatous encephalitis. Early diagnosis, followed by aggressive treatment using a combination of drugs is a prerequisite in successful treatment but even then, prognosis remains poor due to lack of effective drugs. The overall aim of the present study was to determine the anti-Acanthamoebic potential of natural compounds, resveratrol and curcuminoids. Adhesion and cytotoxicity assays were performed using primary human brain microvascular endothelial cells, which constitute the blood-brain barrier. Pre-exposure of organisms to 100 μg resveratrol and demethoxy curcumin prevented amoeba binding by 57% and 73%, respectively, while cytotoxicity of host cells was inhibited by 86%. In an assay for viability of amoebae in the absence of host cells, resveratrol and de-methoxy curcumin exhibited significant amoebicidal effects (23% and 25%, respectively) at 100 μg concentrations (P<0.01). Neither resveratrol nor demethoxycurcumin had any effect on the proteolytic activities of Acanthamoeba castellanii. Of both compounds, resveratrol is of most interest for further investigation, because of the selective toxicity of resveratrol on A. castellanii but not the human brain microvascular endothelial cells.

Structurally modified curcumin analogs inhibit STAT3 phosphorylation and promote apoptosis of human renal cell carcinoma and melanoma cell lines

The Janus kinase-2 (Jak2)-signal transducer and activator of transcription-3 (STAT3) pathway is critical for promoting an oncogenic and metastatic phenotype in several types of cancer including renal cell carcinoma (RCC) and melanoma. This study describes two small molecule inhibitors of the Jak2-STAT3 pathway, FLLL32 and its more soluble analog, FLLL62. These compounds are structurally distinct curcumin analogs that bind selectively to the SH2 domain of STAT3 to inhibit its phosphorylation and dimerization. We hypothesized that FLLL32 and FLLL62 would induce apoptosis in RCC and melanoma cells and display specificity for the Jak2-STAT3 pathway. FLLL32 and FLLL62 could inhibit STAT3 dimerization in vitro. These compounds reduced basal STAT3 phosphorylation (pSTAT3), and induced apoptosis in four separate human RCC cell lines and in human melanoma cell lines as determined by Annexin V/PI staining. Apoptosis was also confirmed by immunoblot analysis of caspase-3 processing and PARP cleavage. Pre-treatment of RCC and melanoma cell lines with FLLL32/62 did not inhibit IFN-γ-induced pSTAT1. In contrast to FLLL32, curcumin and FLLL62 reduced downstream STAT1-mediated gene expression of IRF1 as determined by Real Time PCR. FLLL32 and FLLL62 significantly reduced secretion of VEGF from RCC cell lines in a dose-dependent manner as determined by ELISA. Finally, each of these compounds inhibited in vitro generation of myeloid-derived suppressor cells. These data support further investigation of FLLL32 and FLLL62 as lead compounds for STAT3 inhibition in RCC and melanoma.