Biological properties of curcumin-cellular and molecular mechanisms of action

Polymeric Nanoparticles for Increasing Oral Bioavailability of Curcumin

Despite the promising biological and antioxidant properties of curcumin, its medical applications are limited due to poor solubility in water and low bioavailability. Polymeric nanoparticles (NPs) adapted to oral delivery may overcome these drawbacks. Properties such as particle size, zeta potential, morphology and encapsulation efficiency were assessed. Then, the possibility of storing these NPs in a solid-state form obtained by freeze-drying, in vitro curcumin dissolution and cytocompatibility towards intestinal cells were evaluated. Curcumin-loaded Eudragit^® RLPO (ERL) NPs showed smaller particle diameters (245 ± 2 nm) and better redispersibility after freeze-drying than either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) NPs. The former NPs showed lower curcumin encapsulation efficiency (62%) than either PLGA or PCL NPs (90% and 99%, respectively). Nevertheless, ERL NPs showed rapid curcumin release with 91 ± 5% released over 1 h. The three curcumin-loaded NPs proposed in this work were also compatible with intestinal cells. Overall, ERL NPs are the most promising vehicles for increasing the oral bioavailability of curcumin.

Neuroprotective effect of curcumin nanoparticles against rat model of status epilepticus induced by pilocarpine

Background

The present study aims to investigate the neuroprotective effect of curcumin nanoparticles (Cur-NP) on the rat model of status epilepticus (SE) induced by pilocarpine.

Methods

In the present study, animals were divided into three groups: control animals, rat model of SE induced by a single dose of pilocarpine (380 mg/kg) injected intraperitoneally, and rat model of SE that received a daily intraperitoneal injection of Cur-NP (50 mg/kg) for four consecutive days prior to pilocarpine administration.

Results

The present results revealed a state of oxidative stress in the cortex and hippocampus of rat model of SE as compared to control. This was evident from the significant increase in lipid peroxidation and the significant decrease in reduced glutathione and nitric oxide. In addition, a significant increase in the levels of tumor necrosis factor-alpha (TNF-α) and caspase-3 was detected in the two studied brain regions of rat model of SE. The activities of acetylcholinesterase (AchE) and Na+/K+-ATPase decreased significantly in the cortex and hippocampus of rat model of SE. Protection with Cur-NP prevented oxidative stress and improved the elevated level of caspase-3 in the hippocampus and cortex and the hippocampal TNF-α to nonsignificant changes. Although Cur-NP prevented the decrease in AchE activity in the two studied brain regions, it failed to return Na+/K+-ATPase activity to its normal value.

Conclusions

It is clear from the present findings that Cur-NP could prevent the oxidative stress and neuroinflammation and cell death that were induced during SE. This in turn may help in ameliorating the subsequent cascades of events that follow SE and its development into epileptogenesis.

Effects of Curcumin on Bone Loss and Biochemical Markers of Bone Turnover in Patients with Spinal Cord Injury

BACKGROUND

Osteoporosis is one of the most common problems of patients with spinal cord injuries (SCIs). The current study aimed to evaluate the antiosteoporotic effects of curcumin on densitometry parameters and biomarkers of bone turnovers among patients with SCI.

MATERIALS AND METHODS

The current controlled clinical trial was conducted among 100 patients with SCI referred to an outpatient clinic of rehabilitation in Ilam City, Iran, in 2013-2015. The intervention group received 110/mg/kg/day curcumin for 6 months and the control group received placebo. Bone mineral density (BMD) was measured in all patients. The level of procollagen type I N-terminal propeptide, serum carboxy-terminal telopeptide of type I collagen, osteocalcin, and bone-specific alkaline phosphates were compared before and after study.

RESULTS

BMD indicators of lumbar, femoral neck, and total hip in the control group significantly decreased compared with the beginning of study. However, in the curcumin group, a significant increase was observed in BMD indicators of lumbar, femoral neck, and hip at the end of study compared with the beginning. There was also a significant difference between interventional and control groups for the mean BMD of femoral neck and hip at the end of study (0.718 ± 0.002 g/cm² vs. 0.712 ± 0.003 g/cm² and 0.742 ± 0.031 g/cm² vs. 0.692 ± 0.016 g/cm², respectively).

CONCLUSIONS

Curcumin, via modulation of densitometry indices and bone resorption markers, showed inhibitory effects on the process of osteoporosis. Treatment with curcumin was significantly associated with a decrease in the osteoporosis progression and bone turnover markers of patients with SCI after 6 months.

Deciphering PPARγ activation in cardiometabolic syndrome: studies by in silico and in vivo experimental assessment

Cardiometabolic syndrome (CMetS) is a consolidation of metabolic disorders characterized by insulin resistance, dyslipidemia and hypertension. Curcumin, a natural bioactive compound, has been shown to possess notable anti-oxidant activity and it has also been included as a super natural herb in the super natural herbs database. Most of the beneficial effects of Curcumin are possibly due to activation of the nuclear receptor, peroxisome proliferator-activated receptor gamma (PPARγ). The present study investigates molecular interactions of curcumin with PPARγ protein through molecular docking and molecular dynamics (MD) simulation studies. Further, effect of curcumin on high fat diet induced CMetS was studied in rats along with western blot for PPARγ and nuclear factor-κB (NF-κB) expressions and histopathological studies. Computational studies presented several significant molecular interactions of curcumin including Ser289, His323, His449 and Tyr473 of PPARγ. The in vivo results further confirmed that curcumin was able to ameliorate the abnormal changes and also, increased PPARγ expressions. The results confirm our hypothesis that activation of PPARγ by curcumin possesses the therapeutic potential to ameliorate the altered levels of metabolic changes in rats in the treatment of CMetS. This is the first report of CMetS treatment by curcumin and study of its underlying mechanism through in silico as well as in vivo experiments.

Curcumin ameliorates cadmium-induced nephrotoxicity in Sprague-Dawley rats

Chronic exposure to cadmium (Cd) causes remarkable damage to the kidneys, a target organ of accumulated Cd after oral administration. The aim of the present study was to investigate the protective effect of curcumin against Cd-induced nephrotoxicity. Sprague-Dawley male rats were divided into the following four treatment groups: control, curcumin (50 mg/kg, oral), CdCl₂, (25 mg/kg, oral), and pre-treatment with curcumin (50 mg/kg) 1 h prior to the administration of CdCl₂ (25 mg/kg, oral) for 7 days. At 24 h after the final treatment, the animals were killed, and the biomarkers associated with nephrotoxicity were measured. Our data indicated that blood urea nitrogen (BUN) and serum creatinine (sCr) levels were significantly reduced by curcumin pre-treatment in CdCl₂-treated animals. Histopathological studies showed hydropic swelling and hypertrophy of the proximal tubular cells in the renal cortex after Cd treatment. Pretreatment with curcumin ameliorated the histological alterations induced by Cd. The urinary excretion of kidney injury molecule-1 (Kim-1), osteopontin (OPN), tissue inhibitor of metalloproteinases 1 (TIMP-1), neutrophil gelatinase-associated lipocalin (NGAL), and netrin-1 significantly reduced by curcumin treatment compared to that in the CdCl₂-treated group. The administration of curcumin provided a significant protective effect against Cd-induced nephrotoxicity.

Pharmacological Review on Asiatic Acid and Its Derivatives: A Potential Compound

Natural triterpenes represent a group of pharmacologically active and structurally diverse organic compounds. The focus on these phytochemicals has been enormous in the past few years, worldwide. Asiatic acid (AA), a naturally occurring pentacyclic triterpenoid, is found mainly in the traditional medicinal herb Centella asiatica. Triterpenoid saponins, which are the primary constituents of C. asiatica, are commonly believed to be responsible for their extensive therapeutic actions. Published research work has described the molecular mechanisms underlying the various biological activities of AA and its derivatives, which vary for each chronic disease. However, a compilation of the various pharmacological properties of AA has not yet been done. Herein, we describe in detail the pharmacological properties of AA and its derivatives that inhibit multiple pathways of intracellular signaling molecules and transcription factors that are involved in the various stages of chronic diseases. Furthermore, the pharmacological activities of AA were compared with two natural compounds: curcumin and resveratrol. This review summarizes the research on AA and its derivatives and helps to provide future directions in the area of drug development.

Curcumin inhibits TGF-β1-induced connective tissue growth factor expression through the interruption of Smad2 signaling in human gingival fibroblasts

BACKGROUND/PURPOSE

Many fibrotic processes are associated with an increased level of transforming growth factor-β1 (TGF-β1). TGF-β1 can increase synthesis of matrix proteins and enhance secretion of protease inhibitors, resulting in matrix accumulation. Connective tissue growth factor (CTGF) is a downstream profibrotic effector of TGF-β1 and is associated with the fibrosis in several human organs. Curcumin has been applied to reduce matrix accumulation in fibrotic diseases. This study was aimed to evaluate whether curcumin could suppress TGF-β1-induced CTGF expression and its related signaling pathway involving in this inhibitory action in primary human gingival fibroblasts.

METHODS

The differences in CTGF expression among three types of gingival overgrowth and normal gingival tissues were assessed by immunohistochemistry. Gingival fibroblast viability in cultured media with different concentrations of curcumin was studied by MTT assay. The effect of curcumin on TGF-β1-induced CTGF expression in primary human gingival fibroblasts was examined by immunoblotting. Moreover, the proteins involved in TGF-β1 signaling pathways including TGF-β1 receptors and Smad2 were also analyzed by immunoblotting.

RESULTS

CTGF was highly expressed in fibroblasts, epithelial cells and some of endothelial cells, smooth muscle cells, and inflammatory cells in phenytoin-induced gingival overgrowth tissues rather than in those of hereditary and inflammatory gingival overgrowth tissues. Moreover, CTGF expression in the epithelial and connective tissue layers was higher in phenytoin-induced gingival overgrowth tissues than in normal gingival tissues. Curcumin was nontoxic and could reduce TGF-β1-induced CTGF expression by attenuating the phosphorylation and nuclear translocation of Smad2.

CONCLUSION

Curcumin can suppress TGF-β1-induced CTGF expression through the interruption of Smad2 signaling.

Regulation of the intestinal tight junction by natural polyphenols: A mechanistic perspective

Impairment of the epithelial barrier function is closely linked to the pathogenesis of various gastrointestinal diseases, food allergies, type I diabetes, and other systematic diseases. Plant-derived polyphenols are natural secondary metabolites and exert various physiological benefits, including anti-inflammatory, anti-oxidative, anti-carcinogenic, and anti-aging effects. Recent studies also show the role of plant polyphenols in regulation of the intestinal barrier and prevention of intestinal inflammatory diseases. Here we summarize the regulatory pathways and mediators linking polyphenols to their beneficial effects on tight junction and gut epithelial barrier functions, and provide useful information about using polyphenols as nutraceuticals for intestinal diseases.

Curcumin attenuates oxidative stress in liver in Type 1 diabetic rats

We investigated the effect of curcumin on liver anti-oxidative stress in the type 1 diabetic rat model induced by streptozotocin (STZ). Experimental diabetic rats were induced by STZ intraperitoneally. All rats were fed for 21 days including three groups of control (NC), diabetic model (DC) and curcumin-treated (Cur, 1.5 g/kg by gavage). The results showed that curcumin-treatment significantly decreased the blood glucose and plasma malondialdehyde levels, but significantly increased the plasma superoxide dismutase, glutathione peroxidase and reduced glutathione levels. Curcumin treatment decreased the activity of aldose reductase, but increased the plasma glucose-6-phosphate dehydrogenase, glucose synthetase and glucose-polymerizing activities. Curcumin treatment significantly decreased the protein of protein kinase C (PKC) and poly ADP ribose polymerase (PARP) expression in the Cur group compared with the DC group. Moreover, the sorbitol dehydrogenase activity was significantly decreased and deterred glucose enters into the polyol pathway leading to an increased NADPH content in the Cur group compared with the DC group. Our data provides evidence that oxidative stress in diabetic rats may be attenuated by curcumin by inhibiting polyol pathway associated with down-regulated expression of PKC and PARP, as evidenced by both an increase the antioxidant enzymes levels and glycogen biosynthesis enzymes activities.

Improved Chemical Stability and Antiproliferative Activities of Curcumin-Loaded Nanoparticles with a Chitosan Chlorogenic Acid Conjugate

A chitosan (CS)-chlorogenic acid (CA) conjugate was successfully prepared through free-radical-induced protocols with a substitution of CA on CS of 103.5 mg/g. ATR-FTIR and ¹H NMR results validated the covalent conjugation of CA onto CS. XRD results indicated the decrease of crystallinity after CA conjugation. DPPH-scavenging activity and reducing-power studies indicated that the CS-CA conjugate had stronger antioxidant activity than chitosan. The particle diameters of curcumin-loaded CS and CS-CA nanoparticles simultaneously formed by ionic gelling in the presence of tripolyphosphate (TPP) were less than 300 nm (243.6 and 256.5 nm, respectively), and zeta-potential values between 25 and 30 mV were obtained. TEM results showed that the nanoparticles were spherically shaped and homogeneously dispersed. Curcumin with the CS-CA conjugate showed better heat stability than with CA at both temperatures (25 and 95 °C) (p <0.05). Curcumin release was inhibited by the CS-CA conjugate. The total release amount of curcumin from CS and CS-CA-conjugate nanoparticles were 70.5 and 61.7%, respectively (p <0.05). A methyl thiazolyl tetrazolium (MTT) assay showed that the antiproliferative activity of curcumin in CS-CA nanoparticles was remarkably higher than that in CS nanoparticles because of the higher chemical stability. The results suggest that CS-CA-based nanoparticles are promising candidates for the encapsulation and controlled release of hydrophobic, bioactive compounds and can improve these compounds' chemical stabilities and anticancer activities.

Enhanced selective cellular uptake and cytotoxicity of epidermal growth factor-conjugated liposomes containing curcumin on EGFR-overexpressed pancreatic cancer cells

Pancreatic cancer is one of the most malignant cancers with a high mortality rate. Some types of pancreatic cancer cells overexpress epidermal growth factor receptor (EGFR), which is a potential target for anticancer agents. In this study, we examined the effect of epidermal growth factor (EGF)-conjugated liposomes containing curcumin (EGF-LP-Cur) on three different EGFR-expressed human pancreatic cancer cell lines, BxPC-3, Panc-1 and Mia Paca-2. We have demonstrated that it is feasible to prepare liposomal vesicles of EGF-LP-Cur and that it is stable in the liquid vehicle at ambient conditions for three weeks. In addition, the formulation of curcumin had higher cytotoxicity on BxPC-3 than on any other cells. It is also shown that the cellular uptake of curcumin on BxPC-3, which is essential for the cytotoxicity, is associated with EGFR-mediated mechanism of action. In summary, our results have showed that targeting EGFR with EGF-conjugated curcumin liposomes enhanced the antitumor activity of curcumin against human pancreatic cancer cells.

Beneficial Effects of Curcumin on the Wound-healing Process after Tooth Extraction

This study evaluated the effects of curcumin, a naturally occurring compound with numerous health-beneficial properties, on the wound-healing process of extraction sockets (soft tissue that surrounded the extracted tooth) in rats. The effects of topically applied curcumin were monitored by tracking changes in myeloperoxidase activity and nitric oxide concentrations in soft tissue homogenates 3 and 7 days following surgery. Additionally, pathohistological examination of tissue sections was used to reveal the effects of curcumin on the course of wound healing on a microscopic level. Compared to the untreated control, topically administered curcumin statistically significantly decreased soft-tissue myeloperoxidase activity and nitric oxide concentrations after both 3 and 7 days of application. Microscopic analysis showed a reduced inflammatory infiltrate (subjectively and morphometrically estimated as the number of polymorphonuclear cells/100 μm2) and an increased collagen deposition in rats treated with curcumin. The obtained results point to the great potential of curcumin in the acceleration of tooth extraction wound-healing processes partially through the reduction of the inflammatory response and increase in collagen deposition. Thus, these results significantly contribute to the previously suggested application of curcumin in the skin wound treatment by potentially broadening its usage in the treatment of mucosal wounds.

Response to TNF-α Is Increasing Along with the Progression in Barrett's Esophagus

BACKGROUND AND AIMS

Barrett's esophagus, a metaplasia resulting from a long-standing reflux disease, and its progression to esophageal adenocarcinoma (EAC) are characterized by activation of pro-inflammatory pathways, induced by cytokines.

METHODS

An in vitro cell culture system representing the sequence of squamous epithelium (EPC1 and EPC2), Barrett's metaplasia (CP-A), dysplasia (CP-B) to EAC (OE33 and OE19) was used to investigate TNF-α-mediated induction of interleukin-8 (IL-8).

RESULTS

IL-6 and IL-8 expressions are increasing with the progression of Barrett's esophagus, with the highest expression of both cytokines in the dysplastic cell line CP-B. IL-8 expression in EAC cells was approx. 4.4-fold (OE33) and eightfold (OE19) higher in EAC cells than in squamous epithelium cells (EPC1 and EPC2). The pro-inflammatory cytokine TNF-α increased IL-8 expression in a time-, concentration-, and stage-specific manner. Furthermore, TNF-α changed the EMT marker profile in OE33 cells by decreasing the epithelial marker E-cadherin and increasing the mesenchymal marker vimentin. The anti-inflammatory compound curcumin was able to repress proliferation and to activate apoptosis in both EAC cell lines.

CONCLUSION

The increased basal expression levels of IL-8 with the progression of Barrett's esophagus constrain NFκB activation and its contribution in the manifestation of Barrett's esophagus. An anti-inflammatory compound, such as curcumin, could create an anti-inflammatory microenvironment and thus potentially support an increase chemosensitivity in EAC cells.

Turmeric (Curcuma longa): miRNAs and their regulating targets are involved in development and secondary metabolite pathways

Turmeric has been used as a therapeutic herb over centuries in traditional medicinal systems due to the presence of several secondary metabolite compounds. microRNAs are known to regulate gene expression at the post-transcriptional level by transcriptional cleavage or translation repression. miRNAs have been demonstrated to play an active role in secondary metabolism regulation. The present work was focused on the identification of the miRNAs involved in the regulation of secondary metabolite and development process of turmeric. Eighteen miRNA families were identified for turmeric. Sixteen miRNA families were observed to regulate 238 target transcripts. LncRNAs targets of the putative miRNA candidates were also predicted. Our results indicated their role in binding, reproduction, stress, and other developmental processes. Gene annotation and pathway analysis illustrated the biological function of the targets regulated by the putative miRNAs. The miRNA-mediated gene regulatory network also revealed co-regulated targets that were regulated by two or more miRNA families. miR156 and miR5015 were observed to be involved in rhizome development. miR5021 showed regulation for terpenoid backbone biosynthesis and isoquinoline alkaloid biosynthesis pathways. The flavonoid biosynthesis pathway was observed to be regulated by miR2919. The analysis revealed the probable involvement of three miRNAs (miR1168.2, miR156b and miR1858) in curcumin biosynthesis. Other miRNAs were found to be involved in the growth and developmental process of turmeric. Phylogenetic analysis of selective miRNAs was also performed.

Curcumin sensitizes lymphoma cells to DNA damage agents through regulating Rad51-dependent homologous recombination

Curcumin is a natural compound isolated from the rhizome of Curcuma longa. It possesses anti-tumor activity through arresting cell cycles and promoting cell apoptosis. However, the effect of curcumin on DNA damage is not well defined. In this study, we investigated the effect of curcumin on inducing DNA damage and on sensitizing lymphoma cells to anti-tumoral DNA damage drugs. Western blot showed curcumin induced γ-H2AX foci in CH12F3 lymphoma cells, which suggests curcumin induces DNA breaks. In addition, curcumin decreased the expression of Rad51, which suggests curcumin induces DNA damage through regulating Rad51-dependant homologous recombination. Rad51-dependant homologous recombination is a vital DNA repair pathway for cancer cells to resist anti-tumoral DNA damage drugs, therefore, we studied the effect of curcumin on the sensitizing lymphoma cells to various chemotherapeutic drugs. We found low level of curcumin (5μM) sensitized lymphoma cells to anti-tumoral DNA damage agents including cisplatin, methyl methanesulfonate, hydroxyurea and camptothecin. We also found curcumin sensitized CH12F3 lymphoma cells to DNA-PK and PARP inhibitors. Flow cytometry analysis showed curcumin promoted apoptosis and western blot analysis confirmed curcumin activated caspase3-dependent apoptosis. Taken together, these results demonstrate that curcumin induces DNA damage through regulating Rad51-dependant homologous recombination and triggers caspase3-dependent apoptosis, more importantly, curcumin sensitizes lymphoma cells to various DNA damage drugs. Consequently, curcumin would be a potent agent for sensitizing lymphoma cells to anti-tumoral chemotherapeutic agents.

Curcumin alleviates liver oxidative stress in type 1 diabetic rats

The aim of the present study was to determine the effects of curcumin on antioxidants using a rat model of type 1 diabetes. Seven-week-old male Sprague-Dawley rats were injected with Streptozotocin (STZ) intraperitoneally to induce this model, and then treated with 1.0% curcumin (weight ratio) mixed in their diet for 21 days. The present study included three groups: Control group (NC), diabetic rat model group (DC) and a curcumin treated group (Diab-Cur). The results demonstrated that curcumin treatment markedly decreased the blood glucose levels, plasma malondialdehyde concentration and plasma activity of glutathione peroxidase (GSH-Px) and catalase (CAT); however, it increased the plasma superoxide dismutase (SOD) and insulin levels. Curcumin treatment increased the expression of the CAT, GSH-Px, HO-1 and norvegicus NAD(P)H quinone dehydrogenase 1, and decreased the SOD1 expression, which, led to a diminished oxidative stress status. In addition, curcumin treatment significantly increased the protein expression of Keap1 in the Diab-Cur group when compared with the DC group, decreased cytosolic concentrations of Nrf2 while increasing nuclear accumulation of Nrf2. The results provide evidence that oxidative stress in the STZ-induced diabetic rat model may be attenuated by curcumin via the activation of the Keap1-Nrf2-ARE signaling pathway, as evidenced by a decrease in the blood glucose concentration and an increase in the transcription of several antioxidant genes.

Anti-Inflammatory Effects of Curcumin on Insulin Resistance Index, Levels of Interleukin-6, C-Reactive Protein, and Liver Histology in Polycystic Ovary Syndrome-Induced Rats

OBJECTIVES

Curcumin protects the liver against injury and fibrosis through suppressing hepatic inflammation, attenuating hepatic oxidative stress (OS), and inhibiting hepatic stellate cells (HSCs) activation. Non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) are considered as common metabolic disorders. Low-grade chronic inflammation with different markers, such as elevated C-reactive protein (CRP) and interleukin-6 (IL-6) levels, play a crucial role in PCOS. This study aimed to evaluate the therapeutic effects of curcumin on IL-6 and CRP levels as well as insulin resistance (IR) index on liver function in PCOS rats.

MATERIALS AND METHODS

In this experimental study, 90 adult Wistar rats were divided into control (n=18), sham (n=18), PCOS (n=18) and curcumin-treated PCOS groups (n=36). PCOS group was injected subcutaneously with 2 mg estradio-valerate (E2V). After 60 days, PCOS group was treated with curcumin [100 and 300 mg/kg body weight (BW)] for 14 days and anesthetized by chloroform. Blood and liver samples were collected for histological and serological analyses. Data were analyzed using In-Stat 3 via one-way analysis of variance (ANOVA).

RESULTS

Histological and serological analyses showed a reduction in number of necrotic cells, IR index, as well as IL-6 and CRP levels in PCOS rats that were treated with various concentrations of curcumin.

CONCLUSIONS

In this study, curcumin decreased liver inflammation by induction of insulin sensitivity and reduction of hepatic necrosis. Therefore, curcumin may be considered as protective factor against inflammatory state of PCOS.

Visible Light-Cured Glycol Chitosan Hydrogel Containing a Beta-Cyclodextrin-Curcumin Inclusion Complex Improves Wound Healing In Vivo

Scarless wound healing is ideal for patients suffering from soft tissue defects. In this study, we prepared a novel wet dressing (β-CD-ic-CUR/GC) based on the visible light-cured glycol chitosan (GC) hydrogel and inclusion complex between beta-cyclodextrin (β-CD) and curcumin (CUR). We also evaluated its efficacy in the acceleration of wound healing as compared to that of CUR-loaded GC (CUR/GC). The conjugation of glycidyl methacrylate (GM) to GC for photo-curing was confirmed by ¹H-NMR measurement, and the photo-cured GC hydrogel was characterized by the analyses of rheology, swelling ratio, SEM and degradation rate. After visible light irradiation, the surface/cross-sectional morphologies and storage (G′)/loss (G′′) moduli revealed the formation of hydrogel with interconnected porosity. The dressing β-CD-ic-CUR/GC exhibited a controlled release of 90% CUR in a sustained manner for 30 days. On the other hand, CUR/GC showed CUR release of 16%. β-CD acted as an excipient in improving the water-solubility of CUR and affected the release behavior of CUR. The in vivo animal tests including measurement of the remaining unhealed wound area and histological analyses showed that β-CD-ic-CUR/GC may have potential as a wet dressing agent to enhance soft tissue recovery in open fractures.

The Effects of Curcumin on Wound Healing in a Rat Model of Nasal Mucosal Trauma

We explored the effects of topical curcumin on the healing of nasal mucosal wounds. A total of 32 Sprague-Dawley Albino rats were randomized in equal numbers into four groups, and unilateral nasal wounds were created using an interdental brush. Group 1 (the sham-control group) contained untreated rats with traumatized right-side nasal cavities; Group 2 and 3 rats were similarly traumatized and treated with topical curcumin (5 and 10 mg/mL) dissolved in dimethyl sulfoxide daily for 7 days after trauma; Group 4 rats were treated with topical dimethyl sulfoxide only. All rats were decapitated on day 15 and the healing sites evaluated by blinded observers in terms of the presence of cellular hyperplasia, goblet cell hypertrophy and degeneration, leucocytic infiltration, ciliary loss and degeneration, edema, and vascular dilation. On histopathological evaluation, all of cellular hyperplasia, leukocytic infiltration, and edema were significantly reduced in Group 3 compared with Group 1 (p = 0.001, p = 0.004, and p = 0.008, resp.). Thus, curcumin reduced the inflammatory response and significantly accelerated wound healing.

Aluminium-Induced Oxidative Stress, Apoptosis and Alterations in Testicular Tissue and Sperm Quality in Wistar Rats: Ameliorative Effects of Curcumin

Background

Reproductive toxicity is a major challenge associated with aluminum (Al) exposure. No studies have evaluated the possible effects of curcumin (CUR) on Al-induced reproductive dysfunction. Therefore, this study investigated the effects of CUR treatment on Al-induced reproductive damage.

MATERIALS AND METHODS

In this experimental study, 40 male Wistar rats were allocated to the five groups (n=8) based on the treatment they received: no treatment (control), solvent [dimethyl sulfoxide (DMSO) or distilled water], CUR 10 mg/kg body weight (BW), Al chloride 10 mg/kg BW, and CUR+Al chloride (10 mg/kg BW/each alone). Treatments were performed by intraperitoneal (IP) injections for 28 days. The left testis was assessed for histopathological analysis as well as the incidence of germ cell apoptosis. One-way analysis of variance (ANOVA) followed by the Tukey's test was used. P<0.05 was considered significant.

RESULTS

Significant reductions in body and testis weight; plasma testosterone and luteinizing hormone levels; sperm count, motility, morphology, and viability; germinal epithelium thickness; seminiferous tubules diameter; as well as, superoxide dismutase activity were observed in rats treated with Al. Moreover, Al exposure caused significant increments in the lumen diameter of tubules, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells and malondialdehyde (MDA) levels compared to the control group. However, in rats receiving CUR+Al, CUR significantly reversed the adverse effects of Al on testis and sperm quality. No significant differences in follicle-stimulating hormone (FSH) levels and nuclear diameter of spermatogonia were detected among all groups.

CONCLUSION

It can be concluded that Al causes reproductive dysfunction by creating oxidative damage. CUR, on the other hand, reduces the toxic effects of Al and improves the antioxidant status and sperm quality in male rats.

The Therapeutic Effects of Combination Therapy with Curcumin and Alendronate on Spine Fusion Surgery in the Ovariectomized Rats

Objective

The purpose of this study was to evaluate the therapeutic effects of combination therapy with curcumin and alendronate on spine fusion surgery in ovariectomized rats.

Methods

Thirty-two female Sprague-Dawley rats (12 weeks old) underwent bilateral ovariectomy (OVX). Eight weeks after surgery, animals underwent intertransverse spine fusion at L4–5. The rats were randomly distributed amongst 4 groups; untreated OVX group, curcumin administered group, alendronate administered group, and the combination therapy group. At 8 weeks after fusion surgery, the animals were sacrificed and the fusion mass was assessed by manual palpation, radiographic scan, and micro-computed tomographic scan. In addition, mechanical strength was determined by a 3-point bending test.

Results

Based on the results of manual palpation testing and 3-dimensional micro-computed tomography scanning, solid bone fusion rate was 50% (4 of 8) in the OVX group, 75% (6 of 8) in the alendronate-only and curcumin-only group, and 87.5% (7 of 8) in the combination therapy group, respectively. The combination therapy group had a higher fusion rate compared with the other treatment groups, though not statistically significantly (p>0.05). And the combination therapy group had a significant increase in fusion volume at 8 weeks after spine fusion surgery compared with curcumin-only group (p=0.039). The 3-point bending test showed that combination therapy group had a significantly greater maximal load value compared to that of curcumin-only group (p=0.024).

Conclusion

The present study demonstrated that additional treatment of curcumin and alendronate after spine fusion surgery in rat can promote higher fusion volume, and improve bone mechanical strength.

Low dose oral curcumin is not effective in induction of remission in mild to moderate ulcerative colitis: Results from a randomized double blind placebo controlled trial

AIM

To evaluate the role of oral curcumin in inducing clinical remission in patients with mild to moderate ulcerative colitis (UC).

METHODS

A prospective randomized double-blind placebo-controlled trial comparing the remission inducing effect of oral curcumin and mesalamine 2.4 g with placebo and mesalamine 2.4 g in patients of ulcerative colitis with mild to moderate severity was conducted from January 2003 to March 2005. The included patients received 1 capsule thrice a day of placebo or curcumin (150 mg) for 8 wk. Patients were evaluated clinically and endoscopically at 0, 4 and 8 wk. The primary outcome was clinical remission at 8 wk and secondary outcomes were clinical response, mucosal healing and treatment failure at 8 wk. The primary analysis was intention to treat worst case scenario (ITT-WCS).

RESULTS

Of 300 patients with UC, 62 patients (curcumin: 29, placebo: 33) fulfilled the inclusion criteria and were randomized at baseline. Of these, 21 patients did not complete the trial, 41 patients (curcumin: 16, placebo: 25) finally completed 8 wk. There was no significant difference in rates of clinical remission (31.3% vs 27.3%, P = 0.75), clinical response (20.7% vs 36.4%, P = 0.18), mucosal healing (34.5% vs 30.3%, P = 0.72), and treatment failure (25% vs 18.5%, P = 0.59) between curcumin and placebo at 8 wk.

CONCLUSION

Low dose oral curcumin at a dose of 450 mg/d was ineffective in inducing remission in mild to moderate cases of UC.

Therapeutic Nanoparticles Based on Curcumin and Bamboo Charcoal Nanoparticles for Chemo-Photothermal Synergistic Treatment of Cancer and Radioprotection of Normal Cells

Low water solubility, extensive metabolism, and drug resistance are the existing unavoidable disadvantages of the insoluble drug curcumin in biomedical applications. Herein, we employed d-α-tocopherol polyethylene glycol 1000 succinate (TPGS)-functionalized near-infrared (NIR)-triggered photothermal mesoporous nanocarriers with bamboo charcoal nanoparticles (TPGS-BCNPs) to load and deliver curcumin for improving its bioavailability. This system could considerably increase the accumulation of curcumin in cancer cells for enhanced curcumin bioavailability via simultaneously promoting the cellular internalization of the as-synthesized composite (TPGS-BCNPs@curcumin) by the size effect of NPs and considerably triggering controlled curcumin release from TPGS-BCNPs@curcumin by NIR stimulation and reducing efflux of curcumin by the P-glycoprotein (P-gp) inhibition of TPGS, so as to enhance the therapeutic effect of curcumin and realize a better chemo-photothermal synergetic therapy in vitro and in vivo. Besides cancer therapy, studies indicated that curcumin and some carbon materials could be used as radical scavengers that play an important role in the radioprotection of normal cells. Hence, we also investigated the free-radical-scavenging ability of the TPGS-BCNPs@curcumin composite in vitro to preliminarily evaluate its radioprotection ability for healthy tissues. Therefore, our work provides a multifunctional delivery system for curcumin bioavailability enhancement, chemo-photothermal synergetic therapy of cancer, and radioprotection of healthy tissues.

Using curcumin to prevent structural impairments of testicles in rats induced by sodium metabisulfite

Sodium metabisulfite (Na-MBS) is a disinfectant and preservative agent. Some organ including testicle would be in danger in the case of Na-MBS consumption. Curcumin (CUR) is the constituent of turmeric with protective properties. The effect of CUR on testicles in rats exposed to Na-MBS evaluated using stereological methods. Sprague-Dawley rats were divided into eight groups. The rats in groups I to VIII received the following respectively: distilled water, CUR (100 mg/kg/day), low (0.7 mg/kg/day: acceptable daily intake), intermediate (7 mg/ kg/day), and high (70 mg/kg/day) doses of Na-MBS, and low, intermediate, and high doses of Na-MBS plus CUR. After 7 weeks, the testicles were analyzed. The volume of seminiferous tubule, tubular epithelium and tubule length reduced (25-40 %) on average in the rats that received intermediate and high doses of Na-MBS, while the connective tissue volume increased (15-20 %) in both groups (P<0.01). Besides, 19-36 % and 41-57 % of the cells (spermatogonia types A and B, spermatids, Sertoli and Leydig) were lost in the rats that received intermediate and high doses of Na-MBS respectively in comparison to the control groups. Nonetheless, all the above-mentioned alterations ameliorated drastically in the rats that received Na-MBS plus CUR compared to those exposed to Na-MBS without CUR therapy (P<0.01). The acceptable daily intake of Na-MBS for 7 weeks did not affect on testicular parameters. CUR (100 mg/kg/day) could prevent structural impairments of testicles in the rats induced by Na-MBS (7 and 70 mg/kg/day).

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.

Curcumin and linseed oil co-delivered in phospholipid nanoemulsions enhances the levels of docosahexaenoic acid in serum and tissue lipids of rats

Docosahexaenoic acid (DHA) is an important long chain omega-3 polyunsaturated fatty acid (PUFA) primarily found in marine fishes. The diets of vegetarian population do not contain preformed DHA, but they can derive it from shorter chain α-linolenic acid (ALA) found in plant oils. However, the conversion efficiency of ALA to DHA is minimal in human adults. This may cause insufficiency of DHA in the vegetarian population. Curcumin, diferuloyl methane found in the spice turmeric, has the potential to increase the formation of DHA from ALA by activating the enzymes FADS2 and elongase 2. The present study was designed to prepare curcumin nanoemulsion using phospholipid core material (Lipoid™) and exploring the possibility of enhancing its bioavailability and its impact on DHA levels in rats. Curcumin was dissolved in coconut oil (CNO, MCFA rich), Sunflower oil (SNO, n-6 PUFA rich) or Linseed oil (LSO, n-3 PUFA rich) and nanoemulsions were prepared after mixing with Lipoid™ using high pressure homogenizer. The nanoemulsions were fed to weaning rats for 60 days along with AIN-93 diets. Rats fed nanoemulsion containing curcumin in LSO showed high levels of curcumin in serum liver, heart and brain. Significant increase in DHA levels of serum and tissue lipids were observed in rats given LSO with curcumin in nanoemulsions. Therefore, supplementation of diets with ALA rich LSO and curcumin could increase DHA concentrations in serum, liver, heart and brain lipids which have implications for meeting the DHA requirements of vegetarian populations.

Curcumin suppresses gastric tumor cell growth via ROS-mediated DNA polymerase γ depletion disrupting cellular bioenergetics

Background

Curcumin, as a pro-apoptotic agent, is extensively studied to inhibit tumor cell growth of various tumor types. Previous work has demonstrated that curcumin inhibits cancer cell growth by targeting multiple signaling transduction and cellular processes. However, the role of curcumin in regulating cellular bioenergetic processes remains largely unknown.

Methods

Western blotting and qRT-PCR were performed to analyze the protein and mRNA level of indicated molecules, respectively. RTCA, CCK-8 assay, nude mice xenograft assay, and in vivo bioluminescence imaging were used to visualize the effects of curcmin on gastric cancer cell growth in vitro and in vivo. Seahorse bioenergetics analyzer was used to investigate the alteration of oxygen consumption and aerobic glycolysis rate.

Results

Curcumin significantly inhibited gastric tumor cell growth, proliferation and colony formation. We further investigated the role of curcumin in regulating cellular redox homeostasis and demonstrated that curcumin initiated severe cellular apoptosis via disrupting mitochondrial homeostasis, thereby enhancing cellular oxidative stress in gastric cancer cells. Furthermore, curcumin dramatically decreased mtDNA content and DNA polymerase γ (POLG) which contributed to reduced mitochondrial oxygen consumption and aerobic glycolysis. We found that curcumin induced POLG depletion via ROS generation, and POLG knockdown also reduced oxidative phosphorylation (OXPHOS) activity and cellular glycolytic rate which was partially rescued by ROS scavenger NAC, indiating POLG plays an important role in the treatment of gastric cancer. Data in the nude mice model verified that curcumin treatment significantly attenuated tumor growth in vivo. Finally, POLG was up-regulated in human gastric cancer tissues and primary gastric cancer cell growth was notably suppressed due to POLG deficiency.

Conclusions

Together, our data suggest a novel mechanism by which curcumin inhibited gastric tumor growth through excessive ROS generation, resulting in depletion of POLG and mtDNA, and the subsequent disruption of cellular bioenergetics.

Activation of the CRABPII/RAR pathway by curcumin induces retinoic acid mediated apoptosis in retinoic acid resistant breast cancer cells

Due to the anti-proliferative and anti-apoptotic effects of retinoic acid (RA), this hormone has emerged as a target for several diseases, including cancer. However, development of retinoid resistance is a critical issue and efforts to understand the retinoid signaling pathway may identify useful biomarkers for future clinical trials. Apoptotic responses of RA are exhibited through the cellular RA-binding protein II (CRABPII)/retinoic acid receptor (RAR) signaling cascade. Delivery of RA to RAR by CRABPII enhances the transcriptional activity of genes involved in cell death and cell cycle arrest. The purpose of this study was to investigate the role of curcumin in sensitizing RA-resistant triple-negative breast cancer (TNBC) cells to RA-mediated apoptosis. We provide evidence that curcumin upregulates the expression of CRABPII, RARβ and RARγ in two different TNBC cell lines. Co-treatment of the cells with curcumin and RA results in increased apoptosis as demonstrated by elevated cleavage of poly(ADP-ribose) polymerase and cleaved caspase-9. Additionally, silencing CRABPII reverses curcumin sensitization of TNBC cells to the apoptotic inducing effects of RA. These findings provide mechanistic insights into sensitizing TNBC cells to RA-mediated cell death by curcumin-induced upregulation of the CRABPII/RAR pathway.

Enhancement of curcumin wound healing ability by complexation with 2-hydroxypropyl-γ-cyclodextrin in sacran hydrogel film

Curcumin is one of promising agents to accelerate the wound-healing process. However, the efficacy of curcumin is limited due to its poor water solubility and stability. To enhance the properties of curcumin, 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CyD) can be used through complexation. Recently, we revealed that sacran has the potential to form a hydrogel film (HGF) as a wound dressing material. Therefore, in the present study, we investigated the wound healing ability of curcumin/HP-γ-CyD (Cur/HP-γ-CyD) complex in sacran-based HGF (Sac-HGF). We prepared the Cur/HP-γ-CyD complex in Sac-HGF without surface roughness. Additionally, the amorphous form in the Cur/HP-γ-CyD complex in Sac-HGF were observed. In contrast, the curcumin in Sac-HGF and curcumin/HP-γ-CyD physical mixture in Sac-HGF formed inhomogeneous films due to crystallization of curcumin. Furthermore, HP-γ-CyD played an important role to increase the elastic modulus of the Sac-HGF with high re-swelling ability. The Cur/HP-γ-CyD complex in Sac-HGF maintained antioxidant properties of curcumin. Curcumin was gradually released from the HP-γ-CyD complex in Sac-HGF. Notably, the Cur/HP-γ-CyD complex in Sac-HGF provided the highest wound healing ability in hairless mice. These results suggest that the Cur/HP-γ-CyD complex in Sac-HGF has the potential for use as a new transdermal therapeutic system to promote the wound-healing process.

Zinc and curcumin lower arylsulfatses and some metabolic parameters in streptozotocin-induced diabetes

In rats with induced diabetes, Zinc and curcumin treatment showed a significant increase of catalase and a significant decrease of glucose, lipid profile components and arylsulphatases activity compared to the untreated rats. We suggest that dietary zinc and curcumin are promising protective agents for reducing the metabolic defect of diabetes.

Effect of curcumin and paclitaxel on breast carcinogenesis

Global cancer burden increased to 14.1 million new cases in 2012; and breast cancer is the most common cancer in women worldwide, with nearly 1.7 million new cases diagnosed in 2012. Curcumin is the major bioactive ingredient extracted from the rhizome of the plant Curcuma longa (turmeric). Paclitaxel is a microtubule-stabilizing agent originally isolated from the bark of Taxus brevifolia. Curcumin and paclitaxel were evaluated with two human breast cancer cell lines as the luminal MCF-7 and the basal-like MDA-MB-231 that are either positive or negative for hormonal receptors estrogen receptor, progesterone receptor and HER2, respectively. Results indicated that curcumin combined with paclitaxel decreased c-Ha-Ras, Rho-A, p53 and Bcl-xL gene expression in comparison to control and substances alone in MCF-7 cell line. These two substances alone and combined decreased gene expression of Bcl-2 and NF-κB. However, CCND1 increased when both substances were combined in MCF-7 cells. Such substances decreased Bcl-2 and increased Bax protein expression. However, curcumin alone decreased IκBα and Stat-3 gene expression. Paclitaxel alone and combined increased IκBα and Stat-3. Curcumin alone and combined with paclitaxel increased p53, Bid, caspase-3, caspase-8 and Bax gene expression in MDA-MB-231, whereas Bcl-xL decreased such expression in MDA-MB-231 cells. When paclitaxel and curcumin were combined the expression of Bcl-2 protein was decreased. However, either substance alone and combined increased Bax protein expression corroborating the apoptotic effect of these substances. It can be concluded that curcumin may be of considerable value in synergistic therapy of breast cancer reducing the associated toxicity with use of drugs.

Nanoencapsulation, an efficient and promising approach to maximize wound healing efficacy of curcumin: A review of new trends and state-of-the-art

Wound healing is a multifarious and vibrant process of replacing devitalized and damaged cellular structures, leading to restoration of the skin's barrier function, re-establishment of tissue integrity, and maintenance of the internal homeostasis. Curcumin (CUR) and its analogs have gained widespread recognition due to their remarkable anti-inflammatory, anti-infective, anticancer, immunomodulatory, antioxidant, and wound healing activities. However, their pharmaceutical significance is limited due to inherent hydrophobic nature, poor water solubility, low bioavailability, chemical instability, rapid metabolism and short half-life. Owing to their pharmaceutical limitations, newer strategies have been attempted in recent years aiming to mitigate problems related to the effective delivery of curcumanoids and to improve their wound healing potential. These advanced strategies include nanovesicles, polymeric micelles, conventional liposomes and hyalurosomes, nanocomposite hydrogels, electrospun nanofibers, nanohybrid scaffolds, nanoconjugates, nanostructured lipid carriers (NLCs), nanoemulsion, nanodispersion, and polymeric nanoparticles (NPs). The superior wound healing activities achieved after nanoencapsulation of the CUR are attributed to its target-specific delivery, longer retention at the target site, avoiding premature degradation of the encapsulated cargo and the therapeutic superiority of the advanced delivery systems over the conventional delivery. We have critically reviewed the literature and summarize the convincing evidence which explore the pharmaceutical significance and therapeutic feasibility of the advanced delivery systems in improving wound healing activities of the CUR and its analogs.

Curcumin and insulin resistance-Molecular targets and clinical evidences

Curcumin ((1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), the main component of the Indian spice turmeric, has been used in traditional medicine to improve diabetes and its comorbidities. Since the last two decades, scientific research has shown that in addition to its antioxidant properties, curcumin could also work as protein homeostasis regulator and it is able to modulate other intracellular pathways. Curcumin supplementation has been proposed to improve insulin resistance (IR) through the activation of the insulin receptor and its downstream pathways in several experimental models, pointing out that its clinical use may be a good and innocuous strategy to improve IR-related diseases. IR is associated with many diseases and syndromes like carbohydrate intolerance, diabetes, metabolic syndrome, and cardiovascular disease. Therefore, it is imperative to identify safe therapeutic interventions aimed to reduce side effects that could lead the patient to leave the treatment. To date, many clinical trials have been carried out using turmeric and curcumin to improve metabolic syndrome, carbohydrate intolerance, diabetes, and obesity in individuals with IR. Results so far are inconclusive because dose, time of treatment, and type of curcumin can change the study outcome significantly. However, there is some clinical evidence suggesting a beneficial effect of curcumin on IR. In this review, we discuss the factors that could influence curcumin effects in clinical trials aimed to improve IR and related diseases, and the conclusions that can be drawn from results obtained so far. © 2016 BioFactors, 42(6):561-580, 2016.

Structure and gelation properties of casein micelles doped with curcumin under acidic conditions

In this study, the ability of micellar casein (MC) to interact with curcumin during acidification and to produce acid gel was investigated. Steady-state fluorescence spectroscopy of curcumin variation and fluorescence quenching of caseins upon binding with curcumin molecules were evidenced. Increasing the temperature from 20 to 35 °C enhanced MC-curcumin interactions as reflected by the increase in the binding constant from 0.6 ± 0.3 × 10(4) to 6.6 ± 0.6 × 10(4) M(-1). From changes in entropy, enthalpy and Gibbs free energy, hydrophobic interactions were proposed as major binding forces. Static fluorescence MC quenching was demonstrated for the MC-curcumin complex during acidification. From pH 7.4 to pH 5.0, the binding site numbers varied in the range from 1.25 ± 0.05 to 1.49 ± 0.05 and the binding constant kb varied from 3.9 ± 0.4 × 10(4) to 7.5 ± 0.7 × 10(4) M(-1). Small angle X-ray scattering profiles demonstrated that the MC internal structure was unchanged upon curcumin binding. The ζ-potential value of curcumin-doped MC indicated that curcumin did not modify the global charge of MC particles. Acid gelation studied by oscillation rheology and static multiple light scattering at 20 and 35 °C led to a similar behavior for native and curcumin-doped MC suspensions. For the first time, it was demonstrated that the colloidal and functional properties of MC were unchanged when doped with curcumin during acidification.

Protandim Protects Oligodendrocytes against an Oxidative Insult

Oligodendrocyte damage and loss are key features of multiple sclerosis (MS) pathology. Oligodendrocytes appear to be particularly vulnerable to reactive oxygen species (ROS) and cytokines, such as tumor necrosis factor-α (TNF), which induce cell death and prevent the differentiation of oligodendrocyte progenitor cells (OPCs). Here, we investigated the efficacy of sulforaphane (SFN), monomethyl fumarate (MMF) and Protandim to induce Nrf2-regulated antioxidant enzyme expression, and protect oligodendrocytes against ROS-induced cell death and ROS-and TNF-mediated inhibition of OPC differentiation. OLN-93 cells and primary rat oligodendrocytes were treated with SFN, MMF or Protandim resulting in significant induction of Nrf2-driven (antioxidant) proteins heme oygenase-1, nicotinamide adenine dinucleotide phosphate (NADPH): quinone oxidoreductase-1 and p62/SQSTM1, as analysed by Western blotting. After incubation with the compounds, oligodendrocytes were exposed to hydrogen peroxide. Protandim most potently promoted oligodendrocyte cell survival as measured by live/death viability assay. Moreover, OPCs were treated with Protandim or vehicle control prior to exposing them to TNF or hydrogen peroxide for five days, which inhibited OPC differentiation. Protandim significantly promoted OPC differentiation under influence of ROS, but not TNF. Protandim, a combination of five herbal ingredients, potently induces antioxidants in oligodendrocytes and is able to protect oligodendrocytes against oxidative stress by preventing ROS-induced cell death and promoting OPC differentiation.

Simultaneous determination of curcumin diethyl disuccinate and its active metabolite curcumin in rat plasma by LC-MS/MS: Application of esterase inhibitors in the stabilization of an ester-containing prodrug

Four esterase inhibitors, ethylenediamine tetraacetic acid disodium (Na2EDTA), sodium fluoride (NaF), bis(4-nitrophenyl) phosphate (BNPP) and phenylmethanesulfonyl fluoride (PMSF), were evaluated for their inhibitory effects on enzymatic hydrolysis of labile phenolate esters in curcumin diethyl disuccinate (CDD), a prodrug of curcumin (CUR), in rat plasma. BNPP and PMSF at 10mM exhibited stabilization by preventing degradation of CDD. BNPP at a final concentration of 10mM was subsequently selected to prevent ex vivo metabolism of CDD throughout LC-MS/MS analysis of CDD and CUR in rat plasma. A simple protein precipitation technique using acetonitrile as a precipitating agent was used to extract CDD, CUR and dimethylcurcumin (DMC), an internal standard, from rat plasma. Chromatographic separation was performed on a Halo C8 column (4.6×50mm, 2.7μm) using an isocratic mobile phase containing acetonitrile-0.2% formic acid in water (73:27v/v) with a flow rate of 0.4mLmin(-1). An AB SCIEX QTRAP(®) 6500 mass spectrometer was operated using a positive ion electrospray mode for ionization and detection of analytes and internal standard. Calibration curves for CDD and CUR were established using 50μL of rat plasma over the concentration range of 1-500ngmL(-1). The developed method was fully validated according to US Food and Drug Administration (FDA) guidelines for selectivity, sensitivity, linearity, accuracy, precision, dilution integrity, recovery, matrix effect, and stability. The validated method was applied to evaluate the pharmacokinetics of CDD and CUR in rats after a single intravenous dose of 40mgkg(-1). The method using BNPP as an esterase inhibitor was successful in determining the remaining CDD in rat plasma. The pharmacokinetic results indicate that CDD in rats is converted instantaneously to CUR after intravenous administration and a higher CUR plasma concentration at 5min is achieved in comparison with direct intravenous injection of CUR.

Development of surface curcumin nanoparticles modified with biological macromolecules for anti-tumor effects

The rationale of this study was to improve the stability, cellular uptake, and evaluate the cytotoxicity of surface modified curcumin nanoparticles (CUR NP). CUR NP were surface modified with proteins (transferrin [Tf] and gelatin [GT]) by adsorption to improve their stability and targeting property. CUR NP were evaluated for stability, in vitro drug release, cellular uptake and cell cytotoxicity. The particle sizes of CUR NP were 153.2±56.4nm (CUR NP), 145.0±26.8nm (Tf-CUR NP), and 167.7±42.7nm (GT-CUR NP). The stabilities of Tf-CUR NP and GT-CUR NP were higher than that of CUR NP. Tf-CUR NP and GT-CUR NP showed faster drug release than those shown by CUR NP and CUR (pure) in pH 7.4 PBS and cell media (RPMI) for 36h. The cellular uptake and cytotoxicity of Tf- and GT-modified CUR NP were higher than those of CUR NP in MCF-7 and A549 cells. In conclusion, Tf-CUR NP and GT-CUR NP exhibited improved stability, enhanced cellular uptake, and stronger cytotoxicity.

Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding

One of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an "Achilles heel," revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility of Salmonella, a foodborne pathogen. It reduced the motility of Salmonella enterica serovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175.

IMPORTANCE

This work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important appendages of Salmonella Curcumin is an important component of turmeric, which is a major spice used in Asian cooking. The loss of flagella can, in turn, change the pathogenesis of bacteria, making them more robust and fit in the host.